Powerpoint about the Human Excretory System

1. Unit 3.D:
The Excretory System

2. Index
1. The Urinary System in Humans
2. Excretion
3. The anatomy of the kidneys
4. The production of urine
5. Diseases of excretory system

3. 1. Parts of the Urinary System in Humans

Kidneys  they remove urea and other
waste products from the blood
and form urine.

4. 
Ureters  they carry urine from the kidney to the bladder

5. 
Bladder  it stores urine before it is released from the body.
It has a muscular wall.

6. 
Urethra  It carries urine out of the body.
• Men urethra is common to the reproductive system
• Women urethra is an independant tube

7. 2. Excretion
Excretion is the elimination of waste products that are produced by the body cells.
The cells release the waste substances into the blood. The blood must, therefore,
be purified.
Metabolic waste products are:
• Nitrogen compounds  excess of protein is broken down in the liver
and forms urea
• Carbon dioxide
• Water
• Mineral salts
EXCRETORY ORGAN
WASTE PRODUCTS
Lungs
Carbon dioxide, water
vapour
Kidneys
Urea, water and salts
Skin
Water and salts

8. 4. The anatomy of the kidneys
 Blood enters the kidneys through the renal arteries
 Each kidney is made up of thousands of small functional units known
as nephrons. Each one of these nephrons filters and purify the blood
independently.
Glomerulus = capsule which contains
lots of blood capillaries
 Bowman’s capsule surrounds the
glomerulus
 The tubules and the loop of Henle
carry the urine to the ureters
Nephron

9.  Renal cortex  Bowman’s capsules
 Renal medulla  loops of Henle and
collecting ducts
 Renal pelvis  ducts which collect the urine
produced by the nephrons.

10. 4. The production of urine
The formation of urine is a very selective process. Urine contains:
 water
 toxic substances (urea, uric acid, etc.)
urea
uric acid
The composition of sweat is similar to urine.
It is produced by filtering the
blood that reaches the skin.
Activity 4, page 71
ammonia

11. 1. Filtering:
Substances go from the glomerulus to the Bowman’s
capsule
2. Reabsorption:
Water and useful substances go back from the tubules
to the blood
3. Urine (water, urea, uric acid, salts) arrives to the renal pelvis,
where reaches the ureters.

12. 5. Diseases of Excretory System
 Kidney stones  crystals of uric acid

13.  Cystitis inflammation of the bladder caused by a bacterial infection.

14.  Renal insufficiency kidneys do not filter the blood correctly and
waste products are not removed from the blood

15.  Hemodialysis  filtering of blood in an apparatus to remove
waste products. It is performed in cases of kidney failure.

16.  Kidney transplant
Video  Urinary System, the nephron