Animal Survival

1. Animal Survival Water & Waste Mr G Davidson

2. Water & Waste • Getting rid of poisonous wastes and regulating the amount of water in the body are two important processes that occur in animals. • If they are not performed correctly then the animal may die. • The kidneys deal with both of these processes.

3. Water Gain • Drinking • In a typical day we drink a variety of liquids e.g. tea, coffee, milk, etc…. All of these liquids consist mainly of water. Our bodies gain weight in three different ways.

4. Water Gain • Water from food. • All the foods we eat contain different amounts of water. • Water from chemical reactions. • The food we eat is used up by the cells of the body to supply energy and materials for growth and repair. The chemical reactions that release the energy from food also produce water.

5. Water Loss Our bodies lose weight in four different ways. • Sweat. • Our skin produces sweat in order to cool the body down. The hotter we are the more sweat we produce. • Breath. • The air we breathe in may be dry or moist depending on the weather. The air we breathe out is always moist.

6. Water Loss • Urine. • We get rid of excess water and waste products such as urea and some salts in our urine. Urine is about. • 96% water. • 2% urea. • 2% minerals. • Faeces. • Our faeces are moist so that they can be passed out of the body easily.

7. The Kidneys The kidneys have 2 main functions. • Maintaining water balance. • Getting rid of poisonous waste substances from the body.

8. The Kidneys

9. The Kidneys • In humans the kidneys are solid, oval shaped structures found towards the back of the body below the ribcage. • Blood enters the kidneys through the renal artery and leaves through the renal vein. • The blood contains useful substances like glucose and a poisonous waste called urea.

10. Testing for Glucose & Urea • Test samples of blood from the renal artery and renal vein for both glucose and urea. • Test samples of urine for both glucose and urea.

11. The Kidneys • Blood entering the kidneys is filtered. • This removes water containing harmful urea and useful glucose. • Reabsorption is another process in the kidneys which takes back glucose and some of the water into the blood. • This leaves behind the urea and the rest of the water. • The amount of water reabsorbed depends on the body’s requirements.

12. Water Regulation • The kidneys regulate water, but this regulation is under control from the brain. • The brain produces ANTI-DIURETIC HORMONE (A.D.H.) which controls the amount of water reabsorbed by the kidney nephrons. • Different amounts of ADH are produced to suit the varying water conditions of the body, ensuring water balance is maintained. • ADH is one of a group of chemicals called HORMONES.

13. Role of ADH Water content of blood too low Water content of blood too high Salt eaten or much sweating Too much water drunk Brain releases little ADH Water content of blood normal Brain releases much ADH High volume of water passes into blood Low volume of water passes into blood High volume of water reabsorbed by kidney Low volume of water reabsorbed by kidney Small volume of concentrated urine passed to the bladder High volume of dilute urine passed to the bladder

14. How the Kidneys Work • To explain filtration and reabsorption we have to look at the detailed structure of the kidney. • Each kidney is made up of about 1 million tiny tubes called NEPHRONS which filter the blood and then reabsorb the useful substances.

15. How the Kidneys Work • We know that proteins are broken down to amino acids in digestion. • These amino acids are used to build new cells or repair tissues within the body. • Any extra amino acids not needed at the time are broken down in the liver to a carbohydrate and a poisonous waste called urea.

16. How the Kidneys Work • The urea is then transported by the blood to the kidney where it is removed. • If, due to kidney damage, the urea is not removed from the blood its level will build up and eventually cause death.

17. 8 How the Kidneys Work 1. Renal artery. 2. Renal vein. 3. Glomerulus. 4. Distal convoluted tubule. 5. Proximal convoluted tubule. 6. Loop of Henlé. 7. Collecting duct. 8. Bowman’s Capsule

18. When Kidneys go Wrong • If the kidneys stop working because of disease or damage, then the person will die. • This is known as total kidney failure. • Sometimes kidney stones form in the kidneys. This condition is not usually fatal but can be very painful, and occasionally blockages may occur in the kidney.

19. When Kidneys go Wrong • These stones can usually be removed by operation and the patient recovers. • If, however, total kidney failure occurs then this must be treated in one of two ways or the patient will die. • dialysis on a kidney machine (artificial kidney) • Kidney transplant

20. Sugar Diabetes • This is a common disease which in 1987 affected 600,000 people in the U.K. • It is caused by the inability of the body to deal with glucose in the blood. • This results in too much glucose in the blood and can be very serious to the patient. • When the blood passes through the kidney, much of this extra glucose can’t be reabsorbed and so is found passed out in the urine.