Unit 3(D): The excretory system.

HOW WE PERFORM EXCRETION

We excrete ………….. through our lungs. We excrete the residues of ……… through the anus. To excrete other substances we use our urinary system and sweat glands.

HOW WE PERFORM EXCRETION

We excrete carbon dioxide through our lungs. We excrete the residues of the food through the anus. To excrete other substances we use our urinary system and sweat glands.

EXCRETIONis the expulsion of residues.

We expel residues :We expel residues : in URINE, through the urinary system

in SWEAT through the sweat glands.

Organs of the Human Urinary System

1.THE KIDNEYS are organs which filter the blood. They extract toxic substances and form urine.

1.THE KIDNEYS are organs which filter the blood. They extract toxic substances and form urine.

2.-THE URINARY TRACT is the tube through which urine flows out of our bodies. It includes:

THE URETERS

THE BLADDER

THE URETHRA

3.-THE BLOOD VESSELS, include: THE RENAL VEINS AND THE RENAL ARTERIES.

HOW THE URINARY SYSTEM WORKS→Blood containing residues flows to

the KIDNEYS through the RENAL ARTERIES.

→Each KIDNEY filters the blood and extracts waste products.

→The clean blood returns to the body through the RENAL VEINS.

→The residues are mixed with water to form urine which flows out of the KIDNEYS through the URETERS. It collects in the BLADDER.

→When the BLADDER is full we expel the urine through the URETHRA.

DialysisDialysis

EXCRETION THROUGH THE SKIN

OUR SKIN has million of SWEAT GLANDS which produce sweat.

1.- Blood filled with waste products flows to the sweat glands through capillaries.

2.- The sweat glands filter the residues, mix them with water and expel them as sweat through the pores in the skin.

3.- The clean blood retursn to the body through the capillaries.

SWEATGLAND