Lecture 3

Question 1

What are the animal response when stressed

Answer 1

Physiological: Neural and Endocrine

Emotional : Fear, anxiety and suffering

Question 2

Effects of adrenalin and other catecholamine

hormones

Answer 2

– increased heart rate and cardiac output
– increased blood flow to muscles
– decreased blood flow to
gastrointestinal system
-- dilation of pupils

Question 3

What are the two basic systems involved in stressors

Answer 3

1. SA (Sympathetic-adrenomedullary)
   – As much a neural as an endocrine response.
   – Activated by a perceived threat (control retained).
   – “Fight or flight” response.
2. HPA (hypothalamo-pituitary-adrenocortical)
   – Mainly endocrine
   – Results in conservation/withdrawal type response

Question 4

What is the Hypothalamic-Pituitary-Adrenal Axis

pathway

Answer 4

stress > brain > adrenal > Cortisol

Question 5

What will cortisol lead to

Answer 5

hypothalamus and pituitary > adrenal

Stimulus → brain (hypothalamus) → CRH release → pituitary → ACTH release → adrenal cortex → cortisol release

Question 6

Duration of SA response

Answer 6

Catecholamines- short half-life, difficult to measure

• Overall response may be short-lived

Question 7

Duration of HPA response

Answer 7

Cortisol & corticosterone- longer half-life, but care needed in interpretation

Question 8

Why measure physiology?

Answer 8

• Measurement of biological function • May directly reflect the environmental challenge for the animals • Can indicate risk of further adverse welfare- e.g. impaired health

Question 9

What are factors affecting responses

Answer 9

• Type of stressor
• Extent of homoeostatic disturbance – The greater the gap between actual and optimum environmental conditions the greater the response.

• Predictability and ability to control outcomes – Learning increases predictability and reduces the magnitude of stress responses. – Control

Question 10

What is the pathway for SA response

Answer 10

Stimulus → brain → sympathetic nervous system → adrenal medulla → adrenalin/noradrenalin

Question 11

What is SA

Answer 11

Sympathetic Adrenal Medullary Axis

Question 12

What is the relationship between respiration rate and body temperature

Answer 12

Breathing more as the temperature increase