The Excretory System Learning Objectives OB 20 Understand

The Excretory System

Learning Objectives OB 20 Understand the structure and function of the urinary system: the bladder, renal artery, renal vein, ureter, urethra and kidney OB 21 Name the products of excretion: CO 2, water and urea OB 22 Understand the function of the skin in the excretion of waste products made in the body

Excretion “Process by which the body removes toxic waste substances that have been produced by the body’s own cells”

Organs of Excretion 1 Lungs • Excrete CO 2 and H 2 O oc H o H o o H c o

Organs of Excretion 2 Skin • Excretes H 2 O and salts as sweat section of skin pore sweat gland blood capillaries

Organs of Excretion 3 Kidneys • Excrete H 2 O, salts, and urea as urine

Location of kidneys • Humans have two kidneys. • They are located in the abdominal cavity, towards the back. • They are protected by fatty tissue.

Kidney • Fatty tissue surrounding a kidney.

Urinary system Renal vein Renal Artery Kidney Ureter Bladder bladde r Urethra

Formation of Urea Excess Protein Liver breaks down excess protein and converts amino groups to urea Liver

• What three things have you learned? • What two things were new to you? • What one thing do you want to learn?

Define the term excretion Excretion is the process by which the body removes toxic waste substances that have been produced by the body’s own cells.

How is CO 2 formed? Lungs take in O 2 so that it can be used by the cells to get energy from food, i. e. , in respiration. CO 2 is a by-product of the energy production system (respiration).

What are the components of sweat? • Salt & water (and a small amount of urea in some sweat glands)

O Urea N C synthesised by Wöhler in 1828 N H How is urea formed? H • Breakdown of amino acids in the liver. • It is a relatively simple nitrogen compound with two amino groups (NH 2) and much less toxic that NH 3. • It is the body’s way of getting rid of the amino groups from amino acids that are no longer needed. H H

Where are the kidneys located? • In the abdominal cavity

The kidney is usually covered in a layer of fat can you suggest a reason for this? • For protection.

Lesson Two OB 23 Recall that waste products are removed from the bloodstream by filtration in the kidneys in the form of urine, which contains urea, water and salts, and that urine is stored in the bladder before being released from the body

Urinary system Renal vein Renal Artery Kidney Ureter Bladder bladde r Urethra

The Renal Arteries Impurities in the blood are removed in the kidneys.

Renal artery in kidney Blood in renal artery is filtered in the nephrons.

Renal Veins Renal veins contain little O 2. Blood returns to heart via the inferior vena cava, and is pumped to the lungs for O 2 via the pulmonary artery

Circulatory System

Ureters conduct urine from the kidneys to the bladder.

Bladder (stores urine)

Urethra Expulsion of urine from the body, controlled by the sphincter muscle. Urethra

Kidney failure prevents toxic substances being excreted. Dialysis removes blood, filters it and returns it to the body.

Through which blood vessel of the kidney does the blood return to the heart? • Through the renal vein.

Urine is passed from the kidneys to the bladder through tubes called …. ? • Ureters

The function of the bladder is to store. . . • Urine

Urine passes out of the body through a tube called the ……? • The urethra

What is the function of the sphincter muscle? • It controls the release of urine from the body. This is usually a voluntary action.