urinary system Flashcards
endocrine function of urinary system?
secretion of renin and EPO, and conversion of steroid prohormone vitamin d to active form
what is the function of renin?
regulation of blood pressure
what is the function of erythropoietin?
stimulates erythrocyte production in bone marrow
active form of vitamin D?
1,25-dihydroxyvitamin D3 or calcitrol
hilum
located at concave medial border of kidney. where nerves, blood, and lymph vessels pass and ureter exits
renal pelvis?
where ureter expands at hilum and divides into 2-3 major calcyes that branch into minor calcyes
outer cortex of kidney?
mostly renal corpuscle and tubule cross sections
medulla of kidney?
mostly linear tubules and ducts
renal pyramid
attached to each minor calyx. 8-15 conical shaped region of medulla where bases meet at cortex
what separates the renal pyramids?
renal columns which are extensions of the cortex
what makes up a renal lobe?
each pyramid, upper cortex, and surrounding renal column
renal papilla
tip of each pyramid that projects into a minor calyx and collects urine by tubules in one renal lobe
medullary rays
straight tubules and collecting ducts from the medulla that extend into the cortex
what is the fundamental, structural, and functional unit of the kidney?
nephron
what are the two parts of a nephron?
renal corpuscle and a tubule system
renal corpuscles
extend from vascular pole. found only in cortex. and consist of glomerulus and Bowman’s capsule
gomerulus
large tuft of FENESTRATED capillaries
what does the vascular pole consist of?
afferent and efferent arterioles
tubule system
leads from renal corpuscle at urinary pole to PCT to PT to loop of henle w hairpin turn to ascend back to DT to DCT to collecting tubules to collecting ducts
PCT
proximal convoluted tubule. originates from urinary pole and twists and curves through cortex. simple cuboidal epithelium with long microvilli.
PT
proximal tubule. where PCT straightens out to descend into medulla
loop of henle
PT thins to become simple squamous epithelium that descends further into medulla before taking hairpin turn to ascend back to cortex
DT
distal tubule. where loops of henle thicken and re enters cortex where it begins to twist again. simple cuboidal epithelium.
DCT
in cortex. fewer covolutions than PCT, empties into collecting tubules which merge to form collecting ducts
role of afferent arterioles in the renal corpuscle?
bring blood to glomerulus at vascular pole
what happens after afferent arterioles bring blood to glomerulus at vascular pole?
blood circulates through glomerular capillaries where filtration occurs
what happens after blood is filtered?
exits efferent arteriole at vascular pole.
where does initial plasma filtrate enter the PCT?
urinary pole
what helps to modify the urine in the tubule system?
peritubular capillaries and vasa recta
filtration
allows water and solutes in the blood to leave the vascular space of the capillaries of the glomerulus and enter Bowman’s capsule
secretion
substances move from epithelial cells of the tubules into the lumen, usually after uptake from surrounding interstitum and capillaries (peritubular capillaries and vasa recta)
reabsorption
substances move from the tubular lumen across epithelium into surrounding interstitium and capillaries
what happens to blood in kidneys production of urine?
blood is filtered into an intial glomerular ultra plasma filtrate (“pre urine”) and modified by selective reabsorption and secretion by the cells of the kidney tubules
where does PCT begin?
urinary pole
bowman’s capsule?
double walled epithelial capsule composed of 3 sub parts of parietal layer, visceral layer, and bowman’s space
parietal layer of bowman’s capsule
outermost layer that forms surface of renal corpuscle. consists of simple squamous epithelium.
visceral layer of bowman’s capsule
inner portion of capsule that closely envelops the glomerular capillaries and lined by podocytes
podocytes
epithelial cells that line visceral layer of bowman’s capsule of renal corpuscle. extend primary processes that curve around capillary below
bowman’s space
capsular or urinary space that receives initial plasma filtrate, pre urine fluid filtered through capillary wall and visceral layer
primary processes
give rise to pedicels that are in direct contact with basement membrane of capillary endothelial cells
filtration slits pores
spaces between pedicels
GBM
glomerular basement membrane. between podocytes and endotherlial cells of capillaries. thick membrane made by fusion of podocyte and capillary endothelial cell basal laminae
glomerular filtration barrier components
fenestrated capillary endothelium, thick combined basal laminae, and filtration slit pores between pedicels of podocytes act as a selective size barrier
