The stress response system (4)

Question 1

What is homeostasis?

Answer 1

Coordinated physiological processes which maintain most of the steady states in the organism.

Question 2

How does the body regulate temperature?

Answer 2

• When your body temperature falls too low it leads you to feel cold so you begin to shiver. The muscles contracting release heat and regulate your internal temperature. - When your body temperature is too high it leads you to feel hot, so you begin to sweat.

Question 3

What is the updated definiton of stress?

Answer 3

Events that are threatening to an individual and which elicit physiological and behavioural responses.

Question 4

What is allostasis?

Answer 4

Active process that leads to adaptation to a stressor.

Question 5

Describe the relationship and process of homeostasis and allostasis.

Answer 5

• When the coordinated processes that make up homeostasis experience a stressful event (acute stressor), the body and brain’s physiological and behavioural responses are initiated, leading to allostasis.
• Allostasis then initiates restorative processes. These processes ensure repair or replenishment of bodily systems to allow a return to a state of homeostasis and normal functioning.

Question 6

What is the effects of chronic stress on the body and brain?

Answer 6

Energy is taken from other systems and can result in:
- System breakdowns (e.g. heart failure).
- System dysfunction, hyperactive system (e.g. inflammation).
- Hypoactive system.
- Disrupted communication (e.g. blunted hormonal response).

Question 7

What are the two major branches controlling the stress response?

Answer 7

1. The autonomic nervous system.
2. The hypothalamic-pituitary axis.

Question 8

What is the autonomic nervous system mediated by and where are these released?

Answer 8

• It is mediated by neurotransmitters, specifically adrenaline and noradrenaline.
• These are released in the medulla.

Question 9

What are the limbic structures and their effects on the hypothalamus?

Answer 9

1. Prefrontal cortex – inhibitory.
2. Hippocampus – inhibitory.
3. Amygdala – excitatory.

Question 10

How does the immune system respond to acute stress?

Answer 10

Mobilises lymphocytes and produces an anti-inflammatory effect.

Question 11

How does the immune system respond to chronic stress?

Answer 11

Hyperactivates the immune system and increases proinflammatory substances.

Question 12

What pathways do physical and psychological stress signals trigger?

Answer 12

Psychological stress signals – top-down regulation (limbic forebrain).
Physical stress signals – stress-response triggers (brainstem, hypothalamus, CVO).

Question 13

What hormone does the hypothalamus release in the HPA axis?

Answer 13

Corticotropin-releasing hormone.

Question 14

What hormone does the pituitary gland release in the HPA axis?

Answer 14

Adrenocorticotropic hormone.

Question 15

What hormone does the adrenal gland release in the HPA axis?

Answer 15

Cortisol.