Topic 7: Endocrine System - Stress Flashcards
What is stress?
- any extreme external or internal stimulus
ex. surgery, infections, strong emotions exams
What does stress trigger?
- set of body changes called general adaptation syndrome
How is stressed co-ordinated?
- directly or indirectly by the hypothalamus
What are the 3 phases of stress?
- Alarm Reaction (fight or flight)
- Resistance Reaction
- Exhaustion
What occurs in phase 1?
- immediate
What are the effects of SNS and endocrine system in Phase 1? (5, 7 points)
- increased blood glucose (energy)
- SNS inhibits insulin release
- Epi. NE triggers conversion of glycogen to glucose in liver - Increased HR, force of contraction
- increased respiration rate
- decreased blood flow to skin and abdominal viscera
- Decreased digestion and urine production
What happens when you get decreased blood flow to skin in the SNS and endocrine effects of phase 1? (2)
- more available blood to skeleton and cardiac muscle and brain
- O2 and glucose to working organs
What are the effects of the SNS and endocrine system in phase 1 of stress to digestion and urine production?
- decreased digestion
- decreased urine production
What is phase 2 of stress called?
resistance reaction
Is phase 2 long term or short term? What system does it use?
long term -> endocrine
What is the function of phase 2 stress?
- permits recovery from effects of phase 1
- tissue repair, etc
- or response to longer term stress (ie. starvation)
What hormones initiate phase 2?
hypothalamic hormones
Phase 2 diagram of hormones
What does GH do in phase 2? (2)
- stimulates growth (protein production) and cell reproduction
What does cortisol do in phase 2? (3)
- released within 30 sec of the stress but the response not for hours
– steroid hormone acts at nuclear receptors - inhibits insulin release
What does the release of hormones cause? (3)
- increased blood glucose
- inhibition of immune system, bone formation, formation of CT (delayed healing)
- Release of aldosterone and antidiuretic hormone
WHY does blood glucose increase in phase 2? (2)
- liver stimulated to produce new glucose from fats and later from proteins
- There is little insulin bc of inhibition, so glucose is not taken up well especially by skeletal muscle (at rest) and adipose tissue
HOW does blood glucose increase in phase 2 due to release of hormones?
- 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)
Why does the release of aldosterone and ADH occur when hormones are released in phase 2?
- reduces salt and water loss at kidney to maintain blood volume
What are the long term effects of phase 2? (6)
- decreased weight
- increased bp
- increased HR
- immune suppression (cortisol)
- decreased bone density
- increased risk of type 2 diabetes (bc increased blood glucose)
What is phase 3?
EXHAUSTION
Why does phase 3 occur? (3)
- depletion of body resources ie. lipid reserves
- Loss of K+ (aldosterone effect)
- Damage to organs (heart, liver, kidneys)