Readings

• Allostasis: the ability to successfully adapt to challenges and retain stability through changes.
• Parameters are readjusted in allostasis in accordance with the environment.
• Hans Selye came up with General Adaptation Syndrome(GAS). It consists of the alarm phase, resistance phase and exhaustion phase
• Alarm phase is akin to the fight or flight response. It begins with the hypothalamus which secretes CRH to activate the SNS which releases NE and EPI from the adrenal medulla.
• In alarm phase, the paraventricular nucleus in the hypothalamus releases CRH which stimulates the anterior pituitary to release ACTH which causes the adrenal cortex to release cortisol; this is called the HPA Axis or the hypothalamic pituitary adrenal axis
• The alarm phase progresses to the resistance phase once the pituitary gland has been activated
• During resistance phase, glucose, amino acids and fatty acids are used as energy
• After resistance phase is over and an individual returns to their original state, they may be functioning at a newer baseline for homeostasis
• Exhaustion phase occurs when the body cannot deal with its stressors and dies. This occurs because the stress response is harmful when its repeatedly activated, not because the body is depleted of its resources
• Allostatic load is a cost to the body's organs for responses that are excessive or unable to deactivate
• NE is released from the hypothalamus as a neurotransmitter and both NE and EPI are also released from the adrenal medulla
• Circulating adrenal catecholamines are seen as an extension of the SNS
• NE is the primary source of vasoconstriction
• EPI enhances inotropy, chronotropy and venous return which enhances overall cardiac output
• EPI also increase glycogenolysis and inhibits insulin secretion which elevates BGL
• Glucocorticoids regulate fluid volume, metabolism, immune response and brain fxn
• Glucocorticoids are lipid soluble
• Cortisol binds to receptors on the hypothalamus and anterior pituitary to complete the negative feedback loop
• Cortisol has an anabolic effect in protein synthesis but catabolic effect in other types of tissues such as muscle, lymphoid and adipose tissues.
• Cortisol stimulates gluconeogenesis in the liver to 6-10x increase in the rate of conversion from amino acid to glucose
• Glucocorticoids suppress the acute phase response to infection and inflammation.
• Aldosterone reabsorbs sodium and excretes potassium
• Endorphins and enkephalins are small peptides that inhibit pain
• Opioid receptors have been identified as immune cells
• Cortisol inhibits the female reproductive system
• Testosterone and DHEA(dehydroepiandrosterone) may inhibit the effects of gluccocorticoids
• Prolactin suppresses ovulation and has roles in lactation, metabolism and hair growth
• Immune cells respond to the hormones released by the HPA axis and SNS; they could also release cytokines that affect these systems as well
• Resilience is a the measure of the capacity to adapt to challenges
• Maladaptation: ineffective change to altered circumstances
• Coping that achieves unintended goals is considered maladaptive
• Hypertension, atherosclerosis, MI and CVAs have been known as stress related illnesses are associated with excessive catecholamine and cortisol levels
• Transient microorganisms: bacteria that are present in the environment but are not harmful to humans
• Commensal microorganism refers to an organism that normally inhabits the human body; either the microbe or the host derives benefit
• High fat content of the skin inhibits growth of fungi and bacteria
• Immunosuppressive drugs(cancer treatment), autoimmune disorders and inflammatory disorders lead to a compromised immune system; other factors are malnutrition and chronic diseases
• Virulence: refers to the potential of a microorganism to cause diseases in a host
• The ability to adhere to a surface is critical to the success of a microorganism
• Many bacteria have an outside coating to prevent phagocytosis
• Escape from immune detection is established through encapsulation, spore formation, mutation, flagella and toxin production