Theory L8 - Biochemical Perspective 2 Flashcards
What is Epigenetics?
Changes in the phenotype without changes in the genotype - NO GENETIC MUTATION.
Changes are due to changes in chemical environment - eg. methylation if DNA causing for the protein to be expressed or not.
- Thought to be how cells terminally differentiate, and how diseases develop.
- TURNS GENES OFF AND ON
What is DNA methylation?
when DNA is methylated, strands cannot separate from each other, and information cannot get out - thus, no protein is made.
DE-METHYLATION - results in protein being made - some times this extra protein is not needed = DANGEROUS.
What are 3 ways epigenetics happens?
- dna methylation
- histone modification
- non-coding RNA associated gene silencing - these moderate gene expression - if they aren’t there, a protein may not be expressed / or silenced and thus create problems!!
What are some epigenetic diseases?
- Cancer
- Neuropsychiatric disorders - Scz, Mood Disorders, Neurodegenerative disorders (AD), Autism (chr 15)
- Fetal Alcohol Syndrome
What are instances where epigenetic disease can occur
- hormonal influences - the pill
- alcohol during pregnancy
- stressed mother
What are the two systems involved in stress?
- Autonomic NS - quick, direct connection between adrenal medulla and hypothalamus.
- Endocrine system
Describe the biological systems involved in stress.
Direct connections between hypothalamus and adrenal medulla lead to hormone supply of adrenaline and noradrenaline.
These lead to different bio changes in the body, and has a -ve feedback loop to prevent extra production of these hormones.
endocrine responses are slower, but their effect lasts longer - cortisol and other glucocorticoids - measured in saliva.
ANS divisons?
Sympathetic - increase HR, increase respiration o2, increased BP
Parasympathetic - digestion, slow HR,
effects of arousal works SYNERGISTICALLY - work together not against.
What is the two-system view of stress response?
Stressor –> Brain–>
- anterior pituitary > adrenal cortex > glucocorticoids
- Symp NS > adrenal medulla > norepinephrine & epinephrine.
2 different responses. one quick one slow.
What are catecholamines?
- released from adrenal medulla following SNS
- NA (associated with physical stress) and Adrenaline (associate with psychological stress) - Type of stress results in different concentrations of the hormones
What does the release of catecholamines trigger?
- CNS arousal (alertness)
- Muscle contraction
- Cardiac output
- Blood pressure
- Oxygen consumption
^ these are secondary effects - measure these if you can’t measure the hormone itself.
- mobilises glucose stores
- inhibition of gastrointestinal and sexual activity.
What are corticosteroids?
they are the slow endocrine response to stress.
- these hormones are secreted by endocrine system, by the adrenal glands in response to stress.
- response to the kind of stress that is - novel, uncertain, unpredictable, helpless and distressing - BOTH psychological and physical.
- GLUCOCORTICOIDS (CORTISOL) , MINERAL CORTICOIDS
provides body with glucose energy
What do corticosteroids achieve in the body?
Mineralcorticoids
- Regulation of ion concentrations.
Glucocorticoids (Cortisol)
- Increase glucose by increasing metabolism of carbohydrates, proteins and fats.
Chronic secretions can have detrimental effects:
- Inhibits immunity (stomach ulcers, illness).
- High levels destroy hippocampal neurons.
Why is it important to use both objective and subjective measures of stress?
Objective measures are good.
However, people vary in levels of stress. The subjective experience of a situation may differ across people. Need to make sure that what you are actually measuring, is stress. - use self report scales to make sure the two experimental groups aren’t too different due to participant variables.
- biopsychosocial model
Can investigate the interactions between objective and subjective experiences of stress.
what are some patterns of hormone responses?
- With repeated exposure to a stressor, the increase in stress will diminish.
- Some hormones will increase AFTER the stressor - due to slow response - EPINEPHRINE
- CORTISOL may also increase AFTER stressor on the first time - because the individual will not have known how stressful the situation was going to be. Couldn’t anticipate, so got stressed. but stress response will DECREASE with repeated exposure
- NOREPINEPHRINE decreases with repeated exposure
- TESTOSTERONE increases with repeated exposure, but decreases after the actual jump in every trial
- growth hormone decreases with repeated exposure, but decreases after actual jump in every trial
