111 terms

Chapter 26 The Urinary System (Study Guide)

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glomerular filtration
blood plasma spills out
tubular reabsorption
some items are selectively reabsorbed into the blood
tubular secretion
some blood plasma items are selectively sent out into the tubules
glomerular filtration
the only process of urine that occurs in the renal capsule
glomerular filtration rate
rat at which filtrate collectively accumulates in the Bowman's capsule of each nephron
glomerular filtration rate
125 ml/min (180 liters/day)
glomerular filtration, tubular reabsorption and tubular secretion
processes that form urine
glomerular hydrostatic pressure
blood pressure in the glomerulus
glomerular hydrostatic pressure
promotes filtration
glomerular osmotic pressure
inhibits filtration
glomerular osmotic pressure
This pressure is created as a result of the movement of water and solutes out of the glomerular capillaries, while protein and blood remain
glomerular osmotic pressure
This decreases the concentration of water in the glomerulus and promotes the return of water to the glomerulus by osmosis
capsular hydrostatic pressure
inhibits filtration
capsular hydrostatic pressure
This pressure develops as water collects in the Bowman's capsule
capsular hydrostatic pressure
The more water in Bowman's capsule, the greater this pressure
glomerular hydrostatic pressure, glomerular osmotic pressure, and capsular hydrostatic pressure
characteristics which enhance filtration by the glomerulus
renal autoregulation, neural regulation, and hormonal control
types of regulation for the GFR
renal autoregulation
the ability of the kidney to maintain a constant GFR even when the body's blood pressure fluctuates
renal autoregulation
this is accomplished by cells in the juxtaglomerular apparatus that decrease or increase secretion of a vasoconstrictor substance that dilates or constricts, respectively, the afferent arteriole.
neural regulation
occurs when vasoconstrictor fibers of the sympathetic nervous system constrict afferent arterioles
neural regulation
this stimulation may occur during exercise, stress, or other fight-or-flight conditions and results in a decrease in urine production
hormonal control
accomplished by the reninangiotensinogen mechanism
reninangiotensinogen mechanism
When cells of the juxtaglomerular apparatus detect a decrease in blood pressure in the afferent arteriole or a decrease in solute (Na+ and Cl−) concentrations in the distal tubule, they secrete the enzyme rennin, this occurs during hormonal control.
proximal convoluted tube (PCT):
largest amount of solute and water reabroption from filtered fluid occurs here
65%
PCT reabsorbs ________of the filtered water, Na and K
100%
PCT reabsorbs ________most filtered organic solutes such as glucose and amino acids
50%
of the filtered urea (phosphate)
H+ ions,
PCT secretes a variable amount of
ammonium ions (NH4) and urea
PCT secretes a variable amount of
Na+
most solute reabsorption in the PCT involves
symport and antiport mechanisms
Na+ transport occur where in the PCT
glucose
Na+ glucose symporter transport what via the apical membrane
symporters
glucose, carbon dioxide, chloride, potassium, calcium magnesium, urea and water are transported via the apical membrane how
apical membrane of PCT
where are symporter located that transport nutrients
synports and antiport mechanisms
how do Na+ ions transport
osmosis of water
solute reabsorption in proximal convoluted tubules promotes
osmotic gradient
reabsorbtion of the solutes creates an
reabsorbtion of water via osmosis
osmotic grandient caused by reabsorption of solutes promotes
isotonic
at end of PCT tubular fluid is__________ to blood.
glucose
reabsorption through PCT is100%
carbon dioxide
reabsorption through PCT is 80-90%
chloride
reabsorption through PCT is 50%
potassium
reabsorption through PCT is 65%
calcium
reabsorption through PCT varies
magnesium
reabsorption through PCT is varies
urea
reabsorption through PCT is 50%
water
reabsorption through PCT is 65%
glucose
reabsorbs throught PCT via facilitated diffusion
carbon dioxide
reabsorbs throught PCT via facilitated diffusion
chloride
reabsorbs throught PCT via diffusion
potassium
reabsorbs throught PCT via diffusion
calcium
reabsorbs throught PCT via diffusion
magnesium
reabsorbs throught PCT via diffusion
urea
reabsorbs throught PCT via diffusion
water
reabsorbs throught PCT via osmosis
antiporters
hydrogen ions are secreted by the apical membrane of the PCT how
20-30%
reabsorption by the apical membrane of cells of the ascending limb of loop of Henle for sodium is
35%
reabsorption by the apical membrane of cells of the ascending limb of loop of Henle for chloride is
20-30%
reabsorption by the apical membrane of cells of the ascending limb of loop of Henle for potassium is
water
reabsorbtion occurs in descending limb of loop of Henle
osmosis
water is reabsorbed in loop of Henle via
symporters in ascending limb
sodium is reabsorbed in loop of Henle via
symporters in ascending limb
chloride is reabsorbed in loop of Henle via
symporters in ascending limb
potassium is reabsorbed in loop of Henle via
sodium potassium pump and sodium channels stimulated by aldosterone
how is sodium reabsorbed by the principal cells in the last part of the DCT and collecting duct
1-4%
sodium reabsorption in DCTand collecting ducts
leakage channels
K+ reabsorbtion by principal cells in the last part of the DCT and collecting duct occurs where
5-9%
water resorption in DCTand collecting ducts
angiotensin II
triggered by low blood volume or low blood pressure
angiotensin II
stimulates activity of Na+ / H+ antiporters in proximal tubule cells
angiotensin II
increases reabsorption of Na+ other solutes, and water which increases blood volume
aldosterone
triggered by increased angiotensisin II level and increased level of plasma K+ promote release of aldosterone by adrenal cortex
aldosterone
stimulates activity of sodium-potassium pumps in basolateral membrane and Na+ channels in apical membrane of principal cells in collecting duct
aldosterone
increases secretion of K+ and reabsorption of Na+, Cl-; increases reabsorption of water, which increase blood volume
blood volume
aldosterone increase secretion of K+ and reabsorption of Na+, Cl, increases reabsorption of water which increase
ADH
triggered by increased osmolarity of extracellular fluid or decreased blood volume, promotes release of ADH from the posterior pituitary gland
ADH
stimulates insertion of water channel proteins (aquaporin-2) into the apical membranes of principal cells
ADH
increases facultative reabsorption of water, which decreases osmolarity of body fluids.
ANP
triggered by stretching of atria of heart stimulates secretion of ANP
ANP
suppresses reabsorption of Na+ and water in proximal tubule and collecting duct; also inhibits secretion of aldosterone and ADH
ANP
increases excretion of Na+ in urine (natriuresis); increases urine output (dieresis) and thus decreases blood volume
dieresis
decrease of urine output
natriuresis
increase of urine output
parathyroid hormone
triggers decreased level of plasma calcium promotes release of PTH from parathyroid glands
parathyroid hormone
stimulates opening of calcium channels in apical membranes of early distal tubule cells
parathyroid hormone
increases reabsorption of calcium
ADH
control whether dilute urine or concentrated urine is formed
dilute
in the absence of ADH urine is very
reabsortion
high level of ADH stimulates __________ of more water into blood producing a concentrated urine
concentrated
high level of ADH in urine
increases
when dilute urine is being formed the osmolarity of the fluid in the tubular lumen
decreases
as dilute urineflows down the descending limb of the loop of Henle the osmolarity
decreases
as dilute urine flows up the ascending limb the osmolarity _______even more as it flows through the rest of the nephron and collecting duct.
concentrated urine
when water intake is low or water loss is high such as heavy sweating, the kidneys musct conserve eater while still eliminating wate and excess ions this will produce
ADH
the kidneys produce a small volume of highly concentrated urine under the influence of this
300mOsm/liter
osmolarity of flomerular filtrate
urine
this can be four times more concetrated than blood plasma or glomerular filtrate
osmotic gradient of solutes in the interstitial fluid of the renal medulla
the ability of ADH to cause excretion of concentrated urine depends on the presence of
sodium, chloride, and urea
the three major solutes that contribute to high osmolarity in the renal medulla are
building and maintaing osmotic gradient
difference in solute and water permeability and reabsorption in different sections of the long loops of Henle and colllecing ducts are responsible for
building and maintaing osmotic gradient
the countercurrent flow of fluid through tube-shaped structures in renal medulla are responsible for
countercurrent flow
refers to the flow of fluid in opposite directions
concurrent flow
the flow of tubular fluid throguh the descending and ascending limbs of the loop of Henle and the flow of blood through the ascending and descending parts of the vasa recta are and example of
multiplication and exchange
two types of countercurrent mechanism exist in the kidneys name them
kidneys
multiplication countercurrent mechanism is located where
kidneys
exchange countercurrent mechanism is located where
BUN
test that measures the blood nitrogen that is part of the urea resulting from catabolism and deamination of amino acids.
rise steeply
when glomerular filtration rate decreases severly as may occur with renal disease for obstructionof the urinary tract Bun may
minimize protein intake
one way to treat paitens with a high BUN result is to
poor renal function
a creatinine level above 1.5 mb/dL is an indication
renal plasma clearance
the volume of blood that is cleaned or cleared of a substnce per unit of time