PSYC 302 Exam 3

Stress

The physiological response to a challenge or perceived challenge - activates the sympathetic nervous system and the HPA axis

Parasympathetic Nervous System

Slows heart beat, stimulates digestion, constricts lungs

Sympathetic Nervous System

Adrenalin rush (epinephrine), increased heart beat, inhibits digestion, dilates lungs

HPA Axis (Hypothalamic-Pituitary-Adrenal Axis)

Feel stressed, Hypothalamus releases CRH into the pituitary gland circulatory system

CRH binds to receptors in pituitary which causes pituitary to release ACTH into the blood

ACTH causes adrenal gland to release glucocorticoids into the blood

Glucocorticoids

Stress hormones (cortisol is best known one)

What do glucocorticoids do?

Turn stored energy (fat, glycogen) into usable energy (glucose) when stressed

Insulin

Hormone secreted by the pancreas that causes cells to absorb glucose

Steps of the reproductive system

LHRH (GnRH)released from hypothalamus

Pituitary releases LH and FSH

Luteinizing Hormone (LH)

Males: Stimulates testes to release testosterone and produce sperm

Females: Regulates menstrual cycle, stimulate ovaries to release estrogen, produce/release egg

Macrophages and Neutrophils

White blood cells that phagocytose (engulf) dead/foreign material and release alarm signals

Lymphocytes

White blood cells that recognize, remember, and respond to foreign invaders

Innate Immune System

Inflammation: Vasodilation (swelling), cytokines (alarm signals), neutrophils and macrophages

Acquired (Adaptive) Immune System

Antibodies and antigens, Lymphocytes (white blood cells) (B and T cells)

Cytotoxic T Cells

Lymphocytes that kill infected/targeted cells

T Cells

Lymphocytes that recognize and remember antigens and signal other cells to their presence

Glucocorticoids and the immune system

Glucocorticoids kill lymphocytes and cause them to be removed from the system (immune suppression)

How does stress stunt growth?

Reduced release of GHRH from the hypothalamus

Increase release of GHIH

Reduces sensitivity to growth hormone

Fail to absorb nutrients

Memory Trace

Biochemical change in the brain that ENCODES AN EXPERIENCE, which lasts beyond the stimulus

Consolidation

Stabilization of the memory trace

Reconsolidation

Stabilization of the memory trace AFTER BRINGING IT BACK INTO AWARENESS

Retrieval

Bringing the memory into awareness

Extinction

Learning that a context is no longer associated with a stimulus

Forgetting

Loss of memory trace

Implicit Memory

Procedural - Riding a bike, driving a car, etc.

Explicit Memory

Declarative - Remembering the presidents, etc.

Cerebellum and Dorsal Striatum in memory

Critical for habit learning, procedural, and skill learning

Hippocampus and memory

Critical for forming declarative memories

Hippocampus memory system

DG > CA3 > CA2 > CA1 > Entorhinal Cortex

How does stress increase the risk for heart disease?

Increasing blood pressure chronically

Heart Disease

Plaque forms in the coronary arteries and blocks the blood to the heart

Type 1 Diabetes

Auto immune disease, reduced insulin production

Type 2 Diabetes

Related to obesity, decreased insulin sensitivity

Insulin

Brings sugar into the cells to store it as glycogen

Stress and diabetes

Adds more sugar to the blood, reduces sensitivity of insulin receptors, makes it difficult to balance blood sugar

Stress and digestive system

Turns on and off the digestive system, takes time to re-coordinate = IBS

Peptic Ulcer

Bacterial infection from reduced immune system and decrease energy to protect the stomach walls and gut

Severe childhood trauma and growth

Stunts growth by increasing GHIH and decreasing GHRH, reduces absorption of nutrients

Rat licking study and stress response

Rats who were licked more as pups had reduces methylation of the promoter region of the gluccocorticoids receptors in the hippocampus = greater inhibition of the HPA axis = Less reactive to stress

Two ways epigenetic inheritance can manifest

Parents treat their children differently which passes on the stress reactivity

Markers on the sperm or egg in the gonads

Stress and the reproductive system

Reduces GnRH signaling, interferes with menstrual cycle (amenorrhea) and reduced testosterone

Stress and pregnancy

Stress increases the risk for miscarriage, reduced blood flow to uterus - body does not want to expend the energy needed for gestation and birth

Two ways the immune system can fail

Not repair the damage, autoimmune disorders (attacks healthy cells, overreaction)

Acute stress and the immune system

Acute stress can enhance the effects of the innate immune system

Chronic stress and the immune system

Chronic stress inhibits the immune system - synthetic gluccocorticoids are used as immunosuppressants in organ receivers

Short term memory

Not dependent on gene expression

Long term memory

Dependent on gene expression

Acute stress and memory

Enhances memory due to increased glucose in the blood and increase blood flow to the hippocampus

Chronic stress and memory

Impairs memory due to loss of hippocampus neurons - hippocampus has a lot of glucocorticoid receptors and chronic stress causes the hippocampal neurons to die, weaken, and starve for energy = reduced neurogenesis

Cushing’s Disease

Smaller hippocampus

Types: Hypothalamic tumor, pituitary tumor, synthetic glucocorticoids, lung cancer that releases ACTH

Negative feedback loop in HPA axis

Not enough glucocorticoids in the hippocampus

Hypothalamus releases CRH

CRH causes pituitary to release ACTH into the blood

ACTH causes glucocorticoids to be released into the blood

Increased glucocorticoids stops the loop from continuing

Aging and stress response

Reduction in hippocampus leads to inhibited control of the HPA axis which causes cortisol levels to rise and take longer to return to baseline

Outlets for frustration

Aggression, meditation, exercise

How is exercise different from psychological stress?

Exercise is acute and not chronic

Exercise uses the stress response adaptively

Exercise trains the body physiologically, so future stressors are less stressful

Exercise increase adult hippocampal neurogenesis - psychological stress decreases neurogenesis

Stress and social support

Social support is a huge factor in how you cope with stress

Predictability

If we know when to expect a stressor we can relax during the interim

Control

You have control over your health and stress level (exercise, work to overcome, social network, etc.)

Perceived Control

Perception that things are getting better (optimism)

Depression

Stress-related disorder, occurs when the individual is no longer to cope with stress

Hypotheses for how SSRIs work

Reducing auto-receptors on serotonin neurons which increases serotonin signaling

Increases adult hippocampal neurogenesis