Homeostasis

Question 1

What is homeostasis?

Answer 1

Homeostasis is where condition in the body are controlled to provide a constant internal environment.

Question 2

What sorts of things are controlled during homeostasis?

Answer 2

The conditions that must be controlled include body temperature, water content, carbon dioxide level, and blood sugar level.

Question 3

What is diabetes?

Answer 3

Diabetes is a condition where the body cannot effectively regulate the levels of blood sugar.

Question 4

How is blood sugar level controlled?

Answer 4

This is controlled to provide cells with a constant supply of energy. The blood sugar level is controlled by the release and storage of glucose, which is in turn controlled by a hormone called insulin.

Question 5

How is body temperature controlled?

Answer 5

This is controlled to maintain the temperature at which enzymes work best, which is 37°C. Body temperature is controlled by:

• controlling blood flow to the skin
• sweating
• shivering

Question 6

What does the body regulate it’s temperature through?

Answer 6

The body regulates it’s temperature through thermoregulation.

Question 7

How does the body respond to increased body temperature?

Answer 7

• Increases blood flow through the blood vessels 0 more blood causes more heat to be lost from the skin’s surface.
• Sweat - heat from the body evaporates the water in sweat, transferring heat away from the skin.
• Body hairs lie flat - to prevent air becoming trapped next to it.

Question 8

How does the body respond to decreased body temperature?

Answer 8

• Less blood flows through the blood vessels 0 less heat is lost from the skin’s surface.
• Shivering - creates muscle fells to release heat because the tiny muscles under the skin contract and relax very quickly.
• Body hairs rise up - trapping a layer of air next to it to insulate the body.

Question 9

Where in the brain is body temperature monitored by?

Answer 9

It is monitored by the thermoregulatory centre, in the part of the brain called the hypothalamus.

Question 10

What is vasoconstriction?

Answer 10

Vasoconstriction is the narrowing of blood vessels in the skin so that blood flow through the skin is reduced, therefore heat loss is decreased and body temperature rises.

Question 11

What is vasodilation?

Answer 11

Vasodilation is the widening of the blood vessels so that blood flow is increased and more heat is lost through the skin.

Question 12

How is the body’s water content controlled?

Answer 12

This is controlled to protect cells by stopping too much water from entering or leaving them. The process is called osmoregulation.

Question 13

What does the body do if there is too little water?

Answer 13

The hypothalamus detects too little water in the blood, pituitary gland releases ADH, the kidneys maintain blood water level, less water is lost in urine and the blood water level returns to normal.

Question 14

What does the body do if there is too much water?

Answer 14

The hypothalamus detects too much water in the blood, pituitary glands release less ADH, kidneys reduce blood water level, so more water reaches the bladder and blood water level returns to normal.

Question 15

How is ion (salts) in the body controlled?

Answer 15

This is controlled to protect cells by avoiding too much water entering or leaving them. Ion content is controlled by loss of ions from:

• the skin by sweating
• the body, in urine produced by the kidneys

Question 16

What hormone is the brain and what does it do?

Answer 16

The brain contains a sensitive centre called the hypothalamus which controls the pituitary glands.

Question 17

What hormone is in the thyroid gland and what does it do?

Answer 17

The thyroid gland produces thyroxine which controls the rate of metabolism.

Question 18

What hormone is in the adrenal gland and what does it do?

Answer 18

The adrenal gland produces adrenaline which prepares the body for rapid activity by increasing the heart rate and level of sugar in the blood and diverting blood to muscles and the brain.

Question 19

What hormone is the pancreas and what does it do?

Answer 19

The pancreas produces insulin which controls blood sugar level.

Question 20

What hormone is in the testes and what does it do?

Answer 20

The testes produces testosterone which causes the changes at puberty and stimulate sperm production.

Question 21

What hormone is in the ovary and what does it do?

Answer 21

The ovary produces oestrogen which causes changes at puberty and helps to control the menstrual cycle.

Question 22

What hormone and organ goes with the ovary?

Answer 22

Hormone - oestrogen

Organs - ovaries and uterus

Question 23

What hormone and organ also goes with the ovary?

Answer 23

Hormone - progesterone

Organ - uterus

Question 24

What hormone and organ goes with the pancreas?

Answer 24

Hormone - insulin

Organ - liver

Question 25

What hormone and organ goes with the testes?

Answer 25

Hormone - testosterone

Organ - male reproductive organs

Question 26

Why is glucose needed for cells?

Answer 26

Glucose is needed for cells for respiration.

Question 27

What happens when the glucose level is too high?

Answer 27

There is too much glucose in the blood, the pancreas produces insulin which enters the blood, the insulin allows the glucose to be absorbed by body cells and blood glucose is reduced.

Question 28

What happens when the glucose level is too low?

Answer 28

There is not enough glucose in the blood, insulin is not produced by the pancreas, less glucose absorbed by body cells and blood glucose is increased.

Question 29

How does glucagon affect blood sugar levels?

Answer 29

The pancreas releases another hormone, glucagon, when the blood sugar levels fall. This causes the cells in the liver to turn glycogen back into glucose which can then be released into the blood. The blood sugar levels will then rise.

Question 30

How can diabetes be treated?

Answer 30

It can be treated by injecting insulin. The extra insulin allows the glucose to be taken up by the liver and other tissues, so cells get the glucose they need and blood-sugar levels stay normal.

Question 31

What is type 1 diabetes?

Answer 31

Type 1 diabetes is caused by a lack of insulin. It can be controlled by:
- monitoring the diet
- injecting insulin
People with type 1 diabetes have to monitor their blood sugar levels throughout the day as the level of physical activity and diet affect the amount of insulin required.

Question 32

What is type 2 diabetes?

Answer 32

Type 2 diabetes is caused by a person becoming resistant to insulin. It can be controlled by diet and exercise. There is a link between rising levels of obesity (chronic overweight) and increasing levels of type 2 diabetes.

Question 33

At what point is someone considered obese?

Answer 33

Someone is considered obese if their BMI is over 30.

Question 34

How is BMI measured?

Answer 34

Weight (kg) divided by height (m2)