urinary system (ch 24) Flashcards
kidney/urinary functions
rid waste products
water level maintenance
ion level maintenance
pH
vitamin D activation
hormones
nitrogen wastes from amino acids
deaminated amino acids
urea (formed in liver - uric acid and ammonia)
metabolic wastes
acids
creatinine (from muscle creatine)
toxins/drug wastes
created through liver conversion into water-soluble substances
hormones
created through liver conversion into water-soluble substances
function of water in the body
solvent, fluid levels, BP
major ions in the body
Na+, K+, Cl-, Ca++, HCO3-
how does the kidney maintain pH level
acid or base in urine
vitamin D function
regulating and absorbing calcium ions
hormonal function of kidneys
BP
erythropoietin for RBCs
anatomy overview of the urinary system
kidneys, ureters, urinary bladder, urethra
kidney location
retroperitoneal (at the back)
around the 12th rib
right lower than left due to liver
size of kidneys
5 x 3 x 1 inches in adults
hilum/hilus
indent of the kidney, located medially
adrenal gland location
on top of kidney
coverings of the kidney
renal capsule - dense irregular CT with shiny collagen outside
adipose capsule - perirenal fat
renal fascia - loose CT
renal cortex
where blood is filtered (glomerulus)
has proximal and distal convoluted tubules
renal pyramids
cone-shaped structures - base is against cortex, apex (papilla) near renal pelvis
renal columns are found
between the pyramids
purpose of the renal pelvis
collecting urine formed by the kidney
branches of the renal pelvis/their purpose
minor - associated with the papilla and apex
major - where the minors come together
flow of the renal blood supply
renal arteries, segmental arteries, interlobar arteries, arcuate arteries, cortical radiate arteries, afferent arteriole, glomerular capillaries, efferent arteriole, vasa recta and tubular capillaries, cortical radiate veins, arcuate veins, interlobar veins, renal veins
function of the ureters
move urine from the kidney pelvis to the urinary bladder base
retroperitoneal
behind peritoneal cavity
the ureters enter the bladder at
the base, at the trigone
muscularis of the ureter wall consists of
smooth muscle (inner longitudinal layer + outer circular layer)
mucosa of the ureter wall consists of
transitional epithelium (urothelium) and lamina propria
adventitia of the ureter wall consists of
collagen connective tissue
kidney stones
precipitated (usually) calcium salts
function of urinary bladder
store urine so you can pee when you want to
mucosa of the urinary bladder consists of
transitional epithelium (urothelium) and lamina propria
detrusor muscle of the urinary bladder consists of
smooth muscle (3 layers - longitudinal, circular, deep longitudinal)
adventitia of the urinary bladder consists of
connective tissue (serosa on top of the bladder)
trigone
triangle at the base of the bladder formed by two ureters and one urethra, where the bladder attaches to other tissues
anatomy of the urethra
stratified epithelium (wear and tear)
two sphincters (internal - smooth muscle, external - skeletal muscle)
difference between male and female urethras
male - 8 inches, multiple parts (prostatic, membranous, spongy)
female - 1.5 inches, UTIs more common
processes of the kidney tubule
filtration, reabsorption, secretion, concentration
filtration
blood fluid into the glomerular capsule and renal tubules
reabsorption
putting tubular fluid back into blood
secretion
adding substances from blood to tubule fluid
concentration
retaining or not retaining water in fluid (filtrate), happens in collecting duct
microscopic parts of the kidney
renal corpuscle
nephron tubules
collecting duct
glomerulus
part of the renal corpuscle, tuft of capillaries where fluids and solutes are filtered out
served by two vessels - afferent (in) and efferent (out) arterioles
glomerular capsule
part of the renal corpuscle, collects ultrafiltrate from the blood
nephron tubules
functional unit of kidney, includes glomerular capsule
proximal convoluted tubule
in cortex, 70% of reabsorption occurs here (stuff that is filtered out and returned)
loop of henle
goes into medulla (nephron loop), sets up medullary concentration gradient
descending limb - into medulla
ascending limb - out of medulla
distal convoluted tubule
goes back to cortex/glomerulus, forms juxtaglomerular apparatus
fine tuning of filtrate (due to hormones)
collecting duct
goes through medullary concentration gradient in the pyramids
permeable or non-permeable to water because of hormone ADH
the filtration barrier is made up of
capillary endothelial cells
basement membrane
capsule cells
capillary endothelial cells
fenestrated (with windows) - acts to increase filtration
basement membrane
connective tissue at the base of epithelial cells
negative charge
finest filtration
capsule cells
aka podocytes (foot cells)
has filtration slits and slit diaphragm
filtration forces include
blood (hydrostatic) pressure
blood colloid osmotic (oncotic) pressure
capsular (hydrostatic) pressure
blood pressure
55 mg Hg out (blood to filtrate)
blood colloid osmotic pressure
30 mm Hg in (causing blood to retain fluid)
proteins in blood are not filtered
capsular pressure
15 mm Hg in (blood retains fluid)
net filtration pressure
10 mm Hg
homeostasis in relation to the urinary system
maintaining glomerular filtration rate
intrinsic mechanisms of homeostasis
myogenic reflex
vasoactive chemicals from juxtaglomerular apparatus
myogenic reflex
fall in BP causes afferent arteriole to dilate, allowing more blood into the glomerulus and increasing the GFR
rise in BP causes afferent arteriole to constrict, meaning less blood and decreased GFR
extrinsic mechanisms of homeostasis
sympathetic nervous stimulation
renin-angiotensin system
what is the renin-angiotensin system stimulated by
a decrease in sympathetic nervous stimulation
decrease in Na+ or flow rate in distal convoluted tubule (DCT)
decrease in BP
anatomy of the juxtaglomerular (JG) apparatus
macula densa of DCT senses Na+ levels and fluid flow in the DCT
JG (granular) cells contain renin - specialized muscle cells in the afferent arteriole
renin
enzyme for hormone
process of renin-angiotensin system
angiotensinogen (blood protein from the liver) gets piece cut off by renin –> angiotensin I (active but weak) gets converted by angiotensin converting enzyme to angiotensin II (active and strong)
effects of the renin-angiotensin system
vasoconstriction
promotion of aldosterone release so Na+ and water are retained
(processes increase BP so GFR is back to normal)
how much reabsorption of filtrate occurs at the proximal convoluted tubule (PCT)
around 70%
function of the Na+ gradient in the PCT
Na+ is pumped back so mitochondria for Na+/K+ ATP pumps can increase
H2O and Cl- passively follow
used to pump glucose and amino acids back into the blood, along with other vitamins and ions
what is secreted in the PCT
nitrogen waste (urea and ammonia)
drugs (aspirin, antibiotics)
acid (H+) and base (HCO3-)
the loop of henle acts to form
the medullary concentration gradient
characteristics of the descending limb of the loop of henle
water permeable so water diffuses out of the filtrate (osmosis)
Na+Cl- impermeable so salt and urea stay
concentration of filtrate can increase up to 4x
characteristics of the ascending limb of the loop of henle
water impermeable so water stays
Na+Cl- pumped and diffuses so salt leaves filtrate
concentration of filtrate decreases down to 1/3 of normal body concentration
vasa recta
“straight vessels” that take away water and salt that is diffused out - helps maintain medullary concentration gradient
concentration of solute at the DCT
1/3 of normal body concentration
what happens to filtrate at the DCT
fine tuned - reabsorption and secretion
hormones that work at the DCT
aldosterone
atrial natriuretic factor (ANF)
parathyroid hormone (PTH)
aldosterone
hormone secreted by the adrenal cortex
induces Na+ (and H2O) reabsorption
causes K+ secretion
atrial natriuretic factor
“atrium of heart, Na+, urine”
induces Na+ (and H2O) secretion
parathyroid hormone
from parathyroid
induces Ca++ reabsorption
collecting duct
tube with many nephrons connecting through it
purpose of the collecting duct
concentrating and diluting urine
anti-diuretic hormone (ADH) or vasopressin is stimulated by
an increase in blood/body fluids overall osmolarity (low H2O, high solute)
ADH is inhibited by
an decrease in blood/body fluids overall osmolarity (high H2O, low solute)
ADH is made in the _____ and secreted by _____
hypothalamus, posterior pituitary neurohypophysis
ADH make the collecting ducts _____
permeable to water
collecting duct events (other than ADH)
Na+ regulation by aldosterone
urea reabsorption -stimulated by ADH
acid/base balance
micturition reflex steps
urine in bladder increases stretch, leading to parasympathetic bladder contraction (spinal cord reflex - S2-S4), brainstem response (if no go, urge subsides for a while until more urine in the bladder increases stretch again)
