Chapter 6 Flashcards
Define transcription and translation
- transcription: DNA is read by transcriptional factors that bind to DNA strands, ultimately producing mRNA
- translation: mRNA read in triplets which gives code to put together amino acids necessary for prod of proteins
What is the promotor region of a gene
- marks start of gene where transcription factor will bind
DNA methylation is an _____ process of long-term ___ that involves attaching a methyl group to cytosines in the promoter region of a gene
epigenetic; gene silencing
What are 3 hormones that have transcriptional effects?
- cortisol
- GH
- testosterone
**all act in nucleus
What is homeostasis
ability to maintain optimal conditions in the body
(T/F) there is always an external trigger for stress
FALSE, can be internal
What are the 3 main categories of sources of stressors?
- environmental factors
- physiological factors
- psychosocial factors
Stress can be defined as any significant _____
disturbance of homeostasis
What are the 2 key components of the stress response
- epinephrine from adrenal medulla
- glucocorticoids from adrenal cortex
current stress research focusses mainly on ___
psychological features of stress (mainly degree of control individual has over situation)
Who discovered the non-specificity of the stress response and what does this mean?
- Hans Selye (rats injected w saline vs hormone had similar stress responses–probs due to manipulation)
- epinephrine and glucocorticoids are released in response to almost any stressor
What are the 3 stages of the General Adaptation Syndrome?
- Alarm Reaction Stage (fight or flight, low stress resistance)
- Stage of Resistance (body adapts to restore homeostasis)
- Stage of Exhaustion (can no longer cope w stressor, can even lead to death!)
What are 2 key limitations to the homeostatic concept of stress?
- does not address issue that psychological stressors can evoke full physiological stress response
- does not account for individual differences in perception of stressors (ex sky diving)
What are the 3 elements of the modern definition of stress?
- condition in which indiv is aroused by aversive stimuli
- must perceive stimuli as aversive
- lack of perceived control over aversive stimuli
Within seconds of exposure to a stressor, the ____ secretes ____ and then the ______ secretes ______
sympathetic NS secretes norepinephrine; adrenal medulla secretes epinephrine
The effects of (epinephrine/norepinephrine) are 6x stronger than (epinephrine/norepinephrine)
epinephrine 6x stronger than norepinephrine
Within the short-term stress response, epinephrine and norepinephrine lead to what 6 symptoms?
- increased HR
- increased BP
- liver converts glycogen to glucose and releases it into blood
- dilation of bronchioles
- decreased digestive system activity and reduced urine output
- increased metabolic rate
How is the HPA axis involved in the stress response?
- after release of nor/epinephrine
- HYPOTHALAMUS releases corticotropin-releasing hormone
- stimulates release of adrenocorticotropin hormone from anterior PITUITARY gland
- within minutes ADRENAL cortex begins to secrete glucocorticoids
In the long-term stress response, what are 2 impacts of mineralcorticoids and 3 impacts of glucocorticoids?
Mineralcorticoids:
- retention of sodium and water by kidneys
- increased BP and volume
Glucocorticoids:
- proteins/fats converted to glucose or used for energy
- increased blood glucose
- suppression of immune system
(T/F) glucocorticoids are only involved in the long-term stress response
FALSE, also act on metabolic pathways within minutes to replenish energy reserves
The fact that predators and prey experience similar acute stress responses is an example of ____
nonspecificity of the stress response
The implication of a hormone in behaviour requires evidence of _____
hormonal signaling in the CNS
Why are glucocorticoids good candidates for mediating behavioral effects of stress (3)?
- released in response to numerous stressors
- can easily diffuse past blood-brain barrier (so act on CNS unlike epinephrine which struggles to pass through)
- there are glucocorticoid receptors in several brain regions
How does corticotropin releasing hormone (CRH) mediate the stress responsein the hypothalamus and the amygdala?
- in hypothalamus: regulation of HPA axis
- in amygdala: mediating anxiety response
What are the 2 types of corticosteroid receptors in the hippocampus?
- mineralcorticoid (MR): higher affinity, engaged under baseline conditions, role in homeostasis
- glucocorticoid (GR): low-affinity (specific to cortisol), negative feedback to bring stress response under control
Aldosterone is a _____ and cortisol is a ______
mineralcorticoid; glucocorticoid
How does cortisol play a role in the short-term stress response?
- via GABA and endocannabinoids
- causes production of endocannabinoids which inhibit GABA secretion to disinhibit norepinephrine secretion
What are 5 pituitary hormones that play an important role in the stress response?
- ACTH
- Vasopressin (enhances memory)
- Urocortin (amplifies stress signals)
- Prolactin (inhibits reproduction)
- Endorphins and Enkephalins (pain relief, inhibit reproduction)
What are the 4 of the most costly health diagnoses and what do they all have in common?
- cardiovascular conditions
- diabetes
- depression
- asthma
- stress can play a role in all of them!!
What is the pathological state ass w long-term stress for each of these acute stress responses?
- shift from energy storage to energy use
- increased cardiovascular tone
- inhibited digestion
- inhibit growth
- inhibited reproduction
- altered immune function
- enhanced cognition
- shift from energy storage to energy use = fatigue, myopathy (muscle loss), steroid diabetes
- increased cardiovascular tone = hypertension
- inhibited digestion = peptic ulcers
- inhibit growth = psychosocial dwarfism
- inhibited reproduction = impotence, anovulation, loss of libido
- altered immune function = impaired disease resistance, cancer
- enhanced cognition = accelerated neural degeneration in aging
What impact does moderate stress have on memory?
- corticosteroids activate threat response which prompts hippocampus to consolidate stressful exp into memory
- only works when stress is related to memory task
- acute stress unrelated to memory task makes it harder to form memories
- inverted U shape for effects of stress on memory
What is hypercortisolism?
- hippocampus, which is key part of HPA axis negative feedback, is damaged in chronic stress
- vicious cycle, prolonged elevated glucocorticoids cause hippocampal dysfunction and impair negative feedback so glucocorticoid conc keeps going up
How does the stress response differ in dominant and subordinate animals?
- dominant: good cortisol response, have efficient HPA neg feedback system so can return cortisol to baseline faster
- subordinate: blunted sensitivity to CRH so low cortisol response but long term elevation of glucocorticoids
What was the Romanian example given of exposure to stress in humans?
- stress via deprivation
- forced increase in births led to lots of abandoned babies
- orphanages w little human interaction and strict rules
- children who remained in institutional care had significantly blunted sympathetic response
- kids moved into foster care also had lasting damage
kids with secure attachment styles have (higher/lower) cortisol levels
lower
