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104 Cards in this Set
- Front
- Back
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What is the kidney functions?
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Maintain ion balance
regulate: osmolarity, extracellular fluid volume and bp regulate acid/base excrete metabolic waste and foreign substance hormone production |
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What is a nephron?
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Functional unit of kidney
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How many nephrons are there?
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There are about 10 ^5 nephrons/kidney
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Name the two types of Nephrons
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Coritcal Nephrons
Juxtamedullary nephrons |
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Where is the cortical nephrone located?
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cortex (8o% total)
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Where is the juxtamedullary nephron located?
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deeper w/lg extension into medulla
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How much flood flow to the two kidneys?
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25% 0.5% total body weight
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Describe the Blood flow pathway
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Renal artery --> interlobar artery -->arcuate artery --> interlobular artery --> afferent arteriole --> glomerfular capillaries (glomerulus) --> efferent arteriole --> peritubular capillaries --> vasa recta (only in juxtamedullary nephrons) --> interlobular vein --> arcuate vein --> interlobar --> renal vein
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Where is a nephron located?
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its a tube, continuous outside the body.
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On one end of the Nephron tube, what will you find?
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Is the Bowman's capsule, inside is the glomerular capillaries (glomerulus).
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The Bowman's capsule and the gomerulus, together is called the:
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renal corpuscle
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List the sections of the Nephron Tube:
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Bowman's capsule--> Proximal tubule-->(Loop of Henle): (tDLH) thin Descending limb-->thin Ascending limb (tALH), (TAL) thick Ascending limb--> Collecting tubule --> Medullary Collecting Duct (MCD)--> multiple nephrons--> minor calyx
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Define Filtering
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Plasma is filtered in capsule. Selective process. The filtered fluid is called fitrate.
Happens in Bomen's Capsule |
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Define Absorption
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Solute and water can be taken back from tubule to blood stream along entire length of tubule from proximal tubule to collecting duct.
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Define Secrete
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additional molecules can be selectively secreted into the tubule in the proximal and distal tubules as well as collecting duct.
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Define Excrete
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What remains in the tubule after the collecting duct and enters the renal pelvis travels to bladder and it excreted out of body.
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Where does Filtration occur in the Nephron?
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Bowman's capsule
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Where does Afferent arteriole give rise to?
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Afferent arteriole gives rise to glomerular capillaries
(which are surrounded by lumen of Bowman's capsule) |
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Where podocytes located?
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Glomerular capillary are surrounded by modified epithelial cells called podocytes
(Podocytes extend foot processies to the capillaries) |
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List the 3 filtration barriers
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Fenestrations in Endothelium
Basal Lamina Podocytes Foot Processes |
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What do Fenestrations (openings in structure) function?
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Fenestrations in endothelium are small enough to exclude blood cells from leaving capillary.
Negative charge on the pore surfaces repel negatively charged plasma proteins |
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What is the function of basal lamina and what do they consist of?
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consists of negatively charged glycoproteins further limiting negatively charged plasma proteins
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What is the function of podocytes foot processes?
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They form narrow fitration slits that contain proteins that limit negatively charged proteins from entering filtate.
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What is exclused from filtrate?
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Negatiely Charged Large Molecules excluded from filtrate
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Why is Albumin excluded from filtrate?
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B/c negatively charged.
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What happens if albumin is filtered?
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it will be reabsorbed by Proximal tubule.
Normally no albumin in urine! |
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What happens if there are negative charges on filtration?
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will lead to immunologic damage and inflammation
lead to proteinuria and albinminuria |
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What is the normal composition of the glomerular filtrate?
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- protein free
- lack cellular elements (RBC, WBS, plts) - Most salts and organic molecules similar to plasma |
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What is the volume of plasma?
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3.5
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How much is the entire plasma volume filtered a day?
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50x/day
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What is the total amount that is filtered at a given time can vary called?
Or: this is the sum of all filtration rates of all functioning nephrons |
Glomerular Filtration Rate (GFR)
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why is the GFR important?
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important index of renal function and health
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Define Oncotic pressure
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Osmotic pressure due to proteins
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Define Osmotic Pressure
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Osmotic pressure is the pressure which needs to be applied to a solution to prevent the inward flow across a semipermeable membrane.
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What is reflection coefficient?
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It is the permeability through capillary membrane for substance of interest. This is the permeability/area available surfave area.
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What are the determinants of GFR?
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Net filtration pressure
Glomerular capillary reflection coefficeint, Kf, Kf |
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Define Net filtration pressure
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The sum of hydrostatic and oncotic forces across the glomerular membrane
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Define Glomerular capillary reflection coefficient, Kf Kf
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product of the permeability and filtering surface area of the capillaries
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What opposes filtration?
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Hydrostatic pressure in Bowman's capsule (Pbs)
Oncotic osmotic pressure of glomerular capillary plasma proteins |
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What promotes filtration?
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Hydrostatic pressure inside the glomerular capillaries (Pgc)
Colloid osmotic pressure of the proteins in Bowman's capsule Reflection (Kf) LARGE value |
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What is the Normal level of GFR?
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125
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What is the equation of the Law of mass balance?
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total amount of substance x in the body equals its intake + production - excretion - metabolism
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What is the formular for renal clearance?
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Clearance of A = excretion rate of A (in mg/min)/ [A] plasma (in mg/ml)
OR Clearance A = Excretion A / Plasma Volume |
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What is the renal clearance?
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volume of plasma from which all substance has been removed and excreted into urine per unit time.
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When measuring the GFR with clearance, what is the criteria that the substance need to meet?
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Whatever is filted that is also seen in urine = can measure the rate.
* Amount excretd in urine per minute equals the amount filtered across the filtration barrier each minute 1. FREELY filtered across filtration barrier into Bowman's space 2. Not be reabsorbed or secreted by nephron 3. Not be metabolized or produced by kidney 4. Not alter GFR |
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What is inulin?
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Not normally found in body; it's a plant, freely filtered by glomerulus.
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Is Inulin reabsored or secreted?
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NO! all inulin will be filtered and end up in urine.
Inulin clearnance = GFR (the volume of plasma filtered in one minute) |
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What is Creatinine?
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Endogenous (made in body) substance
Product of muscle creatine phosphate metabolism. - Rate of urinary cratinine excretion = rate of metabolic production EAsy, noninvasive, reliable |
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What is the normal plasmal level?
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1 mg/dl
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what is the normal creatinine level for normal adult male?
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90-140 ml/min
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What is the normal creatinine level for normal adult female?
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80-125 ml/min
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If GFR decrease, will the creatinine level decrease or increase?
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increase because:
Given a normal Cr of 1 mg/dl, if patient Pcr is 2 mg/dl, there has been a 50% reduction in GFR |
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What is GFR?
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total vomume of plasma filtered through glomerulus per unit of time
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What is RPF? Renal Plasma Flow
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total volume of plasma (not blood) passing though kidney per unit of time
* includes both the portion of plasma which is filtered/not filtered |
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What is the normal RPF?
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approx 600 ml/min or 864 L/day
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Who recieves the most kidney blood flow? The renal cortex or renal medulla?
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Renal cortex
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Who supplies blood flow to medulla? total renal blood flow is 1-2%
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Vasa recta--
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What role does vasa recta play?
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concentrating urine.
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Oxygen consumption by kidney is high or low?
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HIGH, 8% of total O2 consumption of body.
Depends on hemoglobin and CO |
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What is the normal level of GFR?
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125 ml/min (180 L/day)
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What is the normal level of RPF?
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600 ml/min (864 L/day)
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What is the normal level of filtration fraction (FF)?
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125/600 = 0.2
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What increases Kf (reflection coefficient)?
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some drugs and hormones dilate glomerular arterioles
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What reduce Kf?
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some kidney disease = decrease # of filtering glomeruli
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Increased Bowman's Capsule Hydrostatic Pressure (Pbs)-- decrease or increase GFR?
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decreases
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Examples of increased bowman's capsule hydrostatic pressure decreasing GFR
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acute obstruction of urinary tract (kidney stone occlude urinary tract)
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Does increased glomerylar capillary colloid osmotic pressure decrease or increase GFR?
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decreases
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What is the glomeruluar colloid osomotic pressure influenced by?
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1. aterial plasma colloid osmotic pressure
2. fraction of plasma filtered by glomerular capillaries (filtration fraction) |
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What is the average glomerular colloid osomotic pressure?
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32 mmHg
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What is the filtration fraction?
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GFR/RPF
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Does increasing the filtration fraction also concentrates the plasma proteins and raises the glomerular colloid osomotic pressure?
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TRUE
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Doe a greater rate of blood flow into the glomerulaus increase or decrease GFR?
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increase GFR
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Will the lower rate of blood flow into the glomerulus increase or decrease GFR?
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decrease GFR
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Does increased glomerular capillary hydrostatic pressure (Pgc) increase or decrease GFR?
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increase
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What is the primary function of clomerular capillary hydrostatic pressure?
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physiologic regulation of GFR
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Increased glomerular capillary hydrostatic pressure increases GFR is DETERMINED by?
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1. arterial pressure i.e. increase pump
2. afferent arteriolas resistance 3. efferent arteriolat resistance |
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If arterial pressure increase, the GFR will increase or decrease?
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increase GFR
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If afferent arteriolar resistance decrease, GFR will increase or decrease?
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decrease GFR
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If efferent arteriolar resistance increase, GFR will increase or decrease?
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increase GFR
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List the three major segments that Renal Vascular REsistance reside in
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Interlobular arterier
Afferent arterioles Efferent arterioles |
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Waht is Renal Vascular resistance controled by?
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SNA
hormones local internal renal control |
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A Increase in resistance, decrease or increase renal blood flow?
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decrease renal blood flow
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What is Autoregulation?
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Relative constancy of GFR and RBF (renal blood flow), despite changes in arterial blood pressure
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How is autoregulation acieved?
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by changes in vascular resistance, maininly afferent aterioles
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What is the function of Autoregulation?
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maintain constant GFR and allows precise control of renal excretion of water and solutes
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What does autoregulation respond to?
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increased arterial pressure is increase in resistance of afferent arterioles
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What are the two mechanisms of autoregulation?
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Myogenic response
Tubuloglomerular feedback |
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What is myogenic response?
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responds to changes in arterial pressure
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What is tubuloglomerular feedback?
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responds to changes in NaCl concentration of tubular fluid
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What is related to myogenic mechanism?
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related to intrinsic property of vascular smooth muscle. The tendency to contract when it is stretched.
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True of false:
When arterial pressure rises and the renal afferent arteriole is stretched, the smooth muscle contracts |
true
--RBF and GFR remain constant |
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Where is teh tubuloglomerular feedback loop mediated?
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mediated by juxtaglomerular appartus (JGA)
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In tubuloglomerular feedback, the amount of NaCl of tubular fluid is sensed by what?
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maculas densa of JGA
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What happens when NaCl of tubular fluid is sensed by the macula densa of JGA?
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Uptake of Na+ and Cl- into macula densa cells
Leads to deplorizatio nand opening of nonselective cation channels. Increased Ca+ leads to release of effector substance. Then converted to signal that affects afferent arteriolar resistance and GFR |
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Give a example of a effector substance
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adenosine
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What does adenosine do?
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constricts affernt arteriole
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List the three points of autoregulation
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1. absent when arterial pressure is LESS than 70 mmHG (severe hemmorphage?)
2. not perfect; RBF and GFR do change slightly as arterial bp varies 3. despite autoregulation, RBF and GFR cna be changed by certain hormones and by changes in sympathetic activity |
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What does sympathetic nerve innervate?
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* NOTE: no parasympathetic in kidneys
- innervate afferent and effect arterioles |
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When is sympathetic Nerves activated?
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dehydration and stong stiuli (fear, pain, trauma)
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Sympathetic Nerves release what?
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norephinephrine (NE)
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NE works also with ___________ released by adrenal medulla.
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ephinephrine
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What does NE do?
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vasoconstriction by binding to a1 adrenoreceptors. located on AFFERENT arterioles
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What induces renin secretion by granular cells?
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Low BP (hemorrhage)
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What does renin convert to?
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Renin convert inactive plasma protein angiotensinogen --> angiotensin 1 (inactive) --> ACTIVE angiotensin 2 by AVE (Angiotensin converting enzyme)
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