EXCRETION

PREPARED BY: FAIZ ABDULLAH

EXCRETIONThe removal of toxic waste products of metabolism from the body

What for?

If these waste products are allowed to build up, they would quickly become toxic

REMOVE WHAT EXACTLY?

Waste products of metabolism

Carbon dioxidewater Bile pigments

Ammonia Uric AcidUrea

ORGANS OF EXCRETION

Lung

Kidney

Organs Products excreted Method of removal

CO2

Urea, Nitrogenous waste, variety of ions dissolved in water

Exhalation/Expiration

Urine

CAUTION: EGESTION OF FAECES FROM ANUS NOT

EXCRETION

This is because faeces is not a product of metabolism

NOW, LET’S LOOK AT YOUR URINARY SYSTEM

SEVERAL STRUCTURES YOU NEED TO KNOW..

Removes excess water and wastes, such as urea, from the blood to form urine

Note: In a diabetic patients, kidneys remove some glucose present in blood thorough urine

Two muscular tubes

Urine moves down here

How?

Spontaneous rhythmic peristaltic constrictions of the uterus wall

Helped by gravity

To where?

Urinary bladder

Bladder is a muscular bag in which urine accumulates gradually

Stores urine

Urine goes down to Urethra next by contraction of muscles

Carries urine out of the body

In males urethra passes through penis

Spincter muscle

Controls the flow of urine

Urination can be delayed as per convenience

IF YOU CUT YOUR KIDNEY IN HALF….

NEPHRON

About a million microscopic tubes called nephrons are located in each of the kidneys

Nephrons consist of a capsule shaped like a cup Bowman’s capsule, and a long narrow tube

STRUCTURE OF A NEPHRON (SING.)

LET US LOOK AT SOME PROCESSES THAT HAPPEN IN THE NEPHRON, PARTICULARLY….

Ultrafiltration Selective REabsorption

Ultrafiltration

Ultrafiltration of BLOOD from glomerulus takes place in the BOWMAN’S CAPSULE

A high pressure is built up

Squeezes water, urea, ions and glucose out of blood and into Bowman’s capsule

Large molecules move back into the blood through the capillaries that surround the tubule

As the liquid flows along the tubules in the nephron

Useful substances (like water, glucose, amino acids) are selectively reabsorbed

SELECTIVE REABSORPTION

These substances move back into the blood through capillaries that surround tubule

Excess water, mineral salts, urea and uric acid pass into the pelvic region of the kidney to form urine

NEXT: ROLE OF ADH IM REGULATION OF OSMOTIC CONCENTRATION

ADH ANTIDIURETIC HORMONE

Pituitary Gland releases ADH into blood

ADH

HOWEVER, IT DOES NOT RELEASE ANYHOW.

NEEDS INSTRUCTION FROM BOSS HYPOTHALAMUS

=

Detects problem

High water concentration in blood plasma

OR

Low water concentration in blood plasma

Hey pituitary gland, something is wrong.

FIX IT!

UGH….SHOULD ASK FOR A RAISE NEXT TIME!BIAR KO SASAK AKU GANYA KAU SURUH

High H2O

Pituitary gland secrete less ADH

Kidney tubules to reabsorb less water

More urine produced (diluted)

Less H2O

Pituitary gland secrete more ADH

Kidney tubules to reabsorb more water

Less urine produced (concentrated)

Water conc goes back normal

KIDNEY FAILURE

Kidney failure may result from infection or sudden shock.

Kidney failure patients must be treated with artificial kidney machines or undergo kidney transplants

DIALYSIS

The diffusion of some molecules across a partially permeable membrane is called dialysis

Impurities, such as urea molecules, high concentration in blood, move into dialysis fluid

HAEMODIALYSISThe dialysis of blood