Term
| Simplified Overview of Steps |
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Definition
kidneys produce urine
ureters move urine from kidney to bladder
bladder stores urine
urethra excretes urine |
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Term
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Definition
arota-->renal artery-->kidney
kidney-->renal vein-->inferior vena cava
kidneys receive 25% of cardiac output |
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Term
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Definition
outer cortex
inner medulla
contains nephrons |
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Term
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Definition
functional unit of kidney
composed of renal corpuscle and associated tubules
80% found in cortex
20% found in medulla |
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Term
| Tubule Components of Nephron |
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Definition
| bowman's capsule-->proximal tubule-->descending loop of henle-->ascending loop of henle-->ascending loop of henle-->disal tubule-->collecting duct-->renal pelvis |
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Term
| Vascular Components of Nephron |
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Definition
| afferent arteriole-->glomerulus-->efferent arteriole-->peritubular capillaries (vasa recta if in the medulla)-->venules-->veins |
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Term
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Definition
| glomerulus + bowman's capsule |
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Term
| Juxtaglomerular Apparatus |
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Definition
distal tubule + aterioles
distal tubule composed of macula densa cells
arterioles composed of granular cells
section in between the distal tubule and ascending loop of henle passes between the afferent and efferent arteriole |
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Term
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Definition
1. Filtration=movement of fluid from glomerulus to bowman's capsule
2. Reabsorption=filtrate from lumen to blood of peritubular capillaries
3. Secretion=selected molecules from blood moved to lumen of tubules of nephron |
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Term
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Definition
| occurs in renal corpuscle fluid moves from glomerulus capillaries to bowman's capsule fluid must pass through 3 barriers to get to lumen of bowmans capsule -glomular capillary epithelium -basal lamina -epithelium of bowman's capsule dependent on high hydro static pressure (55mgHg in capillaries) -favors fluid movement out of capillaries -net movement (10mmHg) along entire length of glomerulus 20% of plasma volume is filtered (filtration fraction) -80% flows straight to peritubular capillaries filtrate is isosmotic to plasma (300mOsM)-same osmotic pressure |
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Term
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Definition
1. glomerular capillary epithelium
-fenestrated capillaries doesn't allow blood cells or plasma proteins to filter through
2. basal lamina
-separates capillary endothelium from bowman's capsule epithelium
-blocks filtration of plasma proteins
3. epithelium of bowman's capsule
-contain podocytes with foot processes
-surround glomerular capillaries
-form filtration slits to allow filtrate to enter bowman's capsule
-increase surface area for more filtration |
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Term
| Glomerular Filtration Rate (GFR) |
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Definition
volume fluid filtered into Bowman's Capsule
per unit ime
180L/day or 125mL/min
factors that control GFR
- net filtration pressure (dependent on renal flow and presence)
-permeability of interface between glomerulus capillaries and bowmans capsule |
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Term
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Definition
maintain a nearly constant GFR when mean arterial blood pressure is between 80-180mmHg
accomplish by controlling blood flow through arterioles
protects filtration batteries from damage due to increase in BP
4 types
1. Myogenic Response
2. Tubuloglomerular Feedback
3. Neural Control
4. Renin-Angiotensin System |
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Term
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Definition
overall effect is to decrease blood flow across a vessel after an increase in blood pressure
increase in BP causes smooth muscles in AFFERENT arterioles to stretch
in response, AFFERENT arterioles constrict
-increases resistance to blood flow
-decreases renal blood flow to glomerulus
-decrease GFR and BP
helps conserve blood volume |
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Term
| Tubuloglomerular Feedback |
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Definition
autoregulation of GFR
occurs when BP is high
occurs in distal tubules with macula densa cells
contains chemoreceptors to measure NaCl solute levels in distal tubule
-high NaCl level=high BP=high GFR
when NaCl levels are high, macula densa cells release paracrine
paracrine=vasoconstriction of AFFERENT arterioles
-increase resistance
-decrease GFR and BP |
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Term
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Definition
autoregulation of GFR
sympathetic neurons innervate arterioles
sympathetic stimulation on alpa receptor on vascular smooth muscle causes vasoconstriction, which increases BP
if BP falls dramatically (below autoregulatory range), sympathetically induced vasoconstriction of arterioles decreases blood flow and GFR
-helps to conserve fluid volume |
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Term
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Definition
function is to increase BP
begins with release of renin from granular cells
-macula densa signal actin when BP and NaCl is low
-sympathetic neurons stimulate granular cells when BP is low
renin converts angiotensinogen (inactive plasma protein in liver) to angiotensin I
ACE (angiotensin converting enzyme) found in lungs converts angiotensin I to angiotensin II
angiotensin II effects
-vasoconstriction
-greater vasoconstriction of EFFERENT arterioles because more receptors for A2 then in afferent arterioles
-increase GFR and BP |
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Term
| Reabsorption Transport Mechanisms |
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Definition
active (primary and secondary)
passive
transepithelial
paracellular
Na+ dependent |
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Term
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Definition
Primary=use of ATP
Secondary=electrochemical gradients
used by Na+ |
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Term
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Definition
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Term
| Transepithelial Transport |
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Definition
| Na+, anions, H2O, solutes |
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Term
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Definition
between cells
anions and water |
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Term
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Definition
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Term
| Primary Active Transport of Na+ |
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Definition
Na+ enters by passive facilitated diffusion
Na+ leaves by Na+-K+-ATPase (1* active transport because using ATP) |
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Term
| Secondary Active Transport of Na+/Glucose |
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Definition
Na+ enters with SGLT transporter down concentration gradient
SGLT transporter pulls glucose in against its concentration gradient
GLUT facilitated diffusion carrier carries glucose out
Na+ leaves by Na+-K+-ATPase |
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Term
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Definition
Na+ reabsorbed by active transport
anions reabsorbed
water moves by osmosis
permeable solutes (K+, Ca2+, urea) reabsorbed by diffusion |
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Term
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Definition
occurs during reabsorption (mostly in proximal tubule)
saturation=all available transporters are occupied with substrate
renal threshold=substrate concentration in plasma where saturation occurs
transport maximum=max rate of transport of saturation
Ex: glcuose
x axis=plasma glucose concentration
y axis=reabsorption rate glucose
Tm=375
renal threshold=300
glucose can't be transported once it reaches saturation/renal threshold so it is excreted
presence of glucose in urine is indicator of transport maximum |
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Term
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Definition
enhances excretion of substances already in lumen
active process (secondary active trasport)
secretion of H+ and K+ important |
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Term
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Definition
controls pH (stable at 7.4)
increase in H+ in blood=increase H+ secretion
decrease in H+ in blood=decrease H+ secretion
also use ventilation and buffers to remove excess H+ |
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Term
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Definition
influenced by hormone aldosterone (hormone produced in adrenal cortex)
function is to: increase BP, increase K+ secretion, increase Na+ reabsorption
released during by: increase plasma K+, decrease plasma Na+, angiotensin II
stimulates principal cells in the distal tubule
increase K+ secretion and Na+ reabsorption
water wants to follow Na+ reabsorption (needs another hormone to increase permeability of distal tubule->anti-duretic hormone) |
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Term
| Anti-diuretic Hormone (ADH) |
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Definition
function: increase water permeability of collecting duct, increase blood volume and blood pressure, and decrease urine output
synthesized from: posterior pituitary gland
release stimulated by: angiotensin II stimulates hypothalamus to release ADH from posterior pituitary
major mechanism for controlling water content in blood by regulating permeability of collecting duct to water
absent=dilute urine, increase urine volume
present=concentrated urine, decrease urine volume |
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Term
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Definition
main effect=increase in BP
vasoconstriction of arterioles
stimulates cardio control center to increase cardiovascular response
stimulates hypothalamus to increase thirst and release ADH from posterior pituitary gland
stimulates adrenal cortex to release aldosterone to increase Na+ reabsorption and K+ secretion |
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