Cortisol and Stress Flashcards
What is cortisol?
Steroid hormone that is lipid soluble (has a carrier protein) so has an intercellular receptor
It cannot be stored so is produced as required
Effector protein : Increases conversion of DNA to mRNA so new proteins can be formed which causes cell to do things differently
Sequence of events that lead to cortisol secretion
Non stress neural inputs stimulates hypothalamus to secrete corticotropin releasing hormone (CRH)
CRH stimulates anterior pituitary to secret ACTH
ACTH stimulates adrenal cortex to secrete cortisol
Cortisol inhibits ACTH and CRH release in non stress responses
Response of target cells due to cortisol secretion
Increased protein breakdown, fat breakdown and glucose synthesis
Increased blood pressure, heart and blood vessel contraction
Decreased glucose uptake
Suppresses immune system if long term
Activation of CNS
Daily pattern of cortisol secretion
Pulses during day, highest peak upon waking up
Any disturbances in sleep schedule will affect pathway
Hyposecretion
Secrete too little hormones
Hypersecretion
Secrete too much hormones
Hyposensitive
Little or no response to hormone receptors
Hypersensitive
Too much response to hormone receptors
What can cause problems with hormone signalling?
Autoimmunity
Genetic mutation
Tumors
Other
What is addisons disease?
Reduction in secretion of both cortisol and aldosterone
Low cortisol concentration leads to increase ACTH secretion and cortisol can’t inhibit ACTH
Excess ACTH stimulates melanin synthesis resulting in change in skin pigmentation
Symptoms : low blood pressure, weakness
What is cushings disease?
Too much cortisol : hypersecretion
Symptoms : buffalo hump, moon face, high blood pressure, weakness
What is stress stimulus?
Stress activates the hypothalamus which organises a response and activates the adrenal glands, sympathetic nervous system and posterior lobe of pituitary glands
What is exhaustion phase in relation to stress?
Homeostatic processes start to fail which can be fatal due to prolonged stress
What is the alarm phase?
Often known as fight or flight which causes immediate short term responses to crisis
What is the resistance phase?
Long term metabolic adjustments
Glucose, salts and water are conserved
Integrated stress response : adrenaline
Stress stimulates integration of stress in hypothalamus
Hypothalamus rapidly responses by secreting adrenaline
Adrenaline release stimulates increase in blood glucose, heart rate and blood pressure
Integrated stress response : ADH
Stress stimulates integration of stress in hypothalamus
Hypothalamus stimulates posterior pituitary to secrete ADH
Secretion of ADH stimulates decrease in water excretion and increase in blood volume and blood pressure
Integrated stress response : CRH
Stress stimulates integration of stress in hypothalamus
Hypothalamus stimulates anterior pituitary to secrete ACTH
Secretion of ACTH stimulates adrenal cortex to secrete cortisol
Cortisol secretion stimulates increase in blood glucose and blood pressure
