unit 10 urinary system
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what are the amjor organs of the urinary system? and what are their functions?
- kidneys: many functions, formation of urine
- ureters: transport urine from kidneys to bladder
- urinary bladder: stores urine
- urethra: exit for urine to leave the body
what are the major function of the kidneys?
- regulation of extracellular (ECF) fluid volume.
- regulation of osmolarity
- maintenance of ion balance
- homeostatic regulation of pH
- excretion of waste and foreign substances
- production of hormones and enzymes
what happens to blood pressure when ECF volume decreases? and when ECF volume increases?
- ECF decreases= blood pressure decreases
- ECF increases= blood pressure increases
what helps to maintain blood osmolarity?
mechanisms such as thirst.
what is osmolarity?
number of ions or molecules per liter of solution, or solute concentration
how are key ions (Na, K,Ca)kept within normal range?
by balancing dietary intake and loss through urine
what happens if ECF becomes to acidic?
the kidneys remove hydrogen and conserve bicarbonate ions
what happens when ECF becomes to alkaline (basic)?
the kidneys rmove bicarbonate ions and conserve hydrogen
what wastes are removed from the body through urine?
- metabolic wastes like: creatinine urea uric acid
- environmental toxins
what hormones and enzymes are synthesized and secreted from the kidney?ad what are their functions
- erythropoietin:to regulate RBC production
- secretion of th enzyme renin for the regulation of hormones involved in sodium balance and BP homeostasis
where are the kidneys located?
where are the adrenal glands located?
- kidneys: located retroperitonelly (behind the parietal peritoneum)
- in the lumbar region
- adrenal glands: located superior to the kidneys
the blood vessels, ureter, and nerves pass through the ______ _____at the _____ ____.
- renal hilum
- concave surface
what does the renal capsule do?
surrounds the kidney
what does the renal medulla contain?
apex of the pyramid = ?
what surrounds the renal medulla?
the renal cortex
what are th ereanl columns?
parts of the renal cortex that lie between the reanl pyramids
from the ureter the renal _____ leads to a _____ ______ which leads to a minor ______.
how many major calyces lad to several calyces?
what does each kidney lobe contain?
how many lobes per kidney?
- each contains a single pyramid plus surrounding cortical tissue
- 5 to11 lobes per kidney
what does each nephron contain?
how many nephrons per kidney?
- contains the reanl corpuscle and renal tubule
- approx. 1 million nephrons per kidney
what is the renal corpuscle composed of?
includes the glomerular capsule (Bowman's capsule) and glomerulus(mass of glomerulus cappillaries)
what is the real tubule composed of?
includes hte proximal convoluted tubule(PCT) loop of Henle (descending and ascending) distal convoluted tubule(DCT)
what does the collecting duct do?
- not part of the nephron
- invovled in concentrating urine
- fus and empty into the minor calyces via papillae of the pyramids
what re the collecting duct and nephron made of?
mainly simple cuboidal epithelium
what are the 2 classes of nephrons?
- cortical nephrons
- juxtamedullary nephrons
where are cortical nephrons located? adn what % are they?
- located almost entirely in teh reanl cortex only a small part in the loop of Henle
- 85%of all nephrons
where are the juxtamedullary nephrons located? and what % are they?
- means near medulla, reanla corpuscles lie nea the cortex-medulla junction; lops of henle dip deep into the medulla
- 15% of all nephron
the long loops of Henle fo the juxtamedullary nephrons along wit the collecting ducts allow the kidneys to produce?
what is a glomerulus?
whereis it located?
- located in th ereal corpuscle
- filters incoming blood from the afferent arteriole and produces filtrate
where are the peritubular capillaries located?
what are their function?
- arise from the efferent aretioles of cortical nephrons,
- adapted fro absorbation and secretion
where is the vasa recta located?
what is its function?
- arises from the effrent arterioles fo th juxtamedullary nephrons
- helps the kidneys to concentrate urine
what is the juxtagloomerular apparatus involved in?
what is it composed of?
- its involved in the regulation of blood pressure.
- composed of: the distal convolutes tubule (DCT) plus the afferent arteriole
what contains the macula densa?
what is the macula densa?
the distal convoluted tubule.
group of cells that have chemoreceptorsfor monitoring solute concentrations in filtrate
what happens when the solute concentrationsconcentrations of the filtrate fall below a certain level?
the cells of the macula densa signal the juxtaglomerular cells to secrete renin which starts the chemical reactionsin the blood that results in the secretion of aldoterone from the adrenal glands which causes blood volume, and BP to rise
what is glomerular filtration?
movement of fluid from the bloodinto the lumen of the nephron;takes place only in therenal corpuscle
what is tubular reabsorption?
process of moving filtered material from the lumen of the nephron back into the blood; anything not reabsorbed exits as urine.
where does reabsorption take place?
wheredoes secretion take place?
- reabsorption:in the PCT, ascending and descending loops of Henle, DCT, and collecting duct.
- secretion: in the PCT DCT and collecting duct
what is secretion?
removing selected molecules from the blood and adds them to the fluid in the lumen of the nephron; uses membrane proteins and is a more selective process than filteration
what is excretion?
material that leaves the collecting duct is transported to the bladder for storage and removed by mictuurition (urination)
what is filtration?
a nonspecific process that creates a filtrate much like plasma but without the proteins
what cant pass through the filtration membrane?
blood cells and proteins
what si the driving force for filtraton?
the hydrostatic pressure of the blood in the glomerular capillaries of the glomerulus
only about ___% of plasma that passes through the glomerulus is filtered and enters the bowman's capsule ; ____% continues on to the efferent arterioes and peritubular capillaries; less than__% of the filtered fluid is eventually excreted as urine?
on average how much does the nephron filter per minute?
how much per day?
how much of it is excreted in urine?
what happens to the rest?
- 125ml per minute
- 180L of fluid per day
- only 1.5 L of this fluid is excreted as urine
- the rest is reabsorbed
what happens to glomeruluar filtrtion rate (GFR) when BP rises?
nothing it stays constent as long as mean arterial pressure stays within 80-180-mm Hg
how is GFR controlled?
what happens if resistance of the renal arterioles increases?
mainly by the regulation of blood flow through the reanl arterioles.
renal blood flow decreases and blood is diverted to other organs of the body
what happens to the GFR if resistance increases in the affrent arteriole?
hydrostatic pressure decreases at the downside of the constriction, which results in a decrease in GFR
what happens toGFR if resistance increases in the efferent arterioles?
blood "dams up?in front of the increased resistance and hydrostatic pressure in the glomerular capillaries increases, this results in an increase in GFR
how do hormones and sutonomic neurons influence GFR?
intergreating centers outside of the kidneys start signals that affect GFR by changing resistance in the arterioles. these are often in response to changes in systemic BP or blood volume
what is a powerful vasoconstrictor?
what are example of vasodilators?
- angiotensin II
what is autoregulation?
local control process in which kidneys maintain a relatively constant GFR
where does most ar reabsorption take place?
in the PCT
what is primary active transprt of sodium?
NA is pumped out the basolateral side of the tubule cell and into the intersistial fluid by the Na/K pump
what is secondary active transport of sodium?
Na entes the tubule cell from the ubule lumen side through the open chanels, movig down its concentration gradient
what is passive transport (diffusion) of sodium?
Na enters the peritubular cappilarry from te intersistial fluid
how is water reabsorbed by osmosis?
as the solute leaves the PCT by primary and secondary transport, water follows because of osmosis, it is a passive process
what is endocytosis?
when proteins that have passed through the glomerular filtration barrier (most do not) are reabsorbed by epithelial cells
what does the secretion of H+ help regulate?
where is urine concentrated?
in the loop of henle using a countercurrent multiplier/exchange mechanism
the longer the loop of Henle the more ________ that a organism can make its urine.
the release of ADH signal the kidneys to?
produce more concetrated urine, this is accomplished by increasing the reabsorption of water
what color is urine?
where does the color come from?
what is the odor of fesh urine and standing urine?
- usually clear and pale yellow to amber in color
- color is due to urochrome(from the destruction of hemoglobin)
- fresh:slightly aromatic
- standing : ammonia like odor
what are the pH urine ranges?
what usually the pH of Urine?
is it acidic or alkaline?
- ranges from 4.5-8.0
- usually about 6.0
- slightly acidic
what are the usual ranges of the specific gravity of urine?
the lower the specific gravity the more?
ranges from 1.001 to 1.030.(urine will always be higher that 1.000 because it contains dissolved solutes
the dilute the urine
what are the normal constituents of urine in order from decreasing concentration?
- sulfate ions
- uric acid
what are the abnormal urine constituents?
- ketone bodies
- bile pigments
what causes proteinuria?
what are the effects?
caused by excessive physical exertion, pregnancy, high protein diet,
heart failure, severe hypertension, renal diease
what causes ketone uria?
starvation, or untreated diabetes
what is hematuria?
what causes it?
- RBc's in the urine
- caused by beeding UTI, kidney trauma, kidney stones or infection
what causes hemoglobinuria?
- various causes including:
- transfusion reaction, hemolytic anemia, severe burns
what causes bilirubinuria?
symptom of liver diease, hepatitis cirrhosis or obstruction of the bile ducts from liver or gallbladder
what causes pyuria (leuks)?
caused by a UTI
what are the ureters made of?
what is the trigone?
triangler region containing openings of the uretrs and urethra
what is he bladder made of?
what is the internal urethral sphincter made of? can we control it?
what is the external urethral sphincter made of? can we control it?
- internal: composed of smooth muscle; involuntary
- external: composed of skeletal muscle; voluntary
what are the symptoms of a UTI?what is found in lab samples of their urine? what causes UTI?
- pain or buring while urinating
- RBC's WBC's
- cause of infection is the bacterium Escherichia coli
wha causes kidney stones?
crystallized calcium, magnesium or uric acid salts
what is gout
metabloic disease caused by high concentrations of uric acid, crystals form in th eperipheral joints mainly feet ankles and knees
bladder cancer is about _% of all cancers, and most commonly found in ____.
kidney cancer arises from?
epithelial cells of nephrons and collecting ducts
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