urinary system (theory) Flashcards
what are the two cells to note in the urinary system?
- principle cells
- intercalated cells
principle cell function
-respond to aldosterone
-reabsorb sodium
intercalated cell function
-respond to pH changes
-excrete H+
-keep HCO3-
functions of the urinary system
-regulate plasma ion concentration
-regulate blood volume and pressure
-stabilize pH
-prevent nutrient loss
-synthesize calcitriol
-prevent dehydration
-help the liver
TS and TR
TR = tubular reabsorption
TS = tubular secretion
these mechanisms help nutrients in normal ranges
how does the urinary system affect blood pressure?
kidneys produce renin which is needed to convert angiotensinogen to angiotensin I
angiotensin I is a weak vasoconstrictor
pathway of filtrate through the nephron
afferent artery –> renal capsule –> (glomerulus + bowman’s capsule) –> proximal convoluted tubule –> descending limb –> ascending limb –> distal convoluted tubule –> collecting duct –> papillary duct –> minor calyx –> major calyx –> renal pelvis –> ureter –> urinary bladder –> urethra –> voiding of urine
what are the components of the urinary system?
-kidneys
-ureters
-urinary bladder
-urethra
what does the suprarenal gland produce?
hormones
which kidney is lower?
the right kidney bc the liver pushes it down
male vs female urethra and bacterial infection of the bladder
the female kidney is shorter than the male kidney which can result in bacterial infection because bacteria can travel a shorter distance to the bladder
what are the 3 layers of connective tissue for the kidneys?
-fibrous capsule
-perinephric fat
-renal fascia
what does the hilum of the kidney contain?
-renal artery
-renal vein
-ureters
what does the renal medulla consist of?
-renal pyramids
-renal papillae (pyramid apexes)
-renal columns (reach into cortex)
what does the renal pelvis consist of?
-minor calyces
-major calyces
where are the majority of nephrons?
85% of the nephrons are in the renal cortex
15% of nephrons are in the renal medulla (juxtamedullary nephrons)
branching of the renal artery
renal artery –> suprarenal artery –> segmental artery –> interlobar artery –> arcuate arteries –> cortical radiate arteries –> afferent arterioles –> glomerular capillaries
branching of the renal vein
starts opposite to the renal artery
glomerular capillaries –> efferent arteriole –> peritubular capillaries –> interlobular veins –> arcuate veins –> interlobar veins –> renal vein –> inferior vena cava
nephron components
-glomerulus
-proximal convoluted tubule
-loop of Henle
-distal convoluted tubule
-collecting duct
cortical nephrons vs juxtamedullary nephrons
juxtamedullary nephrons have more concentrated urine because they have longer loops of Henle to collect more from the filtrate
how much of the water from the filtrate is absorbed in the nephron?
more than 80%, to prevent dehydration
contents of the renal corpuscle
-glomerulus
-bowman’s capsule
layers of bowman’s capsule
-visceral layer
-parietal layer
bowman’s capsule parietal layer
made up of squamous cells and is continuous with the PCT lining
bowman’s capsule visceral layer
made up of podocytes (pseudo legs)
podocytes have openings between them called filtration slits that allow desirable nutrients to pass into the PCT and be absorbed
mesangial cells
phagocytes of the nephron
3 layers of the renal corpuscle
-capillary endothelium
-basal lamina
-glomerular epithelium
what does the capillary endothelium of the renal corpuscle allow through?
they allow nutrients that are smaller than 0.1 microns to enter
they prevent RBCs from entering the filtrate
basal lamina function in the renal corpuscle
surrounds the capillary endothelium
this prevents large proteins from passing but lets smaller ones through
also lets ions and nutrients through
glomerular epithelium function in the renal corpuscle
this is the site of podocytes and filtration slits
lets through… ions, water, small organic molecules
very few plasma proteins pass through here
proteinuria
when there are proteins present in the urine
this can be normal in physiological states like pregnancy but can become a concern when they reach too high concentrations
preeclampsia and eclampsia
preeclampsia conditions
-protein in urine
-increased BP
-swelling in the legs
eclampsia extra condition
-seizures
PCT characteristics and function
proximal convoluted tubule
-lined with cuboid epithelium
-reabsorbs all organic nutrients
-reabsorbs ions too (Ca2+, Mg2+, K+, Bicarb, Phosphate, …)
descending limb vs ascending limb
-water leaves the descending limb and enters the bloodstream
-ions are pumped out of the ascending loop to prevent ion loss
the ascending limb is impermeable to water because it is thicker than the descending limb
also filtrate is more concentrated in the ascending limb
DCT characteristics and function
selective reabsorption of sodium and calcium ions
little H2O reabsorption
active secretion of ions and acids
juxtaglomerular complex components
-macula densa cells
-juxtablomerular cells –> hormone producing cells
-mesangial cells
what are the hormones produced by the juxtaglomerular complex?
-renin
-erythropoietin
collecting system components
-collecting duct
-connecting tubules
-papillary ducts
the function of the collecting system is to make final adjustments to the concentration of the urine before sending to the urinary bladder
ureteral openings
do not confuse with urethral opening
these are the openings of the ureters into the urinary bladder, ureters enter in the trigone area
does the urinary bladder have rugae?
yes, this is to help with stretching of the bladder
does the trigone area have rugae?
what is the trigone’s function?
-no it does not have rugae
-the function of the trigone area is to provide a smooth funnel for urine pass down into the urethra when the detrusor muscle contracts
histology of the ureters (3 layers)
-inner mucosa
-middle muscular layer
-adventitia
the two smooth muscle layers of the middle muscular layer of the ureter
-inner circular
-outer longitudinal
these layers help with peristaltic movement of urine
location of the urinary bladder in males vs females
males –> between the rectum and the pubic symphysis
females –> inferior to the uterus and anterior to the vagina
what are the two ligaments that help position the uterus
-medial umbilical ligament
-lateral umbilical ligament
sympathetic and parasympathetic control of the detrusor muscle
parasymp –> contracts
symp –> relaxation
subdivision of the male urethra vs the female urethra
males –> prostatic urethra, membranous urethra, spongy urethra
females –> just the external urethra orifice
prostatic urethra
passes through the prostate gland
membranous urethra
passes through the urogenital diaphragm
spongy urethra
passes through the penis (longest urethral section)
the micturition reflex
peeing
at what volume does the urge to urinate first appear?
200 mL, the bladder can accommodate more volume if needed but can become painful
what happens to both sphincter muscles when the bladder reaches capacity?
both open due to pressure
how much urine remains in the bladder after complete voidance?
10 mL, if the prostate enlarges the amount of residual urine can increase
