Topic 7: Endocrine System - Stress

Question 1

What is stress?

Answer 1

• any extreme external or internal stimulus
  ex. surgery, infections, strong emotions exams

Question 2

What does stress trigger?

Answer 2

• set of body changes called general adaptation syndrome

Question 3

How is stressed co-ordinated?

Answer 3

• directly or indirectly by the hypothalamus

Question 4

What are the 3 phases of stress?

Answer 4

1. Alarm Reaction (fight or flight)
2. Resistance Reaction
3. Exhaustion

Question 5

What occurs in phase 1?

Answer 5

• immediate

Question 6

What are the effects of SNS and endocrine system in Phase 1? (5, 7 points)

Answer 6

1. increased blood glucose (energy)
   - SNS inhibits insulin release
   - Epi. NE triggers conversion of glycogen to glucose in liver
2. Increased HR, force of contraction
3. increased respiration rate
4. decreased blood flow to skin and abdominal viscera
5. Decreased digestion and urine production

Question 7

What happens when you get decreased blood flow to skin in the SNS and endocrine effects of phase 1? (2)

Answer 7

• more available blood to skeleton and cardiac muscle and brain
• O2 and glucose to working organs

Question 8

What are the effects of the SNS and endocrine system in phase 1 of stress to digestion and urine production?

Answer 8

• decreased digestion
• decreased urine production

Question 9

What is phase 2 of stress called?

Answer 9

resistance reaction

Question 10

Is phase 2 long term or short term? What system does it use?

Answer 10

long term -> endocrine

Question 11

What is the function of phase 2 stress?

Answer 11

• permits recovery from effects of phase 1
• tissue repair, etc
• or response to longer term stress (ie. starvation)

Question 12

What hormones initiate phase 2?

Answer 12

hypothalamic hormones

Question 13

Phase 2 diagram of hormones

Answer 13

Question 14

What does GH do in phase 2? (2)

Answer 14

• stimulates growth (protein production) and cell reproduction

Question 15

What does cortisol do in phase 2? (3)

Answer 15

• released within 30 sec of the stress but the response not for hours
  – steroid hormone acts at nuclear receptors
• inhibits insulin release

Question 16

What does the release of hormones cause? (3)

Answer 16

1. increased blood glucose
2. inhibition of immune system, bone formation, formation of CT (delayed healing)
3. Release of aldosterone and antidiuretic hormone

Question 17

WHY does blood glucose increase in phase 2? (2)

Answer 17

1. liver stimulated to produce new glucose from fats and later from proteins
2. There is little insulin bc of inhibition, so glucose is not taken up well especially by skeletal muscle (at rest) and adipose tissue

Question 18

HOW does blood glucose increase in phase 2 due to release of hormones?

Answer 18

• recall little insulin bc of inhibition and glucose not taken up well by skel. and adi.
  1. Glucose is spared for use by NS
  2. Metabolism of non-nervous tissue is directed to use fats for energy (control = GH, cortisol)
  3. If stress continues, cortisol inhibits GH release and proteins are then also used
  4. Overall increase blood FA and AA -> energy (except brain)

Question 19

Why does the release of aldosterone and ADH occur when hormones are released in phase 2?

Answer 19

• reduces salt and water loss at kidney to maintain blood volume

Question 20

What are the long term effects of phase 2? (6)

Answer 20

• decreased weight
• increased bp
• increased HR
• immune suppression (cortisol)
• decreased bone density
• increased risk of type 2 diabetes (bc increased blood glucose)

Question 21

What is phase 3?

Answer 21

EXHAUSTION

Question 22

Why does phase 3 occur? (3)

Answer 22

1. depletion of body resources ie. lipid reserves
2. Loss of K+ (aldosterone effect)
3. Damage to organs (heart, liver, kidneys)