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143 Cards in this Set
- Front
- Back
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How much fluid is produced in the renal system per hour? |
7L/hr |
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How much of this fluid is reabsorbed? |
99% (gives 1% for fine tuning) |
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What is an endocrine function of the kidneys? |
EPO production (renin production, too)
Activation of Vit D (cofactor for intestinal Ca++ absorption) |
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What is reduced in the healthy kidney donor?
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Renal reserve (the rest is unaffected)
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At what % damage would you begin to see clinical signs of deterioration of the kidney? |
75-90% renal impairment |
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Through what structure does the vascular supply to the kidney travel? |
Hilum |
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What part of the kidney contains the nephrons? |
Cortex |
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What part of the kidney contains the urinary structures? |
Pelvis |
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What are the 4 regulating processes of the kidney? |
1. Filtration-fluid and solutes from plasma to nephrons 2. Reabsorption-out of renal tubules into peritubular capillaries 3. Secretion-of substances from peritubular capillaries into tubular fluid (exogenous and endogenous) 4. Excretion-excess fluid, electrolytes, urea, bilirubin, H+ |
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The opening and closing of water channels in what part of the nephron produces concentrated and dilute urine? |
Renal collecting ducts (allows for regulation of plasma osmolarity) |
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Excretion of metabolic waste products: (name the byproduct)
1.Urea 2.Creatinine 3.Bilirubin 4.Uric acid |
1. protein 2. muscle 3. hgb 4. nucleic acids |
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What are the functional units of the kidneys? |
Nephrons |
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What enters into the calyces, and ultimately, the ureter? |
Loops of Henle Collecting Ducts |
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The flow of blood......1
Blood is first filtered through what structure? |
Glomerular capillary membrane into Bowman's Space |
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Flow of blood.......2
Blood flows from Bowman's Capsule into? |
Nephron (becomes tubular fluid) |
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Flow of blood.......3
The remaining fluid (urine) flowing via collecting ducts exits what structure? |
Exits renal pyramids into the minor calyces |
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Flow of blood......4
The minor calyces combine to form what? |
Major calyces, which empty into the ureter.....bladder......excretion |
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What are the two populations of nephrons? |
Cortical -(superficial) Juxtamedullary- (deep) |
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What are most nephrons, cortical or juxtamedullary? |
Cortical (80%)
(juxtamedullary is 20%) |
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What is a similarity, and difference between cortical and juxtamedullary nephrons? |
Both composed of same structures
Differ in LOCATION of kidney |
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Where are the cortical nephrons located? |
From glomuruli in upper and middle regions of cortex
Loops of Henle are SHORT (only to inner stripe of medulla) |
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Where are the juxtamedullary nephrons located? |
Located DEEPER in cortex (by medullary junction)
LONG Loops of Henle extending deep into inner medulla (forming papillae) |
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What artery supplies the kidneys? |
Renal arteries (from aorta) |
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What is the parenchyma divided into? |
Cortex Inner/Outer medulla |
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Trace the blood flow through the kidney from the renal artery.......... |
1. Interlobar artery 2. Arcuate arteries 3. Interlobar artery/cortical radial artery 4. Afferent arteriole 5. Glomerular capillaries 6. Efferent arteriole 7. Cortical peritubular capillaries/vasa recta (deep) 8. Venule 9. Veins |
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Where do the afferent and efferent arterioles enter and exit respectively? |
At the capillaries |
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What surrounds the glomerulus that contributes to the filtration barrier and structure of the glomerulus? |
Epithelial cells (podocytes) |
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What are two principle parts of the urinary bladder? |
Body (urine storage0 Neck |
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What type of muscle is the urinary bladder composed of? |
Smooth muscle
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How much urine typically is stored in the bladder that will send a sensory message for excretion? |
300-500mL |
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What part of the urinary sphincter is involuntary? |
INTERNAL urinary sphincter |
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What part of the urinary sphincter is voluntary? |
EXTERNAL urinary sphincter |
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Blood enters the capillary via what? |
Afferent arteriole |
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Efferent arterioles associated with cortical nephrons, lead to what? |
Peritubular capillaries which collect material reabsorbed from nephrons |
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Efferent arterioles associated with juxtaglomerular nephrons lead to what? |
Vasa Recta (straight vessels) which collect material reabsorbed from medullary tubules |
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Juxtamedullary nephrons do what to urine? |
Concentrate and dilute |
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Cortical nephrons do what to urine? |
Dilute urine only!!!!! |
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The glomerulus is a capillary system, from which ultrafiltrate of plasma enters into a dense capillary network called? |
Bowman's Capsule |
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Substances that don't make it through the glomerulus will exit via what? |
Efferent arteriole |
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In general, if you make it through the glomerulus, you will enter what? |
PCT (prox convoluted tubule) |
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What is significant about the proximity of the tubular and peritubular capillaries to one another? |
They are so close to one another that this promotes the extremely high rate of reabsorption of 99% |
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What special feature do nearly all cells in the nephron possess? |
Cilium |
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What is the role of the cilium? |
To act as mechanoreceptors and chemoreceptors to sense flow rate and concentration of tubular filtrate |
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What are the 2 prototypes of smooth muscle associated with the renal system? |
Contractile Secretory |
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What is a special feature concerning secretory cells of smooth muscle? |
They change their phenotype during diseased states by secreting MATRIX which forms the shape of tissue (hardening of arteries seen) |
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What type of cells secrete extracellular matrix? |
Mesangial matrix |
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What type of cells within the glomerulus can contract, and therefore affect the surface area and thus rate of filtration? |
Mesangial cells |
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Filtration by the glomerulus occurs according to what two things? |
Size and charge of solutes
*considered barriers*
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Why don't proteins pass via the glomerulus? |
The basement membrane and podocytes are neg charged, and proteins are neg charged too |
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All endothelial cells sit on what, which makes direct communication to Bowman's Capsule and the PCT easier? |
Sit on a capillary basement membrane |
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What are 3 types of cells within the glomerulus? |
Endothelial Podocytes Mesangial cells |
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What consists of the glomerular-filtration barrier? (3) |
Endothelial cells Basement membrane Podocytes |
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What are part of the juxtaglomerular apparatus and sense Cl- concentration in the distal tubule and adjusts the diameter of arterioles....regulating glomerular blood flow? |
Macula densa cells |
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In the PCT, the filtrate is closer to what side?
Basolateral side is closer to? |
Apical side
Blood vessel |
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Reabsorption takes what pathway? |
Tubule to epithelial cell to blood |
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Secretion is from? |
Blood to epithelial cell to tubule |
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Where should you find high concentrations of Na+? |
PCT
100% Na+ filtered |
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What 2 molecules piggy back on Na+? |
Glucose Amino acid |
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What are the exchangers for the kick out of Na+? |
H+ |
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What leaves the proximal tube passively? |
H20 and Cl- |
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What pump is used to move Na+ back into the blood from the tubule? |
Na+/K+ pump |
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What part of the Loop of Henle is permeabel to water and receives filtrate from the PCT? |
Thin, descending limb |
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What does the thick ascending limb of the Loop of Henle contain? |
Na+, K+, 2Cl- cotransporters that pump ions into interstitium
IMPERMEABLE TO WATER |
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The hairpin turn should have what qualities? |
High concentration of solutes (little water) |
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What happens to the solutes as you ascend up the thick limb? |
Solutes begin to move into the interstitium (reason for the ion channel pump...to dilute) |
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What is always present in the interstitium? |
Urea |
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Which nephrons have the longest loops and responsible for concentrating urine? |
Juxtamedullary nephrons |
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What is important about the countercurrent mechanism? |
It is responsible for creating the high interstitial osmolarity and diluting urine |
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Fluid that is reabsorbed by the Loop of Henle is picked up by what? |
Vasa recta and returned to venous circulation |
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Where does the fine tuning of solutes take place immediately after the ascending limb? |
DCT (distal convoluted tubule)
Its about 150mOsm/L by this point |
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The longer the tube, |
The more concentrated and more blood supply needed |
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What is another name for peritubular capillaries and juxtamedullary? |
Vasa recta=straight tube |
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Blood flow via nephron? |
Interlobular artery, afferent arteriole, glomerulus, efferent arteriole, peritubular capillaries, venules, interlobular vein |
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What plays a large role in concentrating the interstitium (other than urea)? |
Active transport of NaCl from ascending limb |
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Why is water moving passively out of the descending limb? |
Trying to equilibrate with the interstitial space |
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What are some characteristics of urea? |
From breakdown of protein Freely filtered Majority of movement in collecting duct Some movement in LOH |
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Which side is osmosis occuring on the LOH? |
Descending limb |
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Active transport? |
Ascending limb |
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Where is glucose reabsorbed? |
100% reabsorbed in PCT by Na+/glucose cotransporters |
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What are some functions of the kidney? |
Excretion of excess body acid Regulation of fluid and electrolyte homeostasis Activation of vit D Ammoniagenesis |
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A decrease in glomerular filtration rate affects permeability how? |
Reduction in permeability of glomerular filtration barrier |
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What transporter is affected by the use of loop diuretics? |
Na+/K+/2Cl- co transporters
Also the interstitium is washed out (less concentration gradient=sustained diuresis) |
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Where are ADH-sensitive water channels (aquaporins) located? |
Collecting duct |
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What factors all play a role in establishing or maintaining the medullary interstitial concentration gradient? |
Na/K/2Cl cotransporters on thick ascending side Solute-free H20 reabsorption in descending side Counter-current multiplier effect Urea recycling
*DCT Na reabsorption has nothing to do with this!!!!!!!!* |
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What are the two direct effects Angiotensin II has on the kidneys? |
Increase PCT Na+ reabsorption Constrict afferent and efferent arterioles |
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Renin is released by what cells? |
Juxtaglomerular cells in response to low Na+ and low tubular fluid flow rate in distal tubule |
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When plasma HC03 is low due to metabolic acidosis, H+ ion secretion will increase or decrease? |
Increase |
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In the DCT, what stimulates tubule cells to reabsorb Na+ and H20? (2) |
Aldosterone and Angiotensin II |
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What does Angiotensin II do to get Na+ from the tube to inside the cell? |
Upregulates epithelial Na+ channel |
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What does aldosterone do to increase the Na+ reabsorption? |
Effects the Na/K pump (against gradient) |
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What are inhibitors of reabsorption of Na? |
ANP Urodilatin |
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What part of the collecting duct is HC03 recycled? |
Late distal (exchanged for Cl-) |
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What are 2 cell types in the collecting duct? |
P cell- respond to ADH via aquaporin channels
I cell- acid base balance by regulating secretion of acid |
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Where does urea get permeability? |
Collecting duct (dumped into interstitium) |
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Finish the pathway from the medullary pyramid to the minor calyces...... (2) |
Papilla to renal pelvis |
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Intercalated Cells have 2 functions in the distal tubule: |
Secretion: H+ or HC03
Reabsorption: HC03 via Cl/HC03 exchanger (reabsorb K+) |
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Principle cells reabsorb? |
Na and H20 and secrete K |
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The brush border and high number of mitochondria permit the reabsorption of 60% of glomerular filtrate here? (the highest) |
PCT |
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Where does filtration only occur? (2) |
Glomerulus PCT |
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Secretion |
Blood supply to tubule
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Reabsorption |
Tubule to Blood supply |
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Where does the countercurrent mechanism take place? |
LOH |
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Fine Tuning? |
DCT (reabsorption and secretion) |
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Where is ADH NOT required for reabsorption? |
PCT |
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Where is ADH REQUIRED for reabsorption? (2) |
Distal tubule Collecting duct |
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Where is the site of free water reabsorption through water channels controlled by ADH? |
Collecting ducts |
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What is the CD also important for? |
Acid base balance |
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What is the juxtaglomerular apparatus? |
Where the DCT returns to its "parent" glomerulus |
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Each neuron can regulate its own? |
GFR |
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What type of cells produce and release renin? |
Juxtaglomerular cells (communicate with macula densa) |
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Which tubule is in close proximity to the glomerulus and makes it easier to communicate? |
Distal |
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What does renin activate? |
Aldosterone Angiotensin II
****increase in Na+ reabsorption*** |
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How will sympathetic innervation affect renin? |
Stimulates renin release
Think fight or flight....want more blood volume to feed heart, so will increase Na reabsorption to increase blood volume to FIGHT!!!! |
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If you have an increase in blood volume, how will this affect renin release? |
Inhibits renin release
Good blood flow, can afford to not reabsorb Na and pee it out |
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What cells sense the volume/pressure increase in the tubuloglomerular feedback system? |
Baroreceptors (afferent arterioles) |
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What cells sense NaCl concentration in the distal tubule? |
Macula densa (increased concentration will inhibit renin too)
These sense concentration in DT via Na/K/Cl transporter |
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Afferent constriction and efferent dilation? |
Decrease GFR |
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Afferent dilation and efferent constriction? |
Increase GFR |
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What is an important chemical mediator of arteriolar resistance? |
Angiotensin II (important afferent/efferent vasoconstrictor)
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What is the effect of an increased amount of Glucose and amino acids in tube? (increased load) |
More Na+ reabsorbed by proximal tube
Increase workload, have to increase regeneration or lose function |
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Less Na transported to macula densa in distal tubule, they assume they should...? |
Increase GFR to hold on to Na and not excrete it |
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What are some freely filtered molecules in the glomerulus? |
Water, glucose, creatinine, urea |
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Normal GFR rate? |
100-125ml/min |
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Where is glucose normally reabsorbed? |
Proximal tubule by Na-dependent cotransporter |
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Too much tubular load of glucose, what will you see? |
Glycosuria |
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What is the renal threshold? |
Point at which glucose begins to spill into urine |
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Is HC03 directly reabsorbed into the renal epithelium? |
No, it must combine with a H+ in the tubule to form H2C03 |
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What does carbonic acid dissociate into in the tubule? |
H20 and C02 |
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What catalyzes this reaction? |
Carbonic anhydrase |
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What happens in the intracellular space to the HC03? |
Transported out through the basolateral membrane and the H+ is pumped back on the apical side by Na/H+ pumps |
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What else can H+ bind to in order to buffer urine pH? |
NH3 and HP04=NH4 and H2P04 |
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If there is no HC03 to bind with H+, what happens to this H+? |
Excreted |
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The increased ability of the kidneys to excrete an acid load comes from what two urine buffers? |
H2P04 and NH4 |
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Secretion of K+ is promoted/affected by what on the basolateral side of the DCT? |
Aldosterone
(affects Na/K ATPase pump)
Aldosterone increases K+ secretion |
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How do diuretics work against the reabsorption of water? |
They increase the osmolarity of filtrate, which causes more water to remain in the tubule, which is excreted |
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Where do loop diuretics work on the LOH? |
Block the Na/K/2Cl pumps in ascending LOH
Prevent reabsorption of filtrates |
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What are examples of K+ wasting diuretics? |
Osmotic diuretics ACE inhibitors Loop diuretics Thiazides (block Na+ reabsorption) |
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What are potassium-sparing diuretics? |
Aldosterone-blocking agents |
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If an ion is kept in the filtrate, what does this mean? |
It is not reabsorbed, and stays in the filtrate to be excreted |
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Who has the most impaired renal function in life span? |
Infants and elderly |
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With infants, what part of the renal system is affected? |
GFR is low Reduced ability to make concentrated urine Predisposed to volume depletion Volume regulation improves with maturity |
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When do kidneys begin to decrease in size and function? |
40's (more in the 60's) |
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Geriatric considerations? |
-Loss of nephrons -Diminished renal blood flow -Decreased GFR and conservation of H20 & Na+ -More susceptible to fluid and electrolyte imbalance and renal damage |
