Urinary System Part 2 Flashcards
Distal convoluted tubule is a continuation of
thick ascending limb of Loop of Henle
Distal convoluted tubule is present within the
cortex
Distal convoluted tubule is lined with
simple cuboidal epithelium with short apical microvilli
what does the DCT lack?
distinct brush border
DCT is responsible for (2)
active resorption of Na and Cl
secretion of H and K ions
DCT is controlled by 2 cell types
principal cells
intercalated cells
principal cells—resorb (2), secrete (1)
Na & water
K
• intercalated cells—resorb (1), secrete (1)
K
H
DCT is controlled by
aldosterone (adrenal mineralcorticoid)
collecting tubule is the — portion of nephron
terminal
several tubules converge to form larger
collecting duct
collecting tubule is visible as — —, lined with
medullary rays
thick, simple cuboidal to columnar epithelium
collecting tubule converge at
renal papilla
Collecting tubule function in (3)
Na resorption,
maintenance of acid-base balance,
K secretion & resorption
Collecting tubule contains both (2)
principle and intercalated cells
Epithelial cells of collecting duct are normally impermeable to —
water
However, in presence of ADH (=vasopressin), secreted by posterior pituitary, collecting tubules
become permeable & will resorb water
In conjunction with Loop of Henle & vasa recta forms counter-current exchange mechanism to
concentrate urine
Proximal convoluted tubule ~2X as long as distal convoluted
tubule (& much more convoluted), so most tubules in cortex
are
proximal convoluted tubules
proximal convoluted tubules appear — in cross section, with — epithelium (+/- — —)
round
cuboidal
brush border
Distal convoluted tubules more —, with —epithelium
oval to elongate
thinner, flatter (but still cuboidal)
DCT staining
Lighter staining cytoplasm, nuclei more prominent
In medulla, see mostly —, fewer —, & occasional —, & surrounding —
Loop of Henle (smallest tubules, with squamous to cuboidal epithelium) collecting tubules (medium sized) collecting ducts (largest, with simple cuboidal epithelium) blood vessels (vasa recta)
Juxtaglomerular apparatus (JGA)
combined baroreceptor (pressure) & chemoreceptor ([ion])
JGA are specialized areas of
affarent arteriole and distal convoluted tubule
JGA are used to regulate systemic BP via
renin-angiotensin-aldosterone system
three components of JGA
macula densa
juxtaglomerular cells
extraglomerular mesangial cells
Macula densa—
thickened region on one side of distal convoluted tubule
macula densa contains
densely packed cuboidal to columnar epithelial cells
macula densa- chemoreceptor sensitive to changes in
[Na] in filtrate
Juxtaglomerular cells—
modified smooth Mm cells in wall of afferent arteriole
juxtaglomerular cells act as
baroreceptors; detect changes in blood pressure
juxtaglomerular cells produce — in response to
renin
decrease in blood pressure (converts angiotensinogen to angiotensin I)
Extraglomerular mesangial cells—
(= Goormaghtigh cells or Lacis cells)
Flattened cells surrounding afferent and efferent arterioles
function of extraglomerular mesangial cells (2)
Exact function unclear; provide structural support & phagocytosis
May assist in tubular glomerular feedback (by transmitting signals from cells of macula densa to glomerular mesangial cells)
decrease in bp (detected by JG cells) results in
renin release
from JG cells in afferent arteriole
decrease in bp results in decrease of GFR which results in
decrease in Na in distal convoluted tubule (macula densa)
Angiotensin II increases blood pressure 3 ways:
- Vasoconstriction (↑ bp)
- Release of aldosterone from zona glomerulosa of adrenal cortex results in resorption of Na & water from distal convoluted tubule which ↑ bp
- ADH secretion from posterior pituitary results in ↑ water resorption from collecting tubule (↑ bp)
— prevent conversion of angiotensin I
ACE-inhibitors
ACE inhibitors result in..
angiotensin II by blocking action of ACE, preventing bp increase
Ureters are muscular tubes, conduct urine from
kidneys to bladder
Ureters: — shaped lumen in X-S,
lined by
stellate or star
transitional epithelium thrown into folds
Ureters are fairly —, — lamina propria
thick
fibre-elastic
Muscularis externa of ureters contains 3 layers of smooth Mm—
inner longitudinal & outer circular, plus third outermost
longitudinal layer in lower third of ureter
Ureters produce
peristaltic contractions to move urine
Ureters: surrounding — — of connective tissue
fibroelastic adventitia
Urinary bladder is lined by
transitional epithelium (urothelium) with underlying fibroelastic lamina propria
Urinary bladder: three openings define — area of bladder,
two for…
one for…
trigone
entry of urine from ureters
exit of urine via urethra (surrounded by internal sphincter of smooth Mm)
Peritoneal or visceral surface of bladder covered by
fibroblastic adventitia (= serosa)
Urethra transfers urine from
bladder to outside world
length of bladder in humans,
~3-5 cm in female, 20 cm in male
Urethra is lined by —, with —
stratified or pseudostratified columnar epithelium (occasionally
squamous), with paraurethral mucus glands
In male, urethra has 3 sections:
Prostatic, membranous, & spongy (penile)
Prostatic urethra lined by
transitional epithelium, like bladder
remaining portions of urethea lined by
columnar
Females more susceptible to bladder infections because of
short urethra
Bacterial/fungal (yeast) infection (cystitis, pyelonephritis) results in (2)
rbc’s, wbc’s, bacteria in urine,
painful/ burning urination
how to diagnose yeast infection
urine culture (c.f. sensitivity)
treatment of yeast infection
antibiotics/antifungals
Urination =
micturition
Excretion of protein (usually albumin) =
proteinuria
Excretion of glucose =
glucosuria
Excretion of glucose = glucosuria results in
diabetes mellitus (insulin deficiency)
increase frequency of urination (polyuria—PU) & drinking (polydypsia—PD) results in
diabetes insipidus
diabetes insipidus is due to – insufficiency
ADH
high volume, dilute (hypotonic) urine
Various drugs or metabolites concentrated in urine, may precipitate as
crystals; basis of drug testing
Crystal, stone formation results in
urinary calculi (nephrolithiasis/urolithiasis)
~80% of stones =
calcium oxalate
components of nephrolithiasis (2)
genetic
dietary
Nephrolithiasis may loge in (3)
renal pelvis
ureters
urethra
treatment of Nephrolithiasis
ultrasound (illithotripsy)
complications of Nephrolithiasis (2)
hydronephrosis
hydrometer (usually unilateral)
BUN (blood test) measures
renal function
BUN is an indirect measure of
renal disease
Doesn’t increase until ~75% of functional nephrons lost, known as
uremia
