L6 Stress Flashcards
Define stress (physiology definition)
the physiological responses of the body to stressful stimuli
define stressor
any stimulus which causes a disruption of homeostasis leading to specific behavioural, endocrine and autonomic changes
name and define the two types of stressor
psychological stressors: stimuli which lead to fear, anxiety or frustration (includes traumatic events such as death, divorce, conflict, abuse, war and natural disasters; can also include excitement and nervousness; stimuli can be real or imagined)
physical stressors: stimuli which disrupt normal body function, can be due to internal or external factors
- internal factors: hypoxia, hypoglycaemia, infection, physical strain, injury, starvation, dehydration
- external factors: exposure to heat or cold
define acute stress
the acute stress response is a normal and beneficial adaptive response
benefits of acute stress
increases alertness and focus and provides energy to respond and cope with stressful situations
results of mild stress
improves mood, creates new memories, encourages creative thinking, promotes neural growth in brain, facilitates problem solving
results of severe stress
detachment, reduction in awareness, derealisation, depersonalisation, dissociative amnesia
define chronic stress
when stress is prolonged or persistent, homeostasis is unable to be maintained (disrupting bodies ability to function normally)
what happens to the body during chronic stress (physically and psychologically)
physical - the body enters an exhausted state, when damage to health can occur, immune suppression, hypertension, gastrointestinal disturbances
psychological - anxiety, mental dysfunction, social withdrawal
what is general adaptation syndrome
describes the stages of your bodies response to stress
what are the stages of general adaptation syndrome
- ALARM: preparing you for ‘fight-or-flight’, heightened alertness, energy mobilised
- RESISTANCE: stay alert but keep on with normal functioning (adaptation), homeostasis (maintained)
- EXHAUSTION: resources are depleted, ‘burnout’ sets in, homeostasis cannot be maintained so function impaired, long term damage occurs
which of these could be considered a physical stressor?
a. anxiety
b. hypoglycaemia
c. frustration
d. excitement
B
what does the acute stress response do to your body?
- increased cardiovascular function: HR, contractility, mostly vasoconstriction, vasodilation to muscles, increase blood pressure
- increased respiratory function: respiratory rate and total volume, bronchodilation
- liberation of nutrients: increased blood glucose and fatty acids
- skin: paling or flushing, sweating, piloerection
- sensory: mydriasis (pupil dilation), auditory exclusion, tunnel vision
- muscle tension and shaking
- inhibition of gastrointestinal motility, contraction of sphincters
- inhibition of the lacrimal gland and salvation
- relaxation of bladder, inhibition of erection
the physiological response to stress are coordinated by the ________ and involves both ________ and _______ systems
the physiological response to stress are coordinated by the HYPOTHALAMUS and involves both SYMPATHETIC and ENDOCRINE systems
what happens to the following when a stressor occurs?
- posterior pituitary
- anterior pituitary
- sympathetic nervous system
posterior pituitary = increase vasopressin (helps to retain fluid in your body = retain water or reabsorbs water back from your urine = increase fluid = helps keep up blood pressure)
anterior pituitary gland is stimulated by corticotrophin releasing hormone = increases ACTH = affects adrenal cortex to release cortisol
sympathetic NS acts on the adrenal medulla to produce epinephrine (adrenaline)- also effects:
- arteriolar system: vasoconstriction in arteries = decreases blood flow through kidneys = decrease filtration rate and response from RAAS (increase renin, increase angiotensin, increase aldosterone) systems
- pancreas responds by increasing glucagon and decreasing glucose to release more energy from the energy stores
in relation to the adrenal cortex, what does mineralocorticoids (aldosterone) do?
- produced in response to changes in ECF volume/blood and stress
- promotes water retention in kidneys by increasing Na+ reabsorption
in relation to the adrenal cortex, what does glucocorticoids (cortisol and corticosterone) do?
- produced in response to stress
actions: - allows body to cope with stress by increasing availability of energy and aminoacids
- increase vascular reactivity (by largely unknown mechanisms)
- affects mood and behaviour- improving mood, increasing alterness
- stimulates brain function- promotes neural growth in the brain which improves memory, creative thinking, problem solving ability
- in chronic stress, may be responsible for immune suppression and other health defects
what does adrenaline/noradrenaline do when a person becomes stressed?
- elicits acute physical reactions of body to prepare for ‘fight or flight’
- increases cardiac and respiratory function, slows digestion/kidney function, tenses muscles, increasing sweating
- vasoconstriction to skin and organs (including kidneys), vasodilation to skeletal muscles
- inhibits parasympathetic nervous system
- acts on pancreas to reduce insulin secretion, increases glucagon secretion to increase blood glucose
what does renin-angiotension-aldosterone/vasopression do when. a person becomes stressed?
maintain blood pressure and blood volume
The endocrine response includes the release of glucocorticoids from via the adrenal ______, whereas the sympathetic response is via adrenaline release from the adrenal ______.
The endocrine response includes the release of glucocorticoids from via the adrenal CORTEX, whereas the sympathetic response is via adrenaline release from the adrenal MEDULLA.
what happens when you become overstressed?
- chronic and/or excessive stress can cause immune suppression, weight loss, poor growth, hypertension, reproductive failure, mental disorders and is associated with higher mortality
- stress disorders can develop in response to severe life threatening events
chronic stress can cause…
- immune supression through excess glucocorticoid production = increasing risk of infection
- hypertension and Na+ & water retention - through excess glucocorticoid exposure, activation of RAAS and vasopressin
- disruptions of body weight- weight loss or obesity, redistribution of body fat
- poor growth in children through suppression of growth hormone production
- inhibition of parasympathetic NS can result in reproductive failure, poor digestion
- psychological disorders such as anxiety, depression, social withdrawal, increased substance abuse
what is innate immune system and adaptive immune system
innate immune system:
- includes physical barriers (skin, mucous membranes), inflammatory response and phagocytosis
- creates ‘antigen-presenting’ cells to activate adaptive immunity
adaptive immune system:
- responds to antigens, produces antibodies
- destroys circulating microbes and infected cells
- creates immune ‘memory’ in T and B lymphocytes
