The Excretory System

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What does it do?

Every cell produces metabolic wastes such as: Salt Carbon dioxide Urea (toxic compound produced when making

energy)

The excretory system’s job is to remove these useless and harmful wastes from the body.

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The Organs The main organs of the excretory system are:

Kidneys SKIN Lungs

skin covers and protects your body lungs located in chest and protected by ribcage kidneys found on either side of backbone and about the size of a

fist

Kidneys Structure Made of Inner (renal medulla) and

outer (renal cortex) The functional units of the kidney are

nephrons

Each nephron has its own blood

supply through the use of 4 parts.

Ateriole :: Where the blood enters

Capillaries :: Filtration

Collecting duct :: Waste from blood ends up here which leads to ureter

Venule :: Where the purified blood exits

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Blood Purification

It is broken into three processes: filtration, reabsorption, and secretion.

Filtration

:: Blood enters nephron and flows into the glomerulus, a small network of capillaries is held in the upper end of the nephron by Bowman’s capsules

:: Because the blood is under pressure and the capillaries are permeable fluid flows into Bowman’s capsule

:: The filtrate (filtered materials) contains water, urea, glucose, salts, amino acids, and some vitamins

Blood Purification

Reabsorption

:: Most material removed from the blood goes back into the blood through reabsorption

:: The nutrients are taken out of the filtrate with active transport and then put back in the blood

Secretion

:: The cells of the tubules remove certain molecules and ions from the blood and deposite these into the fluid within the tubules.

: Tubular secretion of H+- is important in maintaining control of the pH of the blood..

Filtration, reabsorption, and secretionanimation

Urinary system Urine is the material that remains after reabsorption

It is concentrated in the loop of Henle where water is conserved and the volume of urine minimized

Urine is collected in the urinary bladder

while purified blood goes back into normal

circulation

Urine is released through the urethra

tube

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The Kidneys and Homeostasis

:: The kidneys regulate water content in the blood, which controls blood volume, pH, and waste in the blood.

:: How do they do it? Liquid that you consume goes

into the blood

This increased concentration should force water into cells, swelling your body

However the kidneys control this by lowering the rate of reabsorption of water

As for salt, the more you eat, the less that is returned to the blood

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Skin and Lungs Skin excretes waste products from the body through perspiration

This includes water, salt, and a small amount of urea and other toxic substances

The lungs excrete carbon dioxide during respiration

CO2 is produced when energy is taken from food

Simple breathing animation >>>>>>>Blue: oxygen, purple: CO2

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When something goes wrong… The major disease to the excretory system is kidney disease

This can lead to kidney failure, and the inability to remove waste products

Many kidney problems can be treated by dialysis, where a machine acts as a kidney. However, it is very expensive and time consuming. Kidney transplants are an alternative to dialysis.

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Dialysis Animation

:: Medical science is workingon developing an artificialkidney transplant for the future!

A Healthy Excretory System

As with all of your body systems eating well promotes a healthy excretory system, especially getting enough dietary fiber

Diabetic kidney disease can be prevented by keeping blood sugar in your target range

For more information visit:http://www.emedicinehealth.com/chronic_kidney_disease/article_em.htm (kidney

disease)http://health.howstuffworks.com/kidney3.htm (detailed explanation of reabsorption)

http://www.quazen.com/Science/Biology/Human-Body-the-Excretory-System-.18801 (overview)

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Bibliography http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/K/Kidney.html (slide 6, “Secretion”)

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookEXCRET.html (slide 9)

http://www.skin-care-information.org/how-the-skin-works.html (slide 10, “Skin”)

http://www.diabetes.org/type-1-diabetes/kidney-disease.jsp (slide 11)