5.5.8: Coordinating responses

Question 1

What response does a threat to survival stimulate in mammals?

Answer 1

A ‘fight or flight’ response.

Question 2

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
1. Pupils dilate

Answer 2

-Allows more light to enter eyes, making the retina more sensitive.

Question 3

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
2. Heart rate and blood pressure increase.

Answer 3

-Increased rate of blood flow to deliver more oxygen and glucose to the muscles and to remove carbon dioxide and other toxins.

Question 4

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
3. Arterioles to the digestive system and skin are constricted, whilst those to the muscles and liver are dilated.

Answer 4

-Diverts blood flow away from the skin and digestive system and towards muscles.

Question 5

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
4. Blood glucose levels increase.

Answer 5

-Supplies energy for muscular contraction.

Question 6

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
5. Metabolic rate increases.

Answer 6

-Converts glucose to usable forms of energy such as ATP.

Question 7

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
6. Erector pili muscles in the skin contract,

Answer 7

-Makes hairs stand up which is a sign of aggression.

Question 8

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
7. ventilation rate and depth increases

Answer 8

Increase in gaseous exchange so that more oxygen enters the blood and supplies aerobic respiration.

Question 9

There are many physiological changes associated with the ‘fight or flight’ response. What are the survival values?
8. Endorphins (natural painkillers) are released in the brain.

Answer 9

Wounds inflicted on the mammal do not prevent activity.

Question 10

What do receptors that can detect an external threat include?

Answer 10

-Eyes, ears, nose.

Question 11

What could internal receptors detect?

Answer 11

-A threat, such as pain or a sudden increase or decrease in blood pressure.

Question 12

The cerebrum uses sensory input to coordinate a response. What are the 4 steps involved?

Answer 12

1. Inputs feed into the sensory centres in the cerebrum.
2. The cerebrum passes signals to the association centres.
3. If a threat is recognised, the cerebrum stimulates the hypothalamus.
4. The hypothalamus increases activity in the sympathetic nervous system and stimulates the release of hormones from the anterior pituitary gland.

Question 13

Nervous communication is used for rapid response rather than prolonged response. How is a prolonged response achieved?

Answer 13

-By the endocrine system.

Question 14

What stimulates the adrenal medulla?

Answer 14

-The sympathetic nervous system.

Question 15

What is adrenaline and how does this affect its action?

Answer 15

• Adrenaline is a first messenger.
• it is an amino acid derivative and is, therefore, unable to enter the target cell.
• It must first cause an effect inside the cell without entering the cell itself.

Question 16

Outline the effect of adrenaline action.

Answer 16

1. Adrenaline binds to the adrenaline receptor on the plasma membrane. This receptor is associated with a G protein on the inner surface of the plasma membrane, which is stimulated to activate the enzyme adenyl cyclase.
2. Adenyl cyclase converts ATP to cyclic AMP (cAMP)
3. cAMP causes an effect inside the cell by activating enzyme action. (precise effect depends on cell)

Question 17

What does the hypothalamus secrete and where do these secretions go?

Answer 17

• The hypothalamus secretes releasing hormones (AKA, releasing factors into the blood.
• These pass down a portal vessel to the pituitary gland and stimulate the release of tropic hormones from the anterior of the pituitary gland.

Question 18

What do tropic hormones released from the anterior of the pituitary gland do?

Answer 18

Stimulate activity in a variety of endocrine glands.

Question 19

What does CRH stand for?

Answer 19

-Corticotropin-releasing hormone.

Question 20

Wat does CRH from the hypothalamus do?

Answer 20

-Corticotropin-releasing hormone causes the release of adrenocorticotropic hormone (ACTH).

Question 21

What does ACTH do?

Answer 21

-Adrenocorticotropic hormone passes around the blood system and stimulates the adrenal cortex to release a number of different (corticosteroid) hormones.

Question 22

corticosteroid hormones include glucocorticoids such as cortisol what does this do?

Answer 22

• Regulate the metabolism of carbohydrates.
• As a result, more glucose is released from the glycogen stores.
• New glucose can also be produced from fat and protein stores.

Question 23

What is TRH

Answer 23

-Thyrotropin-releasing hormone.

Question 24

What does thyrotropin-releasing hormone do?

Answer 24

-Causes the release of thyroid-stimulating hormone TSH.

Question 25

What does thyroid-stimulating hormone (TSH) do?

Answer 25

-Stimulates the thyroid gland to release more thyroid hormone (thyroxine).

Question 26

What does thyroxine do?

Answer 26

-Thyroxine acts on nearly every cell of the body, increasing metabolic rate and making cells more sensitive to adrenaline.