Excretion (triple)

define excretion

the removal of metabolic waste

define selective reabsorption

the reabsorption of useful substances like glucose, mineral ions and water

define osmoregulation

controlling water content in the body

define filtration

the filtering out of waste products like water, ions and urea at high pressure to form urine

what are the excretory products of the lungs?

CO2 and water vapour

what are the excretory products of the kidney?

urea, water and excess salts

what are the excretory products of the skin?

mineral ions and water

where does urea come from?

from the breakdown of amino acids in the liver

what is the inner part of the kidney called?

the medulla

what is the outer part of the kidney called?

the cortex

describe the path of blood in the kidney

• kidney is supplied with oxygenated blood by the renal artery

• the renal vein takes deoxygenated blood away

function of the ureter

carries urine from the kidneys to the bladder to be excreted

STRUCTURE OF NEPHRON:

1. The renal artery

transports oxygenated blood to the bowman’s capsule under high pressure

STRUCTURE OF NEPHRON:

2. The glomerulus

it is a ball of capillaries in the capsule and the pressure increases as the efferent arteriole (capillaries leaving) is narrower than the afferent arteriole (capillaries entering)

STRUCTURE OF NEPHRON:

3. Ultrafiltration

this high pressure leads to ultrafiltration where water, salts, glucose and urea pass out the capillary, into the bowman’s capsule and out the tubules

STRUCTURE OF NEPHRON:

4. Proteins and blood

protein and blood cells are too big to leave the capillaries so they stay in the blood