Lecture 41 and 42: Urinary Microanatomy I and II Flashcards
2 layers of kidney capsule
outer
inner
what is the capsule of kidney continuous with
connective tissue of walls of calyces and renal pelvis
which layer of kidney capsule is adjacent to parenchyma
inner layer
capsule outer layer: features and function
fibroblasts, collagen
protection
capsule inner layer: features and function
myofibroblasts
contractibility, aid in resisting volume and pressure variations
2 components of kidney parenchyma
cortex
medulla
what 2 structures make up medulla
renal pyramids
renal columns
renal pyramid
pyramidal tissue masses within medulla
renal columns: definition and function
spaces in between renal pyramids
where blood vessels pass through
renal lobe: 2 components
renal pyramid + adjacent renal cortex and column tissue (cortical region)
each lobe drains into
1 minor calyx
renal papilla
pyramid projection into minor calyx
area cribosa
surface of papilla with openings of papillary ducts
path of urine from kidney to bladder
minor calyx –> major calyx –> renal pelvis –> ureter
functional unit of kidney
nephron/uriniferous tubule
uriniferous tubule: 2 components
nephron + collecting duct
2 tubules in nephron
proximal
distal
each tubule is divided into 2 regions
straight
convoluted
what 3 structures make up the loop of henle
straight region of proximal tubule
straight region of distal tubule
thin loop of henle
what structures make up the renal tubule
straight and convoluted regions of both proximal and distal tubules
thin loop of henle
which nephron structure is not included as part of the renal tubule
renal corpuscle
renal corpuscle function
filter blood in capillaries –> form ultrafiltrate in urinary space
2 components of renal corpuscle
glomerulus
glomerular/bowman’s capsule
2 features of glomerulus
-renal corpuscle
-fenestrated capillary bundle
-afferent and efferent arteriole
2 layers of glomerular capsule
parietal
visceral
epithelium of parietal layer: glomerular capsule
simple squamous
visceral layer: glomerular capsule
layer of podocytes that covers glomerulus
pedicels
secondary processes that interdigitate
foot processes that extend from podocytes and wrap themselves around capillaries of glomerulus to form filtration slits
what forms filtration slits: glomerular capsule
pedicels
2 specialized cells in renal corpuscle
mesangial cells
podocytes
mesangial cells: definition and functions
modified smooth muscle cells
secrete extracellular matrix (mesangium) for support
regulate glomerular distension (contraction)
keep glomerular filtration apparatus clean from filtration residues
3 components of glomerular filtration apparatus
glomerular endothelium
glomerular basement membrane
podocyte filtration slits
what kind of capillaries are found in glomerular epithelium
fenestrated
glomerular basement membrane features
thick basal lamina with collagen, laminin, fibronectin, entactin
podocyte filtration slits definition
filtration slit diaphragm
zipper like frame of nephrin and adhesion proteins
glomerular filtration apparatus: contributions of each region
fenestrations = size selective filter
basal lamina = physical barrier and ion selective filter
filtration slit diaphragm = size selective filter
Proximal tubule of kidney: functions
Reabsorption of ions and fluid
Secretion of calcitriol
Calcitriol
Increases Ca+ uptake and concentration in blood
Secreted in proximal tubule of kidney
Convoluted/straight regions of proximal tubule: histology
Simple cuboidal epithelium
Microvilli brush border
Lateral and basal folds
Many mitochondria, vesicles and lysosomes at basal
Thin loop of henle: functions
Absorption of fluid by countercurrent exchange with vasa recta
Concentrate urine
countercurrent exchange: definition and transport of fluid
Gradient dependent transport of fluid into blood
Lower osmolarity in ultrafiltrate, higher osmolarity in blood plasma —> fluid transport into blood
Occurs in thin loop of henle
Thin loop of henle: epithelium (hint: remember function)
Simple squamous epithelium
Distal tubule of renal tubule: function
Selective secretion and absorption of ions
Osmoregulation of distal tubule : secretion vs absorption
Secretion to ultrafiltrate if high concentration of ions in blood
Absorption if low concentration of ions in blood
What ion is juxtaglomerular apparatus specific to
Sodium
Juxtaglomerular apparatus functions
sensor that helps maintain sodium homeostasis and regulates blood pressure
Where is juxtaglomerular apparatus located
Distal tubule of renal tubule
Distal tubule: histology
Simple cuboidal epithelium
No clear cell borders
Many mitochondria
Proximal vs distal tubule: epithelium difference
Proximal = simple squamous
Distal = simple cuboidal
blood supply kidney
renal artery and vein
2 arterioles in kidney
afferent
efferent
afferent arteriole: blood flow
from renal artery to glomerular capillaries
efferent arteriole: blood flow
from glomerular capillaries to cortical and medullar capillaries
efferent arteriole: function
nourish cortical and medullary tissue
efferent arteriole: 2 types of capillary networks
peritubular cortical
peritubular medullary
efferent arteriole: peritubular cortical capillary network
reabsorption of ultrafiltrate in cortex
endothelium secretes erythropoietin
erythropoietin: function
increase rate of production of RBCs in response to falling levels of oxygen in tissues
efferent arteriole: peritubular medullary capillary network
vasa recta for countercurrent exchange
in thin henle loop
where is erythropoetin secreted
endothelium of peritubular cortical capillary network within efferent arteriole of kidney
2 components of juxtaglomerular apparatus
macula dense
juxtaglomerular cells
juxtaglomerular cells functions (2)
monitor sodium concentration in blood
secrete renin
macula densa function
monitor sodium concentration in ultrafiltrate
secrete ATP, adenosine, NO and prostaglandins to stimulate juxtaglomerular cells
when do juxtaglomerular cells secrete renin
low concentration of sodium in blood
when does macula dense stimulate juxtaglomerular cells
low concentration of sodium in ultrafiltrate
renin function/effects (renin-angiotensin aldosterone system)
increase reabsorption of sodium = fluid transfer from tissues to blood = greater blood volume
increases blood pressure
collecting duct of kidney: function
conduct urine into minor calices
3 regions of collecting ducts
cortical collecting duct
medullary collecting duct
papillary duct
cortical and medullary collecting ducts: epithelium
cuboidal epithelium
2 types of cells found in kidney collecting ducts
light cells
dark cells
collecting duct light cells: stimulated by, function
stimulated by ADH (antidiuertic hormone)
provide water permeability
collecting duct dark cells: function (general)
acid base balance
dark cells response when blood is too basic
secrete carbonate into urine to decrease pH
dark cells response when blood is too acidic
secrete H+ to increase pH
papillary duct: epithelium
columnar
are light or dark cells more predominant
light
location of papillary ducts
distal
toward papillary tip
2 regions within outer medulla
thin stripe
thick stripe
2 types of nephrons
juxtamedullary
cortical
juxtamedullary nephron: appearance, function
long looped
performs most urine concentration
cortical nephrone: appearance, function
short looped
performs most filtration/absorption
microanatomy of urinary passages (mucosa, etc)
mucosa: transitional epithelium
lamina propria: fibroelastic CT
muscularis: smooth and CT, peristalsis
adventia: peritoneum
transitional epithelium in urinary passages aka
uroepithelium
uroepithelium: features, specialized cells
stratified
surface cells, intermediate cells, basal cells
-highly distensible
impermeable to water and salts
what structure makes uroepithelium impermeable to water and salts
urothelial plaques
urothelial plaques definition
lipid layer on surface of superficial cells
uroepithelial surface cells: function
secrete lipids/urothelial plaques to make epithelium imermeable to water and salt
surface cells location
apical surface of epithelium
distended vs undistended lumen: uroepithelium
distended: cells flattened (bladder empty)
undistended: cells are round and bulge into lumen (bladder full of urine)
what muscle is found in muscularis layer of urinary bladder
detrusor muscle
rugae in bladder: function
folds that give bladder distensible property
which layer of bladder is rugae located
mucosa
3 male urethras
-prostatic
-pelvic
-penile
prostatic vs pelvic vs penile urethra: epithelium
prostatic: transitional
pelvic: stratified/pseudostratified columnar
penile: stratified squamous nonkeratinized
female urethra is divided into ________ regions
2
2 regions of female urethra
initial segment
terminal segment
initial vs terminal segment of female urethra: epithelium
initial: transitional
terminal: stratified squamous nonkeratinized
paraurethral mucus glands: definition and function
open to urethra of both males and females
lubrication and protection
where does filtration occur within renal corpuscle
glomerulus
where is urinary space within renal corpuscle
bowman’s capsule