(8) Stress and Disease

Main stress hormone

Cortisol

General Adaptation Syndrome

3 stages:

• Alarm

• Resistance

• Exhaustion

Alarm

• immediate response to stress/threat

• activates fight or flight

• activates hypothalamus / sympathetic system / HPA axis

• ↑ heart rate

• ↑ blood pressure

Resistance

• body tries to cope/defensive

• cortisol helps short-term

Exhaustion

• body cannot keep up anymore

• this is when stress-related disease happens

• can lead to depression / illness effects

Chronic stress =

BAD

With chronic stress, memorize:

• ↑ cortisol

• ↑ catecholamines

• ↑ cytokines

• ↑ sympathetic activity

Main effects of chronic stress

• lowers ability to fight infection

• causes immune suppression

• changes body composition

• causes inflammation

• raises blood sugar

• contributes to diabetes risk

Gluconeogenesis =

making new glucose

Gluconeogenesis

Sources he emphasized

• pyruvate

• amino acids

chronic stress breaks down…

•  skeletal muscle

• this can cause muscle atrophy

In humans:

• fat does NOT…

• directly become glucose

• lipids/fatty acids do not directly convert to sugar

• glycerol can contribute, but not fat directly

Stress and diabetes

Memorize this chain:

chronic stress → cortisol/fight-or-flight stay high → blood glucose stays high → diabetes / insulin resistance risk

Fight or flight organ effects

Lungs

• bronchodilation

• more airflow

• more oxygen

Heart

• ↑ heart rate

• ↑ force of contraction

Gut

• less digestion

• less blood flow

• less activity

Heart terms

Chronotropic

Inotropic

Chronotropic

• effect on heart rate

• positive chronotropic = increases HR

• negative chronotropic = decreases HR

Inotropic

• effect on strength of contraction

• positive inotropic = stronger contraction

• negative inotropic = weaker contraction

 Immune effects

Chronic stress changes:

• cytokines

• natural killer cells

• T cells

• causes chronic inflammation

• causes immune suppression

Hormones

Oxytocin

Testosterone

Growth hormone

Oxytocin

• pair bonding

• love / attachment

• helps modulate stress

Testosterone

• chronic stress can decrease testosterone

• can cause:

  • loss of libido

  • loss of fertility

Growth hormone

• tends to decrease with chronic stress