Kidneys

Homeostasis

maintaining a stable internal environment witting set limits

Negative feedback

Restores system to their original level by reversing any change

Functions of kidneys (2)

Excretion of nitrogenous waste

Osmoregulation

Label A-H

Renal artery

Renal vein

Ureter

nephron

cortex

medulla pelvis

What is the basement membrane

Sieve at base of Bowmans capsule - only allowing small molecules

Describe ultrafiltration

Driven by hydrostatic pressure from the afferent arteriole

Basement membrane acts aa a molecular sieve to filter out large molecules

Then moves onto PCT

How are PCT adapted to function

Microvilli - increase surface area

Plenty mitochondria - provide ATP

Membrane bound transport protein - carry out selective reabsorption

What substances are reabsorbed in PCT

Glucose, amino acids

What happens in the descending and ascending limb of the loop of henle

Water moves out into the high solute concentration

creating a low water potential at bottom

Na+ / Cl- ions actively transported out in via active transport

Water cannot follow as it is impermeable

This makes medulla very salty helping draw out water in the collecting duct

What does hypothalamus do

Has osmoreceptors to detect solute concentration

Pituitary release ADH

Travels to collecting duct and makes them more permeable through use of aquaporins

ADH = more reabsorption of water