Stress Response

Question 1

During stress response:

4 main responses

Answer 1

Heart and breathing rates increase
Cognition and alertness sharpened
Metabolic processes release stored energy, nutrients, oxygen are directed to CNS
Feeding, reproduction restricted

Question 2

NE & E
(Early effects)
- secreted from…
- responses

Answer 2

Released from adrenal medulla/sympathetic nerve terminals
Trigger increases in sympathetic responses:
Heart rate, respiration rates, BP, blood flow to skeletal muscles and heart, air flows to lungs and bronchial airways, skin blood vessels constricted, digestive functions supressed, E stim release of glucose into blood from liver/muscles, release fatty acids from lipid stores, inhibit insulin and stim glucagon secretion

Question 3

Vasopressin, E, CRH 
(Early effects)
- secreted from...
- responses 
- POMC

Answer 3

Released from hypothalamic neurosecretory cells
Synergistically stim secretion of ACTH:
ACTH is co-secreted w B-endorphin from anterior pituitary
- promote POMC and increase analgesia and decrease pain perception

POMC: chopped by enzymes into several segments in adenohypophysis to produce diff hormones
- Decreased activity in POMC cells = increased food intake and obesity

Question 4

Glucocorticoids (Cortisol)

Later effects

Answer 4

Stim catabolism (breakdown) of pr in muscles and bones and stim liver to release aa to produce glucose
Liver release newly formed glucose into blood
Glucocorticoids oppose action of insulin
Stim catabolism of fats (fatty acids can be used as alt sort of energy)
Increase vasoconstriction stim by CA
Inhibit secretion of gonadotropin (FSH & LH), TSH, GH

Question 5

Animal experiencing severe wound and loses blood:

3 hormones

Answer 5

Blood volume affects BP –BP ensures enough O2 and nutrients to brain and other essential organs
CA: increase BP by affecting heart and blood vessels
Vasopressin (pit. gland): increase water retention/reabsorption by nephrons
Aldosterone (adrenal cortex): increase sodium retention/reabsorption

These three=increase blood volume and BP

Question 6

Immune System

Answer 6

Works to prevent invasion of foreign pathogens
Neutralizes toxins and dispose abnormal cells
CA and GCH stim immune system
Immune system causes inflammation in response to infection
At later stage (higher conc), GC have anti-inflammatory effects and keep immune system from over-reacting and damaging healthy cells and tissues

Question 7

When certain cells of immune system detect pathogens tumor cells:

Answer 7

Immune cells–>cytokines (bind to specific receptors) –>excitatory/inhibitory messages

Cytokines travel in blood –>hypothalamus–>stim CRH neurosecretory cells–>inform CNS about invading stressor

Question 8

Cytokines

Turn on stress response for 2 goals:

Answer 8

1) Physiological responses of HPA axis (mobilization of energy stores) –to help animal fight infection
2) GCH (at high conc) –inhibit production of agents that cause inflammation

Question 9

Chronic Stress

• definition
• consequences

Answer 9

Exposed to stressor for long periods or exposed repeatedly to stressors such as physiological stressors: Continuously constricted blood vessels, Retention of salt and fluid, Hypertension and cardiovascular maladies

Prolonged exposure to GC =muscle wasting and bone thinning
Suppression of immune system=susceptibility to infections/diseases
Chronic activation of HPA axis=suppresses reproductive functions
High levels of GC =atrophy of dendrites of neurons in hippocampus and hippocampus shrinkage

Question 10

Plasma GC

• conc in humans
• seasonal variations

Answer 10

Blood conc of GC in humans: higher levels of cortisol in early morning, lowest at night

GC highest during breeding season, may be b/c of high energy-demand breeding, disease, predation and severe weather

Question 11

GH, Prolactin & Insulin changes due to stress

Answer 11

GH: level increases during acute physical stress and repeated stressful situations
Prolactin: may increase in response to psychosocial stress in humans
Insulin: may decrease during stress