Excretion Flashcards
Distinguish between egestion and excretion
Excretion is the process by which waste products produced by metabolism are removed, while egestion is the removal of undigested food not produced by the body’s metabolism
Discuss the importance of excretion in living organisms
State how metabolic wastes are excreted from plants and animals
Leaf loss
Loss of bark
The lungs excrete bile pigments
The skin excretes water, urea and salts as sweat
The kidneys excrete water and salts as urine
What does the renal artery do
Carry blood to each kidney
What does the renal vein do?
Carry blood away
Urine is produced in the nephrons by two processes:
Ultra-filtration
Selective reabsorption
Function of the sphincter muscle
Keeps bladder closed
Where does ultrafiltration occur?
In the glomerulus
Where does selective reabsorption occur?
In the nephrons
Define osmoregulation
The regulation of the concentration of blood plasma and body fluids
What happens if body fluids become too concentrated
Excessive sweating, drinking too little or eating salty foods causes body fluids to become too concentrated.
The hypothalamus detects that the blood plasma is too concentrated and stimulates the pituitary gland to secrete ADH. The blood carries the ADH to the kidneys. Very small quantities of concentrated urine are produced
What happens if body fluids become too dilute
The hypothalamus detects this and the pituitary gland stops secreting ADH. Large amounts of dilute urine are produced
What happens when kidney failure occurs?
The nephrons stop functioning properly so they’re unable to remove waste from the blood and regulate the volume and composition of blood plasma. Harmful waste builds up in the blood, which can lead to death
