Chapter 7 - Homeostasis

Question 1

Water loss

Answer 1

When we breathe out, sweat, in urine (produced by the kidneys) and ions in sweat and urine.

Question 2

Hormones

Answer 2

Chemical substances that coordinate many bodily processes

Question 3

Why we must keep our core temperature constant

Answer 3

So enzymes work at an optimum temperature, so we do not get hypothermia and our cells stop working.

Question 4

Sugar levels

Answer 4

Sugar is the energy source for our cells, our sugar levels in the blood are controlled by the pancreas.

Question 5

What is removed via the lungs

Answer 5

Carbon dioxide (when we breathe out)

Question 6

Urea

Answer 6

Produced in the liver from the breakdown of amino acids and removed by the kidneys in the urine and temporarily stored in the bladder.

Question 7

Liver

Answer 7

Excess amino acids changed to urea and amino group removed (deamination) which forms ammonia which is converted to urea, passed in the blood to the kidneys and excreted in urine.

Question 8

In urine

Answer 8

Poisonous substances such as ethanol are detoxified and excreted in urine. Old red blood cells are broken down and the iron is stored to make new ones.

Question 9

Selective reabsorption

Answer 9

Filtering the blood, reabsorption has the sugar, reabsorbing the dissolved ions needed by the body, reabsorbing water and releasing urea, excess ions and water in the urine.

Question 10

ADH

Answer 10

Is released by the pituitary gland if the water content of the blood is too low. This causes the kidneys to reabsorb more water, making the blood concentration return to normal levels and resulting in more concentrated urine.

Question 11

Low water content of blood

Answer 11

less ADH released into blood and less water reabsorbed in kidneys, resulting in more dilute urine.

Question 12

Dialysis

Answer 12

Blood flows between partially permeable membranes and has the same concentration of useful substances as the patients blood.

Question 13

Dialysis machine process

Answer 13

Arterial blood leaves arm ➡️ blood thinners prevent clotting ➡️ dialysis machine (waste and urea removed) ➡️ clean blood flows through bubble trap ➡️ clean blood returns to a vein in the arm

Question 14

Advantages of dialysis

Answer 14

Access to medical support, no equipment needed at home, treatment performed for you.

Question 15

Disadvantages of dialysis

Answer 15

Travelling to centre 3 times a week, takes 8 hours, limiting fluid intake and risk of infection.

Question 16

Rejection of kidneys (transplanted)

Answer 16

Antigens on donor organ different, antibodies of recipients immune system attack antigens, kidney is rejected. Immunosuppressant drugs can prevent it.

Question 17

Advantages of kidney transplants

Answer 17

Closer than dialysis to having own kidney, fewer diet and fluid restrictions and more energy.

Question 18

Disadvantages of kidney transplants

Answer 18

Rejection, daily medication, susceptible to infection and risks associated with major surgery.

Question 19

Thermoregatory centre

Answer 19

In hypothalamus, has receptors detecting temp of blood flowing through brain.

Question 20

Cooling down

Answer 20

Blood vessels supplying blood to the surface of the skin dilate so more blood flows through the capillaries. Skin flushes, heat energy lost by radiation. Hair lies flat (less air trapped) and rate of sweating increases and water evaporates from skin, taking heat energy from blood.

Question 21

Warming up

Answer 21

Blood vessels constrict, reduces blood through capillaries near surface of skin, reduces energy released by radiation at surface of skin. Muscles contract and relax rapidly - shivering requires respiration which releases energy and raises temp. Less sweating.

Question 22

High glucose levels

Answer 22

Insulin produced, moves glucose into cells. In liver and muscles, excess glucose converted to glycogen for storage. When full is stored as a lipid.

Question 23

Homeostasis

Answer 23

The process by which our body maintains a constant internal environment. Controls water content, ion content, temperature and blood sugar level.

Question 24

Low glucose levels

Answer 24

Pancreas releases glucagon, causing glycogen in liver to change to glucose which is released back into blood.

Question 25

Type 1 diabetes

Answer 25

Little insulin produced by pancreas, blood glucose level v high. Controlled by restricted diet.

Question 26

Type 2 diabetes

Answer 26

Body does not respond to insulin, controlled by diet, exercise and drugs.

Question 27

Treating type 1 diabetes

Answer 27

Pancreatic transplants, using embryonic stem cells to produce insulin secreting cells.

Question 28

Treating type 2 diabetes

Answer 28

Balanced diet, weight loss, regular exercise and drugs to help insulin work on body cells.