Lecture 13 – Review questions Flashcards
what are the 4 main organs of the urinary system?
- kidneys (2)
- ureters (2)
- urinary bladder (1)
- urethra (1)
what are the 3 primary functions of the kidneys? Give examples.
function (1)
synthetic function
kidneys produce:
- erythropoietin
- calcitriol
- renin
what are the 3 primary functions of the kidneys? Give examples.
function (2)
excretion
blood w/ metabolic waste:
metabolic waste products:
- urea
- creatnine
- uric acid
- bilirubin
ingested toxins:
- drugs
- pesticides
what are the 3 primary functions of the kidneys? Give examples.
function (3)
regulation
- water and electrolytes
- acid-base
- arterial BP
what is the functional unit of the kidney responsible for filtering the blood and producing urine?
nephron
what are the 2 major parts of the nephron?
renal corpuscle
renal tubule
what is the renal corpuscle?
part of the nephron
filters the blood plasma
what are the 2 main parts of the renal corpuscle?
Bowman’s capsule
glomerulus
what is the Bowman’s capsule?
cup-shaped hollow structure
completely surrounds the glomerulus
what is the glomerulus, and what is its function?
knot of capillaries wrapped by podocytes
functions as a filter
what is meant by glomerular filtration?
process where water and some solutes in the blood plasma pass from capillaries of the glomerulus into the capsular space of the nephron
where does glomerular filtration take place?
capillaries of glomerulus into the glomerular capsular space
what are the functions of the afferent and efferent arterioles in the kidney?
afferent – enters capsule, brings blood into the glomerulus
efferent – leave the capsule and carries blood away
in which structure does the filtrated blood (filtrate) enter before flowing into the renal tubule lumen?
glomerular capsular space
what is net filtration pressure?
total pressure that promotes filtration
what pressures determine the net filtration pressure (how to calculate it)
forces favoring filtration - forces that oppose it
(GHP) - (GCOP + CHP)
what are the 3 components of the filtration membrane?
1) fenestrated endothelium of the capillary
2) basement membrane of glomerulus
3) filtration slits b/n pedicels
what are the podocytes in the kidney?
are podocytes and pedicels the same?
podocytes – specialized cells of kidney glomerulus
pedicels – foot processes from the podocytes that wrap around capillaries and interdigitate w/ each other
what substances are found in the kidney filtrate?
what should filtrate not contain?
should contain:
- H2O
- free amino acids
- vitamins
- small ions (Na+, K+, Cl-)
- glucose (~1 nm)
- nitrogenous wastes (< 3 nm)
should not contain:
- blood cells
- plasma proteins (e.g. albumin)
what are the body’s main nitrogenous waste products?
indicate their sources
AUUC
1) ammonia
- by-product of protein catabolism
- toxic, converted to urea in the liver
2) urea
- by-product of protein catabolism
3) uric acid
- produced by the catabolism of nucleic acids
4) creatinine
- breakdown product of creatine
what is meant by glomerular filtration rate?
amount of filtrate formed per min by the 2 kidney combined
what is a normal GFR for males and females?
males – 125 mL/min (180 L/day)
females – 105 mL/min (150 L/day)
is it better for GFR to be high or low?
how about too high?
when GFR too low –> fluid flows sluggishly thru renal tubules –> reabsorb wastes that should be eliminated in the urine
when GFR too high –> fluid flows thru the renal tubules too rapidly for them to reabsorb water and solutes –> dehydration and electrolyte depletion
which are the 2 intrinsic autoregulation mechanisms for maintaining GFR?
1) myogenic mechanism:
- based on tendency of smooth muscle to contract when stretched
when BP too high: vasoconstriction of afferent arteriole
when BP too low: vasodilation of afferent arteriole
2) tubuloglomerular feedback:
- uses the juxtaglomerular apparatus – to maintain GFR and efficient sodium reabsorption
what is the difference b/n intrinsic vs. extrinsic regulation of GFR?
intrinsic:
- intra-renal
- responses are local
- initiated and maintained by kidneys
- directly regulate GFR despite moderate changes in BP
- goal – maintain a nearly constant GFR over a wide range of MAP
extrinsic:
- extra-renal
- responses are system-wide and require transport in bloodstream
- neural and hormonal responses
- act to prevent damage to the brain and other crucial organs
- indirectly regulate GFR by maintaining systemic BP
- goal – maintain blood volume and pressure
what is the main goal of the intrinsic control of the GFR?
maintain nearly constant GFR over a wide range of MAP
what is the main goal of the extrinsic control of the GFR?
maintain blood volume and pressure
how does myogenic response regulate the glomerular filtrate rate?
based on tendency of smooth muscle to contract when stretched
high BP == increased tension in vascular wall == vascular smooth muscle contracts
low BP == low tension in vascular wall == vascular smooth muscle relaxes
considering the myogenic mechanism, how does the afferent arteriole react to increased or decreased blood pressure?
when BP is too high == GFR is too high –> constricts afferent arteriole –> lowers GFR to normal
when BP is too low == GFR is too low –> dilate afferent arteriole –> raises GFR to normal
how do changes in the afferent arteriole’s diameter affect the GFR?
vasoconstriction == lowers afferent arteriole’s diameter == lowers GFR
vasodilation == raises afferent arteriole’s diameter == raises GFR
what are the 3 components of the juxtaglomerular apparatus, and where are they located?
1) macula densa – line the tubule walls
2) mesangial cells – located in inter capillary space
3) granular cells – wrap around the afferent arteriole
how does the juxtaglomerular apparatus regulate the GFR? (Role of ATP and adenosine, indicate cell source)
when GFR too high == juxtaglomerular apparatus constricts afferent arterioles
MaMeG
macula densa sense tubule [NaCl] –>
when GFR is high –>
macula densa cells secrete ATP –>
mesangial cells metabolize ATP to adenosine –>
granular cells constrict afferent arteriole (Vc) [JG cells also release renin] –>
lowers GFR
where is angiotensinogen produced?
liver
continuously circulates in plasma
what does ACE stand for?
angiotensin-converting enzyme
where is ACE produced?
lungs and kidneys
(in their vascular endothelium)
what is renin, and where is it produced?
hormone enzyme that allows production of angiotensin protein
produced by the juxtaglomerular cells in the kidneys
what is another name for granular cell?
juxtaglomerular cell
when is renin released? (high BP or low BP?)
low BP == low GFR
once angiotensin-II is released –> vasoconstriction –> raises blood
which enzyme converts angiotensinogen into angiotensin-I?
renin
which enzyme converts angiotensin-I into angiotensin-II?
ACE
(angiotensin-converting enzyme)
is angiotensinogen active or inactive?
inactive protein
which effect does angiotensin-II have on the afferent arteriole’s diameter?
and in systemic blood vessels?
vasoconstriction of afferent arteriole
vasoconstriction of efferent arteriole
vasoconstriction of systemic blood vessels
does angiotensin-II promote the reabsorption or the excretion of Na+ in the urine? How?
promotes reabsorption of Na+ and Cl- from the proximal tubule by stimulating the Na+/H+ antiport
what is the order in which fluid flows thru the kidney? (from the glomerulus to the renal pelvis)
(0) glomerulus
(1) proximal convoluted tubule
(2) loop of Henle
(3) distal convoluted tubule
(4) collecting duct
(5) papillary duct
(6) minor calyx
(7) major calyx
(8) renal pelvis
what is a major calyx made of?
minor calyces
