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365 Cards in this Set
- Front
- Back
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What is the primary function of the kidney
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is to BALANCE the body's water and inorganic ion in teh extraceullular fluid
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What are other functions of the kidney
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VASE
regulation of the volume and osmolarity of the extraceullar fluid, regulation of acid-base balance, excretion and production and secretion of certain hormones |
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What does the kidney excrete products of
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protein metabolism, fat metabolism, carbohydrates, drug and exogenous chemcials
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The kidney is an endocrine organ, what hormones does it produce and secrete
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Erthyropoietin, renin, and 1,25 dihydroxy vitamin D3
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What is the function of erthropoietin
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involved in stimulating the maturation of RBC in the bone marrow
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What is the function of Renin
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involved in control of blood pressure and blood volume
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What is the function of 1,25 dihydroxy vitamin D2
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is required for absoroption of Ca+2 by the GI tract and for depoistion of Ca+2 in the bone
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Can the kidney also do gluconeogenesis, and when
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YES, during prolonged fasting
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Blood supply to the kidney is via, and they receive what % of CO
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the left and right renal arteies
25% of cardiac output |
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Urine is drain via, and what drains the bladder
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Urine is drained via the ureters to the bladder, and the urethra drain the bladder
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What are the 3 distinct sections of the kidney
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Cortex, the medulla, and pelvis
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What is the cortex
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The outer region that is granular in apperance, and receives the greatest blood flow
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Where are the glomeruli located
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cortex
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What is the medulla
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the inner region that is striated and less blood flow into this area
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Why is there less blood flow in the medulla, and it furtehr decreases deeper into the medulla
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this is necessary in maintaining an osmotic pressure gradient
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Each kidney contains 12 lobes, and each lobe represents a
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pyramid of medullary tissue surrounded by cortical tissue
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The terminal end of each pyramid forms, which drains into
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the papilla, which drains into the minor calyx,
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Minor calyx unites into, which then further expands to form and ultimately into
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unites into the major calyx, which fruther expands to form the renal pelvis, and enters urter to bladder
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What is the basic unit of renal structure and function
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nephron
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Each kindey contains approx 1.5 million nephrons, which represents
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a functional reserve
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Each nephron contains
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a renal corpusucle, and and renal tubule
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What is a renal corpuscle
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tuft of cappilary beds (glomerulus) surrounds by a doubled wall (Bowman's capsule)
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Fluid filers out of the capillaries, acroos the enpithelial cells and into
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Bowman's space
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The Bowman's space is an
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invaginated protion of the proximal tubles,fluid then flows down the proximal tubules
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The sapce within the Bowman's Capsule is continuos with
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proximal tubule
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The renal tubules which as it penetrates the cortex and medulla changes in anatomical apperance and function, the renal tubules is divided into 3 major sections
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1. Proximal Tubule
2.Loop of Henle 3. Distal convoluted tubule |
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THe proximal tubules is the most active reabsorber, what does it reabsorb and located
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2/3 of electroyles (Na+) and water, and all glucose and amino acids are reabsorbed
located in cortex |
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What is the ideal region to target for therapetics
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the proximal tubule
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Once the proixmal tubules, once they eneter into the outer medulla, they become
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The Loop of Henle (1st thin descending limb, and the thick ascending limb
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The loop of Henle is importnat in
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water reabsorption, but OVERAL reabsorbs a small amount of total fluild reabsrobed (10-20%)
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The Loop of henle play a central role in
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formation of urine that is more concentrated or dilute
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After the Loop of Henle drains into
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Distal convoluted tubule
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The distal convoluted tubulbe become, then
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connecting tubules,then cortical collecting ducts
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What do the cortical collecting ducts drain into
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outer medullary collecting ducts, then inner medullary collecting ducts,
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The outer and inner medullary collecting ducts drain into
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papillary collecting ducts into minor calyx
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The collecting ducts perform very important fucntions including
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reabsroption of small and variable volume of filtered fluid
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What is the major site of action of most hormonal control mechanisms
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collecting ducts
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Where is the nephrons last change to regulate filtrate is
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distal convoluted tubule
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Nephrpns differ depending in relation to their
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1. location
2. filation rates 3. tubular transport proteins 4. renin content |
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What are the 2 types of nephorons
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Cotrical nehrpones, and Juxtrmedullart nephrons
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Cortical nehprons comprise 85% of nephrons, they have
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small glomeruli and short segments
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Where are the glomeruli located in teh juxtramedullary nehprons
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deep inner coretex
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How far do the loops of henele extend in juxtamedullary nephrons
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deep into the inner medulla, where the tubular wall b/c very thin
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What are 4 common features of the tubular cells
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1 Tight junction
2. Microvilli or brush borders 3. Basolateral cell surface 4. Basement membrane |
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Where are the tight junctions located
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at the luminal surface (apical cell) joining cells
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The surface area of the brush border has a very large
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surface area
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The basolateral cell surface is different from teh apical cell membrane, differance are
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numerous mitochondria along basolateral surface, and Na/K ATPase in membrane
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The supportive sturcture for the tubular cells is
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the basement membrane
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Renal arteis originate from , and branch many times before terminating as
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the abdominal aorta, in the cortex as afferent arterioles
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The afferent arterioles form what in the glomerulus
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capillary beds
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Blood exits the glomerulus via
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efferent arteriolies
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What do the efferent arterioles do
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form the peritubular capillaries and vasa recta
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What do the pertitubular capillaries and vasa recta surround
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much of the proximal and distal tubulues of the nephron and neighbor nephrons tubulues
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What are the 2 distinct cappilary beds in series..
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the glomerular adn pertibular cappilaries or(vasa recta)
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Blood supply to the medullary regions is supplied by, assoicated with
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efferent arterioles associated with the juxtamedularry nephrons
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The capillaries of the juxta medullary nephrons develop into, and are important for
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vasa recta, which is important for tubular reabsoprtion
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Glomeruli are specialized for filtration, peritubular apillaries and vasa recta are for
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reabsorption
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After supply the tubules with blood, the peritbular or vasa recta join to form
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the veins which carry the blood from the kidney
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Blood pressure is high, and where is it low in nephron
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high in the glomeruli and low in the peritubular capillaries and vasa recta
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What is the Juxtaglomerular Apparatus
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a complex of the distal straight tubule and the affernt and efferent arterioles
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What cells comprise the Jutxtaglomerular appratatus
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mascular densa, juxtaglomeruluar cells, and extraglomeruluar mesangial cells
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What type of cells are macula densa
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tubular eptielial cells
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Where are the granular juxtaglomerular cells
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toching the smooth muscle of the afferent arteriole walls
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What type of apperance do juxtaglomerular have,
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GRANULAR
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What are the funcion of the juxtaglomerular cells
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synthesize, store and release renin
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Between the afferent and efferent ateriolies and distal tubules, what is here
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extraglomerular mesangial cells
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What do the extraglomerular mesangial cells do
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allow chemical communications between the macula densa and the juxtaglomerular cells and blood vessel wall
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What are the primary homeostatic functions of the juxtaglomerular apparatus
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1. Renin production
2. Regulation of nehpron blood flow 3. tubuloglomerular feedback mechanism |
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What is the tubuloglomerular feedvack regulatory mechanism
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monitors changes in tubular fluid composition, adn changes in blood flow/filration rates
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What is renal blood flow
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1200 ml/min
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Is the high flow rate reflective of the kidney's eneryg demand
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NO
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Why does the kidney have such a high blood flow
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to sustain glomerular filtration
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Filtrate is formed at
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10% of the rate of renal blood flow (filtrate 120ml/min)
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Changes in aterial blood pressure between what have very little effect on glomerular filtration
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80-180 mm Hg
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The precise contrl of glomerular filtration rates results from
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renal autoregulation intrsinic SAME flow dispite pressure changes
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Cortical radial ateries are an example autoreguation, what happens when BP increases
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these arteries constirct to minimize an increase in renal blow blood
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Autoregulatory systems are limited, what happens when BP is below 80 mmHg
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decrease filtration rate
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Renal blow flow is also regulated extrinsically by, which does
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sympatehtic, which innervate blood vessels and cause vasoconstrition
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What does sympathetic fibers adjacent to tubular cells influence
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Na+ reabsorption
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What are hormones that trigger vasoconstriction
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angiotensin II, thromboxane, and epinepherine
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What hormones regulate vasodialtion
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Ach, bacterial pathogens, bradykinins and prostaglandins
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What are the 3 basic processes involved in urine formation
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filtration
tubular reabsorption tubular secretion |
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Where does filtration occur
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at each glomerulus
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What is tubular reabsorption
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movment of moeculres FROM tubular lumen to PERITUBULAR capillaries
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What is tubular secretion
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movement of molecules INTO the tubular lumen
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What is the first step in urine formation or AKA
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glomerular filtration or ULTRAFILTRATION
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Why is blood plasma FILTRATE pushed into the urnary space of the Bowman's capsule
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b/c of HIGHER hydrostatic pressure in the glomerular capillary bed
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What is the product known as from glomerular filation
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ultrafiltrate
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What are the unique featuers of the filtering processes of Glomerular filtration
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1. Most molecules <10,000 are freely filtered (while larger molecules like albumin or plasma proteins retatined
2. The filtration process is nonselective glucose is filtered |
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Is the urine excreted quite different from the ultrafiltrate appearing in the Bowman's capsule, what does it represent
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YES--it represents a precise balance of filtration, reabsoprtion and secretion
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A small % change in Na+ reabsorption can have a MAJOR impact on, why
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the amount of Na+ excreted--we have lots of sodium
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What follows Na+ besides water
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Cl and K+ also
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Why is more creatinine excreted then filtered oringally
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waste product of muscle
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The glomerulat filtration membrane is composed of what 3 layers
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1. capillary endothelium
2. basement membrane 3. Podocytes of foot cells |
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What is the capillary endothelium have
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large fenestrations or pores that are 50-100 um
hemoglobin is 3.2 nm |
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What does the capillary endothelium block
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ONLY filters OUT RBCs from leaving, to avoid blockage of susequent filter processes
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What does the basement mebrane do
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intermediate filter that screens out larger plasma protein, and carries a net negative chagne
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How big are the openings of the basement membrane
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(7nm)
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The podocytes of foot cells rest their appendages on the basement membrane, which results
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in silt pore diaphragm
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How wide are the pores in slit pore diaphragm
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20 mnm width
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The glomerular filter is freely permeable to
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water, mineral ions, small organic and glucose
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Filtrate must pass thorugh all 3 laters BETWEEN slits and pores and NOT
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NOT thorugh cells
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Of the 3 membrane, what is the major size-selective membrane
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basal lamina or basement membrane
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The endothelial pores, basal lamina and podocyte surfaces all contain
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NEGATIVELY chagneed glycoprtoeins, which impede filration of negatively charged plasma proteins
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The surfaces having the most negatives charges are
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capillary lumen and innermost part of basal lamina
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A primary indication of glomerular disease is
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loss of proteins such as albumin in the ultrafiltrate
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Factors that affect the movemnt of fluid across the capillary walls are teh same as those that
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determine glomerular filtration rate
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What is a major factors that affects glomerular filtration rate
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glomerular capillary hydrostatic pressure from heart beating
HP (g) |
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The movement of fluid through the glomerular mebrane is opposed by
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hydrostatic pressure in the urinary space of Bowmans and the intracapillary osmotic presure
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Net filtration pressure is =
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HP(g) - (OPg + HPc)
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Why is HP (g) is 2x higher than most other capillaries
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b/c of low resistance of upsteam arteries, and high resistance of Effernt artrioles
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What are 2 forces that HPc typicall 15 exerts
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it opposes filtration, and provides taht force for fluid to flow down the tubule
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Where is OP (g) greatest
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effernt
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What is net average of NFP
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55-(30+15) =10
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What is equation for GFR
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Kf X NFP
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What is Kf (flomerular filatration coefficent)
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accounts for the resistance of the fluid as it passes through the glomerular mebrane
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What are 3 physiological factors taht affect GFR
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1. BP < 50mm Hg =0
2. Changes in diament of afferent and efferent arterioloes 3. Kf can be influence by a change in permeability or surface area of glomerular mebranes |
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What happens to a decrease in (albumin concentraton in blood)
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decrease OP (G), may increase GFR
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What happens when to a decrease in BP <40 mmhg
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GFR=0
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What happens when the glomerular membrane thickens
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GFR decreases
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What does constrction of afferent arterioles do
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lowers DOWN-stream presure and GFR
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What does dilation of afferent arterioles to
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increases GFR
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Modest constrction of Efferent aterioles does what to GFR
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may increase GFR
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Severe constriction of Efferent atrioles does what to GFR
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Decrease GFR
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What is renal plasma clearance
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the RATE of excretion of an agent in the urine compared to the concentration in blood
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What was the first compound use to determine GFR, and why
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inulin--neither abosorbed or secreted
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Why is cretainine used, and from
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ALMOST completely filtered and exrected, from creatine a product of muscle breakdown
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What is probelems of creatinine
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is secreted into urine in the proximal tubles so its rate of extretion exceeds its rate of filtration
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The clearnace of creatine thus exceeds its filtration rate by
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5-10% so creatine clearance overestimates GFR
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The plasma of normal indivdiuals contains cretainien at
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6-20MM
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How is the plasma level of creatine determinined
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determined by the arate at which creatinine is release by the muscle cells, and teh rate at which it is excreted
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What is require to estimate GFR using creatine clearance
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single plasma sample, and 24 hours urine collection
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Many filterable plasma componetns are either absent or only present in small quantities in the urine, this suggests
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that tubular reabsroption is an EXTREMELY efficient process
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Volume of water filtered per day is 180 Liters, while the body stores 40 Liters, what would happen if water reabsroption ceased and filtration continued
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total plasma volume would be depleted in 30 minutes
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Reabsportion of waste procuts is usually
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INCOMPLETELE
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Reabsprotion of useful plasma components (glucose, electrolytes and water) is usally
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COMPLETE
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What mechanisms are responsible for reabsoprtion
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F PEDS
Facilitated diffusion Primary active transport endocytosis diffusion secondary active transport |
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What does diffusion require
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an electrochemical gradient (always downhill)
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What is facilitated diffusion
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binding of the substane to a transporter to facilitate diffusion
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What is primary active transport
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system that requires ATP and specificity, saturtability and competition (uphill)
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What is secondary active transport
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one substance is being transported downhill, while the other is moving AGAINST an electrochemcial gradient
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Is secondary transport directly linked to ATP
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NO
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What is endocytosis
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invagination of cellular membrane with an enclosed marcomolecule, process is energy dependent
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Endocytosis is relatively important for
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reabsoprtion
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Glucose is freely filtered and nearly all is reabsorbed by
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the proximal tubules
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What transport mechansims allows glucose reabsorption
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secondary active transport system in luminal brush border
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The energy required for the transport of Glucose is dervied from
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Na+ gradient, b/c Na+ less in proximal tubule CELL, Glucose is co-transported with Na+
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Why is there less sodium in proximal tubule cell or a DECREASED OSMOLARITY, than the tubule LUMEN? this favors Na+ movment, what follow
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b/c of Na+K+ ATPASe pump in the basolateral cell membrane, water follows
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B/c Na+ is constantly being pumped out into interstital fluid by Na+/K+ ATPase what does this cause
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increases the osmolarity of the interstital fluid, and forces water to follow into pertibular capillaries
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Once glucose is co-transported into the tubule cell what happens
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diffues down concentration gradient into peritubular cappillaries
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Amino acids are freely filtere and efficeintly reabsrobed in
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the proximal tubules
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Can the proximal tubules reabsorb large proteins such as albumin, and how
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YEs, involves pinocytosis
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The presence of excess protein in the urine is termed, and suggests
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proteinuria, and suggests abnormal leakiness of glomerular membrane
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Smaller petides are completely filered and catabolized into
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amino acids via peptidases on the luminal plasma membrane
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Plasma uric acid concentrations are regulated by
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a balance of reabsoprtion and secretion
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Is uric acid freely filtered from the plasma
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YES
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Where is the primary site for reabsroption of urate (uric acid)
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proximal tubule
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Where is the primary site for urate secretion
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proximal tubule
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Where is urea form, and the result of
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Liver, and result of the product of protein catabolism
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The movement of urea in and out of the tubule depends on
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th permeability of the tubule to water and urea and as well as the concentration of urea in the medulla
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100% of urea is filtered during glomerular filtration, what happens in the proximal tubules
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50% of the filter urea follow reaborbed water out of the tubular fluid into the peritublar cappillaries
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Why does distal tubular fluid have 100% conecentration of urea
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b/c urea has diffused from the medullary tissue into the loop of henle
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What happens to urea in the outer collecting duct
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urea remains there and 100% concetrated b/c it is imperamable to urea
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What happens once urea penetrates into the inner medullar collecting duct?
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the concentrtion decreases via diffusion of urea to the loop of henle and the vasa rector
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What influences urea to be reabsobed in the inner medullary collecting duct
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the extent of water reabsorption and urine flow rate
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What is tubular secretion
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movement of solultes from surrounding kidney into tubular urine
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Where does tubular secretion occur primarily in
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the promimal tubule
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What 2 things characterize tubular secretion
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1. active systems one for organic bases (+) and acids at pH 7.4
2. Passively secreted lipid soluble acids or bases |
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Secretory systems show maximal transport rate at
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high plasma concentrations and display competition
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What are some important compunds that are secreted that may require adjustment in patients with questionable renal status
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Penicllin and cephalosprotins
Probenecid and chlorothiazide and Axetazolamide and histamine |
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What is the main driving force for water reabsorption
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Na+
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Na+ reabsorption is coupled with reabsorption of
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Glucose, amino acids, Cl- and inorganic phosphate
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Na+ reabsroption is couple to secretion of
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H+ and K+
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What is responsible for 80% of the oxygen consumed by the kidney
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Na+ reabsorption
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Na+ transport operates in 3 tubular regions
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PCT, Loop of Henle, and the DCT
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In the Proximal tubules what % of water and Na+ are reabsorbed
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70%
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Proximal tubule Na+ reabsroption occurs with cotransport of
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Cl-, Glucose, amino acid,a nd inorganic phostate
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Proximal tubule Na+ reabsorption occurs with exchange of
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H+ and HCOO-
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In Loop of henele what % of water and Na+ are reabsorbed
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10% of water
20% of Na+ |
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What type of transport mechanism occurs at the thick ascending loop of henele
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1 Na+/KATPase in the basolateral cell membrane, creates 1Na/1K+/2Cl- K+ uphill
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The loop of henle is the site of action for
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loop diuretics, fursoemide, and bumetanide
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What is the function of the DCT and collecting duct
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reabsorb all remaining Na+, BUT 2-Fold more water
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The DCT has INTRSICALLY low water pereability, so how does water reabsorption occur
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hormonally by Aldosterone or ADH (anti-diretic hormone)
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Where ist he site of action for teh antidiuretic hormone
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collecting duct
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The rate of water elimination in the urine depends
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GFR and water reabsorption
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What is plasma osmoalaity
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300
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What is Urine osmolality
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600-800, but also depends on water consumption (30-1400)
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The kidney has a capacity to concentrate urine and is dependent on maintaining
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a hyperosmotic inner medullary interstital fluid
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How does the medullary tissue become hyperosmotic
(countercurrent hypothesis) |
due to descending and ascending loop of henele
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How is urine concentrated in the descending loop of henele
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Water permeability high and Na+ permaeability low, results in an INCREASE in osmolaity of TUBULAR fluid
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How is urine concentrated in the ascending loop of henele
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Water permeability is low, and Na+ permabililty is high results in a decrease in osmolality of tubular fluid
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The Descending loop is
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is very water permeable, and is NOT active in Na+ transport
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The Ascending loops is
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water imperable, and very active in Na+
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The ascending loop becomes more concentrated or dilute
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DILUTE--decrease in osmolarity
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What happens in the outer medullar cortical collecting duct
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is imperaeable to urea, and TUBULAR urea concentrations rise and water is absorbed
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What happens inthe inner medullary region
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urea pereable, so urea acuumulates in the inner medullar, water follow and urine is concentrtaion
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What is primary function of vasa recta
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removed water, Na+, and urea from medullary region
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What does vasa recta alos help maintain
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hyperosmotic medullaru interstitial fluid
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THe kidneys are the major site of K+ elmination from the body and represent the primary site for regulation of
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K+ balance
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Where is most filtered K+ reabsrobed
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PCT, and loop of henele
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Where is excess K+ secreted
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by principal cells in collecting ducts
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Potassium is transported by specfic cell types present in
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Principal cells in the cortical collecting ducts
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Na+/K+ ATPase locted in basolateral membrane lead to an intracellualr accumation of K+, what happens
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K+ then diffused of of tuble into cell lumen
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What happens if their is excess of EXTRAcellular K+
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enhances cellular uptake of K+
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What happens with increased plasma aldosterone
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increased luminal membrane permerability to both K+ and Na+--K+ secretion is enchanced and Na+ is reabsrobed
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What are the mineral electrolytes
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Calcium, magnesium and phosphate
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What percent of of our daily calcium intake is excreted
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10%
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Caclium is both filtered and reabsrobed, what percentage is filtered and why
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60% is filtered, b/c 40% is bound to proteins
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What % of magensium that is filtered is excreted
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5%
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Where is most magesium reabsorbed
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loop of henel
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Inorganic phosphate is filtered, and reabsorbed how
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Na+ dependent active transport system in proximal tubule
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What locations are the Na+/K+ ATPase
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PCT, Thick ascending loop of henele and DCT
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45-75% of our body weight is water, body water contnet is INDIRECTLY releated to
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FAT
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What percentage of Body water is intracellular
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40%
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What % of body wather is extra ceullar
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20-30%
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Where is interstital and lymph water and plasma water extraceullar or interceullar
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extraceullar
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Equivalents of cations and anions are
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equal in each compartemnt (allows solution to be electrically neurtral
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Proteisn contribute to the net negative charge in
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plasma water, and intraceullar fluid NOT interstital fluid
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What contibues to the negative chagne in intersitital fluid
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Cl_
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The Cl- and HCO3- differential is maintained by
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lowe membrane potential inside of cell
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Osmotic concentration must be
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the same inside and out to maintain osmotic equilibrum
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What does pure water do to the osmolarity of ECF and ICF and volume
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Osmolarity of both decreases and, and the volume of both increases
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What does istonic saline to do osmolarity and volume of ECF and ICF
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ONLY expands volume of ECF (vein) isotonic-same osmolarity as cells
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What does addtion of NaCL do to osmolarity and volume of ECH and ICF
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increases osmolarity of ECF and ICF and ONLY the volume of ECF, b/c takes water from intraceullar fluid
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The american diet contains how much sodium per day
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6-18 grams of Na a day
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Where is primary loss of sodium
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through skin, GI (5%) and kidneys (95%)
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A postiive sodium balance results when input exceeds outs, what diseases do this
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CHF, hepatic cirrhosis, and kidney disease
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When does a negative soium balance results, and causes
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if sodium output exceeds intake, (sweating, vomiting, diarrhea)
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Sodium is the primary solute in EC fluid, the regulation of sodium balance is closely tied to
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fliuid volume
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Na+ not secreted, so sodium balance
Sodium excreted = |
Sodium filtered-sodium reabsrobed
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What is the direct cause for a change in GFR
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is altered gloerular (HP) (g)
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How is GFR regulated by low Na+ levels
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low Na+ means low plasma volume and low blood presure, so GFR is decreased favoring glomerular reabsorption
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High leels of Na+ leads to
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increased plasma volume, increased BP, and increased GFR--less Na+ reabsorbed
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GFR is indirectly realted to changes in Na+, what responds extrinsically to decrease BV and BP
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baroreceptors
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What happens to baroreceptors rate of firing with low BP
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decrease, which sends brain to incrase HR, and contractility, and constrtion of veins and ateries also stimualte JG cells
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Is GFR regulation is a SHORT-term response
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YES
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What is the long-term regulation of Na+ is through
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reabsorption and excretion (more important than GFR_
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The long-term regulation of Na+ is through
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Aldosterone and renin-angiotensin system
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What is aldosterone and where produced
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salt retaining mineralocortocoid produced by the zona glomeruloa in the adrenal cortex
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What does aldosterone hormone increase, which mean, and location of effects
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synthetsis of protein that fuction as Na+ channels and Na/K Atpase in cortical collecting ducts which means reabsorption of sodium and stimulates potassium secretion in the collecting duct
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In the absence of aldosterone, about 2% of Na+ is excreted, what happens with high levels of aldosterone
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all Na+ is reabsorbed
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Aldosterone also targets Na+ transport into blood from
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the lumens of the large intestine and sweat glands
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What happens extrinsically when there is low BP in renal blood vessels
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Baroreceptors activate sympathic neveres stimulate The JG cells increase renin release
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What is a renin and what does it do
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proteclytic enzyme that converts angiotensiogen to angiotensin I
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What happens after formation of Angiotension I,
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ACE in lungs converted to Anngiotension II
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What is the rate limting enzyme
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renin
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What does angiotension II do
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ateriole contstrction, aldosterone release
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What does angiotensin do to cappillary beds
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decrease blood pressure
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How does the JG act as intral renal barorecptors
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Low Na+, lower volume lower pressure strech less, so release renin
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What do macula densa do
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sense the Na+ concentration in tbulue, and decrease concentration send signal to JG to release renin
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What are the 2 intrsinc mechanisms that regulate GFR
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myogenic autoregulatin
tubuloglomerular regulation |
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What happens intrisinaclly with low BP
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both vasodiation of afferent arterioles-increase GFR
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Atrial Natriutetic peptide is released from, and in response to
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heart atria, increase to increase BV and strech
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What are the 4 major effect of ANP
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inhibits release of aldosterone and renin release
decrease Na reabsoprtion vasodiated arterioles |
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How does is decrease sodium reabsorption
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targeting inner medullary collecting ducts
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What does ANP do to the afferent and efferent arterioles
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dialtion of afferent and constrction of efferen,t
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What is the end result of ANP
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increase sodium excretion
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What happens do ANP for increase BP (generally)
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increased strech, increase release of ANP, signals renal tubules to decreases sodium reabsorption and increase sodium excretion
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Dietary water comes in the form of both
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water and water in food
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Water lost in breath and skin is termed as
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inesensible water loss
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Water excretion =
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water filtered - water reabsorbed
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The regulation of water balance involves what 2 complex mechanism
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1. ADH
2. Thirst |
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Vasopressin (ADH) is a peptide hormones composed of 9 aa, produced by, and axon terminate
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hypothalamus--axons terminte in posterior pituitary
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What controls vasopresin (ADH) release
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osmoreceptors, which recognize cellular dehydration and sometime extracellular dehydration
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What is thrist
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conscoius sensatino that allows us to determine if we need water
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The major stimuli for thirsts are
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cellular dehydration and extraceullar dehydration
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Do the excellular and cellular dehydration mechanism work together
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YES
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What is thirst response to cellular dehydration synapse on
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osmoreceptors in the anterior hypothalamus
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WHat is the most senstive to initating thirst response
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cellular dehydation, needs to be EXCESSIVE for extraceullar dehydation
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What is the primary target of ADH, and is it mediated by cAMP
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collecting duct of kidney, YES
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What is kidneys response to hydration
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diuresis (excretino of a large volume of water
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The inital signaling of hydration responses are mediated via
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increase extraceullar fliud and decrased plasma osmolarity
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An increase extraceullar fluid volume does what 2 things
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increases cardiovascular strech, and decrease ADH release from posterior pitutitary
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What does decreases plasma osmolality trigger
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osmorectpros, decrease release of ADH from posterior pitutiary
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What happens after osmoreceptrs send signals of decrease plasma osmolairty
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decrease release of ADH and decreased reabsorption of water from COLLECTING DUCT
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What happens with decreased levels of ADH
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decreased collecting duct permeability
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What are 3 things that happen during dehydration
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decrease ECF, increase plasma osmolarity, and increased thirst
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What happens with extracellular dehydration
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decreased stech of receptors in left atrium of heart, signals ADH release
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What happens with cellular dehydation
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increase plasma osmoliarity, osmoreceptors cause increase release of ADH
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What do increase plasma ADH do
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increase collecting duct water permeability, increased water reabsorptino
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What happens to plasma osmolarity in response to dehydration, what happens to extracellular fluid
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plasma osmolarity is returned to normal ,a nd ECF is increased
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Where is most of K+ located
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within cells
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Why is maintian K+ extremely important
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1. Maintains membrane potentials
2. Maintence of intracellular volume 3. Maintence of Acid-Base |
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Plasma K+ is tightly regulated and ranges, above and below mean
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3.5-5.5
>5.5 hyperkalemia <3.5 hypokalemia |
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When are plasma concentratin of K+ fatal and cause cardiac arrthmia
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10-12 meq/Liter
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What 3 factors affect the distribution of K+ between cells
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1. Na/K+ ATPase pump
2. Acid-base balance 3. Hormones |
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What hormones stiumulate K+ uptake
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insulin, epinehprine, and aldosterone
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Increased plasma K+ has a direct effect on
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Adrenal cortex, resulting in an increae of aldosterone
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What are 2 ways aldosterone forced to be secreted
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Increased angiotension II
and increase plasma K+ |
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Increased plasma aldosterone, increases sodium reabsorption and what else
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increase potassium secretion in inner medullar collecting ducts
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If K+ intake decrease, what happens to release of aldosterone
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aldosterone release is decreased
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Extracellular concetration of Ca+ must be maintained constant to maintain function
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of GI tract, kidney and bone
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Ca+ is not efficienty absrobed in the GI tract, what plays a role in its absoprtion
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Parathyroid hormone produced by parathroid cells
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What happens with decrease Ca+ levels
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increase parathyroid release,
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What are 3 actions of parathyroid hormone
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increase calcium removal from bone, activate vit D, adn increases renal tubular calcium reabsorption
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It is essential that the pH of the body is strictly maintained, where do H come from
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Metabolsim of carbs, fatty acid, protein, which are oxidized to CO2 adn H20
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Metabolic production of CO2 is a source of
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hydrogen
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The normal adult produces about 300 Liters of CO2 daily, it reacts with H20 to form
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carbonic acid (H2Co3)
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CO2 production and expiration are usually matches, as a result
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the usually is not acid burden at level of lung
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The pH of the blood and interstitial fluid is maintain between
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7.35-7.45 by a series of buffering systems
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What are the 3 buffering systems of the body
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1. Chemical
2. Lungs 3. Kidneys |
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What are the chemicals that are buffered
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phosphate, proteins,a nd bidcarbonate
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What comprise the largest buffer reservior in body, and why are they effective buffers
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proteins, they have very ionizable groups
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Why is bicarb (HC03 or CO2) a very effective buffer system, and where
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extraceullar fluid, b/c it is present in high concentrations
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Is Bicarb (HC03) used by the lungs and kidneys and is it an open system
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YES
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CO2+H20 =
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carbonic acid H2CO3
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Carbonic acid then forms
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H+ and HC03 (H+ is consumed and HC03 is added to blood
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What does the repiartory sysmtem regulate
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PCO2 in the arterial blood
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Normally CO2 pressure in the alveoli and arterial blood are
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eqaul--CO2 is expired athe the same rate it is produced
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What happens in hyperventilation
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CO2 is flushed out of the alveolar spaces faster than it can be added, resulting in a depletion of CO2
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What does Hyperventailation do to reaction and H+ concentrations
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pull reaction to left, and H+ concentrations decrease (more basic)
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What is hpoventilation
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Co2 is added fast than it is removed fromt the aveloar spaces PCO2 rises in the blood and alveli,
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What does hypovenaliton do to reaction, and H+ concentrations
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pulls reaction to right, making more acidic
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The PC02 is blood is well controlled by
|
central chemoreceptors int he medulla
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What is a fixed acid
|
any acid other than carbonic acid
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Accumulation of a "fixed acid" is sensed by
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perihperal cehmoreceptors
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Where are peripheral chemorecpetors,and action
|
carotid and aortic bodies, increase ventilation exhaling carbonic acid ONLY
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Increase ventilation does what do pCO2
|
lowers aterilal PCO2 --to compensate for fixed acid (metabolic acids)
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Buffering of acid-base distrubances by respiratory system are RAPID but
|
NOT very precise
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Does the respiratory system have the ability to eliminate a fixed acid, and if so who
|
NO,,only kidneys have ability
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Do the kidneys have a more fine control over acid-base balance
|
YES
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*How does kidenys regulation H+ concentrations in the body*
|
by increase or decreasing the bicarbonate concentration in the body fliud
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What areas of the kidney secretion H+
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most in proximal tubules, also distal tubules and collecting ducts
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The H+ ions are eventually elminated
|
in the urine by it being acidfied
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|
The process of urinary acidfication can be classified according to
|
reabsroption of filtered bicarb
excretion of trtratble acid excretion of ammonia |
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Using the equation losing HCO3 is the same thing as
|
gaining a H+
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Using the equation absorbing HCO3 is the same thing as
|
losing an H+
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What is the 1st step of reabsorption of filtered HC03
|
CO2 in the ECF (product of metabolism) enters in the tubular cells conbines with H20 to form carbonic acid (H2CO3)
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What is 2nd step of Reabsorption of filtered bicarb
|
H2C02 dissoactes to HC03 and H+, and H+ is secreted into tubular lumen, in exchange for Na+
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What is the driving forces for reabsorptino of filtered bicarb
|
Co2--more Co2 the faster the secretion
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Can tubular cells recliam HCO3 by reabsoprtion directly
|
NO
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What is 1st step how filter bicarb is reclaimed
|
H+ secrted into cell, combines with HCO3 to form carbonic acid
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What happens to carbonic acid formed in filtrate
|
splits to CO2 and H20 by carbonic anhydrase located in brush border, and Co2 diffuses back into tubular cell
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What happens to CO2 in tubular cell,
|
combines with water, and slips again to HCO3 and and H+
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What happens to HCO3 in tubular cell
|
co-transport with Na into peritublar cappilaries
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What is an example of excretino of a titratable acid
|
phosphate
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How is the excretion of tritarable acid phosphate iniated
|
CO2
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What happens in excretion of tiratable acid
|
Co2 diffudes into tubular cell, joins with water to form carbonic acid, then splits in to HCO3, and H+, and H+ is secrted in exhance for Na+
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What happens to secreted H+ in excretion of trtratble acid phosphate
|
HPO4 joings with H+ and excreted
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Meanwhile while the HPO4 is being excreted what is happening in the Type A cells of the COLLECTING DUCT
|
they are making NEW bicarb and Co transporting with Na+ into peributulbar cappilary
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Where does Exretion of ammonia take place
|
PCT
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How is ammonia formed
|
Glutamine is filtered, and enters into tubular cell is metabolized to forms to NH4, and 2 Bicarbs
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What happens to the NH4
|
is secrted in exhcange for Na+
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Why is NH4+ trapped in the urine and secrted
|
b/c urine is acidic
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What happens to the 2HCO3 formed
|
enter in peritubular cappilaries
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Urinary acidfication is driven by
|
CO2
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|
Plasma PH is maintain by regulation of
|
HCO3
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If you have an excess of acid what happens
|
increase acid excretion in urine, adn increase plasma Bicarb
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If you have an excess of base what happens
|
increases excretion of bicarb, adn lower plasma HCO3
|
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|
What pH represent acidemia, and what pH represent alkemia
|
acidemia is <7.35
alkemia is >7.45 |
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What is the cause respiratory acidosis
|
acummulation of CO2 as a result of failute to expire CO2 from the alveolar
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|
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What are disease assoicated iwth respiraotry acidosis
|
pulmonary disease or airway obstruction
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How do kidneys compensate to respitatory acidosis by an increase in PC02
|
increase H+ secretion, which in turns increases plasam HCO3
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What is the cause of repitaory alkalosis
|
excessive loss of CO2 by hyperventilation, CO2 is removed faster than produced
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|
The excessive loss of CO2 pulls the reaction, and what happens to PCO2
|
pulls reaction to LEFT, adn PCO in the arterial blood decreases
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How does body compesate for respitaory alkalosis
|
lower PCO2 means lower H+ secretion and less HCO3 reabsrobed
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What is cause of metabolic acidosis
|
accumulation of a fixed acid such as lactic acid or ketone bodyes
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Why does HCO3 decrease metabolic acidosis
|
it is only an extracellular buffer
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How is metabolic acidosis fixed
|
aveolar hyperventilation
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What can cause metabolic alkalosso
|
increase of fixed based excess intake of sodium bicarb or exessive loss of gastric juice
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How is metabolic alkalosis fixed
|
aveolar hypoventialtion (slow shallow breathing)
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What happens to ph, HCO3 and PCO2 in respiraotry acidosis
|
ph decreases, increaed PCO2, and kidneys compesate by increasing bicarb
|
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What happens to ph, HCO3 and PCO2 in respiraotry akalosis
|
ph increases, PCO2 decreases, and kidney compesate by decreased bicarb
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What happens to ph, HCO# and PCO2 in metabolic acidosis
|
ph decreases, decreased Bicarb, and lungs compesate by decreasing PCO2
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What happens to ph, HCO3 and PCO2 in metabolic alkalosis
|
ph increases, increased bicarb, and lungs compesate by increasing PCO2
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