A&P Kidney's

kidney functions?

• filter blood and excrete toxic metabolic waste

• regulate BV, BP, osmolarity

• secrete erythropoietin—> stimulates RBC production

• regulate calcium levels

• clear hormones from blood

• synthesize glucose from AA (in starvation)

metabolic waste?

substance produced by body

major sources of nitrogenous waste?

• urea (50%)

• uric acid

• creatinine

excretion?

seperating wastes from body flouds and eliminating them (to maintain homeostasis by eliminating toxic substances or too much of)

what are the 2 parts of the nephron?

• renal carpuscle: filters blood plasma

• renal tubule: convert filtrate to urine

renal corpuscle?

made of glomerulus and glomerulus capsule

• 2 layers:

• parietal (outer): simple squamous

• Visceral (inner): elaborate cells (podocytes) that wrap around glomerular capillaries

• capsular space separates the layers

11. Outline the filtrate flow through the nephron and collecting system, starting from the glomerulus

glomerulus→PCT→nephron loop (loop of Henle)→DCT→collecting duct

what is the renal tubule made up of?

PCT, nephron loop, PCT, collecting duct

what are the 4 stages kidney’s convert blood plasma to urine?

1. glomerular filtration

2. tubular reabsorption

3. tubular section

4. water conservation

what is glomerular filtration?

creates plasma like filtrate of the blood

what is tubular reabsorption?

removes useful solutes from filtrate and returns them to blood

what is tubular secretion?

removes additional wastes from blood and adds to filtrate

what is water conservation?

removes water from urine and returns it to blood (concentrates wastes)

what is glomerular filtration?

water/solutes in blood plasma pass from glomerular capillaries into capsular space of nephron (driven by net effect of 3 pressures)

what is the filtration membrane made of?

fenestrated endothelium, basement membrane, filtration slits

• blood capillary, through 3 barriers, to capsular space

What are the 3 pressures that drive glomerular filtration?

blood hydrostatic pressure (BHP), colloid osmotic pressure (COP), and capsular hydrostatic pressure (CP)

why does glomerular filtration occur?

HIGH BHP of capillaries overrises the opposing COP of the blood and pressure of CP

• makes kidney’s vulnerable to hypertension (affects renal function (bursting)

what is glomerular filtration rate (GFR)?

=total amount of filtrate produced

• 99% reabsorbed

• if too high= risk of dehydration

• if too low=wastes reabsorbed

what 3 homeostatic mechanisms regulate GFR?

renal autoregulation, sympathetic stimulation, hormonal control

what is renal autoregulation?

• Myogenic: constricts if BP rises; relaxes if BP falls

• Tubuloglomerular: juxtaglomerular apparatus responds to increased GFR by constricting afferent arteriole

what is sympathetic stimulation?

constricts afferent arterioles in strenuous exercises/acute situations, reducing GFR, directing blood to needed areas

what is hormonal control?

BP decreases causing renin to be secreted (by granular cells) to restore BP to normal

what triggers the release of renin?

sympathetic fibers (angiotensin II raises BP)

• contracts BV, aldosterone release=water retention, ADH=water reabsorption, stimulates sense of thirst and water intake

PCT reabsorption?

66% of filtrate

• reabsorbs: na+ (active transport) glucose, K+, Cl- (by diffusion) water urea uric acid (solvent drag)

• transported: by transcellular (protein transport) and paracellular (solvent drag)

what happens in max rate of reabsorption?

ALL the transported proteins are saturated

function of nephron loop?

generate a salinity gradient to allow collecting duct to concentrate urine and conserve water

function of PCT and DCT?

reabsorb variable amounts of water and salt (regulated by hormones)

what do the hormones aldosterone and ADH do?

increase water retention

what does the hormone atrial natriuretic peptide hormone do?

promote water loss

is the countercurrent multiplier of the nephron loop a + or - feedback loop?

POSITIVE

how does the collecting duct concentrate urine 4x more than fluid?

• tissue fluid osmolarity 4x higher in medullary portion of CD than cortex

• medullary portion is more permeable to water than solutes

what reguates volume and concentration of urine?

ADH

what is polyuria?

>2 L/day of urine

what is oliguria?

<400 ml/day

body can’t maintain low concentration of waste in plasma=azotemia (elevated waste in blood)

what metabilic disorder results in chronic polyuria?

diabetes

what are diaretics?

any chemical that increases urine volume

Ex: caffeine (increases GFR and dilates afferent arterioles) or alcohol (reduces tubular reabsorption of water and inhibits ADH secretion)

what are the 3 layers of the ureter wall?

muscularis, outer adventitia, transitional epithelium

• urine enters and stretches ureter causing muscularis to initiate peristalsis waves to more urine continuously

what are the 3 layers of the bladder?

detrusor (3 layers of smooth muscle), urothelium (rugae) , trigone (triangle)

what are 2 urinary disorders?

renal calculi (kidney stones) and UTI

what are renal calculi (kidney stones)?

crystallized minerals of calcium or phosphate salts that form in renal pelvis=block urine flow

what is a UTI?

• bacteria (like E. Coli)

• treated with antibiotics

• more commonly in women

• may lead to involve kidney’s if not treated

what is dialysis?

artificially cleans blood by attempting to duplicate function of healthy nephrons

what are the 2 ways of dialysis?

continuous ambulatory peritoneal dialysis and hemodialysis

• neither receive homeostats or replace renal hormones ONLY permatent cure=kidney transplant

what is continuous ambulatory peritoneal dialysis?

• may be done at home

• port left in place for a few hour (to remove waste and ions), then drained

• risk of infection at port

what is hemodialysis?

• several visits per week to a dialysis center\

• blood is circulated through a dialyzer

• costly and time consuming