Urinary Tract Flashcards
what are the layers of the kidneys?
- cortex
- medulla
- pelvis
what does the renal cortex contain?
- glomeruli
- proximal convoluted tubules
- distal convoluted tubules
- medullary rays
what are medullary rays?
collection of loops of Henle and collecting ducts that originate from the nephrons that have their renal corpuscles in the outer part of the cortex
what does the renal medulla contain?
- loops of Henle
- collecting ducts
what is the glomerulus?
tuft of convoluted fenestrated capillaries
what is the glomerulus lined by?
podocytes
what are the 3 layers of the glomerular basement membrane?
- fenestrated capillary endothelial cells
- basement membrane
- foot processes of podocytes
what are podocytes made of and what do they do?
- made of several proteins
- project onto basement membrane, creating a gap where filtrates can pass through
what are the components of the JGA?
- granular cells
- macula densa
- lacis cells
what is the function of the granular cells in the JGA?
- sense blood pressure
- secrete renin in response to low blood pressure
- interact with cells of macula densa
what is the function of the macula densa cells in the JGA?
- regulates tubuloglomerular feedback
- senses NaCl concentration
- if filtration is slow, more sodium is absorbed
- sends signal to reduce afferent arteriole resistance & increase glomerular filtration
- interact with granular cells to cause renin secretion
what does the PCT reabsorb?
- NaCl
- proteins, polypeptides, AAs
- glucose
what is the epithelial lining of the PCT?
simple cuboidal
describe the structure of the PCT
- round central/basal nuclei
- brush border of microvilli at apical end on luminal surface
- lots of mitochondria
what is the epithelial lining of the loops of Henle?
thin segments: simple squamous
thick segments: low cuboidal
what is the function of the DCT?
- regulates acid-base
- regulates sodium levels
how does the DCT regulate acid-base?
- secretes H+
- absorbs HCO3-
via cellular carbonic anhydrase
how does the DCT regulate sodium levels?
exchanges Na+ for K+
mediated by aldosterone
what is the epithelial lining of the DCT?
low cuboidal
what are the similarities between the PCT and DCT?
- cuboidal epithelium
- lots of mitochondria
what are the differences between the PCT and DCT?
- DCT has very few microvilli (=> no prominent brush border)
- DCT is much shorter
what are the functions of the collecting duct and which cell performs each function?
- water reabsorption (principal)
- sodium balance (principal)
- acid-base balance (intercalated)
what are the shape of nuclei in collecting ducts?
round central
what is the epithelial lining of the collecting ducts?
cuboidal
what cells are found in the epithelia of collecting ducts?
- principal cells
- intercalated cells
what are the functions of the principal cells in the collecting ducts?
- respond to aldosterone by exchanging Na+ for K+
- respond to ADH by increasing insertion of aquaporins into apical membrane
what are the functions of the intercalated cells in the collecting ducts?
alpha cells: secrete acid
beta cells: secrete bicarbonate
what is the function of the renal pelvis?
transmits filtrate from nephron to ureter
what type of epithelia lines the renal pelvis?
urothelium
where is urothelium found?
collection and drainage parts of urinary tract
what is urothelium?
multi-layered stratified epithelium
- umbrella cells on surface
- overlies pseudostratified layer of polygonal cells
what are the functions of urothelium?
- tight intracellular junctions prevent passage of urine
- can stretch in 3 dimensions
what is the function of the ureter/
convey urine via peristalsis from kidney to bladder
what is the ureter lined by?
urothelium
describe the structure of ureters
- spiral muscular tube
- loose fibrocollagenous adventitia
what are the layers of the spiral muscular tube in the ureter?
- smooth muscular coat
- inner - longitudinal
- outer - circular
what is the bladder lined by?
urothelium
what are the layers of the bladder?
- lamina propria
- muscularis mucosa
- submucosa
- muscularis propria
- subserosa
- serosa
where is the muscularis propria most easily discerned in the bladder?
bladder neck
what creates the valve in the bladder?
passage through muscularis propria
how long is the urethra in females?
4-5cm
what is the female urethra lined by?
proximally - urothelium
distally - non-keratinising stratified squamous epithelium
what glands open into the female urethra?
paraurethral and periurethral glands
how long is the male urethra?
20cm
what are the divisions of the male urethra and what are they lined by?
prostatic: urothelium
membranous: urothelium
penile:
- proximally: pseudostratified
- distally: stratified squamous
describe the blood supply to the kidney
- abdominal aorta
- renal (L1)
- anterior & posterior segmental
- interlobar
- arcuate
- interlobular
- afferent arterioles (feed into glomerulus)
describe the passage of blood leaving the glomerulus
- efferent arteriole
- peritubular capillaries
- vasa recta
- renal veins
- inferior vena cava
