UNIT 4 - HOMEOSTASIS

Question 1

What is the General Adaptation Syndrome (GAS)

Answer 1

By Hans Selye: the stimuli, stressers and response

Question 2

Explain the alarm stage of GAS

Answer 2

• arousal of the CNS
• body’s defenses are mobilized
• fight or flight

Question 3

Explain stage of resistance or adaptation

Answer 3

• arousal of the CNS to release of hypothalamic CRH
• CRH stimulated pit. gland to release ACTH
• ACTH stimulates adrenal cortex to release cortisol
• cortisol mobilizes the bodies energy
• tries to live with it

Question 4

explain stage of exhaustion

Answer 4

• compensatory mechanism break down

- effort of trying to fight it causes impairment of immune response

Question 5

Disease

Answer 5

• failure of the body systems to function within normal range

Question 6

3 components of physiologic stress

Answer 6

1. stressor initiates disturbance
2. a chemical or physical disturbance is produced by the stressor (eg. change in pH)
3. the body responds to counteract the disturbance

Question 7

Intrinsic regulation

Answer 7

• Autoregulation: automatic response in a cell, tissue, or organ

Question 8

Extrinsic regulation

Answer 8

responses controlled by nervous and endocrine system (eg. the brain)

Question 9

Negative feedback

Answer 9

• set point and error are amplified and inverted, therefore the inverted output counteracts the disturbance
• leads to stability

Question 10

Positive feedback

Answer 10

• signal input is amplified but no inverted, therefore the output reinforces the disturbance
• leads to instability

Question 11

What stress is the most important factor that causes cell injury and cell death

Answer 11

decreased oxygen supply

Question 12

Explain the stress response

Answer 12

• initiated by nervous and endocrine system
• stress -> CRF released from hypothalamus ->ACTH released from the adrenal gland -> Cortisol (key stress hormone) released from adrenal cortex