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What are the general functions of the urinary system?
- Regulation of ion concentration in the blood.
- Regulation of PH in the blood
- Regulation of blood volume and blood pressure.
- Regulation of blood glucose level (glucose appear in urine if blood glucose level is beyond maximum)
- Hormone production (erythroprotein & renin)
- Excretion of metabolic waste
How juxtamedullary nephron different from cortical nephron? Why is that important?
- The cortical nephron form 85% of thotal nephrons. It's loop of Henle is no longer then the width of the cortex.
- The juxtamedullary nephron form 15% of the total nephrons. It's loop of Henle is long which allow it to create more concentrate urine
mesentery-like structure that connect the kidneys to the body wall
Perinephric fat capsule
Adipose tissue that cushion and protect the kidney.
Also called renal capsule, a connective tissue that form the outer wall of the kidney
What role does the glomerulus play in formation of urine?
Filters H2O & solute out of the blood that become filtrate. Part of that original filtrate become urine.
What are the two layers comprise Bowman's capsule.
- Parietal layer form the wall of the corpuscle.
- Visceral layer (podocyte) on top of the glomerulus.
What will be released by the juxtaglomerular apparatus?
Renin & etythopoietin
During reabsorption process, is fluid moving towards the blood or towards the filtrate? Is this fluid we want to keep or fluid that we want to loos in the urine?
Fluid moving toward the blood. We want to keep this fluid.
During secretion process, fluid moving towards the blood or towards the filtrate? Is this fluid we want to keep or we want to loos in the urine?
Fluid moving toward the filtrate. we do want to get rid of it in the urine
During filtration process, is fluid moving toward the blood or toward the filtrate?
Toward filtrate. (happens in glomerulus only when H2O & solute move out of the blood and become filtrate)
What are the 3 main metabolic waste that are eliminated at the kidneys? Where will each of them come from?
- Urea: product of amino acid breakdown.
- Creatinine:by-product of creatine phosphate in skeletal muscle.
- Uric acid: by-product of digestion of RNA.
Trace the blood flow through the kidney
- Renal artery→ Segmental artery→ interlobar artery→ arcuate artery→ cortical radiate artery→ afferent arterioles→ glomerulus→
- efferent arterioles→ capillaries of the nephron→ cortical radiate veins→ arcuate vein→ interlobar vein→ renal vein.
What is the rout that filtrate flow through the nephron?
- 1) Bowman,s capsule.
- 2) Proximal convoluted tubule.
- 3) Thick descending LOH.
- 4) Thin descending LOH.
- 5) Thin ascending LOH.
- 6) Thick ascending LOH.
- 7) Distal convoluted tubule.
- 8) Collecting ducts
How will capsular hydrostatic pressure effect filtration? What causes it?
- Oppose filtration pressure.
- Cause by filtrate in the nphron.
What is the cause of BCOP? Does it cause filtration or oppose it?
- Osmotic pressure in the blood (change in proportion to solute concentration in the blood).
- Will oppose to filtration
What causes glomerular hydrostatic pressure? Will it cause filtration or oppose it?
- Blood pressure in the glomerulus.
- Will cause filtration.
List the layers of filtration
- fenestrated capillary endothelium
- Basement membrane (capillary's)
- slits between podocytes
What comprises the renal corpuscle?
- Glomerulus: capillaries whet blood get filtered
- Bowman's capsule: double walled capsule
- Juxtaglomerular apparatus: secrete renin & erytopoetin
In which area of the nephron are nutrients reabsorbed?
Proximal convoluted tubule
What transport mechanism are used to move solutes across the basal surface of the ascending LOH?
- Facilitate diffusion moves Cl- & K+Active transport move Na+(out) K+(in)
What transport mechanism are used to move solutes across the apical surface of the ascending LOH?
Cotransport move Na+, Cl-, and K+
Will solutes secreted or reabsorebed in the ascending LOH?
- Na+ & Cl- are reabsorbed (In the thick part)
In the ascending LOH (loop of Henle) is water secreted or reabsorbed?
Neither, the ascending LOH is impermeable to water.
In the descending LOH (loop of Henle) are solutes secreted or reabsorbed? How about water?
- Solutes are secreted
- Water reabsorbed
How does the concentration of solutes changes as you move deeper into the medulla of the kidney? Why does it matter?
- The concentration of solute will increase as you go deeper into the medulla (from 300 mOsm in the cortex to 1200 mOsm by the papilla).
- This allow for water re-absorption.
What will occur if transport maximum is surpassed?
If TM is surpassed for a particular nutrient, it will appear in the urine
Define transport maximum (TM). What determines TM for a particular nutrient?
- Carrier protein saturation point and cannot transport (reabsorbed) more nutrients back to the body.
- Each particular nutrient has its own TM that beyond that it can no longer be reabsorbed
What transport mechanisms are used to move water and solutes across the basal surface of the proximal convoluted tubule?
- Facilitated diffusion moves solutes such as amino acids, glucose, Cl-, and K+ .
- Active transport (Na+/K+) moves Na+ & K+ in opposite direction.
- Water move by osmosis
What transport mechanisms are use to move solutes across the apical surface of the proximal surface? How about water?
- Cotansport (proteins moving two molecules in the same direction) moving solutes
- Water moving by osmosis
Within the proximal convoluted tubule, are solutes secreted or reabsorbed? How about water?
Solute and water reabsorbed in the proximal convoluted tubule.
How much filtration fraction will actually urine each day.
- If we making 180 L/day of filtrate, only 1.5 L of it become urine.
Define filtration fraction. What is the average for the filtration fraction? How is this number calculated?
- The volume of plasma that become filtrate.
- About 19% of renal plasma flow rate (renal plasma rate) become filtrate
- If renal plasma fraction is 646.8 mL/min(0.19) = filtrate fraction 123 mL/min
Define renal plasma fraction. What is the average value for renal plasma flow rate? how we get this number?
- Volume of plasma passing through the kidneys per minute (plasma is the part of whole blood that can become filtrate).
- Plasma in whole blood =55%.
- whole blood pass in kidneys (renal fraction) 1,176 mL/mim(0.55) = plasma fraction 646.8
Define renal fraction. What is the average value for renal fraction? How is this value determined?
- Volume of blood moving through the kidneys per minute.
- Portion of average cardiac output = 5,600 mL/min.about 21% (1,176 ml/min) of it passes through the kidneys
What is filtration pressure?
Net filtration pressure (NFT) involve tow opposing
pressures capsule hydrostatic pressure (CHP)
and blood colloid osmotic pressure (BOCP) and causing
pressure glomerular hydrostatic pressure (GHP)
- GHP - CHP - BCOP = NFT
- 50 mm Hg - 15 mm Hg - 25 mm Hg = 10 mm Hg
What will cause the release of small volume of concentrated urine? How about large volume of dilute urine?
- With ADH collcting ducts are permeable to water (cause water retention).That will cause release of small volume of concentrated urine.
- Without ADH, collecting ducts are impermeable to water. That will cause large volume of dilute urine.
How ADH changes the water permeability of the collecting duct?
- ADH come from the blood and bind to special ADH receptors in the collecting duct.
- ADH will cause aquaporin (a vesicle that contain H2O transport channels) to be inserted into the membrane of the collecting duct cells.
- That will allow H2O to be reabsorbed
What overall effects will occur as result of the renin-angiotnsing aldosterone system
- Renin will activate angiotnsing.
- Angiotensing II will initiate the release of aldosterone and ADH.
- Aldosterone will increase the level of Na+ in the blood that will draw H2O to the blood. That will increase blood volume which increase blood pressure.
How does aldosterone affect the kidneys?
increases re-absorption of Na+ and secretion of K+ in the distal convoluted tubule and the collecting duct (aldosteron cause sodium retention)
What enzyme catalyzes the conversion of angiotensin I to angiotensin II?
ACE (angiotensin converting enzyme) release from the lungs.
Which secretion activates angiotensinogen?
Renin secreted by the juxtsglomerular apparatus activates angiotensinogen into angiotensin I
From where angiotensinogen released?
How will secretion and re-absorption of hydrogen and bicarbonate change depending on PH?
- If blood PH is higher then normal range (PH>7.45), we need to secrete HCO3- and reabsorb H+ to lower the PH fo the blood.
- If blood PH is below normal range (PH<7.35), we need to secrete H+ and reabsorb HCO3- to raisee blood PH
Are solutes are secreted or reabsorbed in the distal convoluted tubule? What transport mechanism are used to transport those solutes?
- Na+ can be reabsorbed in exchange to K+ via ion channels controlled by adosterone in response to blood concentration.Also H+ and HCO3- are secreted or reabsorbed as needed to stabilize blood PH level.
How countercurrent multiplication will effect concentration of filtrate?
- Water reabsorbed and solutes are secreted at the descending LOH, so filtration become more concentrated.
- At the thin ascending LOH solute reabsorbed by diffusion.
- At the thick ascending LOH solutes reabsorbed by carrier proteins.
- As result the filtrate in part of LOH near the cortex is very dilute and deep in the medulla is very concentrate.
What structures comprise the urinary system?
- urinary bladder