mod 11 urinary Flashcards
kidney
body’s filter; regulates pH, salt and water balance and BP
produces active form of Vit D
functions of kidneys (5)
- regulate ion levels in blood (Na, K, Ca, Cl)
- regulate blood vol and BP (Na/H2O absorption;renin)
- regulate blood pH (by excreting H in urine)
- Produce hormones (calitriol (vit d); erythropoietin)
- Excretes waste (urea, ammonia, bilirubin, creatine, uric acid, drugs/toxins)
retroperitoneal
placement of kidneys; against the body wall behind the peritoneal membrane that encloses the abdomen at level of 12th thoracic and first 3 lumbar
Renal bilium
indentation through which ureter leaves kidney; where blood/lymph vessels enter/exit
Renal capsule
connective tissue sheath surrounding each kidney; maintain shape of kidney and protects
renal cortex
outer region of kidney
renal medulla
inner, dark red-brown region
renal pelvis
large funnel shaped cavity where urine from kidney drains into
urine flow:
from several ducts within kidney into minor calyx to major calyx into renal pelvis which connects to ureter
path of blood flow through kidneys:
renal artery segmental artery interlobar artery arcuate arteries cortical radiate arteries afferent arterioles glomerular capillaries efferent arterioles PERITUBULAR CAPILLARIES (mix) Cortical radiate veins arcuate veins interlobar veins renal vein
Nephron
functional units of kidneys; million/kidney; consist of renal corpuscle and renal tubule
renal corpuscle
filters blood plasma; lies within renal cortex
Bowman’s capsule
double-walled cup surrounding glomerular capillaries; captures filtrate and passes it into renal tubule
podocytes
internal layer of bowman’s capsule; epithelial cells that have spaces btw them to allow passage of small mlcs into capsular space
renal tubule
filters and passes glomerular filtrate; as fluid moves through tubules waste and excess substances are added
Fluid passage through tubule:
proximal convoluted tubule: attached to bowman’s capulse
Nephron Loop: from renal cortex into medulla (Descending limb); turns into cortex becoming distal convoluted tubule (ascending limb)
Distal convoluted tubule: tubules empty into a common collecting duct
Glomerular filtration (step 1 of urine production)
first step of urine production; BP forces water and many solutes in blood across wall of glomerular cap forming filtrate
podocytes and glomerular endothelium
forms filtration membrane that permits passage of water and solutes from blood into capsular space
Glomeruli
site where filtration occurs (like capillaries)
net filtration pressure
pressure that causes filtration BP in glomerular capillaries; opposed by blood colloid osmotic pressure and glomerular capsule pressure
**when glomerular pressure is greater than two opposing pressures (osmotic and glomerular capsule) this forces large amount of fluid INTO capsular space
Net filtration
glomerular capillary BP- (blood colloidal osmotic pressure + glomerular capsule pressure)
how efferent and afferent arterioles maintain net filtration:
constriction of afferent: lowers net filtration
constriction of efferent: increases filtration
Glomerular filtration rate (GFR)
amount of filtrate that forms in both kidneys/minute; dehydration causes decrease in GFR
what if GFR is too high?
needed substances pass too quickly and unable to be reabsorbed and pass into urine
what if GFR is too low?
if too slow even the waste products that are meant to be excreted will become reabsorbed
Atrial natiuretic peptide (ANP)
hormone that promotes loss of Na and water in urine to increase GFR; controlled by stretching in atrium (more stretching=more ANP and thus lowering BP)
what happens to kidney function during exercise?
afferent arterioles are constricted more than efferent causing decreased blood flow into glomerular caps; net filtration will decrease as well as GFR (Reduced urine output)
Tubular Reabsorption (step 2 of urine production)
filtered fluid becomes tubular fluid once it enters proximal convoluted tubule; only 1% of water in filtrate leaves body in urine;
reabsorption carried out by epithelial cells along renal tubules and collecting ducts (diffusion and active transport)
proximal convoluted tubule
makes greatest contribution for reabsoprtion of solutes: 65% of filtered water is reabsorbed, 100% of filtered glucose and amino acids, and large quantities of ions
Tubular secretion (step 3 of urine production)
transfer material from blood through tubule cells into tubular fluid takes place along collecting ducts and renal tubules; secreted substances include creatine, urea, uric acid, toxins/drugs, ammonia, K, H
tubular secretion maintains blood pH
cells of renal tubules secrete H into tubular fluid to bring down acidity
angiotensin II
produced in lungs in response to renin; increases reabsorption of Na and Cl in proximal convoluted tubule
stimulates adrenal cortex to release aldosterone
aldosterone
produced by adrenal cortex; stimulates Na reabsoprtion in collecting ducts and distal convoluted tubule; increase K secretion
ANP
from atrium of heart; increases GFR; inhibits reabsoprtion of Na and Cl in renal tubules; ultimately lowers blood volume
ADH
hypothalamus (osmoreceptors detect amount of water in blood); increase reabsoprtion of water in distal convoluted tubule and throughout collecting ducts; increased water permeability
PTH
released in response to low Ca blood level; stimulates cells in early distal convoluted tubule to reabsorb more Ca
urine pathway
nephron–>minor calyces–>major calyces–>renal pelvis–>ureters–>bladder–>urethra
ureters
transport urine form renal pelvis of one kidney to urinary bladder; bladder compresses ureters to prevent backflow when pressure builds up in bladder during urination
***valve at distal end of ureter prevents backflow of urine when pressure inside bladder increases during micturition
mucosa layer of ureter
contains goblet cells that secrete mucous; transitional epithelium to allow stretching
smooth muscle layer of ureter
peristaltic contraction to move urine along tube to bladder
aerolar CT layer of ureter
outer layer; contains blood/lymphatic vessels and nerves
peritoneum folds of bladder
hold bladder in place
bladder capacity
700-800ml
mucosa layer of bladder
contains transitional epithelium which permits stretching and RUGAE (folds) which permit expansion of bladder
urethra
small tube leading from floor of urinary bladder to exterior of body through external urethral orifice
micturition
urination; process by which urinary bladder store urine prior to elimination and expels urine into urethra; voluntary and involuntary muscle contractions
urination process:
when bladder exceeds 200-400ml stretch receptors transmit nerve impulse to spinal cord
parasympathetic impulses from spinal cord cause contraction of detrusor muscle and relaxation of internal urethra sphincter muscle
at same time, spinal cord inhibits somatic motor neurons which cause relaxation of skeletal muscle in external urethral sphincter
bladder contracts and urine is expelled
