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29 Cards in this Set
- Front
- Back
Urea
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Proteins --> Amino Acids --> NH2 removed --> forms ammonia, liver converts it to urea
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Uric Acid
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Nucleic acid catabolism
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Creatnine
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Creatine phosphate catabolism
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Renal Failure
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Azotemia: elevated BUN levels, nitrogenous wastes in blood
Uremia: Toxic effects as waste accumulates |
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Proximal Convulated Tubule
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Longest, most coiled part part, simple cubodial with brush border
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Nephron Loop
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1.) U - shaped, descending and ascending limbs
- Thick segment (simple cubodial) initial part of descending limb and part or all of ascending limp, active transport of salts - Thin segment (simple squamous) very water permeable |
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Distal convulated tubule
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Cubodial, minimal microvilli
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Cortical nephrons
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85%
- short nephron loops - efferent arterioles branch off peritubular capillaries |
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Juxtamedullary nephrons
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15%
- very long nephron loops, maintain salt gradient, help conserve water |
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Filtration slits
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Podocyte arms have pedicles with negatively charged filtration slits, they allow particles < 3nm to pass
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Effects of GFR abnormalities
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- Increased GFR: urine output rises, dehydration, electrolyte depletion
- Decreased GFR - water reabsorbed (azotemia possible) |
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GFR control
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Controlled by adjusting glomerular BP
- autoregulation - sympathetic control - hormonal mechanism: renin and angiotensin |
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Renal auto-regulation of GFR
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Increased BP --> constrict afferent arteriole, dilate efferent
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Proximal Convulated Tubules (PCT)
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- Reabsorbs 65% of GF to peritubular capillaries
- Great length, prominent mivrovilli and abundant mitochondria for active transport - Reabsorbs greater variety of chemicals than other parts of nephron 1.) transcellular route - through epithelial cells of PCT 2.) paracellular route - between epithelial cells of PCT -Transport maximum: when transport protiens of cell membrane are saturated, blood glucose >220 mg/dL some remains in urine (glycosuria); glucose Tm= 320 mg/min |
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Tubular Secretion of PCT & Nephron Loop
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-Waste removal: urea, uric acid, bile, salts, ammonia, catecholamines, many drugs
-Acid-Base balance: secretion of hydrogen and bicarbonate ions, regulates pH of body fluids |
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Primary Function of Nephron Loop
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-Water conservation
-Generates salinity gradient, allows CD to concentrate urine -also involved in electrolyte re absorption |
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Principal cells and Intercalated Cells in DCT
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- Principal cells: receptors for hormones; involved in salt/water balance
-Intercalated cells: involved in acid/base balance -Function: fluid re absorption here is variable, and secreted by hormonal action (aldosterone and ADH) |
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DCT & Collecting Duct (Aldosterone effects)
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-Decreased BP --> renin release --> angiotensin 2 formation
- Angiotensin 2 stimulates adrenal cortex -Adrenal cortex secretes aldosterone, promotes Na+ re absorption--> leads to decreased urine volume and maintains the BP |
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Effects of ADH (collecting duct and DCT)
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- Dehydration stimulates hypothalamus
- Hypothalamus stimulates posterior pituitary -Posterior pituitary releases ADH - ADH increases water absorption -Decreases urine volume |
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Atrial Natriuretic Peptide
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Atria secret ANP in response to increased BP, leads to four actions:
1.) Dilates afferent arteriole, constricts efferent arteriole, leads to an increased GFR 2.) Inhibits renin/angiotensin/aldosterne pathway 3.) Inhibits secretion and action of ADH 4.) Inhibits NaCl re absorption Promotes Na+ and water excretion, increased urine volume, and decreased blood volume and BP |
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Countercurrent Multiplier
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Recaptures NaCl and returns it t renal medulla
Recycling of urea: collecting duct - medulla - urea accounts for 40% of high osmolarity of medulla |
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Countercurrrent Multiplier - Descending Limb
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- Reabsorbs water but not salt
- Concentrates tubular fluid |
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Countercurrent Multiplier - Ascending Limb -
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- Reabsorbs Na+, K+, Cl-
- Maintains high osmolarity of renal medulla - Impermeable to water - Tubular fluid becomes hypotonic |
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Composition and Properties of Urine
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Appearance - almost colorless to deep amber, yellow color due to UROCHROME, from breakdown of hemoglobin (RBCs)
Odor - as it stands bacteria degrade urea to ammonia Specific gravity - density of urine ranges from 1.001 to -1.028 Osmolarity - ranges from 50 to 1,200 in dehydrated person pH ranges from 4.5 to 8.2, usually 6.0 Chemical composition: 95% water, 5% solutes (urea, NaCl, creatinine, uric acid) |
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Diabetes
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Chronic polyuria of metabolic origin
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Hyperglycemia and Glycosuria
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- Diabetes mellitus 1 and 2, insulin hyposecrete, insensitivity
- Gestational diabetes: 1 to 3% of pregnancies |
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Diabetes - ADH
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Hyposecretion of ADH - diabetes insipidus; CD lowers water re absorption
has nothing to do with insulin, doesn't secrete enough ADH and doesn't absorb as much water and salt |
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Internal Urethral Sphincter
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Detrusor muscle, thickened, smooth muscle, INVOLUNTARY CONTROL
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External Urethral Sphincter
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Skeletal muscle, VOLUNTARY CONTROL
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