Cortisol And Stress Flashcards
What is cortisol
Steroid, lipid soluble hormone.
Produced as required, can not be stored
Carried in blood bound to carrier protein
Outline how cortisol elicits a response from a cell
Travels to target cell on carrier
Seperate from carrier, travels across cell membrane
Binds specific receptor (hormone receptor complex acts as transcription factor
Moves into nucleus
Activates specific genes
mRNA transcribed
Protein translated
Protein mediates cellular responce
Is the cortisol stimulated cellular response fast or slow
Slow
Outline the sequence of events that lead to cortisol secretion
Stimulus: stress, non stress neural inputs
Hypothalamus secretes corticotropin releasing hormone (CRH) into portal blood vessels
Anterior pituitary secretes adrenocorticotropic hormone (ACTH) into systemic circulation
Adrenal cortex secretes cortisol - inhibited hypothalamus and anterior pituitary secretions
Cortisol mediates effects in effector organs
What are the effector organs to cortisol, and their effects
Muscle - increase protein breakdown, decrease glucose uptake
Fat - increase fat breakdown, decrease glucose uptake
Liver - increase glucose synthesis
Other effects - helps one cope with stress
Long term: suppresses immune system
Essential for maintaining normal blood pressure
Why is cortisol secretatory negative feedback loop invalid when it is a stress responce
Stress stimulus is very large and outweighs the negative feedback loop inhibitions to hypothalamus and anterior pituitary
Outline the daily pattern of cortisol secretion
Pulses during the day (in response to specific bodily conditions)
Highest peak upon waking
Any disturbances of normal sleep (e.g. jet lag) will disrupt this pathway
What are the functions of cortisol
Increase blood glucose levels
Increasing fat, protein, carbohydrate metabolism to maintain blood sugar glucose
Promoting anti-inflammatory actions
Increasing blood pressure
Increasing heart and blood vessel tone and contraction
Activation CNS / encourage sympathetic activity
What is Addison disease
Lowered secretion of cortisol and aldosterone
Low cortisol concentration leads to increase ACTH secretion (no cortisol to inhibit ACTH production in anterior pituitary)
Excess ACTH stimulates melanin synthesis
Low blood pressure
Weakness
What is Cushing’s disease
Too much cortisol
Symptoms: buffalo hump, Moon face, High blood pressure, Weakness
Redistribution of excess body fat as no need or excess fat/protein/glucose
Outline the stress response
Activates neural responce in hypothalamus
Hypothalamus organises a response and activates adrenal glands, sympathetic nervous system, posterior pituitary
Body responds
Outline the integrated stress response
Hypothalamus secretes CRH into portal vessels, anterior pituitary secretes ACTH into systemic circulation, and renal cortex synthesises and secretes cortisol
Hypothalamus signals adrenal medulla via sympathetic nervous system, adrenal medulla secretes adrenaline.
Hypothalamus signals for ADH secretion in posterior pituitary
Outline the effects of the integrated stress response
Cortisol from anterior pituitary/adrenal cortex: increase blood glucose, increase blood pressure
Adrenaline from adrenal medulla: increase blood glucose, increase heart rate, increase blood pressure
ADH from posterior pituitary decrease water excretion (urine production), increase blood volume, increase blood pressure
What are immediate short term responses to stress (alarm phase)
Increased mental alertness
Increased energy use by all cells
Mobilisation of glycogen and lipid reserves
Changes in circulation
Reduction in digestive activity and urine production
Increase sweat gland secretion
Increased heart rate and respiratory rate
What are long term metabolic adjustments of stress response (resistance phase)
Mobilisation of remaining energy reserves (lipids from adipose, amino acids from skeletal muscle)
Conservation of glucose (peripheral tissues excluding nervous break down lipids for energy
Increase blood concentration levels (liver increase glucose synthesis)
Conservation of salts and water, loss of K+ and H+
