physiological response to stress

Question 1

stress

Answer 1

-any extreme external or internal stimulus
e.g surgery, infections, strong emotions, exams
-all co-ordinated directly or indrectly by the hypothalamus

Question 2

triggers a set of body changes

Answer 2

General Adaptation Syndrome

Question 3

PHASE 1: ALARM REACTION (FIGHT OR FLIGHT RESPONSE)

Answer 3

immediate reaction to stress = NS

1.CNS - detect change through sensory input

2.hypothalamus ( RAS * increases alertness) - activates SNS

3. SNS
   => directly affects ORGANS to prepare body for action
   => stimulates adrenal medulla
   to release E + NE (prolongs fight or flight response + make body ready for action)

Question 4

effects of SNS + endocrine

Answer 4

a) INCREASE blood glucose
->SNS inhibits insulin release
->E + NE trigger conversion of glycogen to glucose in liver

b) INCREASE HR, force of contraction

c) INCREASE respiration rate

d) blood flow to skin + abdominal viscera
->more available to skel, card, m., and brain (O2 and glucose to working organs)

e) DECREASE digestion, urine production

Question 5

PHASE 2: RESISTANCE REACTION

Answer 5

• longer term stress controlled by endocrine
• permits recovery from effects of 1(tissue repair) or responds to long term stress (starvation)

Question 6

hypothalamic hormones initiate phase 2

Answer 6

1. HYPOTHALAMUS releases
   => growth hormone releasing hormone (GHRH)
   => corticotropin releasing hormone (CRH)
2. GHRH AND CRH go to ANT. PITUITARY
   -GHRH stimulates growth hormone (GH)
   -CRH stimulates adrenocorticotropic hormone (ACTH)
3. ACTH stimulates adrenal cortex
4. adrenal cortex produces cortisol

Question 7

GH

Answer 7

stimulates growth, protein production, cell reproduction

Question 8

cortisol

Answer 8

-released within 30 secs. of stress but the response not for hours
-steroid hormone - acts on nuclear receptors
-inhibit insulin release

Question 9

release of hormones ( GH + cortisol ) causes : part 1

Answer 9

INCREASED BLOOD GLUCOSE
- liver makes new glucose from fats and later to proteins

• low insulin (due to inhibition) _> glucose not taken up well by skeletal muscles and adipose tissue

Question 10

release of hormones ( GH + cortisol )
increasing blood glucose … what happens ?

Answer 10

i. glucose spared for use by NS
ii. metabolism of non-nervous tissue directed to use fats for energy (controlled by GH and cortisol)
->if stress continues , cortisol inhibits GH and proteins are used for energ

iii. overall = INCREASE blood FA and aa (except brain)

Question 11

release of hormones ( GH + cortisol ) causes : part 2

Answer 11

inhibition of
- immune system
- bone formation
- formation of CT

Question 12

release of hormones ( GH + cortisol ) causes : part 3

Answer 12

release of aldosterone and antidiuretic hormone (ADH)
- reduces salt and water loss at kidney to maintain blood volume

Question 13

long term effects of phase 2

Answer 13

DECREASE
-weight loss
-bone density

INCREASE
- bp
- HR
- immune supression (cortisol)
- risk of type 2 diabetes ( due to INCREASE in blood glucose)

Question 14

PHASE 3: EXHAUSTION

Answer 14

• depletion of body resources i.e lipid reserves
  -loss of K+ (aldosterone effect)
  -damage to organs (heart, liver, kidneys)