The stress responses

Stress responses

An organism has to maintain its internal environment stabilized. Several different environmental effects – heavy strain may develop.

1) Physical and/or social strain

2) Physiological or non-physiological strain(the former is present naturally – sunshine, wind, cold the latter is unnatural – nowadays it increases, i.e. special noise, vibration, xenobiotics)

3) Different types of strains affect the organisms (i.e. during eating, metabolic processes, energy changes, information processes)

Milieu intérieur

Claude Bernard was who introduced the concept of „internalenvironment” (milieu intérieur) at the end of XIXth century.

The internal environment

lung intestinaltract

O2 CO2

heart

kidneyurine

food excreta

blood

extracellular fluidintracellular fluid

Stress responses

C. Bernardprinciple

Walter Bradford Cannon introduced the concept of the homeostasis in 1926, and he defined the alarm reaction as fight or flight process

Stress responses

Homeostasis:

Izovolémia - water volumeIzoionia - ionic concentrationIzohidria - pH (acidity)Izozmózis - osmotic pressureIzotermia - temperature

- variables are actively regulated to remain very nearly constant

alarm reaction according to Canon

The „fight or flight” reaction developed during the evolutional processes First steps of alarm reaction:

Stress responses

Ha az állat (vagy ember) veszélyesnek ítél meg egy adott szituációt, szervezetének energiaellátása úgy alakul át, hogy a meneküléshez vagy küzdelemhez szükséges szervek erőteljesebben, egyéb létfenntartó mechanizmusai kevésbé működjenek.

steroid hormons

Stress responses

Hans Selye in 1936 defined stress as the non-specific response of the body to any demand for change

The order of stress responses:

1.) local adaptation syndrome (LAS – i.e. acute infection and inflammation)

2.) general adaptation syndrome (GAS)

- alarm reaction - increased resistance- run-down state

Application corticosteroids – same symptoms appeared in rats(adaptation illnesses: rheumatoid arthritis, gastric ulcer, high blood pressure)

Stress responses

Independently from the stressor the same processes initiate

Stress responses

Stress responses

Stress responses

Stress responses

Stress responses

Heart rate regulation

Stress responses

Breath regulation

Stress responses

Blood glucose level regulation

Blood glucose level increase:glucagoncatecolamines (i.e. adrenalin)glucocorticoidsthyroxine

Blood glucose level decrease:insulin

Stress responses

Ca2+ level regulation

Stress responses

Metabolism regulation

Leptin (peptide hormone): released from adipose tissue, connecting to the receptors stop eating

Ghrelin: produced in the stomach, and induces hunger and eating behavior

Stress responses

Stress responses

Temperature regulation

Neither fight nor fight is possible -passive avoidance (in human

anxiety and some nonspecific disorder may develop)

Chronic stress problems:

Chronic STRESS

Stress responses

Cardiovascular disease: high blodd pressure, abnormal heart rhythms, heart attacks, stroke

Gastrointestinal problems: gastritis, ulcerative colitis,irritable colon, obesity

Sexual dysfunction: impotence and premature ejaculationin men, loss of sexual desire in both men and womenmenstrual problems in women

Skin and hair problems: acne, psoriasis, eczema,permanent hair loss

Mental heals problems: depression, anxiety, sleep-and memory problems

Chronic STRESS

Stress responses

Stress responses

The role of the nervous system in the stressregulation

Stress responses

Stress responses

Stress responses

Stress responses

Main brain stuctures