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 adrenalmedulla.
In alarm phase, the paraventricularnucleus 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 pituitaryadrenal 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 aminoacid 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