Stress and the immune response

Barriers to infection

nonspecific barriers eg muscus membranes Also phagocytosis

Stress and gastric ulcers

500,000 new cases per year in US More common with stress Used to be seen as psychosomatic but found to be caused by helicovacter pylori bacterial HP bacteria causes all cases except those caused by anti inflammitories BUT HP alone isn't enough to cause - 75% of healthy controls have it and while antibiotics help so do psychological treatments

Antibody mediated

B cells bind to specific foreign antigen (has spec receptor) B cell multiplies and synthesises lethal form of receptor molecules Antibodies released into intracellular fluid Bind to foreign antigens and destroy/deactivate Memory B cells for the specific antigen also produced which helps with future immunity

Cell mediated immunity

By T cells Macrophage ("big eater") ingests foreign microorganism Displays invaders antigens on cell surface Antigens atract T cells T cells bind Series of reactions - including multiplication of the T cell Each T cell has two receptors - one fro molecules and one for spefici foreign antigens Millions of antigens on each T cell but only one kind per T cell and only a few T cells with each receptor for that antigen

Specific barriers

Defend against specific invaders - cell mediated and antibody mediated by different types of lymphocytes

Does stress affect susceptibility to infectious disease?

Difficult because relies on correlational data Many positive correlations have been found Immune supression doesn't necessarily result in more illness Lab animal research also shows how chronic stress affects illness

The effect of early experiences of stress

Early exposure to severe stress affects development of the brain and encorine system Raises severity of later stress and effect of Animal models of prenatal stress show evidence Handling of rat pups by researchers in first few weeks had beneficial effects on stress severity - found to be because handled pubs were groomed more by mothers which may explain effect Rat pups with early seperation - showed later greater stress responses high stress reactions in mothers prevents mothering ability and has knock on effect for future generations

Stress and the hippocampus

H particularly affected by stress - density of glucococortoid receptors Stress causes shortening of dendritic axons in pyramidal cells and slower rate of granule cell neurogenesis May be implicated in stress related psychiatric problems Impact mediated by increase in gluco - effects can be locked by adrenalectomy Even a few hours of stress can produce structural changes in the H that last months Natural stressors have greater effect Can disrupt H mediated behaviour Effect greater in males

Subordination stress - long term effects of stress

In mammals threats from conspecifics (animals of the same species) leads to subordination stress SS common in species with social hierarchies Leads to higher chance of attacking juviniles, smaller testes, shorter life spans, lower testosterone and higher glucocortoid levels

HOW stress affects the immune system

Lots of ways anterior pituitary adrenal cortex system influences eg T and B cells have receptors for epinphrine, norepinephrine and glucocococococortoids Cytokines - thought to be produced by the immune system but found in the nervous system Stress induced behavioural patterns also affect - eg lack of sleep

Phagocytosis

Phagocytes consume and destroy invaders and debris - specialised cells such as microglia PHAGO = from Greek "to eat", CYTE from Greek "kyto" a vessel -> a cell A PHAGOCYTE is a cell that eats things

Stress response

Physiological changes in response to threat, when chronic can impact health Strength of response depends on person (coping) and stressor

Antigens

Protein molecules on cell surfaces that help distinguish between foreign (invaders) and bodily cells

Effect of stress on the immune system

Sergerstrom and Miller - meta analysis - maladaptiveness could be unfortunate by product of evolution (spandel) Found effect depends on type of stress - acute stressors can benefit, but chronic negatively affects

Selye's theory of stress

Short term changes are adaptive - help with stressor response Long term changes maladaptive Attributed to the anterior pituitary adrenal cortex system Stressor - ACTH release from anterior pituitary - glucocortoids relased from adrenal cortex Glucos are what cause response effects Stress often measured by gluco levels

Lymphocytes

Specialised white blood cells, produced by bone marrow and stored in the lymphatic system

SNS and stress response

Stressors activate the SNS and trigger epinephrine and norepinephrine release from adrenal medulla

Psychoneuroimmunology

The study of the interaction between psychological factors, the nervous system and the immune system