Stress : Role Of Stress In Illness

Question 1

What is the hypothalamic pituitary adrenal system (HPA)?

Answer 1

The hypothalamic pituitary adrenal system is a system that directly influences the endocrine system to active the stress response.

Question 2

What happens when the brain interprets a stressor?

Answer 2

• When the brain interprets a stressor, the hypothalamus activates the sympathetic nervous system which produces a hormone called CRH (corticotropin releasing factor), which stimulates the anterior lobe of the pituitary gland to secrete ACTH (adrenocorticotropic hormone) via the bloodstream , which stimulates the adrenal cortex, part of the adrenal glands.
• The adrenal cortex then secretes corticosteroids, which help to increase energy levels.

Question 3

What is cortisol

Answer 3

• Often called the stress hormone because it has a central role to play in the body’s stress response.
• Helps the body cope with stress
• e.g because it is a glucocorticoid it affects glucose metabolism by mobilising and restoring energy supplies to power the stress response.

Question 4

What is a negative feedback loop?

Answer 4

A negative feedback loop occurs in biology when the product of a reaction leads to a decrease in that reaction. In this way, a negative feedback loop brings a system closer to a target of stability or homeostasis.

Question 5

How does the Hypothalamic pituitary adrenal system (HPA) self regulate?

Answer 5

• The HPA is self regulating via a negative feedback loop.
• Levels of cortisol circulating in the bloodstream are monitored back at the pituitary and the hypothalamus.
• High levels of cortisol trigger a reduction in both CRH and ACTH resulting in a corresponding reduction in cortisol

Question 6

What is chronic stress?

Answer 6

A consistent sense of feeling pressured and overwhelmed over a long period of time

Question 7

What is immunosuppression?

Answer 7

Immunosuppression is the suppression of the body’s immune system. This is supported by a system of cells that is concerned with attacking viruses and bacteria so they cannot infect the body. If someone is dealing with an ongoing stressor, the HPA system becomes active, which leads to the production of cortisol.

Question 8

How does cortisol lead to immunosuppression?

Answer 8

Stress leads to suppression of the immune system due to the action of the cortisol one of the corticosteroids (released as part of the stress response) as they suppress leukocyte activity and stops the production of the white blood cells, specifically T cells.

Question 9

What does the thymus gland produce?

Answer 9

White blood cells

Question 10

What are white blood cells? ( Lymphocytes)

Answer 10

Lymphocytes produce soluble proteins called antibodies when a foreign body such as a microorganism enters the body.

Question 11

What are two types of lymphocytes?

Answer 11

• B cells- produce antibodies which are released into the fluid surrounding the body’s cells to destroy the invading viruses and bacteria. ( form in bone marrow)
• T cells- if the invader gets inside a cell, these (T cells) lock on to the infected cell, multiply and destroy it. ( form In thymus gland)

Question 12

What is cellular immunity ?

Answer 12

Cellular immunity includes a number of different types of lymphocyte T cells; natural killer (NK) T cells, memory and helper T cells, that work together to attack intracellular (within cells) pathogens such as viruses. The reason they are known as T cells is because they form in the thymus gland.

Question 13

What is Humoral Immunity?

Answer 13

Humoral Immunity uses a different type of lymphocyte known as B cells; these cells work together to attack extracellular (outside cells) pathogens such as bacteria and parasites. The reason they are known as B cells is because they form in the bone marrow that are predominately found in the long bones of the immune system structures.

Question 14

What study did Kiecolt-Glaser do? ( aim and procedure)

Answer 14

Aim : study human responses to stress by using a naturally occurring situation

Procedure :
- Took blood samples from 75 , 1st year medical students ( 49 males and 26 females) all whom were volunteers.
- The samples were taken one month before their final examination ( the baseline sample ) and again on the first day of their final examinations after the students had completed two of the examinations.
- this was taken when the students’ stress should be at its highest
- both occasions they were given questionnaires to asses psychiatric symptoms, loneliness and life events. There are theories that suggest all 3 are associated with increased levels of stress

Question 15

What is common with all stress - lated studies

Answer 15

All the studies have the same evaluation being correlations because there is no cause and effect because it is not just one thing that causes stress there are many different factors so it is a correlation.

Question 16

What are the effects of cortisol on the cardiovascular system?

Answer 16

the arteries become scarred, hardened, and less elastic. Hardened or narrowed arteries may be unable to supply the amount of blood the body’s organs need. The damage caused by hypertension (when high blood pressure persists over weeks) begins the process of arteriosclerosis

Question 17

What is a cardiovascular system?

Answer 17

The circulatory system (cardiovascular system) pumps blood from the heart to the lungs to get oxygen. The heart then sends oxygenated blood through arteries to the rest of the body. The veins carry oxygen-poor blood back to the heart to start the circulation process over.

Question 18

How is cardiovascular disorders linked to stress?

Answer 18

• due to the activation of the sympathetic branch of the autonomic nervous system, leading to an increase in adrenaline.
• High levels of adrenaline increase heart rate, which causes further strain on the heart.
• This can lead to high blood pressure, which can cause the blood vessels to wear away.
• It can also dislodge plaque on the walls of blood vessels, leading to blocked arteries, which can cause heart attacks and strokes.

Question 19

What are cardiovascular disorders?

Answer 19

Cardiovascular disorders are disorders of the heart (e.g. coronary heart disease - CHD); of the circulatory system (e.g. high blood pressure); and can cause as strokes (where blood flow is restricted to parts of the brain).

Question 20

What can acute and chronic stress lead to?

Answer 20

• Hugh blood pressure
• Coronary heart disease
• strokes

Question 21

Summary of stress and heart disease?

Answer 21

Stress increases risk of cardiovascular disease – but is not a direct causal factor
- Effect is mediated by personality (stress prone) 􏰀 The mechanism is complex
- Direct effects and lifestyle-mediated ones are both likely to be important

• Stress effects are clearest with pre-existing CHD
• If you have CHD stress will probably make it worse
• But we still don’t know if stress causes CHD initially

Question 22

What study did Kiecolt-Glaser do? ( findings and conclusions )

Answer 22

Findings :
- natural killer cell activity declined between the two samples, confirming other research findings that stress is associated with a reduced immune response.
- found that immune responses were especially weak in those students who reported feeling most lonely, as well as those who were experiencing other stressful life events and psychiatric symptoms such as depression or anxiety

Conclusion:
- 2 key findings :
- one was that stress was associated with a lowered immune response in humans.
- there were a number of different sources of stress and factors that moderate it.

Question 23

What study did Kiecolt-Glaser do? ( evaluation)

Answer 23

• it was a natural experiment which means that there can be fewer ethical objections however it means it wasn’t a true experiment.
• stress and immune response are negatively correlated ( as one increases , the other decreases) , we cannot say that one caused the other.
• Related to the choice of the IV ( exam stress ) , is that it was a long term form of stress. In previous studies with human participants, stress had been artificially induced.