EXCRETORY SYSTEMWhat do you think some of the functions of the urinary system are?

How is the urinary system related to some of the other systems that you have already learned about?

FUNCTIONS OF THE EXCRETORY SYSTEM elimination of chemical/metabolic wastes from the

body nitrogenous wastes (byproducts of chemical

reactions that are no longer useful such as ammonia, urea, uric acid, creatinine)

control the volume and composition of body fluids water-salt balance

blood volume is closely associated with the salt balance of the body (i.e. the more salt in the blood, the greater the volume of blood and the greater the blood pressure)

the kidneys are involved in regulating blood pressure and also maintain appropriate levels of certain ions in the blood

acid-base balance the kidneys monitor and control blood pH through the

excretion and reabsorption of certain ions the kidneys are the main organ of excretion

principal job is the removal of urea and the regulation of water in the bloodstream

WASTE PRODUCTS urea

end product of amino acid metabolism in body cells

water solubleprimary end product of the urinary systemexcreted in urine

ammoniaend product of the deamination of amino

groupsvery toxic to tissuesconverted to urea in the liver in land mammals

creatinineend product from creatinine phosphate in

muscle metabolism

STRUCTURES OF THE EXCRETORY SYSTEM kidneys

reddish brown organsapproximately the size of a fist (4 inches

long, 2 inches wide, 1 inch thick in an average sized adult)

located on either side of the spinal column, anchored against the dorsal (back) body wall by connective tissue

responsible for excretion of urine and the regulation of blood volume and pH

renal veincarries blood from the kidneys back to the

heart renal artery

carries blood into the kidney

STRUCTURES OF THE EXCRETORY SYSTEM CONTINUED

uretermuscular tubemoves urine from the kidneys to the

bladder through peristalsis urinary bladder

urine storage, can hold up to 600 to 1000 mL of urine

expands and contracts stretch receptors indicate when it is full, signal notifies

the brain resulting in the desire to urinate urethra

tube that connects the urinary bladder to the outside

DIAGRAM

Kidney

Renal Vein (OUT)

Renal Artery (IN)

Ureter

Urinary Bladder

Urethra