Human Excretory System

1
Human Excretory System

• Name ___________________
• Date __________________

2
Excretory System
Excretion removes cellular waste The process
that collects removes harmful or useless
substances that form in the body or are taken
into the body from the blood, tissues, and cells.
3
Excretory System
Although the urinary system has a major role in
excretion, other organs contribute to the
excretory function.
4
Four Organs of the Excretory System

• The lungs in the respiratory system excrete some
  waste products, such as carbon dioxide and water.
  
• The skin is another excretory organ that rids the
  body of wastes through the sweat glands.
• The liver (via the intestines) excretes bile
  pigments that result from the destruction of
  hemoglobin. It also converts nitrogenous waste
  from the break down of proteins into urea.
• The major task of excretion still belongs to the
  kidneys, the major organ in the urinary system.
  If it fails the other organs cannot take over and
  compensate adequately.

5
Cellular Waste
Heat Water Salts CO2 Urea
W/O excretion poisonous wastes build up in blood,
cells, and tissues. Could lead to serious illness
eventually DEATH!
6
Liver Some Functions

• Functions in Excretion
• Detoxifies Blood
• Filters Bacteria, alcohol, drugs, toxic
  substances
• Changes them into inactive or less toxic forms.

• Excretes Bile
• Contains
• Worn-out RBC
• Bile salts
• Cholesterol

7
Liver Produces Urea

• Functions in Excretion
• Forms Urea
• Changes toxic wastes (ammonia from break down
  of amino acids) to Urea.
• Urea ? Blood ? Kidneys
• Filtered out excreted in Urine

8
Lungs Main Function

• Alveoli - Exchange O2 CO2 between air and
• blood (through process of diffusion)
• Lungs excrete CO2 when you EXHALE

9
Skin

• Sweat Glands
• Help cool body Heat escapes through millions of
  pores in skin surface
• Excrete perspiration (evap. cooling)
• 99 H2O
• Mineral Salts
• Urea

10
Kidneys Urinary System

• Urinary System excretes waste and maintains
  homeostasis of body fluids.
• Kidneys (main organ of the system)
• Ureters
• Bladder
• Urethra

11
Kidneys Urinary System

• Kidneys
• Two
• Fist sized
• Bean shaped

12
Kidneys- Functional Units Product

• Nephron (about one million per kidney)
• Microscopic units that filter blood of wastes.
• H2O and waste taken from blood into nephron
• Form URINE

• Glomerulus (clump of capillaries)
• At end of each nephron
• Network of coiled tubes diffusion of wastes -
  while useful substances water are reabsorbed

• Urine
• Pale yellow solution
• Urea, H20, salts, other trace solutions (toxins)

13
Urinary System - continued

• Ureters
• Narrow muscular tubes
• Connect Kidney ? Bladder

• Bladder
• Muscular sac
• Stores Urine
• Expand to fill
• Muscle relaxes
• Urine squeezed into Urethra

14
Urinary System - endpoint

• Urethra
• Tube leading from Bladder ? outside of body

15
Failures of Homeostasis

• Bladder Kidney Infections caused by bacteria
  from colon/rectum entering urethra.
• Kidney Stones - crystallization of mineral salts
  uric acid that block passage of urine
• Kidney Disease - caused by long term diabetes,
  infections, chemical poisoning
• Gout form of arthritis where excess production
  of uric acid leads to deposits of crystals in
  joints (esp. toes)