B3.3 Homeostasis

Question 1

How is carbon dioxide removed from the body?

Answer 1

• Waste product of respiration removed by breathing out

Question 2

How is urea removed from the body?

Answer 2

• Waste product made by the liver removed by the kidneys in urine

Question 3

How is urea made?

Answer 3

• Waste product of the break down of excess amino acids in the liver

Question 4

What happens if the water level and ion level is too high in the body?

Answer 4

• Water damages the cell if there is not enough or too much

Question 5

How do healthy kidneys produce urine?

Answer 5

• High pressure and membranes filter out small molecules into the Bowman’s Capsule
• Big molecules stay in the blood
• All sugar molecules reabsorbed by active transport
• Sufficient ions reabsorbed by active transport
• Sufficient water reabsorbed
• Urea, excess ions and excess water released into the ureter, then released from the body as urine

Question 6

What happens to people who suffer from kidney failure?

Answer 6

• Waste substances build up in the blood
• Kidneys cannot control water/ion level
• Can lead to death

Question 7

What are the solutions to kidney failure?

Answer 7

• Dialysis

- Kidney transplant

Question 8

What happens during dialysis?

Answer 8

• Blood flows between a selectively permeable membrane surrounded by dialysis fluid
• Dialysis fluid contains same concentration of useful substances as healthy blood
• Only excess water/ions and waste products transferr into the fluid
• This cleans the blood/restores to healthy level

Question 9

What are the problems with dialysis?

Answer 9

• Temporary solution
• Risk of clots and infections
• A fluctuate build up of toxins
• Limits diet
• Time consuming, needs to be done 3-4 times a week for 3-4 hours
• Expensive

Question 10

What is the problem with a kidney transplant?

Answer 10

• Rejected by immune system

- Recipient’s antibodies may attack antigens on the donor organ as they may recognise it as ‘foreign’

Question 11

How are transplanted kidneys prevented from being rejected?

Answer 11

• Immunosuppressants suppress immune system of recipient

- A donor type with a similar ‘tissue-type’

Question 12

How is temperature monitored?

Answer 12

• Temperature receptors in the skin send messages to the thermoregulatory centre in the brain
• Body temperature monitored and controlled by thermoregulatory centre which has receptors to detect temperature of blood flow

Question 13

What happens if body temperature is not normal?

Answer 13

• Behaviour, skin receptors detect change cause behaviour changes
• Physiological, thermoregulatory centre detect change to blood flow temperature and sends out messages to fix this

Question 14

What happens if core body temperature is too hot?

Answer 14

• Hair lies flat
• Sweat produced by sweat glands, evaporates from skin, cooling body
• Blood vessels supplying skin dilate so blood flows closer to the skin, transferring heat more easily

Question 15

Why does skin look red when too hot?

Answer 15

• Increased blood flow close to the skin to transfer heat more easily

Question 16

What happens if core temperature is too cold?

Answer 16

• Hair stands up to trap insulating layer of hair
• No sweat produced
• Blood vessels constrict, reducing blood flow close to the skin
• Muscles contract causing ‘shivering’ - needs respiration which releases energy, warming the body

Question 17

What are the roles of the kidney?

Answer 17

• ‘cleans’ the blood, removing poisonous substances like urea
• Adjust ion and water level so only sufficient amounts are kept
• Helps to maintain homeostasis

Question 18

Which organ controls the glucose concentration of the blood?

Answer 18

• Pancreas

Question 19

What is insulin used for?

Answer 19

• Hormone produced by the pancreas which allows glucose to move into the cells

Question 20

What happens if the concentration of glucose is too high in the blood?

Answer 20

• Too much glucose in the blood
• Insulin secreted by the pancreas
• Too much glucose and insulin in blood vessels
• Glucose removed by liver
• Insulin makes liver turn glucose into glycogen
• Blood glucose removed

Question 21

If there is too much glucose in the blood, what does adding insulin do?

Answer 21

• Insulin makes the liver turn glucose into glycogen

Question 22

If there is too little glucose in the blood, what does the pancreas secrete?

Answer 22

• Glucagon

Question 23

What happens if the concentration of glucose is too little in the blood?

Answer 23

• Blood with too little glucose
• Glucagon secreted by the pancreas
• Too little glucose in the blood and glucagon
• Glucagon makes liver turn glycogen into glucose
• Glucose added by the liver
• Blood glucose increased

Question 24

If there is too little glucose in the blood, what does adding glucagon do?

Answer 24

• Glucagon makes the liver turn glycogen into glucose

Question 25

What is Type 1 Diabetes?

Answer 25

• A disease caused by glucose rising to a high level because pancreas cannot produce enough insulin

Question 26

How is Type 1 Diabetes controlled?

Answer 26

• Careful attention to diet
• Exercise
• Injecting insulin