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Chapter 27: Urinary System
Terms in this set (83)
function of urinary system (6)
primary: remove and filter blood
also: regulates blood volume and blood pressure, regulates plasma concentration, stabilizes blood pH, conserves nutrients, and secretes erythropoietin
what do kidneys filter and what do they convert it to?
waste products from blood stream; urine
urinary tract (UT)
ureters, urinary bladder, urethra
what does the UT do?
responsible for transport, storage, and elimination of urine
what does the spleen filter?
aged red blood cells and intruders
how does urinary system regulate blood volume and blood pressure?
monitors amount of water that should be eliminated based on state of hydration
kidneys control volume of ___ and ___ under direction of certain hormones
ISF and blood
how does the urinary system stabilize blood ph?
maintain acid-base balance by altering rates of H+ and ammonium secretion and bicarbonate reabsorption
how does the urinary system conserve nutrients?
reclaiming glucose and things that the body filters out initially
what is erythropoietin?
hormone that is secreted if blood oxygen levels are reduced; increases production of RBC
where is the kidney located?
superior lumbar region
point of entry and exit for nerves, renal artery and vein and ureter; continuous space within renal sinus
houses arteries, veins, lymph vessels, nerves, renal pelvis, renal calyces, and adipose CT
three tissue layers of kidney
surrounds kidney tissue proper, helps maintain shape and protection, prevents infection, compartmentalizes kidney
external to renal capsule, universal packing material, fills empty spaces, completely surrounds kidney and offers cushioning and insulation
dense irregular CT, anchors kidney to the abdominal wall and peritoneum
two layers of fat between renal fascia and renal capsule (outermost layer)
three main elements of kidney
renal cortex (outer), medulla (inner) and renal sinus
compartments of medulla
extended pyramid between capsule and sinus
frequency of rhythmic, continuous smooth muscle contractions results in...
how much urine is produced (peristalsis through ureter to bladder)
how much of cardiac output flows through the kidneys?
flow of blood from heart to kidney
abdominal aorta ->
renal artery ->
medullary area with pyramids ->
afferent arteriole ->
renal corpuscle/glomerulus ->
efferent arteriole ->
peritubular capillaries associated with convoluted tubules or vasa recta associated with nephron loop
capillary network inside the renal corpuscle; arterioles creates high pressure system
what does the efferent arteriole carry and why?
oxygenated blood because gas and nutrient exchange with kidney has not occurred yet
where does gas exchange in kidney occur?
peritubular capillaries or vasa recta
associated with convoluted tubules, primarily reside in medulla of kidney
associated with nephron loop, primarily reside in medulla; only in juxtamedullary system
peritubular capillaries and vasa recta drain into...
network of veins until become renal vein
functional filtration unit of the kidney; blood processing units
what does the nephron consist of?
renal corpuscle, proximal convoluted tubules, nephron loop, distal convoluted tubule
proximal and distal convoluted and nephron loop
80% of nephrons; loop of henle barely enters medulla; short nephron loop
renal corpuscle lies close to corticomedullar junction; long nephron loops deep into the medulla; contain vasa recta
what is the importance of juxtamedullary nephron?
important for reclaiming water
three processes of urine formation
takes place in glomerulus; passive movement of water and some dissolved solutes into capsular space due to pressure differences across filtration membrane (non-selective filtration)
(tubular fluid to blood) in renal tubule; substances in filtrate move by diffusion or active transport across wall of renal tubules to return to the blood; usually needed solutes and most water that formed filtrate are reabsorbed by blood
(blood to tubular fluid) in renal tubule; active transport of solutes out of blood into tubular fluid; allows extra eliminations (greatest in distal) or resorptions (greatest in proximal)
T/F: blood composition is simultaneously adjusted during urine filtration
renal corpuscle consists of...
glomerulus and bowman's capsule
where does formation of urine begin?
renal corpuscle with process of filtration
parietal layer of bowman's capsule
simple squamous epithelium
visceral layer of bowman's capsule
contains podocytes with pedicels that wrap around fenestrated capillaries to support capillary wall, but do not completely ensheathe it
pedicels form finger-like extensions, and fluid is pushed through these fenestrations (pores) and slits; allow materials from blood plasma to reach capsular space
what keeps materials from not being filtered?
size and charge (proteins aren't filtered)
factors influencing filtration
- larger afferent arteriole establishes high pressure to support filtration
- fenestrated capillaries allow plasma and solutes to pass from blood to capsular space
- filtration slits of podocytes permit passage of filtered material
highly coiled; increase length and enhance functional capabilities
tons of microvilli that increase SA and thus absorption capacity; abundance of mitochondria; cells actively resorb materials from tubular fluid; most water absorbed by osmosis
smaller than proximal tubules, few villi, secretes into tubular fluid rather than absorbing; water is also resorbed under ADH and aldosterone
in juxtamedullary nephron; facilitates resorption of water and solutes from tubular fluid
when is the filtrate called urine?
when it hits collection ducts, where ADH (antidiuretic hormone) is effective
what does ADH do?
retains water by affecting water channels on collecting duct
what is the last structure that can modify tubular fluid?
collecting duct; modifies tubular fluid under influence of ADH and aldosterone
region within each nephron composed of 3 different cell types that function together to regulate rate of filtrate formation and systemic BP
3 types of cells in juxtaglomerular apparatus
1. juxtaglomerular/granular cells
2. Macula densa (MD) cells
3. extraglomerular mesangial cells
mechanoreceptors; respond to changes in pressure; regulate BP; modified smooth muscle cells
macula densa (MD) cells
chemoreceptors/osmoreceptors; monitor solute concentration of filtrate
extraglomerular (EG) mesangial cells
surround capillaries, phagocytic as well as contractile, exact function unknown
slender fibromuscular tube that conveys urine to bladder
three layers of uterus
1. mucosa (transitional epithelium)
what is different in the ureteral muscularis layer than the GI muscularis layer?
circular layer is outer layer instead of inner layer
peristaltic waves are adjusted to ...
urine formation rate
distension in ureters
causes smooth muscle layer to contract as urine enters ureters, and propels urine to the bladder
what direction do ureters enter the bladder wall?
what happens to the ureters smooth muscle fibers?
those of the longitudinal layer insert into lamina propria of bladder
why might no reflux occur in the bladder?
because ureter walls are compressed as bladder fills
an expandable muscular sac that temporarily stores urine and collapses after urine is voided into a triangular shape, with walls forming rugae
mucosal folds that allow distension
why is the bladder unique?
it can increase in size with no significant increase in internal pressure thanks to transitional epithelium and smooth muscle
how does smooth muscle assist in no increase in pressure in the bladder?
readjusts as walls are distended and stretch receptors are activated
how does transitional epithelium assist in no increase in pressure in the bladder?
allows sliding across cells without tearing in mucosa
functions to funnel urine into urethra as bladder walls contract
three layers of smooth muscle in bladder
median umbilical ligament
Superior lateral surface of bladder that tethers to the bellybutton
thin-walled fibromuscular tube that drains urine from bladder to be voided from body
which gender gets more UTIs and why?
women have more UTIs because there is a short distance to the trigone region and urine is very supportive for bacteria
protective, mucous membrane of the urethra; contains urethral glands that produce mucous
internal urethral sphincter is made of...
external urethral sphincter is made of...
what surrounds the urethra as it passes through the pelvic floor?
internal and external sphincter?
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