Lec 6

Question 1

What is stressors?

Answer 1

• stimuli that challenge the body’s homeostasis and trigger a response.
• psychological or physical
• May be real, perceived, or imagined threats. If a stimulus causes a stress response, it can be considered a stressor.

Question 2

What is the stress response?

Answer 2

• the body’s response to the challenge of a stressor.
• the stress response involves physiological and behavioural changes that attempt to cope with or escape the stressor.
• All stressors (psychological or physiological) produce a similar pattern of physiological changes.

Question 3

_______ stressors can produce ________ stressors

Answer 3

major; minor

Question 4

How is stress an adaptation to evolution?

Answer 4

Evolutionarily, our ancestors’ stress was a result of getting chased by predators. Therefore, the stress response was episodic and short lived -either you ran away, or you got eaten. Either way, the stress would have been gone. In a life or death situation, they would dump all of their bodies resources into survival mode.

Question 5

What are the two things the stress response accomplishes?

Answer 5

1) Temporarily puts the brain and body into ‘overdrive’ in order to deal with the stressor.
2) Suspends bodily repair, construction and growth in order to conserve energy.

Question 6

What scientist characterized the concept of stress?

Answer 6

Hans Selye (1907-1982

Question 7

What is the general adaptation syndrome and who proposed it?

Answer 7

Hans Selye

• Alarm: Initial reaction to stressor. “Fight or flight (SNS)” activated.
• Resistance: Physiological adaptations take place to help cope with prolonged stressors. Involves cortisol and the HPA axis.
• Exhaustion: Physiological resources are depleted as the body becomes unable to cope with the prolonged stressor. This is where diseases can begin to appear.

This basic progression is the same regardless of the type of stressor. Physical and psychological stressors of all types produce these effects.

Question 8

What are the two pathways of the stress response?

Answer 8

The sympatho-adrenomedullary axis (SAM axis)
– The “fast pathway”
– Mediates the initial “alarm” phase of the stress response.

The hypothalamic-pituitary-adrenal axis (HPA axis)
– The “slow pathway”
– Mediates the physiological adaptations involved in dealing with prolonged stress.

Question 9

____________ is critical for the stress response

Answer 9

the adrenal gland

Question 10

What does the adrenal medulla do?

Answer 10

secretes epinephrine (aka adrenaline) and norepinephrine (aka noradrenaline)

Question 11

What does the adrenal cortex do?

Answer 11

secretes cortisol

Question 12

What are the two steps in the SAM activation?

Answer 12

1. Neural circuits in the hypothalamus project to the spinal cord, where they synapse with neurons of the sympathetic nervous system (SNS).
2. SNS neurons project to the adrenal medulla. The adrenal medulla releases the catecholamines epinephrine and norepinephrine into circulation.

Question 13

What group does norepinephrine and epinephrine belong to?

Answer 13

catecholamines

Question 14

What do norepinephrine and epinephrine bind to?

Answer 14

adrenergic receptors located throughout the body

Question 15

What are the effects of norepinephrine and epinephrine?

Answer 15

Increased heart rate.
Bronchodilation (enlargement of airways.)
Decreased digestion.
Increased blood pressure by peripheral vasoconstriction.

Question 16

What do drugs for hypertension do?

Answer 16

block ß-adrenergic receptors.

Question 17

What are the three steps of the HPA axis?

Answer 17

1. The hypothalamus releases corticotropin-releasing hormone (CRH) into the anterior pituitary (AP).
2. CRH stimulates the AP to release adrenocorticotropic hormone (ACTH) into general circulation.
3. ACTH stimulates the release of cortisol from the adrenal cortex.

Question 18

What family of hormones is cortisol a member of?

Answer 18

glucocorticoid family of hormones.

Question 19

Cortisol is a ligand for what two receptors?

Answer 19

• Mineralocorticoid receptor (MR): daily release of cortisol (cortisol isn’t just released during stress) will bind to MR since it has a higher affinity any little bit of cortisol will bind to MR
• Glucocorticoid receptor (GR): since it has a lower affinity for cortisol, it needs a high amount of cortisol to bind to that cortisol

Question 20

What type of cortisol receptor would be responsible if you were in a car crash?

Answer 20

Glucocorticoid receptor (GR)

Question 21

What type of cortisol receptor would be responsible if you forgot your phone?

Answer 21

Mineralocorticoid receptor (MR)

Question 22

Why does cortisol have a widespread effect on the body?

Answer 22

because both MR and GR are spread widely throughout the body

Question 23

What type of receptors are GR and MR?

Answer 23

Transcription factor type receptors. When they bind with their ligands, they act to increase the expression of certain stress-responsive genes

Question 24

What are cortisol’s effect on the metabolic system?

Answer 24

• Reduced bone and connective tissue formation.
• Increased breakdown of lean body mass.
• Increased blood sugar level by stimulating hepatic gluconeogenesis (the production of new glucose) and glycogenolysis (the release of stored glucose from glycogen).
• Altered sensitivity of tissues or other hormones (you can call these ‘permissive’ and ‘suppressive’ effects.)

All of these together are useful in dealing with the short-term demands of a stressor

Question 25

What drug is often used as anti-inflammatory?

Answer 25

Cortisol (and corticosteroid-like compounds)

Question 26

What does the stress response suppress?

Answer 26

higher level reasoning, flexible thinking, and memory

Question 27

What can the stress response improve?

Answer 27

performance in simpler, well-rehearsed tasks

can promote personal growth or self-improvement.

Question 28

How does stress impair cognition?

Answer 28

• The PFC is involved in concentration, planning, decision making, insight, judgment, error detection, and memory retrieval
• The PFC is the most recently evolved brain structure
• Lower brain regions are not specialized for complex thinking. Instead, they favor inflexible, impulsive behaviors and thoughts. Under the influence of these regions, we may become consumed by anxiety, or give in to impulsive behaviours (drugs, food, drink, etc.)
• Under normal conditions, inhibitory projections from the PFC exert top-down control over lower brain areas. This allows higher level cognitive function to suppress impulsive behaviors and emotions
• Under stress, dopamine and norepinephrine from brainstem shut down these inhibitory projections. This suppresses the PFC, and allows subcortical brain areas such as the amygdala and basal ganglia to exert bottom-up control

Question 29

What happens to the ion channels in the PFC neuron when there are optimal and high levels of epinephrine and norepinephrine?

Answer 29

Optimal: ion channel is closed so the signal is conveyed to the next neuron

High: ion channels are open on receiving neurons so signal is lost

Question 30

What is the role of the hippocampus in regulating stress/anxiety?

Answer 30

Hippocampus is a medial temporal lobe structure implicated in the formation of memories
Highly susceptible to stress
Contains cells that have mineralocorticoid (MR) and glucocorticoid (GR) receptors

Question 31

How is the stress response shut down?

Answer 31

Cortisol secretion is regulated by a negative feedback loop

1. The hippocampus, hypothalamus, and anterior pituitary are all sensitive to circulating cortisol.
2. When cortisol levels start to get too high, these regions work to shut down cortisol secretion (via GR).
   The hippocampus and hypothalamus work to reduce CRH secretion. The anterior pituitary secretes less ACTH.
3. When CRH and ACTH secretion is reduced, the adrenal glands produce less cortisol, thus ending the stress response.

Question 32

How is chronic stress unhealthy?

Answer 32

Prolonged secretion of cortisol can be associated with depression, as well a variety of other stress-related pathologies.

Question 33

What are the effects of chronic stress on the hippocampus?

Answer 33

• The hippocampus can be damaged by excessive or prolonged exposure to cortisol.
• Since the hippocampus is a critical part of the negative feedback loop that controls cortisol secretion, this can lead to a vicious cycle.

Question 34

What is eustress?

Answer 34

“good stress (G.)” – describes experiences perceived as “positive challenges” rather than a threat per se. Contrast with distress.

Question 35

What is the Yerkes-Dodson law?

Answer 35

Performance on tasks is best with a moderate, “optimum” level of arousal and stress. Too much or too little stress seems to impair performance

Question 36

What is psychological resilience?

Answer 36

the ability to cope with stressful events – is improved by routinely conquering stressors.
This is especially true in young children. Their success in life depends a great deal on their resilience, and resilience is shaped by successfully overcoming challenges.