kidney Flashcards
what does urinary system consist of
kidneys
ureters
urinary bladder
urethra
describe what urinary system contributes to
excretion- elimination of waste products of metabolism - such as urea
regulation of total body water
regulation of electrolyte balance
endocrine secretion of renin (enzyme) and epo (hormone)- both released in blood stream = endocrine secretion
describe features of kidney
shape - bean shape
concave border - hilum, convex surface = see renal pelvis
renal pelvis = expanded portion of ureter
human kidney is divided in lobes and lobules
describe capsule of kidney
tough ct capsule
describe cortex of kidney
presence of small renal corpuscles and some tubules gives grainy appearance
describe medulla of kidney
striated due to presence of ducts
describe cortico-medullary junction of kidney
limit between cortex and medulla
describe medullary pyramids of kidney
base faces junction and tip = renal papilla
describe medullary rays of kidney
center of renal lobules
describe columns of bertin of kidney
interlobar cortical tissue and ct
between lobes, can find renal corpuscles
describe renal papilla and area cribrosa area of kidney
tip of pyramid = renal papilla and area cribrosa = means they are perforated, ~25 orifices - openings opens into
ma = major calyx and opens into mi = minor calyx - opens into renal pelvis
name 2 parts of uriniferous tubule
nephron
collecting system
describe nephron
each kidney has 1-4 mil
if less than 1 mil = renal insufficiency, need dialysis
name parts of uriniferous tubule
renal corpuscle
pct
loop of henle
dct
describe renal corpuscle (uriniferous tubule)
dilated portion of nephron which contains glomerular tuft of capillaries - in between 2 arterioles, afferent - thicker and efferent - drains all blood from corpuscle - glomerulus
double wall of epithelial cells enclosing glomerular tuft of capillaries
describe pct (uriniferous tubule)
proximal convoluted tubule
acidophilic
then becomes straight
thin then thick again - ascends in medulla
describe loop of henle (uriniferous tubule)
sd = thick descending limn - in medullary ray
tl = thin limb - in medulla
sa = thick ascending limb - in medulla and medullary ray
becomes dct
describe DCT (uriniferous tubule)
distal convoluted tubule
connected to collecting tubules in cortex
becomes collecting duct after junction - changes name
as approach area cribrosa = huge, called papillary ducts of Bellini - lower end, opens at level of area cribrosa
describe bowmans capsule (renal corpuscle)
2 layers =
Parietal = external, squamous cells, reticular fibers, BM
visceral = podocytes, processes interdigitating surrounding capillaries
visceral layer continous with parietal layer at vascular pole
capsular space= between layers
describe vascular pole (renal corpuscle)
entrance of arterioles - macula densa here
AA enters and divides into 5+ capillaries and EA leaves structure
describe macula densa (renal corpuscle)
appears in section, surrounded by cuboidal cells but near afferent = becomes columnar tight joined together
describe urinary pole (renal corpuscle)
part of dct
ultrafiltrate drained through pct
describe hydrostatic pressure (renal corpuscle)
Pressure of liquid agasint wall so high = plasma is filtered betwen processes of podocytes = ultrafiltrate in capsular space
describe afferent arteriole (renal corpuscle)
branches into 5-6 glomerular capillaries - joins or merges into efferent arteriole
1 layer sm cells seen near entrance, looks cuboidal near entrance
Specialized in secreting renin into blood stream - enzymes
describe capillaries (renal corpuscle)
highly fenestrated
rest on bm
describe podocyte
big nucleus, loose delicate chromatin
big primary processes
thin secondary processes = pedicels surrounds capillaries
describe BM (renal corpuscle)
bm shared by pedicels of podocytes and endothelial cells -similar to lung
describe mesangial cells
between adjacent capillaries (glomerular) and under bm
dark nucleus - can confused with endothelial cell
where are some of mesangial cells located
present between afferent and efferent arteriole and are outside renal corpuscle
called extraglomerular mesangial cells
have intra and extra glomerular mesangial cells
name 2 functions of mesangial cells
implicated in phagocytosis of particles, germs and bm
also implicated in structural support of capillaries
produce cytokines
complex cell with many functions
define mesangial cell
mesos = middle and angeion = vessel
located between blood vessels, intra and extra glomerular and under bm
describe what mesangial cells are believed to do
remove pieces of bm that are already clogged with stuff = sends small processes and removes areas where bm has already filtered and then endothelial cells and pedicles make new bm
for efficient filtration
what is plasma filtered through
openings - slits
describe filtration slits
25nm - extremely small gap
note presence of diaphragms = between 2 adjacent pedicels, closed by small diaphragm
negatively charged proteins and proteins greater than albumin, 70,000mw do not pass these pores
if see many proteins = proteineuria = bad
describe medullary ray
straight thick ascending and descending limbs and collecting tubules
describe PCT in detail
60um - cortex
brushborder microvilli - absorption of 85% of proteins, glucose, na, cl,ca and fluids - reabsorbed from ultrafiltrate
apical layer has microvilii - increases absorptive surface
called microvilli in em and brush/striated border in lm
brushborder = can see actin filaments cut in cross section
what does pct secrete
creatinine into lumen
describe PM of pct
central nuclei
cells columnar
rest on bm
acidophilic
folded pm resting on bm = inside folds = mitochondria - cells very active
describe filtrate of pct
ultrafiltrate is isotonic anyways = wont change osmolarity since passive movement of water and ions across apical membrance
folloed by active resabsorption across basolateral membrane via na/k/atpase pump
pump creates gradient
solutes reabsorbed isotonically = osmotic potential of fluid leaving pct is same of initial glomerular filtrate
what does pct have
prominent endocytic apparatus
for endocytosis
desribe thin limb
12um - medulla
easy to confused with capillaries
empty lumen
flat/squamous cells, rest on bm
permits free diffusion of water
thin descending limb permeable to water but entire ascending limb is not - impermeable to water
describe dct - specifics
60um - cortex
cuboidal cell
apical nuclei - almost kissing
larger lumen than pct
infoldings of pm with many mitochondria
na/k atpase = creates gradient out, water out= active pump
basal laterla pm has pump
describe dct - secretions
few microvilli
absorbs na and secretes k
also secrets protons into lumen - H+ and absorb bicarb or vice versa
site of aldosterone action - regulates absorption of sodium by pump - secreted by adrenals and stimulates incorporation of na and cl
what is also expressed in dct
a arginine vasopressin receptor 2
describe uniporter, symporter and antiporter
uni = one molecule one dir
symporter = 2 molecules, same dir
anti = 2 molecules, opp dir
describe loop of henle SD
thick descending limb
found in medullary rays and upper part of medulla - similar to pct
terminal part of pct but structure will be straight
describe loop of henle TL
found in medulla
describe loop of henle SA
found in medulla and medullary rays
similar to dct
ascending limb
longitudinal section in medullary rays
describe permeability of loop of henle
descending = permeable to water
ascending= impermeable to water
upper cortex/medulla = less concentrated in sodium
near area cribrosa = highly concentrated in sodium
ions actively penetrate into inner tissue of medulla
describe permeability of loop of henle - to solutes
Permeable to solutes but na, cl, k are actively transported into medullary space, making filtrate hypotonic and medulla hypertonic
describe collecting tubule
40-50um diameter
found in cortex and medullary rays
cells cuboidal
pale stain
cells bulge into lumen
similar to dct but nuclei are more central
sometimes see lateral pm since membrane thick - visible with lm
describe collecting duct
aka collecting duct of Bellini
200um
large
closer to area cribrosa
papillary
impermeable to water
site of adh action
describe ADH
antidiuretic hormone
vasopressin
makes collecting ducts permeable to water and water is retained
produced by pituitary gland
describe ADH effect when exercise
hot and sweat a lot, urine concentrated, adh secreted, water retained
describe ADH effect when hypertonic tissue of kidney
adh will make it permeable and water will escape from collecting tubule and urine more concentrated
name parts of juxtaglomerular apparatus
juxtaglomerular cells
macula densa
extraglomerular mesangial cells - not shown
describe juxtaglomerular cells of juxtaglomerular apparatus
secretes renin - enzyme
Modified smooth muscle cell of afferent arteriole = become kinda cuboidal cell, epithelial cell and are called juxtaglomerular cells
what do juxtaglomerular cells do
secrete renin - produced by juxtaglomerular cells in kidney
enzyme acts on plasma angiotensin - liver protein
describe conversion of angiotensin
angiotensin –> (10aa) angiotensin 1 –> angiotensin 2 (8aa)
first arrow = enzyme that removes some aa’s and converts
second arrow= endothelial cell, removes 2 aa’s = octapeptide
describe macula dense - production of factors
composed of specialized epithelial cells in the DCT that detects sodium concentration of fluid in tubule
these cells are also involved in production of nitric oxide (NO) & other factors
describe angiotensin 2
stimulates contraction of arterioles and increases blood pressure and stimulates production of aldosterone - by adrenal glands, acts on dct, water & sodium retained= more fluid in blood = higher bp
describe pathway of blood supply - 1
renal artery and vein
hilum = entrance of renal artery (branches) and exit of renal vein
renal artery branches around renal pyramids - small cones
describe pathway of blood supply - 2
interlobular artery and vein (vein - in opposite direction)
interlobular space
forms elbow
describe pathway of blood supply - 3
arcuate artery and vein - located in corticomedullary junctions
describe pathway of blood supply - 4
lobular artery and vein
straight artery then afferent arteriole going to renal corpuscle
where are arcuate arteries and veins located
corticomedullar junction
what merges into efferent arteriole
afferent then glomerular capillaries and then will merge into efferent arteriole=forms capillaries
describe pathway of blood supply - 5
afferent arteriole
describe pathway of blood supply - 6
efferent arteriole - forms peritubular capillaries
describe pathway of blood supply - 7
peritubular capillaries
provides blood and oxygen and nutrients to pct and dct
capillary network in cortex
drains into venules and then lobular veins
describe pathway of blood supply - 8
under capsule there is also a capillary network that together with peritubular capillaries drain into stellate veins
Lobular arteriole will form network under capsule = subcapsular capillary network at end of lobular arteriole = drain into veins = stellate veins
stellate also drains into lobular arteries
what does stellate mean
looks like stars
describe pathway of blood supply - 9
lobular veins
then arcuate vein then interlobar then renal vein
opposite way
describe erythropoietin
produced by peritubular capillaries - cells of cortex and outer medulla, most likely endothelial
glycoprotein that promotes proliferation and differentiation of erythrocyte precursors
major site epo production = kidney while liver is main extra renal site of epo production
if high altitudes = more epo so more rbcs
recombinant epo = bad in sports
what is close to cm junction and medulla and renal corpuscles
juxtamedullary renal corpuscles - close to medulla
describe vasa recta
capillaries that emerge from efferent arterioles of juxtamedullary renal corpuscles and drain into arcuate veins
forms long capillary that will turn = called vasa recta - seen near collecting ducts of bellini
also forms loops and goes parallel to vasa recta of nephrons
where are vasa recta seen
in cross section of medulla
describe concentration of sodium in medulla
high concentration
describe permeability of CD - collecting duct
Normally the cd are impermeable to water
lots of hypertonic material
vasopressin makes the cd permeable to water
name layers of urinary bladder
mucosa
submucosa
tunica muscularis
describe mucosa of urinary bladder
transitional epithelium
lp is loose ct - small
describe submucosa of urinary bladder
denser with collagen and elastic fibers
describe tunica muscularis of urinary bladder
at entrance of ureter has =
inner longitudinal
middle circular
outer longitudinal
cannot see but must know
describe transitional epithelium
basal columnar cells
middle polygonal cells
superficial facet cells = bulging and apical, prominent apical pm and granulations
similar to strat squa non kera but this gas dome cells
when distended = number of layers decrease = stretched out
