Chapter 24 - Urinary System Flashcards
Primary functions of the US
formation of urine through filtration of blood
functions of urine
excretion of metabolic waste, regulation of blood volume, osmolarity, and pH balance
main type of metabolic waste secreted by urine
nitrogenous waste
functions of Kidney
filter blood, form urine, secrete erythropoietin, calcitriol synthesis, detoxification of free radicals
function of ureters
transport urine to urinary bladder
urinary bladder function
stores urine
urethra funciton
excretes urine from the urinary bladder
erythropoietin
hormone that stimulates erythropoiesis: RBC formation
calcitriol synthesis
active formation of vitamin D that raised blood calcium
free radicals
atoms with an unpaired electron that are highly reactive and destructive
example of free radical
oxygen radical
nitrogenous waste
toxic metabolic waste through which excess nitrogen is created in the body
types of nitrogenous wastes
Ammonia, Urea, Uric Acid, Creatine
Ammonia chemical formula
NH3
Urea Chemical formula
CO(H2)2
ammonia is produced from
amino groups during protein breakdown
urea is produced from
ammonia by the live
uric acid is produced from
the breakdown of nucleic acids
creatine is produced from
the breakdown of creatine phosphate
blood flow through the kidney arteries
abdominal aorta, renal artery, segmental arteries, interlobar arteries, arcuate arteries, cortical arteries, afferent arteriole, efferent arteriole
renal arteries
enter the kidney and branch into the segmented arteries
segmented arteries
branch into interlobar arteries
interlobar arteries
pass through renal columns and branch into arcuate arteries
arcuate arteries
lie at the corticomedullary junction
corticomedullary junction
the border between the renal cortex and medulla that branch into cortical radiate arteries
cortical radiate arteries
move into the cortex and branch into afferent arterioles
afferent arterioles
form the glomerulus capillary bed
efferent arteriole
emerges from the glomerulus and branches into the peritubular capillaries or vasa recta
the kidney veins are the same as the kidney arteries except for
there are no segmental veins
renal fibrous capsule
external layer that encloses and protects the kidney
the renal fibrous capsule is composed of what type of tissue
collagen fiber
renal parenchyma
granular tissue that forms urine and encircles
renal sinus
cavity near the medial aspect of the kidney
regions of the parenchyma
cortex and medulla
the cortex is ____ and the medulla is _____
superficial, deep
renal columns
extensions of cortical tissue
renal pyramids
composed of nephron loops and collecting ducts
nephron
functional unit of kidney
nephron function
filters blood to form filtrate and concentrate and convert waste into urine
filtrate
filtered blood that enters the nephron
how much filtrate goes through a kidney a day
1.2 million
parts of the nephron
renal corpuscle and renal tubule
renal corpuscle is composed of
the glomerulus capillary bed and glomerulus capsule
function of renal corpuscle
filter blood
the renal corpuscle is found in
the cortex
glomerulus
a cluster of capillaries that delivers blood to the kidney
glomerulus capsule
surrounds glomerulus
layers of the glomerulus capsule
visceral layer, capsular space, and parietal layer
glomerulus visceral layer is made of
cells called podocytes surrounding capillaries
glomerulus capsular space
between layers of glomerulus where filtrate enters corpuscle
the parietal layer of the glomerulus
outer wall of the corpuscle
renal tubule function
forms urine from filtrate
parts of the renal tubule
proximal convoluted tubule, nephron loop, distal convoluted tubule, collecting duct
proximal convoluted tubule receives filtrate from
the Renal corpuscle
the proximal convoluted tubule is found in
the cortex
PCT shape
long and coiled
nephron loop receives filtrate from
the PCT
the Nephron Loop is where
descends into the medulla and is part of the renal pyramids
nephron loop shape
u-shaped
distal convoluted tubule receives filtrate from
the nephron loop
the distal convoluted tubule is found in the
renal cortex
the collecting duct receives urine from
multiple DCTs
function of the DCT
delivers urine into larger urine collecting structures
the collecting duct is located within
the renal pyramid
glomerular filtration
blood is filtered from the glomerulus and forms filtrate
glomerular filtration occurs in
the renal corpuscle
where does tubular reabsorption occur
in renal tubule
tubular reabsorbtion
solutes are removed from filtrate and returned to blood
tubular secretion
additional substances are removed from blood or added to filtrate
tubular secretion occurs in
the renal tubule
water conservation
additional substances are removed from blood or added to filtrate
water conservation occurs in
the renal tubule through the collecting duct
what is the first stage of urine formation
glomerular filtration
special capillary exchange that occurs in glomerular filtration
blood in the glomerulus is filtered and removed substances enter the bowman’s capsule as filtate
filtration membrane is made of
capillary membrane, the basement membrane, and filtration slits
filtration membrane
fenestrations that allow substances out of the capillary
anything smaller than ___ nm can go through the filtration membrane
70 nm
basement membrane
negatively charged membrane between glomerulus and podocytes
what substances can filter through the basement membrane
smaller than 8 nm and neutral or positively charged molecules
filtration slits
spaces between feet processes of podocytes that allow substances into capsular space
substances become filtrate when they pass through what part of the filtration membrane
the filtration slits
filtrate is made of
water, glucose, amino acids, fatty acids, nitrogenous waste, salt
glomerular filtration rate
amount of filtration formed per minute by both kidneys
male average GFR
125 mL/min
female average GFR
105 mL/min
how much human blood is filtered through the kidneys each day
50-60x blood volume filtered per day
what percentage of filtrate is reabsorbed and returned to blood
99%
how much urine is excreted per day
1-2 Liters
what happens when GFR is too high
the filtrate flows fast through the renal tubule, preventing reabsorption, causing dehydration and excess urination
what happens when GFR is too low
waste is not removed from blood or reabsorbed
how is GFR controlled by Glomerular blood pressure?
higher G blood pressure causes high blood hydrostatic pressure, which causes high net filtration pressure, leading to high GFR
does Blood hydrostatic pressure favor filtration or reabsorption
filtration
Blood Hydrostatic pressure is high in the glomerulus because
the afferent arteriole is larger than the efferent arteriole
NFP = BHP - (CP+COP) =
10 mmHg
CP
Capsular hydrostatic pressure
CP favors reabsorption/filtration
reabsorption
COP
blood colloid osmotic pressure
COP favors reabsorption/filtration
reabsorption
renal autoregulation
nephrons adjust their own blood flow
myogenic mechanism
prevents sudden/short term increases in systemic BP from overly increasing GFR
myogenic mechanism tries to
maintain baseline
myogenic mechanism contracts the afferent arteriole smooth muscle when
the smooth muscle is stretched by high blood pressure
sudden increase in systemic BP causes what in the kidneys
1) afferent arterioles stretch due to BP and blood flow surge
2) Arterioles contract and less blood flows to the glomerulus
3) Glomerular BP and GFR lowers back to baseline
tubuloglomerular feedback
glomerulus receives feedback of status downstream tubular fluid and adjusts filtration rate
macula densa
patch of sensory cells in the nephron loop just before the Distal CT
macula densa detects _____ levels in filtrate
NaCl
high NaCl in the Macula Densa causes
high GFR and the macula densa to stimulate the juxtaglomerular cells
juxtaglomerular cells
modified smooth muscle cells wrapping around the afferent arteriole
juxtaglomerular cells constrict if stimulated by ____
the macula densa
vasoconstriction of afferent arteriole causes
less blood flow to the glomerulus, leading to lower glomerular BP, causing lower GFR
sympathetic control of afferent arteriole vasoconstriction
sympathetic innervation and catecholamines from the adrenal medulla
what percentage of filtrate is reabsorbed in the PCT
65%
reabsorbed filtrate in the PCT is sent into
the peritubular capillaries
how is the movement of solutes and water osmosis driven in the PCT
cotransport and active transport of Na+
how much of resting ATP is necessary for filtrate reabsorption in the PCT
6%
what percentage of filtrate is reabsorbed in the nephron loop
25%
the filtrate reabsorbed in the nephron loop is sent into the
nephron loop
what molecules are reabsorbed in the DCT using hormone regulation
water, Na+, Cl-
filtrate reabsorbed in the DCT is sent into the
peritubular capillaries
at what part of the kidney is urine finished being produced
DCT
water conservation and urine concentration occurs in what part of the kidney
the collecting duct
purposes of tubular secretion
acid-base balance, waste removal, clearance of drugs and contaminents
H+ secretion in the renal tubule raises/lowers pH of blood
raises
HCO3 secretion raises/lowers pH of blood
lowers
waste removed through tubular secretion
nitrogenous waste and bile acid
tubular secretion occurs in
the renal tubule, mostly the DCT, but also the collecting duct
how does tubular secretion occur
active transport and diffusion
water conservation in the nephron loop
generates the high osmolarity and salinity of medulla ECF
Is the solute concentration in the nephron loop low/high
high
the deeper into the medulla, the higher/lower the salinity
higher
where does urine concentration occur
collecting duct
urine concentration in the collecting duct occurs through what process
osmosis of water
function of nephron loop
generates high salinity of medulla ECF
the nephron loop receives filtrate from
the PCT
descending limb is the thin/thick segment that ascends/descends into the medulla
thin, descends
the descending limb is permeable to water or salts
water
the ascending limb is the thin/thick segment that descends/ascends in the medulla
thick/ascends toward the cortex
the ascending limb is permeable to water/salts
salts
the ascending limbs delivers filtrate to
the DCT
the countercurrent multiplier multiplies
the medulla ECF salinity
how does fluid move in the countercurrent multiplier
fluid moves the opposite direction of the ascending/descending limbs
as fluid moves through the descending limb, there is an environment of
increasing osmolarity to cause water to leave filtrate
how much filtrate is concentrated at the bottom of the nephron loop
1200 mosm/L
in the ascending limb, more/less salt is pumped out of the ascending limb than water lost from the descending limb
more
is filtrate more or less dilute entering the DCT than leaving the PCT
more
vasa recta
capillaries of the medulla that reabsorb material from the nephron loop
does the vasa recta change the medulla osmolarity
no
the vasa recta reabsorbs equal/different amounts of water and alts
equal
diffusion of molecules from the descending capillaries of the vasa recta
mostly NaCl diffusing into blood and some water diffusing out
diffusion of molecules in ascending capillaries of the vasa recta
same NaCl diffuses out of the blood, mostly water diffuses in
more water reabsorption in the collecting duct causes
more concentrated urine and lower urine volume
after water conservation, how many more times can urine be concentrated
4x
renin-angiotensin aldosterone mechanism
hormonal system that regulated blood pressure in the kidney
the RAA mechanism is regulated by
the nephron reabsorption and GFR
when systemic BP falls, what happens to the hormones that act on the kidney
causes the juxtaglomerular cells to secret Renin
renin
hormone that converts angiotensinogen to angiotensin I
angiotensin converting enzyme converts
angiotensin I to angiotensin II
angiotensin II
potent vasoconstriction hormone that raises blood pressure
effects of angiotensin II at the renal corpuscle
constricts the efferent arterioles more than afferent arterioles
how does angiotensin II prevent a GFR drop
keeps glomerular Blood pressure high
the angiotensin II stimulates the adrenal cortex to secrete
aldosterone
aldosterone
hormone that causes Na+ reabsorption in the DCT
what in the blood does aldosterone raise
blood volume and blood pressure
antidiuretic hormone is produced by ________ and secreted by ______-
hypothalamus, posterior pituitary
function of the antidiuretic hormone
reduces urination and increase blood volume and pressure
antidiuretic hormone makes the collecting duct more/less permeable to water
more
antidiuretic hormone causes more/less water to be reabsorbed by the collecting duct
more
less water in urine means what about the characteristics of urine
lower volume, more concentrated
