Stress Flashcards
What is stress?
It is the general term for any condition that actually or potentially poses a serious challenge to the body ability to maintain homeostasis
State some physical symptoms of stress
Dehydration Haemorrhage Infection Surgery Temperature fluctuations
How is the body physiological homeostasis monitored?
Via the central nervous system via the hypothalamus in the brain stem
Which pathway is physiological homeostasis controlled by?
The sympathetic pathways
Slower maintenance is via the endocrine system with secretion from the adrenal glands
What are the two pathways can a stress response take?
Rapid short term response: Fight to flight
Long lasting body response under the endocrine control
Which part of the brain stimulates the sympathetic portion of the autonomic nervous system?
The hypothalamus
The hypothalamus stimulates what?
The sympathetic portion of the anatomic nervous system and the endocrine system via the adrenal glands in the high or flight response
What so the adrenal glands release during the fight or flight response?
Epinephrine (adrenaline)
Norepinephrine (noradrenaline)
Describe the actions of the sympathetic nervous system?
- Nerve endings release noradrenaline
- This increases the heart rate and stroke volume ultimately increasing cardiac output
- Constriction of blood vessels increases. This increases blood pressure
- Blood is diverted from no essential organs to the brain, heart and skeletal muscles
- Ventilation increases
- Sweating may occur
Describe the actions of the adrenal medulla?
- Preganglionic nerve endings stimulate the adrenal medulla
- Adrenal medulla releases catecholamines (adrenaline and noradrenaline)
What is the adrenal glands made of?
2 Small glands:
The inner region: are activated in brief response systems
Outer region: activated in more pre longed lasting responses
What is the inner region of the adrenal glands?
The adrenal medulla
What is the outer region?
The adrenal cortex
Where are the adrenal glands found?
Above the kidneys
What does the adrenal medulla secrete and in what proportion?
Secretes:
Adrenaline 80-90% of cells
Noradrenaline 10-20% of cells
Where are the adrenaline and noradrenaline stored in the adrenal medulla?
They are stored in secratory granules
What stimulate the release of adrenaline and noradrenaline from the secretary granules in the adrenal medulla?
They are released when stimulates by the preganglionic fibres of the sympathetic nervous system
What type of actions does the sympathetic nervous system produce?
Rapid short term actions with rapid release that have a quick action on target cells and a very short life span of activation
What is adrenalines half life?
They have a short half life of 10s
What are the biological effects of catecholamine release?
Re-enforces the actions of the sympathetic nervous system
What receptors do the catecholamine act on?
Alpha 1 Alpha 2 Beta 1 Beta 2 Beta 3
What processes does atecholamine adrenaline stimulate?
Increased Glycogenesis
Increased Gluconeogenesis
Increased Mobilisation of free fatty acids
What is Glycogenesis?
Breakdown of stored of glycogen to release glucose in the blood stream
(ie increases the blood glucose concentration in the blood)
What is Gluconeogenesis?
Release of glucose from pre-cursors in the liver which ultimately increases the blood glucose concentration in the blood
What happens when mobilisation of are fatty acids is increased?
Glucose is released into the blood stream and the are fatty acids are used as an energy source
What is the biological effect of noradrenaline?
Causes vasoconstriction which increases the total peripheral resistance and increases cardiac output
Which receptors does noradrenaline work on?
Alpha 1 receptors
What is the biological effect of adrenaline?
May cause vasodilation in skeletal muscles
This increases oxygen supply to the muscles
Which receptors does adrenaline work on?
Beta 2 receptors in skeletal muscles
Which of the two: noradrenaline or adrenaline has a more potent effect on peripheral vasoconstriction and blood pressure
Noradrenaline
What does adrenaline have a more potent effect on?
The heart
Metabolic activities
What do both noradrenaline and adrenaline do?
They both inhibit insulin and stimulate glucagon which enables ample levels of glucose to be available in the body for use as an energy source
What do both noradrenaline and adrenaline act to support?
The sympathetic system in times of stress
What does familiar emotional stress tend to increase?
The release of noradrenaline
What does unfamiliar emotional stress tend to increase?
The release of adrenaline
What is Phaechromocytoma?
A clinical condition where there is adenoma (benign tumour) on the adrenal medulla
What are the symptoms of Phaechromocytoma?
Increased heart rate
Increased circulating blood glucose
Increased sweating
What is a treatment option for Phaechromocytom?
Surgically removing the adrenal gland as long as the sympathetic nervous system is left in tacts
Describe the longer lasting response to stress
The adrenal cortex is stimulated and the hormone cortisol is released
What is the half life of cortisol?
Around 60-90 mins
What does cortisol stimulate?
Cortisol is released in small burst sand it stimulates energy mobilisation and is beneficial to tissue repair in the body
It is important in the stress response as it releases blood glucose and affects blood pressure
When is cortisol released most in the day?
Stimulated moe in the morning and reduces on an evening
Is cortisol released in times of stress?
No it is secreted regularly as a part of the circadian rhythm
In what rhythm is cortisol released?
Circadian rhythm (24 hours pattern)
What stimulates the release of cortisol?
Who might this cause a problem for?
Input of daylight is recognises by the retina of the ye which triggers secretion
May be a problem for blind people
Which other hormones are secreted for the circadian rhythm to occur everyday?
corticotropin and adrenocorticotropin
Where is corticotropin secreted from?
Released from the hypothalamus
Where is adrenocorticotropin secreted from?
Released from the anterior pituitary gland
When is cortisol secretion impaired?
When our sleep cycle is interrupted
When we cross timezones (Jet lag)
What three main biological effects does cortisol have?
EFFECTS:
Carbohydrate metabolism
Fat metabolism
Protein metabolism
How does cortisol effect protein metabolism?
Increases protein catabolism (breakdown)
Proteins then used for repair and generating enzyme production
How does cortisol effect carbohydrate metabolism?
Leads to increase in blood glucose
Does this by increasing gluconeogenesis
Decreases glucose utilisation
Helps spare the glucose for predominant use by the brain
How does cortisol effect fat metabolism?
Increases free faty acid release by metabolising the fatty acids
Breaks down triglycerides
Increases use of fat to save glucose
What is the overall physiological effect of cortisol?
- Increases blood pressure by increasing vasoconstriction which enhances the sympathetic response
- Increased heart tase
- Has an overall anti-inflammatory response. This response prevents damage of nearby tissues, prevents damage of autoimmune disease
What is cortisol used as outside the body?
Used pharmaceutically as an anti-inflammatory drug.
Epinephrine (adrenaline) and Norepinephrine (noradrenaline) is secreted by what?
The adrenal glands
What are stored in secretory granules in the adrenal medulla?
Adrenaline and noradrenaline
The stimulation of preganglionic fibres causes what?
The release of adrenaline and noradrenaline from the secretory granules in the adrenal medulla
Adrenaline is usually released in times of…?
Unfamiliar emotional stress
What does noradrenaline have a more potent effect on?
Peripheral vasoconstriction and blood pressure
If a patient comes in with symptoms including Increased heart rate Increased circulating blood glucose Increased sweating What might they have?
Phaechromocytoma
Which of the two: noradrenaline or adrenaline has a more potent effect on the heart and metabolic activities
Adrenaline
Noradrenaline is usually released in times of…?
Familiar emotional stress
Which clinical condition is associated with an adenoma on the adrenal medulla?
Phaechromocytoma
Which hormone is secreted by the adrenal cortec in a longer lasting response to stress?
Cortisol
Describe how cortisol is secreted
- The hypothalamus Increases the secretion of Corticotropin Releasing Hormone (due to the circadian rhythm)
- The anterior pituitary gland increases the secretion of Adrenocorticotropic Hormone
- The secretion of these two hormones then prompts the adrenal cortex to increase cortisol secretion
Give the effects of increased cortisol production
In tissues: Glucose and amino acid uptake decreases
In adipose tissues: Lipolysis increases
In muscles:Protein breakdown increases and protein synthesis decreases
In the liver: gluconeogenesis increases
What is Cushing’s disease?
It is the hyper secretion (over secretion) of cortisol
What is Cushing’s disease usually due yo?
A tumour of the adrenal cortex
What are the symptoms of Cushing’s disease?
Moon face
Buffalo hump
Hyperglycaemia
Adrenal diabetes
Increased blood pressure
Loss of protein from the muscles leading to thin limps
Deceased immune response which can lead tome infections
What is a treatment option for bushings disease?
Surgical removal of the tumour
What is Addison’s disease?
Hyposecretion (under secretion) of cortisol
What is Addison’s disease usually caused by?
Damage of the adrenal cortex which leads to a decrease in cortisol and aldosterone
A secondary cause for this disease may be damage of the pituitary gland which leads to decreased secretion of the Adrenocorticotropic hormone resulting in decreased cortisol secretion
What are the symptoms of Addison’s disease?
Decreased blood pressure
Hypoglycaemia
Patients are very susceptible to stress
What is a treatment option for Addison’s disease?
Replacing cortisol, so taking supplements
What type of response is fainting?
A parasympathetic response
What may cause fainting?
It occurs when the body over reacts to certain trigger (Vasovagal syncope)
These triggers may be:
Emotional stress
Phlebotomy
Sight of blood
Acute pain
Loss of blood sue to transient fall in perfusion pressure to the brain
Describe the actions of the brain that may cause someone to loose consciousness
- The adrenal cortex detects emotional stress and sends and impulse to the medulla
- The medulla increases AVP secretion DECREASES sympathetic output and INCREASES vagal output
- DECREASE in sympathetic output causes total peripheral resistance to decrease and INCREASE in vagal output decrease both cardiac output and venous return (also decreases atrial stretch)
- Both these actions decrease arterial pressure which causes the brain to decrease cerebral blood flow
- This decrease in cerebral blood Flo causes a loss of consciousness
Give the effects of increased cortisol production in tissues
Glucose and amino acid uptake decreases
Which clinical condition is associated with damage of the adrenal cortex?
Addison’s disease
If a patient comes in expressing symptoms like:
Moon face
Buffalo hump
Hyperglycaemia
Adrenal diabetes
Increased blood pressure
Loss of protein from the muscles leading to thin limps
Deceased immune response which can lead tome infections
What clinical condition might they have?
Cushing’s disease
Give the effects of increased cortisol production in muscles
Protein breakdown increases and protein synthesis decreases
Give the effects of increased cortisol production in the liver
Guconeogenesis increases
If a patient came in expressing symptoms like: Decreased blood pressure Hypoglycaemia Patients are very susceptible to stress What clinical condition might they have?
Addison’s disease
Which clinical condition is associated with a tumour on the adrenal cortex?
Cushing’s disease
Give the effects of increased cortisol production in adipose tissues
Lipolysis increases
If a patient comes in with a damaged pituitary what may they have and why?
damage of the pituitary gland is a secondary cause for this disease which leads to decreased secretion of the Adrenocorticotropic hormone resulting in decreased cortisol
