Homestasis and excretion 3

Bowman’s capsule

Hollow cup of cells surrounding the glomerelus. Acts as a coarse filter for plasma

Glomerulus

Ball of blood capillaries, blood is filtered from the renal artery. Cells have spaces between them making the wall more permaeble

First coiled tube (PCT)

Section of the nephron where selective reabsorption of all glucose, 80 percent of water, sodium and chloride ions are reabsorbed back into the blood

Loop of Henle

Concentrates the fluid around the tubule causing more water and salts to be reabsorbed into the blood

Second coiled tube (DCT)

Rest of the water and other ions are reabsorbed

Collecting duct

The tube that several nephrons join up that leads to the pelvis

On which parts of the nephron does ADH act on

Makes DCT and collecting duct more permaeble to water

Ultrafiltration

Where small molecules are filtered out of the blood due to high pressure in the glomerulus

What is does not pass through the glomerulus

RBC, WBC, large proteins

Malpighian body

Glomerulus and Bowman’s capsule

Afferent arteriole

Wide, low resistant arteriole where blood goes in

Efferent arteriole

Narrow, high resistance arteriole where blood goes out

Why is it good for the efferent arteriole to be narrow

Constriction prevents a pressure drop

Why do arterioles widen or constrict

To controls blood pressure

Basement membrane

Acts as an additional filter between the glomerulus and bowman’s capsule

Is ultrafiltration passive or selective

Passive

What does ADH do when thirsty

Increases permeability, more H2O reabsorption, concentrated urine

What does ADH do when hydrated

Decreases permaebility, less H2O reabsorption, dilute urine

Negative feedback loop

Causes a change that tries to eliminate the initial stimulus

Positive feedback loop

Causes changes that increase the initial stimulus