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29 Cards in this Set

  • Front
  • Back
Urea
Proteins --> Amino Acids --> NH2 removed --> forms ammonia, liver converts it to urea
Uric Acid
Nucleic acid catabolism
Creatnine
Creatine phosphate catabolism
Renal Failure
Azotemia: elevated BUN levels, nitrogenous wastes in blood

Uremia: Toxic effects as waste accumulates
Proximal Convulated Tubule
Longest, most coiled part part, simple cubodial with brush border
Nephron Loop
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
Distal convulated tubule
Cubodial, minimal microvilli
Cortical nephrons
85%
- short nephron loops
- efferent arterioles branch off peritubular capillaries
Juxtamedullary nephrons
15%
- very long nephron loops, maintain salt gradient, help conserve water
Filtration slits
Podocyte arms have pedicles with negatively charged filtration slits, they allow particles < 3nm to pass
Effects of GFR abnormalities
- Increased GFR: urine output rises, dehydration, electrolyte depletion

- Decreased GFR - water reabsorbed (azotemia possible)
GFR control
Controlled by adjusting glomerular BP

- autoregulation
- sympathetic control
- hormonal mechanism: renin and angiotensin
Renal auto-regulation of GFR
Increased BP --> constrict afferent arteriole, dilate efferent
Proximal Convulated Tubules (PCT)
- 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
Tubular Secretion of PCT & Nephron Loop
-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
Primary Function of Nephron Loop
-Water conservation
-Generates salinity gradient, allows CD to concentrate urine
-also involved in electrolyte re absorption
Principal cells and Intercalated Cells in DCT
- 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)
DCT & Collecting Duct (Aldosterone effects)
-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
Effects of ADH (collecting duct and DCT)
- Dehydration stimulates hypothalamus
- Hypothalamus stimulates posterior pituitary
-Posterior pituitary releases ADH
- ADH increases water absorption
-Decreases urine volume
Atrial Natriuretic Peptide
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
Countercurrent Multiplier
Recaptures NaCl and returns it t renal medulla

Recycling of urea: collecting duct - medulla - urea accounts for 40% of high osmolarity of medulla
Countercurrrent Multiplier - Descending Limb
- Reabsorbs water but not salt
- Concentrates tubular fluid
Countercurrent Multiplier - Ascending Limb -
- Reabsorbs Na+, K+, Cl-
- Maintains high osmolarity of renal medulla
- Impermeable to water
- Tubular fluid becomes hypotonic
Composition and Properties of Urine
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)
Diabetes
Chronic polyuria of metabolic origin
Hyperglycemia and Glycosuria
- Diabetes mellitus 1 and 2, insulin hyposecrete, insensitivity

- Gestational diabetes: 1 to 3% of pregnancies
Diabetes - ADH
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
Internal Urethral Sphincter
Detrusor muscle, thickened, smooth muscle, INVOLUNTARY CONTROL
External Urethral Sphincter
Skeletal muscle, VOLUNTARY CONTROL