Stress Flashcards
Where does the hypothalamus stimulate to provide a short term fight or flight response?
Sympathetic division of the ANS and adrenal medulla
What does the sympathetic nervous system do?
Nerve endings release noradrenaline
Increased heart rate and increased stroke volume - increase cardiac output increased MABP
Blood vessels constrict - increased blood pressure
Blood diverts from non essential organs to skeletal muscle, brain and heart
What do preganglionic nerve endings in the adrenal medulla release?
Catecholamines (adrenaline and noradrenaline)
80-90% adrenaline stored in granules
Where are the adrenal glands located?
Adrenal medulla above kidney inner region, outer region adrenal cortex
what does adrenaline stimulate
Increased glycogenolysis - increases blood glucose and increased gluconeogenesis - increases blood glucose
What does noradrenaline do?
Causes vasoconstriction
What does adrenaline do?
Vasodilation in skeletal muscle, more potent on heart and metabolic activities
What do both adrenaline and noradrenaline do?
Inhibit insulin release and stimulate glucagon - increased glucose
What is pheochromocytoma?
Adenoma of adrenal medulla causing hypertension, increased heart rate, increased blood glucose, sweating
Can someone live without an adrenal medulla?
Yes but not cortex
What does cortisol do?
Long lasting response to stress, can also stimulate tissue repair
What does cortisol secretion reflect?
Corticotropin releasing hormone and adrenocorticotropic hormone in anterior pituitary gland
What does cortisol do?
More gluconeogenesis less glucose utilisation so increased blood glucose.
Increased mobilisation of fatty acids, more triglyceride breakdown and more used for energy - sparing glucose, more protein catabolism
What are the effects of cortisol?
Increased vasoconstriction, enhances sympathetic response, increased heart rate, decreased inflammatory response, decreased immune response, less ACTH and less CRH secretion
What is cushings disease
Hypersecretion of cortisol as there is a tumour in the adrenal cortex, swelling of face, increased blood pressure, thin limbs, decreased immune response
What is Addison’s disease?
Hyposecretion of cortisol caused by damage of adrenal cortex, less blood pressure, hypoglycaemia
What causes fainting?
Decreased vagal output, less CO, venous return, peripheral resistance, decreased atrial pressure less cerebral blood flow
What are the three factors that control stroke volume in the heart?
- Ventricular contractility
- End diastolic volume
- Afterload
Describe Starling’s law of the heart
When the rate at which blood flows into the heart (venous return) changes, the heart will automatically adjust its output to match the inflow
Describe what is meant by after load and its effect on the heart
The load at which arterial pressure places on the myocardium after the heart starts to contract
