lecture 28 - cortisol & stress Flashcards
Where is cortisol produced?
The adrenal cortex
What carrier protein is cortisol bound to during transport through the blood stream?
Corticosteroid binding hormone
What type of target cell receptors does cortisol bind to?
Intracellular (cytoplasmic or nuclear) receptors
What is the process of cortisol target cell binding?
Cortisol diffuses through cell membrane, binds to intracellular receptor to form complex, complex binds to specific region of DNA activating genes which are transcripted to mRNA then translated to make proteins.
What stimulus is cortisol released in response to?
Stress
What are neural inputs that result in the secretion of cortisol, aside from stress?
Day-night rhythm, low blood glucose concentration.
What effect does cortisol have on blood glucose levels?
Increases them
What effect does cortisol have on metabolism of fat, protein and carbohydrates?
Increased metabolism to maintain blood glucose
Are anti-inflammatory actions promoted or inhibited by cortisol?
Promoted
What effect does cortisol have on blood pressure?
Increases it
What effect does cortisol have on the heart and blood vessels?
Increased heart and blood vessel tone and contraction.
What effect does cortisol have on the immune system, in the long term?
Suppresses the immune system
When, over the course of the day, are cortisol levels highest?
After waking in the morning
What is hyposecretion?
When too little hormone is released
What is hypersecretion?
When too much hormone is secreted
What are common causes of hormone signalling problems? (3)
Autoimmunity, genetic mutation, tumors
How does autoimmunity cause hormone signalling problems?
Receptors are destroyed, or they may be artificially stimulated
How do tumours cause hormone signalling problems?
Excess tissue may cause excess release of hormone, or may inhibit release
What is Addison’s Disease?
A condition that occurs when there is insufficient secretion of cortisol and aldosterone from the adrenal cortex.
Why do patients with Addison’s disease often have elevated ACTH levels?
Adrenocorticotropic hormone is released due to low cortisol levels, in a negative feedback loop.
Why do patients with Addison’s disease often have darkened patches of skin?
Increased ACTH levels stimulates melanin synthesis in the skin.
What is Cushing’s disease
A condition caused by the secretion of too much cortisol.
What are the symptoms of Addison’s disease?
Low blood pressure, weakness, hyperpigmentation of skin
What are the symptoms of Cushing’s disease?
High blood pressure, weakness/muscle wasting, tumours, fat deposits
What does stress activate?
The hypothalamus
In response to stress, what anterior pituitary stimulating hormone is released by the hypothalamus?
CRH (corticotropin releasing hormone)
What does CRH trigger the release of, and in which gland, in response to stress?
Adrenocorticotropic hormone (ACTH) in the anterior pituitary
What hormone is secreted by the posterior pituitary in response to stress induced stimulus from the hypothalamus?
ADH - anti-diuretic hormone
What three hormone pathways are activated by the hypothalamus in response to stressful stimulus?
Adrenal cortex releases cortisol, posterior pituitary release ADH, adrenal medulla (via sympathetic nervous system) releases adrenaline
What is the ‘alarm phase’ of the body under stress?
A phase of immediate, short-term responses to stress/crisis, as a result of sympathetic stimulation and the release of adrenaline from the adrenal medulla
What visceral reflexes are activated during the ‘alarms phase’ of stress?
Cardioaccelatory, vasomotor, pupillary light reflexes
What is the cardioaccelatory reflex?
Increase in heart rate and force of heart contraction
What are vasomotor reflexes, in the context of the alarm phase of stress?
Changes in diameter of peripheral vessels
What is the pupillary light reflex?
Reflex that changes the diameter of the pupils in response to light.
How is the pupillary light reflex activated in response to sympathetic nervous system stimulation?
The dilator pupillae muscles of the eye contract to increase pupil diameter
What are some immediate short-terms responses (alarm phase) in response to stress?
Mobilisation of glycogen and lipid reserves, increased energy use by cells, mental alertness,, increased sweat gland secretion, increased heart rate
What is the resistance phase of stress?
Long term effects and changes within the body due to prolonged exposure to stress.
What are some long-term metabolic adjustments made during the resistance phase?
Mobilisation of lipid and amino acid reserves, conservation of glucose as glycogen by peripheral tissues (lipids used for energy instead), increased blood glucose concentration as liver synthesises glucose
What hormone is released by the hypothalamus to trigger cortisol secretion?
Corticotropin releasing hormone
