Stress Flashcards
What is the generalised definition of stress?
The body’s method of reacting to a condition such as a threat, challenge or physical and psychological barrier
What is the definition of acute stress?
How long does it usually last?
- Stress which arises in response to short-term trauma or threat
- Minutes to hours
What is the definition of chronic stress?
How long does it usually last?
- A prolonged response to a stressor or emotional situation that involves the sustained release of cortisol
- Weeks to months
Which part of the nervous system does acute stress activate?
The sympathetic nervous system
What is the biological definition of stress?
Physiological changes, including the release of cortisol, adrenalin and noradrenalin, and an increase in heart rate, which are brought about by the perception of a threat or challenge
What are some of the physical symptoms of stress?
- Dilated pupils
- Dry mouth
- Faster heart rate
- Faster respiratory rate
- Urge to urinate
How is stress considered in the context of homeostasis?
- Stressors are anything which knock you out of homeostatic balance
- The stress response is anything your body does to try and restore that balance
How long do the neurally mediated and hormonally mediated responses to stress take?
- Neurally-mediated short-term response within minutes
* Hormonally medium-term response within hours
Which group of neurotransmitters drive the neurally-mediated part of the stress response?
Catecholamines (dopamine, adrenaline, noradrenalin)
Which corticosteroid drives the hormonally mediated stress response?
Glucocorticoid
What is noradrenalin also known as?
Norepinephrine
What are catecholamines?
A group of neurotransmitters associated with the sympathetic nervous system
What are the neurotransmitters which are considered to be catecholamines?
- Dopamine
- Adrenaline
- Noradrenaline (norepinephrine)
When a stressor is perceived, which part of the brain is responsible for the release of adrenalin?
The adrenal medulla
Where is noradrenaline released from?
Sympathetic nerve endings throughout the body
What are glucocorticoids?
A class of steroid hormones that includes corticosteroids such as cortisol
What effect does cortisol have on energy in the body?
It increases blood glucose, fatty acid and amino acid levels
Name the two hormones involved in cortisol regulation
- Corticotrophin-releasing hormone
* Adrenocorticotropic hormone
Where is CRH (corticotrophin-releasing hormone) released from?
The hypothalamus
What does CRH (corticotrophin-releasing hormone) stimulate the release of and where does that hormone get released from?
- Adrenocorticotropic hormone
* The anterior pituitary
What does ACTH (adrenocorticotropic hormone) do?
It targets the cells of the adrenal cortex to release cortisol
Are hormonal responses to stressors quick to occur?
No, they can take hours from the point of exposure to the stressor
What systems within the body does acute stress have an effect on, and what can some of those effects be?
- Change the cardiovascular system - increase heart rate/contractility
- Metabolism - increased blood levels of glucose, fatty acids and amino acids
- Cognition - changes in perception/memory
- Pain perception - perception of pain is diminished
- Immune system - short term enhancement
- Reproductive system - decreased production of reproductive hormone
Which areas of the heart are innervated by the sympathetic nervous system?
The sinoatrial and ventricular nodes
What happens to activity in the parasympathetic nervous system when there is an increase in activity in the sympathetic nervous system?
It decreases
Where in the brain do neural signals to the sympathetic system originate?
The medulla oblongata, which is in the brain stem
Which part/s of the heart does noradrenalin act on? What is its effect?
- The sinoatrial and atrioventricular nodes
* Increases heart rate
Which parts of the heart does noradrenalin act on in order to increase contractility?
Muscle cells of the ventricles and atria
Blood vessels in which areas of the body suffer vasodilation in response to stress?
- Skeletal muscle
- Brain
- Lungs
Blood vessels in which areas of the body suffer vasoconstriction in response to stress?
- Skin and mucosa
- Kidneys
- Digestive organs
- Reproductive organs
What is the purpose of vasodilation in response to stress?
To deliver more glucose and oxygen to the organs most vital for physical activity
What type of hormone is cortisol?
A corticosteroid
Where in the body is cortisol synthesised?
The adrenal cortex of the adrenal glands
What does cortisol stimulate the breakdown of and why?
- Glucose, amino acids and fatty acids
* In order to provide energy for work in the form of ATP
In response to stress, what happens to blood flow to the frontal cortex area of the brain?
It decreases
In response to stress, what happens to blood flow to the amygdala?
It increases
What is hypoalgesia?
A decrease in pain sensitivity
Why does stress decrease pain sensitivity?
Due to the release of certain neurotransmitters
Which neurotransmitters help reduce the sensation of pain during times of stress?
What is the name for this group of neurotransmitters?
- Endorphins
- Enkephalins
- Dynorphins
- Endogenous opioids
What effect can long-term stress have on pain?
It can induce hyperalgesia - a general increase in pain sensitivity
Which components of the immune system have enhanced activity as a response to stress?
- Dendritic cells
- Neutrophils
- Macrophages
- Lymphocytes
- Cytokines
What is the general effect of stress to the immune system?
To increase activity and signalling amongst immune system cells
Where is the most common site for Cushing’s Syndrome?
The anterior pituitary gland
What are the main symptoms of Addison’s disease?
- Chronic fatigue
- Loss of appetite
- Weight loss
- Hypoglycaemia
- Low mood
- Increased thirst
- Lack of tolerance to stress
What effect is chronic stress likely to have on the immune system?
- Lower resistance to infection
- Slower wound healing
- Lower efficacy of vaccination
What effect is acute stress likely to have on the immune system?
- Boosts efficacy of vaccination
- Increases wound healing
- Increases resistance to infection
What effect does chronic stress have on blood pressure?
It elevates it
What is ideal blood pressure in a healthy adult?
120/80 mmHg
Why would people with high stress levels tend to have high concentrations of fatty acids in their blood?
Because the cortisol response causes fatty acids to be released from adipocytes in order to provide energy
What are the possible consequences of atherosclerotic plaques building up in coronary (vessels which provide blood to the heart) arteries?
- Angina pectoris
* Myocardial infarction
What are atherosclerotic plaques?
Deposits of fat, fibrin, cellular debris and calcium salts on the inside of arterial walls
What are the effects of chronic stress on the amygdala?
What is the outcome of these effects?
- Increases the activity and number of neural connections
* Heightens fear response
What effect does increased cortisol levels have on the hippocampus?
What is the outcome of this effect?
- Electrical signals deteriorate
- Activity of HPA axis deteriorates
- Deterioration in memory, learning and stress control
What are the physiological effects of stress on your brain?
- Shrinks your prefrontal cortex
* Loss of synaptic connections
What does the pre-frontal cortex regulate?
- Concentration
- Decision making
- Judgement
- Social interaction
Where in the brain are new brain cells made?
What effect does chronic stress have on this process?
- The hippocampus
* Fewer new brain cells are made
Which cellular part of the brain is most affected by stress?
Dendrites (short projections on a cell body which receive incoming information from other neurons)
How can stress cause gastritis?
Due to H. Pylori infection causing inflammation of the stomach
What are the physical changes in the stomach caused by H.Pylori?
Slowing down of the replacement of epithelial cells, which causes thinning of the stomach’s mucous membrane
Which reproductive hormones does stress reduce the production of?
- Testosterone
- Oestrogen
- Progesterone
Which part of your brain is activated in response to stress?
The HPA axis
Erection is mediated by which branch of the nervous system?
The parasympathetic nervous system
Ejaculation is mediated by which branch of the nervous system?
The sympathetic nervous system
Erectile dysfunction is linked to insufficient activity of which part of the nervous system?
The parasympathetic nervous system
Premature ejaculation is linked to dysfunction of which part of the nervous system?
The sympathetic nervous system
How do activities of the sympathetic and parasympathetic nervous system tend to be related?
Inversely
What part of the chromosome is affected, and how, in people suffering with chronic stress?
- Telomeres
* Shortened
What are telomeres?
Non-coding, repetitive sequences at the ends of chromosomes that protect the ends of the chromosome from ‘fraying’
What are nucleotides?
What do they consist of?
- Building blocks of DNA
* Phosphate, a sugar, a base
How does stress affect the menstrual cycle?
Cycles tend to become longer and less regular, in extreme cases they can stop altogether
What is epigenetics?
Modifications of DNA which don’t change the code but do change the pattern of gene expression
What are histones?
Protein clusters which DNA is wrapped around
Can epigenetic marks be inherited?
How far can that inheritance be transmitted?
- Yes
* Several generations, maybe even over tens of generations
What are the ways we can mediate or manage stress?
- Mindfulness
- Meditation
- Social support
- Exercise
- Learning coping strategies
What effect does exercise have at a cellular level in the brain?
- Induces production of growth factors
* Stimulates the production of new brain cells
What is chromatin?
The combination of histone and DNA
Which body systems does stress affect?
- Cardiovascular system
- Metabolism
- Cognitive function
- Reproductive hormones
- Pain perception
- The immune system
What are the bodily dysfunctions which chronic stress is linked to?
- Immunosuppression/dysregulation
- Heart disease
- Cognitive impairment
- Gastrointestinal disease
- Obesity
- Reproductive impairments
What is the name of the growth factor which is stimulated in the brain by exercise?
Brain-derived neurotrophic factor
