B5 Hormones And Negative Feedback

Question 1

What are hormones?

Answer 1

Chemical messengers sent in the blood

Question 2

Where are hormones produced?

Answer 2

Endocrine glands

Question 3

What is the system that the glands that produce hormones makes up?

Answer 3

Endocrine system

Question 4

What does the endocrine system allow you to respond to?

Answer 4

Internal and external stimuli

Question 5

Both the nervous system and hormones allow you to respond to internal and external stimuli. Explain the difference between these responses

Answer 5

Hormones are slow compared to nervous impulses.

Hormones have a longer lasting effect than nervous impulses.

Question 6

Where are hormones released?

Answer 6

Directly into the blood.

Question 7

How are hormones carried to other parts of the body?

Answer 7

In the blood

Question 8

What makes a hormone produce a response?

Answer 8

Particular effectors

Question 9

How do particular effectors stimulate a response in hormones?

Answer 9

They have receptors that the hormones bind to.

When hormones bind to receptors, they stimulate a response.

Question 10

What is adrenaline?

Answer 10

A hormone

Question 11

What release adrenaline?

Answer 11

Adrenaline glands

Question 12

Where are the adrenal glands located?

Answer 12

Just above the kidneys

Question 13

What does adrenaline prepare the body for?

Answer 13

Fight or flight

Question 14

How does adrenaline prepare the body for fight or flight?

Answer 14

By activating processes that increase the supply of oxygen and glucose to cells.

Question 15

List the steps involved in adrenaline supplying more oxygen and glucose to cells

Answer 15

Adrenaline binds to specific receptors in the heart.

The heart (effector) contracts more frequently and with more force, increasing heart rate and blood pressure.

Increased blood flow to the muscles, so cells receive more oxygen and glucose for increased respiration.

Adrenaline also bind to receptors in the liver.

The liver breaks down it’s glycogen stores to release glucose.

This increase the blood glucose level, so there is more glucose in the blood to be transported to the cells.

Question 16

How does your brain get your body ready for action in stressful situations?

Answer 16

The brain detects a stressful situation, sends nervous impulses to the adrenal glands, which respond by secreting adrenaline, which gets the body ready for action.

Question 17

What is negative feedback?

Answer 17

When the body detects that the level of a substance has gone above or below the normal level, it triggers a response to bring the level back to normal again.

Question 18

What does thyroxine regulate?

Answer 18

Metabolism

Question 19

Where is thyroxine released?

Answer 19

By the thyroid gland (in the neck)

Question 20

What does thyroxine help to regulate?

Answer 20

The metabolic rate.

Question 21

What is metabolic rate?

Answer 21

The speed at which chemical reactions in the body occur.

Question 22

What processes does metabolic rate affect?

Answer 22

Growth and protein synthesis

Question 23

What response triggers the release of thyroxine?

Answer 23

Thyroid stimulating hormone (TSH)

Question 24

Where is TSH (thyroid stimulating hormone) released from?

Answer 24

The pituitary gland

Question 25

How does a negative feedback system keep thyroxine in the blood at the right level?

Answer 25

When the level of thyroxine in the blood is higher than normal, the secretion of TSH from the pituitary gland is inhibited.

This reduces the amount of thyroxine released from the thyroid gland so the level of the blood falls back towards normal.

Question 26

See p74 for diagram

Answer 26

.

Question 27

Explain how the endocrine system allows communication within the body? (5 marks)

Answer 27

Endocrine glands secrete hormones (1 mark)
These act as chemical messengers (1 mark) and travel in the bloodstream (1 mark) to effectors (1 mark)
These have receptors so they can respond to the hormone (1 mark)