Term
| function of urinary system |
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Definition
| removal of waste products at same rate being produced, excretory pathways function to rid waste => 4 pathways |
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Term
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Definition
* excretes CO2 + H2O
* H2O loss depends on CO2 that needs to be depleted |
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Term
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Definition
* lose H2O in perspiration (contains electrolytes & urine)
* sweat production is related to body temperature |
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Term
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Definition
* rids of solid waste
* lose electrolytes and H2O |
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Term
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Definition
* rids body of H2O, electrolytes, toxic chemicals, & certain excess nutrients, excess acid
* only system that can compensate for the other 3 functions
* of 4 pathways, urinary is only one that regulates how much H2O, electrolytes, & nutrients it excretes
* important because capable of controlling the volume & concentration of blood |
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Term
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Definition
* 2 kidneys are the workhorse of the urinary system, filter
* each kidney drained by a ureter
* bladder is a bag/sac that stores urine
* urethra, tube that drains bladder to the exterior |
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Term
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Definition
* regulate composition of volume of blood by removing selective materials from blood and dump into urine
* major roll in controlling body pH => capable of excreting H+ and dumping into urine
* major roll in controlling blood pressure => secretes the enzyme renin
* role in RBC production (erythropoietin)
* help activate vitamin D |
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Term
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Definition
* just above the waistline, right kidney is slightly lower due to the liver, retroperitoneal, located between last thoracic & third lumbar
* medial border is concave, opening is the hilum, ureter leaves the kidney here
* blood vessels, lymph vessels, & nerves enter/exit
* entrance to a cavity inside kidney (renal sinus)
* surrounded by 3 layers of tissue |
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Term
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Definition
* innermost layer of tissue of the kidney
* thin, transparent, fibrous membrane => if it peels off, the kidney is healthy
* protects from toxins and infection |
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Term
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Definition
* adipose tissue, shock absorber
* helps anchor the kidney in place |
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Term
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Definition
* outermost layer of tissue of the kidney
* dense fibrous CT, anchors the kidney in place as well and makes it sturdy |
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Term
| internal gross anatomy of the kidney |
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Definition
* cortex is reddish, medulla is reddish-brown
* renal pyramids
* renal papillae
* cortex |
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Term
| renal pyramids (medullary pyramids) |
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Definition
* number of triangular-shaped structures
* striated => visible when cut open, formed by the presence of tubules & blood vessels
* base of pyramid faces cortex, apices face the center |
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Term
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Definition
| open into a space called the minor calyx |
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Term
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Definition
* smooth, textured region (3 regions)
- outer cortical zone => closest to renal corpuscle
- juxtamedullary region => adjacent, closest to medulla
- renal columns => in medulla, cortical tissue located between renal pyramids |
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Term
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Definition
* functional unit of the kidney => millions
* nephron is the structure that forms urine
* as it produces, starts in a duct system
* collecting duct => papillary duct => apex of renal papillae => minor calyx => major calyx => renal pelvis => ureter => bladder |
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Term
| blood supply to the kidney |
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Definition
* in resting physiology, kidneys receive 25% of blood
* inter = towards, afferent = away |
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Term
| nerve supply of the kidney |
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Definition
* kidney receives SNS fibers (vasoconstriction)
- terminate in smooth muscle of arteriole walls, regulate the size of the lumen and blood flow through the kidney at any given time |
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Term
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Definition
* filters material from blood and forms a waste (urine)
* regulates H2O, electrolytes, and glucose that goes out
* allows body to secrete organic waste products (urea, uric acid, creatinine)
* made up of the renal corpuscle and renal tubule |
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Term
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Definition
| nitrogen waste compound (deamination) |
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Term
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Definition
| waste product produced during recycling of nitrogen bases from RNA molecules |
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Term
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Definition
| waste product from breakdown of creatine phosphate in skeletal muscle fibers |
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Term
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Definition
| * located in cortex, made up of Bowman's capsule & glomerulus |
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Term
| Bowman's (glomerular) capsule |
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Definition
* double-walled cup-shaped structure
* outer wall is parietal and formed by simple squamous epithelium
* inner wall is visceral and formed by simple epithelium (podocytes)
* CAPSULAR SPACE => space between visceral and parietal |
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Term
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Definition
| capillary bed located in the cup of Bowman's capsule |
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Term
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Definition
* begins at the cortex and extends into the medulla
* made up of proximal convoluted tubule, descending limb of Henle, loop of Henle, ascending limb of Henle, distal convoluted tubule, and collecting duct
* associated with the peritubular capillary |
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Term
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Definition
* most common
* renal corpuscle is located in the outer cortical zone with short loops of Henle that only extend into the medulla |
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Term
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Definition
* renal corpuscle is in the cortex at the corticomedullary boundary
* long loops of Henle extend into the renal papillae
* ascending limb with two regions: thin & thick
* has TWO capillary bed at the renal tubule: peritubular & vasa recta
* responsible for regulating H2O volume in urine |
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Term
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Definition
* proximal convoluted tubule => simple cuboidal with microvilli
* descending loop of Henle => simple squamous
* ascending loop of Henle => simple squamous, simple cuboidal, simple columnar
* distal convoluted tubule => simple cuboidal |
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Term
| modified cells in the ascending loop of Henle |
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Definition
* a region of the ascending limb of Henle touches the afferent arteriole, modified cells @ site
* in the ascending limb => macula densa
* in the afferent arteriole => modified smooth muscle cells called juxtaglomerular cells
*** COMBINED, they form a unit called the juxtaglomerular apparatus (JGA) ====> FUNCTION: monitors BP; when BP decreases, JGA secretes renin |
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Term
| kidney (nephron) physiology |
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Definition
* filter blood, pull H+ out of blood as well as toxic waste to form urine
* 3 principle processes => glomerular filtration, tubular reabsorption, tubular secretion |
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Term
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Definition
* forcing liquid & dissolved solutes into Bowman's capsule through filtration membrane - endothelial capsular membrane (3 components)
* volume of filtrate sig. larger than any other capillary
* filtrate contains anything from blood except plasma proteins and formed elements
* 3 mechanisms required: glomerular blood hydrostatic pressure, capsular hydrostatic pressure, blood colloidal osmotic pressure |
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Term
| 3 components of the endothelial capsular membrane |
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Definition
1) endothelium (wall of glomerulus)
2) basement membrane (extracellular with slit openings)
3) visceral layer of Bowman's capsule (podocytes)
* ALL ALLOW ANYTHING TO PASS THROUGH EXCEPT PLASMA PROTEINS AND FORMED ELEMENTS |
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Term
| glomerular blood hydrostatic pressure |
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Definition
| moves H2O and solutes from glomerulus to Bowman's capsule => 55mmHg |
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Term
| capsular hydrostatic pressure |
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Definition
| moves H2O and solutes from Bowman's capsule back to glomerulus => 15mmHg |
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Term
| blood colloidal osmotic pressure |
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Definition
* created by plasma proteins
* moves material from Bowman's capsule back into the glomerulus => 30mmHg |
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Term
| effective filtration pressure |
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Definition
P.eff = (glom. BHP) - (capsular HP + blood COP)
* in homeostasis, nephrons perform best at 10mmHg & 125ml/min
* if any pressure is changed, you change effective filtration pressure, and change ml/min of filtrate, which thusly affects urine output |
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Term
| regulatory mechanisms for filtrate formation |
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Definition
* all mechanisms work either to adjust blood flow in and out of glomerulus or to alter glomerular capillary surface area available
* three mechanisms => renal autoregulation, neural regulation, hormone regulation |
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Term
| renal autoregulation for filtrate formation |
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Definition
* kidney itself maintains a constant blood flow throughout despite normal fluctuations in BP
* two mechanisms involved => myogenic mechanisms & tubuloglomerular feedback mechanisms |
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Term
| myogenic mechanism in renal autoregulation |
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Definition
* involves smooth muscle in arteriole walls
* when blood pressure goes up, smooth muscle in the afferent arteriole is stretched
* smooth muscle fibers respond to the stretch by contracting => vasoconstriction of the afferent arteriole
* decrease vol. of blood going into the glomerulus, decreases glomerular blood hydrostatic pressure => FIXES BLOOD PRESSURE ISSUE |
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Term
| tubuloglomerular feedback mechanism in renal autoregulation |
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Definition
* macula densa cells are capable of detecting an increase in rate of flow of filtrate
* macula densa secretes vasoconstricting molecules from the juxtaglomerular apparatus
* vasoconstricting molecules go to the afferent arteriole, lowering volume of blood to glomerulus, decrease glomerular blood hydrostatic pressure which decreases filtrate formation |
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Term
| neural mechanism for filtrate formation |
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Definition
* sympathetic nerve fibers that go to smooth muscle fibers in the afferent and efferent arterioles
* SNS fibers release norepinephrine when stimulated; norepinephrine binds to alpha one receptors on the smooth muscle fibers
* there are far more alpha one receptors in the afferent than the efferent arteriole
* AT REST, the nervous system does nothing to blood flow (renal autoregulation)
* IN MODERATE SNS STIMULATION, equal vasoconstriction of afferent and efferent arterioles results in a slight reduction of filtrate formation |
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Term
| neural mechanism for filtrate formation in a fight/flight situation |
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Definition
due to the fact that there are more receptors on the afferent arteriole, greater vasoconstriction results in the afferent arteriole
* leads to a decrease in blood volume in the glomerulus, as well as a reduction in filtrate formation which decreases urine output |
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Term
| hormone regulation for filtration formation |
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Definition
* hormones associated with renin-angiotensin pathway (ANP, BNP)
* 3 stimuli trigger renin production
- drop in blood pressure, SNS stim., decrease in osmotic concentration of filtrate at the macula densa |
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Term
| hormone regulation for filtrate formation when there is a drop in blood pressure |
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Definition
* juxtaglomerular apparatus secretes renin, renin converts angiotensinogen to angiotensin I (inactive) => blood => @ lungs runs into ACE => converts angiotension I to angiotensin II (active)
* causes vasoconstriction of the afferent and efferent arteriole, decreasing filtrate and urine formation, blood volume is maintained by conserving H2O for blood |
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Term
| hormone regulation for filtrate formation with naturetic peptides |
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Definition
* stimulus for ANP & BNP => increase in BP
* in this story, they go to the glomerulus and increase the capillary surface area available for filtration
* increased surface area, more filtrate available, increase urine output, lower blood volume, lower blood pressure |
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Term
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Definition
* taking vital components from filtrate and putting them back into blood
* 123-124 ml of filtrate is reabsorbed, carried out by the epithelial cells of the renal tubule => can occur along entire tubule but MOST occurs at the PCT
* selective process that involves both active transport and passive transport mechanisms |
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Term
| glucose reabsorption from filtrate |
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Definition
* normally all glucose is reabsorbed from filtrate through an active transport mechanism involving a carrier system
* number of available carriers limits the amount of glucose that is reabsorbed => permits reabsorption of glucose from filtrate that accommodates bld. glucose levels that are slightly above the norm
* when blood glu. levels increase above 200 mg, there aren't enough carriers so glucose starts to be dumped in urine |
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Term
| sodium ion reabsorption from filtrate |
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Definition
* active transport mechanism located along renal tubule except ascending limb of Henle
* always on at the PCT, normally off at DCT
* most Na+ is reabsorbed @ PCT, amount reabsorbed varies depending on ECF concentration of Na+
* if Na+ levels decrease, blood pressure decreases which leads to the juxtaglomerular apparatus to secrete renin => converts angiotensinogen to angiotensin I => @ lungs exposed to ACE which converts to angiotensin II |
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Term
| effects of angiotensin II on renal physiology |
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Definition
1) vasoconstriction which reduces filtrate formation
2) active transport mechanism for sodium @ PCT increases absorption @ PCT
3) goes to adrenal cortex to stimulate the secretion of aldosterone => target cells are epithelial cells of DCT, turns on active transport mechanism for Na+, reabsorb even more Na+ than usual
4) stimulate secretion of ADH (made by hypothalamus & stored/secreted from the posterior pituitary) => target cells are epithelial cells of DCT, makes cells permeable to H2O => * H2O passively follows Na+ into blood, increase blood volume and blood pressure |
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Term
| chloride ion reabsorption |
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Definition
* passively follows Na+ except in ascending limb of Henle
* in ascending limb, there is an active transport mechanism for Cl-
* Na+ passively follows Cl- due to opposite charges
* if aldosterone is present, Cl- is more reabsorbed along with Na+ |
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Term
| potassium ion reabsorption |
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Definition
* passive transport mechanisms in PCT
* leakage channels in renal tubules which leads K+ to leak back into filtrate; K+ is lost in filtrate no matter how badly it is needed for physiology
* neurons don't work without K+ |
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Term
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Definition
* reabsorbed at the PCT
* if PTH is available, Ca++ is reabsorbed at the DCT |
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Term
| phosphate ion reabsorption |
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Definition
* passive transport mechanism
* if PTH is available, HPO4- is added to filtrate (urine)
* decrease HPO4- levels, increase calcitonin levels |
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Term
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Definition
* selectively moving materials from blood in the PTC to filtrate of renal tubule
* excess H+, urea, uric acid, certain drugs that bind to plasma proteins
* maintains pH and adds toxic/waste materials to filtrate to clear blood |
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Term
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Definition
* volume of blood that is cleared of a substance per unit time
* measures how effectively kidneys remove a specific substance
* high value = efficient excretion
* low value = inefficient excretion
* determines rate of filtration
* depends on: amount of material that enters filtrate at Bowman's capsule, amount of material that undergoes tubular secretion, amount of material that undergoes tubular reabsorption (only one that decreases clearance) |
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Term
| countercurrent multiplier mechanism |
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Definition
* urine formation 24/7 in all states of hydration
* permits production of urine by kidneys => concentrated (hypertonic) vs. dilute (hypotonic)
* occurs in juxtamedullary nephrons
* involves ADH and the osmoreceptors in the hypothalamus that measure solute concentration in blood => increased solute secretes ADH |
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Term
| ADH's role in the countercurrent multiplier mechanism |
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Definition
* target cells for ADH are the epithelial cells of the DCT and CT
**** along the ascending limb, DCT & CT => normally entire region is NOT permeable to H2O
* when ADH is present, the walls become permeable to H2O; H2O doesn't go anywhere unless it has a reason to go somewhere, so what is the reason?:
* in the PCT, there is active transport mechanism for Na+, as Na+ is pumped out, Cl- passively follows & H2O passively follows both (obligatory reabsorption of H2O - fixed value)
* in the ascending limb, active transport mech. that moves Cl- out, Na+ passively follows, H2O can't follow because the ascending limb is currently impermeable, by the time the filtrate reaches the DCT, filtrate is hypotonic (solute pulled out, water stays in)
* COUNTERCURRENT MULTIPLIER MECHANISM MAINTAINS A HYPERTONIC SOLUTION AROUND THE ASCENDING LIMB |
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