The Human Body:The Excretory System

Textbook Chapter 34

Review Topic 1

Function

• Removes toxins and wastes which build up in the body as a result of metabolism

• Regulates the amount of fluid and salts in the body and maintains pH of the blood

• Helps regulate homeostasis

Parts

• Lungs• Excretes carbon dioxide

• Skin• Excretes water and salts contained in sweat

• Kidneys• Major excretory organ in the body

Kidneys

• Bean-shaped

• Filters out wastes, water and salts from the blood

• Two regions• Renal cortex ~ outer region• Renal medulla ~ inner region

• Contains microscopic tubules and blood vessels

• Renal pelvis ~ center of kidney where these filters are found

• Nephron filtration

• Each kidney has 1 million filtering units called nephrons

• Blood enters each Nephron through a long tube surrounded by capillaries called a glomerulus

• Surrounded by the Bowman’s capsule

• Renal artery transports nutrients and wastes to the kidney

• Branches into smaller blood vessels forming the glomerulus

• Blood vessel walls are thin and under high pressure

• Urea ~ nitrogenous waste product containing water and substances dissolved in water

• Pushed through capillary walls into the Bowman’s capsule

• Red blood cells and proteins are too large and remain in the blood stream

• Reabsorption/formation of urine

• Filtrate collects in the Bowman’s capsule and flows through renal tubules (loop of Henle and collecting tubule)

• Most water and useful substances (ex. glucose, minerals) are reabsorbed back into blood stream (reabsorption)

• Excess fluids and toxic substances are collected to form urine

• Leaves the kidneys through ducts called ureters

• Urine is stored in the urinary bladder

• Exits the body through the urethra

• Each kidney filters 180 L of blood a day in adults to produce 1.5 L of urine

• Process requires large amounts of energy

• Use 20-25% of your body’s oxygen intake for their internal energy requirements!

• Controls pH balance by absorbing or filtering out acids or bases to regulate pH of the blood

• Urinary System BrainPop

Kidney Disorders• Infections

• Start as bladder infections which spread to kidney

• Fever, chills, mid-/lower-back pain

• Can be caused by blockages

• If untreated, kidneys can scar causing a loss in function

• Can be treated with antibiotics

• Nephritis• Inflammation (painful swelling) of the

glomeruli

• Cause by blockages

• Blood in urine, swelling of body tissues, protein in urine

• Can improve on its own but may require a special diet or prescription drugs to treat the infection

• Kidney Stones• Crystallized solid (calcium compound) which

forms in the kidney

• Small stones can be passed out in urine

• Larger stones are broken up using ultrasonic sound waves or removed using surgery

• Diabetes/High Blood Pressure• Causes reduced kidney function or kidney

failure

• Illegal/Prescription Drugs• Can cause kidney damage

Treatments

• Dialysis• An artificial

kidney machine

filters out wastes

and toxins from

a patient’s blood

• Two types• Blood is passed through the machine

temporarily to be filtered and cleaned, then returned (3-4 hours/3 days week)

• Membrane lining the abdomen acts as an artificial kidney by injecting it with a special fluid through a small tube attached to the patients body to collect draining wastes (30-40 min/daily)