5. Homeostasis and Response (human endocrine system and control of blood glucose concentration)

Question 1

What are the two communication systems that the human body has?

Answer 1

the nervous system and the endocrine system

Question 2

What does the endocrine system do?

Answer 2

It sends hormones around the body

Question 3

What are hormones?

Answer 3

chemical messengers

Question 4

What happens when hormones reach a target tissue?

Answer 4

they produce a response

Question 5

What is the endocrine system made up of?

Answer 5

glands

Question 6

What do glands do?

Answer 6

they secrete hormones directly into the bloodstream

Question 7

What is the pituitary gland also known as?

Answer 7

the master gland

Question 8

Why is the pituitary gland also known as the master gland?

Answer 8

because it controls the functions of many other endocrine glands

Question 9

What is the role of the pituitary gland in the endocrine system?

Answer 9

• secretes human growth hormone
• stimulates the thyroid gland
• stimulates ovulation and the production of oestrogen in the ovaries
• stimulates the production of sperm and testosterone in the testes

Question 10

What does the pancreas do?

Answer 10

It secretes insulin

Question 11

What does insulin do?

Answer 11

controls blood glucose levels

Question 12

What does the thyroid do?

Answer 12

secretes thyroxine

Question 13

What is thyroxine?

Answer 13

A hormone that controls the body’s metabolic rate, growth and development

Question 14

What is the release of thyroxine from the thyroid triggered by?

Answer 14

Its release is triggered by the thyroid stimulating hormone (TSH).

Question 15

What does the adrenal gland do?

Answer 15

secretes adrenaline

Question 16

What is adrenaline?

Answer 16

A hormone secreted by the adrenal gland in times of stress. It is responsible for the ‘fight or flight’ response

Question 17

What is the ‘fight or flight’ response?

Answer 17

the body’s response to stressful situations

Question 18

What does the ovary do?

Answer 18

secretes oestrogen

Question 19

What does oestrogen do?

Answer 19

it is involved in the menstrual cycle and the development of female secondary sexual characteristics

Question 20

What are secondary sexual characteristics?

Answer 20

different features that develop during puberty that distinguish a female from a male

Question 21

What do the testes do?

Answer 21

secretes testosterone

Question 22

What does testosterone do?

Answer 22

it is involved in the production of sperm and the development of male secondary sexual characteristics

Question 23

What transports a hormone to a target organ or tissue, where it has an effect?

Answer 23

the blood

Question 24

What is slower, the nervous system or the endocrine system?

Answer 24

the endocrine system is much slower but the effects last for longer

Question 25

How does the pancreas respond when blood glucose levels are too high?

Answer 25

- The pancreas secretes the hormone insulin - insulin binds to the receptors on the liver and muscles - causing excess glucose to be converted into glycogen and stored

Question 26

How does the pancreas respond when blood glucose levels are too low?

Answer 26

- The pancreas secretes the hormone glucagon - glucagon binds to liver cells, causing glycogen to be converted into glucose and released into the blood

Question 27

How is blood glucose concentration controlled using a negative feedback loop?

Answer 27

- when the blood glucose concentration rises or falls below the optimum, a hormone is secreted by the pancreas - the action of either hormone (insulin or glucagon) helps bring back the concentration of glucose to the correct level

Question 28

Which organ monitors and controls blood glucose concentration?

Answer 28

the pancreas

Question 29

What does eating foods rich in carbohydrates do?

Answer 29

it increases the glucose levels in the blood

Question 30

Why does the concentration of glucose in the blood need to be kept at a certain limit?

Answer 30

because glucose is needed by cells for respiration

Question 31

What is negative feedback?

Answer 31

Negative feedback is a type of control where the body responds to an increase or decrease in a factor by returning it to the optimal level

Question 32

How is the release of thyroxine controlled by negative feedback?

Answer 32

- levels of blood thyroxine falls which are detected by the receptors in the brain - the pituitary gland releases more TSH - more thyroxine produced and released by the thyroid gland - blood thyroxine levels return to normal

Question 33

What does TSH stand for?

Answer 33

thyroid stimulating gland

Question 34

What are the effects of adrenaline?

Answer 34

- increase in heart and breathing rate - delivers oxygen and glucose to the body - stored glycogen converted to glucose - dilation of pupils - increased mental awareness - blood diverted away from digestive system to muscles