Urinary System Flashcards
urinary system consists of…
- paired kidneys
- paired ureters
- bladder
- urethra
endocrine functions of kidney
- secretion of renin
- secretion of erythropoietin (EPO)
- conversion of steroid prohormone vitamin D to active form
function of renin
regulate blood pressure
function of erythropoietin (EPO)
stimulate erythrocyte (RBC) production in bone marrow
kidney
hilum
- concave medial border
- nerves, blood & lymph vessels pass
- ureter exits
at the hilum the ureter expands as the ____
renal pelvis
the renal pelvis divides into 2-3 ____
major calyces
major calyces branch into the ____
minor calyces
the kidney is divided into…
- outer cortex (mostly many renal corpuscle & tubules x-sections)
- inner medulla (mostly linear tubules & ducts
attached to each minor calyx is a ____
renal pyramid (conical shaped region of medulla)
bases of renal pyramids meet the cortex and are separated from each other by ____
renal columns (extensions of cortex)
each pyramid, upper cortex, and surrounding renal column make up a ____
renal lobe
the tip of each pyramid is called a ____
renal papilla
renal papilla
projects into a minor calyx and collects urine by tubules in one renal lobe
parallel ducts & tubules from the medulla that extend into the cortex form ____
medullary rays
what is the fundamental structural & functional unit of the kidney?
nephron
2 parts of the nephron
renal corpuscle
tubule system
renal corpuscle extends from the ____
vascular pole (afferent & efferent arterioles)
renal corpuscles are found…
only in the cortex
renal corpuscle consists of…
- glomerulus (large tuft of capillaries)
- Bowman’s capsule
tubule system leads from renal corpuscle at the ____
urinary pole
PCT straightens into ____ and descends into the ____
proximal tubule (PT)
medulla
PT thins into ____
thin Loop of Henle
Loop of Henle
- descends further, takes hairpin turn
- begins to ascend back to cortex
- simple squamous epithelium
Loop of Henle thickens into ____
distal tubule (DT)
collecting tubules merge to form ____
collecting ducts
renal corpuscle
afferent arterioles bring blood…. at the ____
to the glomerulus at the vascular pole
blood circulates through glomerular capillaries where ____ occurs
filtration
filtered blood exits the ____ at the ____
efferent arteriole at the vascular pole
initial plasma filtrate enters the ____ at the ____
PCT at the urinary pole
what helps to modify urine in the tubule system?
peritubular capillaries in the vasa recta
filtration
allows water & solutes in blood to leave vascular space of capillaries of glomerulus and enter Bowman’s capsule
secretion
substances move from epithelial cells of tubules into lumen, usually after uptake from surrounding interstitium and capillaries (peritubular capillaries & vasa recta)
kidneys are highly ____ organs, receiving…
highly vascular
25% of cardiac output
in production of urine, blood is filtered into initial glomerular ultra ____, and modified by…
- plasma filtrate (pre-urine)
- selective reabsorption & secretion by cells of kidney tubules
vascular pole
afferent arterioles enter
efferent arterioles exit
urinary pole
PCT begins
Bowman’s capsule
double-walled epithelial capsule
glomerulus
tuft of networking fenestrated capillaries
3 sub-parts of Bowman’s capsule
- parietal layer
- visceral layer
- Bowman’s space
Bowman’s capsule
parietal layer
- outermost layer
- formed surface of renal corpuscle
- simple squamous epithelium
Bowman’s capsule
visceral layer
- inner portion
- closely envelops glomerular capillaries
- lined by epithelial cells called podocytes
Bowman’s capsule
Bowman’s space
receives fluid (plasma filtrate/pre-urine) filtered through capillary wall & visceral layer
glomerular function
podocytes
from each cell body, extend primary processes that curve around capillary below
podocytes
primary processes give rise to ____
pedicels (foot processes)
pedicels are in direct contact with…
basement membrane of capillary endothelial cells
spaces between pedicels form ___
filtration slits pores
glomerular basement membrane (GBM)
- between podocytes & endothelial cells of capillaries
- thick membrane made by fusion of podocyte & capillary endothelial cell basal laminae (basement membrane)
filtration occurs through the ____
glomerular filtration barrier
3 parts of glomerular filtration barrier
- fenestrated capillary endothelium
- thick combined basal laminae (GBM)
- filtration slit pores between pedicels of podocytes
filtration slit pore act as a…
selective size barrier
mesangial cells
- cover capillary surface in renal corpuscle not covered by podocytes
- phagocytic
- extend contractile processes along capillaries (regulate glomerular blood flow)
mesangium consists of…
mesangial cells & their ECM
function of mesangium
- structural support to podocytes & capillaries
- maintain optimal filtration rate: adjust contractions in response to BP changes
- phagocytic: remove residues & protein aggregates in GBM, including antibody-antigen complexes
- secretion: cytokines & inflammatory mediators for immune defense & repair of GBM
renal corpuscle is the site of ____
blood filtration
nephron tubules are the site of…
secretion & reabsorption
epithelium of PCT
simple cuboidal with long microvilli and basolateral folds that interdigitate with neighboring cells
PCT epithelial cells help with…
reabsorption & secretion
PCT
reabsorption & secretion are associated with ____
peritubular capillaries
PCT location
- begins at urinary pole, convolutes
- straightens before leaving cortex
- enters medulla as descending limb of proximal tubule
(thin) loop of Henle
function
further adjusts salt & water content of filtrate
thin loop of Henle is associated with ____
capillaries (vasa recta)
DT location
ascends in straight path into cortex, then becomes tortuous as DCT
DCT epithelium
simple cuboidal with short microvilli
as DT approaches afferent arterioles of its nephron, it forms a ____
macula densa
macula densa
- DT cells become narrower, taller & more densely packed
- nuclei appear crowded
- part of juxtaglomerular apparatus (JGA)
function of juxtaglomerular apparatus (JGA)
special sensory structure that helps regulate BP
JGA consists of…
- macula densa
- extraglomerular mesangial cells (lacis cells)
- JG cells
JG cells
- modified smooth muscle cells in tunica media of nearby afferent arteriole
- contain secretory granules containing renin
after the macula densa, the DT becomes the ____
DCT
function of DCT
further electrolyte adjustment
DCTs empty into ____
collecting tubules
epithelium of collecting tubules & ducts
- simple cuboidal transitions to simple columnar in larger collecting ducts
- distinct cell boundaries (“halo” around nucleus)
function of collecting tubules & ducts
final site of H2O reabsorption
papillary duct of Bellini
collecting duct descend through medulla towards apex of each renal pyramid, where several ducts merge near the renal papillae
function of ureters
transport urine from renal pelvis to bladder
mucosa of ureters
- lined by urothelium (transitional): apical umbrella-shaped cells
- supporting LP below epithelium
muscularis of ureters
2 layers of smooth muscle
layers of ureters
- mucosa
- muscularis
- adventitia
function of bladder
distensible reservoir for urine
mucosa of bladder
- lined by urothelium (transitional): apical umbrella-shaped cells
- supporting LP below epithelium
- umbrella cells exhibit dense plaques (uroplakins)
bladder
plaques (uroplakins)
modified area of plasma membrane proteins that protect cells from prolonged contact with urine
muscularis of the bladder
3 layers of smooth muscle called the detrusor muscle
detrusor muscle function
help empty bladder
layers of bladder
- mucosa
- submucosa
- muscularis (detrusor m)
- adventitia
function of urethra
carries urine from bladder to exterior
urethra in males
serves as terminal duct for urinary & genital systems
urethra in females
shorter in length
