Urinary System Part 1 Flashcards
what is the urinary system the principle organ responsible for? (3)
water and electrolyte homeostasis
osmoregulation
acid-base balance
primary function of the urinary system
excretion of toxic and metabolic waste products, especially urea and creatinine
urea & creatinine are
nitrogen containing compounds from metabolism of proteins
urea
1’ nitrogenous waste product in mammals
— is soluble, — is insoluble
urea
uric acid
BUN
blood urea nitrogen
BUN includes (4)
urea creatinine uric acid ammonia etc
the urinary system is responsible for (2) of various drugs (eg. abx)
metabolism and excretion
Kidneys synthesize — & maintain normal bp via —
renin
reninangiotensin-aldosterone system
— produced by kidney
Erythropoietin
erythropoietin stimulates
rbc production (erythropoiesis)
Vit D converted from inactive to active form by (2)
liver &
kidney
Kidneys are — organs with fibrous connective
tissue capsule
retroperitoneal
Blood vessels & ureters enter/ exit at —
hilus
Each kidney supplied by
renal A
renal A branches to form (4)
interlobar Aa,
then arcuate Aa,
then interlobular Aa,
which give off affarent arterioles to glomeruli
Kidney divided into
outer cortex & inner medulla
Cortex contains mostly (2)
renal corpuscles & convoluted tubules
Medulla contains mostly (3)
loops of Henle, collecting tubules & collecting ducts
— epithelium unique to urinary tract
Transitional
Transitional epithelium
varying # of layers—
stratified, cuboidal to polygonal, with scalloped outline (= “umbrella cells”)
transitional epithelium is highly —
distensible
transitional epithelium allows for changing
urine volumes
Functional unit of kidney is the —, ~1 million/ each human kidney
nephron
what is the nephron embryologically derived from?
nephrogenic blastema, part of developing urogenital ridge
3 types of nephrons
cortical/subscapular
juxtamedullary
intermediate
3 major types of nephrons are based on
location in the cortex
cortical or subcapsular nephrons— (2)
located. ..
have. ..
located in outer rim of cortex
have short loops of Henle
juxtamedullary nephrons— (2)
location. ..
have. ..
adjacent to medulla;
have long loops of Henle
intermediate nephrons—(2)
location. .
have. .
in middle of cortex;
have intermediate length loops of Henle
two major components of nephrons
renal corpuscle & renal tubule
Renal corpuscle function
filters blood plasma
renal tubule function
collects filtrate
Each renal corpuscle has 2 components—
Bowman’s capsule & glomerulus
Capsule—
single layer of squamous epithelial cells resting on basement membrane (= parietal layer)
what does the capsule form?
hollow, dilated end of proximal convoluted tubule, surrounding glomerulus
Parietal layer continues onto glomerulus as
visceral layer
Cells of visceral layer highly modified, called —
podocytes
Space between visceral and parietal layers is
Bowman’s space
Bowman’s space— (2)
collects…
empties into..
collects glomerular filtrate, empties into renal tubule
Glomerulus—
Network of densely packed, anastomosing, fenestrated capillaries
Glomerulus is supplied by (2)
afferent and efferent arterioles
Blood plasma passes through several cell
layers to become
filtrate
filtrate—
water & small molecular weight molecules filtered from blood into Bowman’s space
First layer of glomerulus consists of (2)
capillary endothelial cells of glomerulus & glomerular basement membrane
Luminal surface of capillary endothelium negatively charged due to surface layer of
glycoprotein, podocalyxin
glycoprotein, podocalyxin sets up — charged barrier, prevents loss of
—, large protein molecules
negatively
anions
Glomerular basement membrane acts as (2)
physical barrier & ion-selective filter
Space between capillary basement membrane & second layer of cells
(podocytes)—
subpodocyte space
Podocytes surround glomerular capillaries, possess cytoplasmic extensions known as
foot processes
Long 1’ foot processes give off
short 2’ foot processes (= pedicels)
Spaces between processes are
filtration slits— ~40 nm in diameter
filtration slits contain — —, made of the protein
slit diaphragms
nephrin
slit diaphragms act as additional barrier, function to restrict passage of (4)
large macromolecules (MW > 69K),
proteins,
negatively charged molecules,
blood cells
Podocytes have — function & can remove trapped —
phagocytic
macromolecules
Resultant glomerular — passed to renal tubule
ultrafiltrate
Renal tubule length
~55 mm long in humans
4 distinct zones of Renal tubule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule
- Collecting tubule/duct
each distinct zone has different — —, starts at — —-
physiological function
Bowmans capsule
renal tubule is lined by
simple, cuboidal epithelium
Filtrate produced at rate of ~— ml/min in humans
120
1’ function of renal tubules —selective resorption of (3) from glomerular filtrate
water, inorganic ions (Na & bicarbonate), large molecules (e.g., AA’s, proteins, glucose)
Concentration of — products in renal tubules
waste
e.g., urea, creatinine, excess H+ & K+
Proximal convoluted tubule is confined to
cortex
Proximal convoluted tubule is the primary site of
water resorption;
resorbs ~75% of water & ions (Na, Cl) from filtrate
Proximal convoluted tubule are facilitated by
aquaporins
aquaporins
integral proteins forming specialized pores or channels for transport of H2O in brush border of epithelial cells
Proximal convoluted tubule also reabsorbs all (3)
proteins
AA
sugars (glucose)
brush border
Simple cuboidal epithelium with apical microvilli
brush border is a characteristic of
proximal convoluted tubule
4 parts of the loop of henle
- pars recta (thick descending limb)
- thin descending limb
- thin ascending limb
- thick ascending limb
Bulk of loop extends into —; — length
medulla
variable
Thin limbs are long in — nephrons & short in — nephrons
juxtamedullary
cortical
Thin limb has — — epithelium; thick limb has — — epithelium
simple squamous
simple cuboidal
Pars recta has brush border of
apical microvilli
Loop of Henle surrounded by peritubular capillary network,
vasa recta
Countercurrent multiplier functions to
generate high osmotic pressure in ECF of renal medulla
via Na-K pumps in thick ascending limb of loop of Henle
Higher extracellular [Na] in medulla combined with water resorption by
proximal convoluted tubule in cortex
Higher extracellular [Na] in medulla combined with water resorption by
proximal convoluted tubule in cortex results in
cortico-medullary interstitial gradient
cortico-medullary interstitial gradient produces
counter current (exchange) multiplier system of urine concentration
counter current (exchange) multiplier system of urine concentration—results in production of
hypertonic urine
