Endocrinology and metabolism 2 - Stress Adaptation Flashcards
How is glucose homeostasis achieved?
Glucagon increases glucose production through glycogenolysis and gluconeogenesis
Insulin increases glucose utilisation through glucose uptake and use
Both are used to maintain blood glucose between 4-8mmol/L
What is the role of adrenaline?
Provision of energy for emergencies and exercise - causes severe hypoglycaemia
What is the role of cortisol?
Mobilisation of fuels during adaptation to stress - causes proonged hypoglycaemia
What is the role of growth hormone?
Promotion of growth - causes prolonged hypoglycaemia
What is stress?
a state of threatened homeostasis or dysharmony; the body responds by a complex repertoire of physiological and behavioural mechanisms to re-establish homeostasis
What is a stressor?
a stimulus that induces state of stress
can be:
-psychological/emotional - anxiety, fear
-physiological - pain, fever, hypoglycaemia, fluid deprivation, injury, heavy exercise
What are the physiological and behavioural responses to stress?
Physiological:
- Increased CV tone & ventilation
- Increased glucose availability
- Decreased energy-consuming activities (digestion, reproduction)
Behavioural:
- Increased arousal
- Increased alertness
- Increased vigilance
What are the components of the integrated response?
- SNS & adrenaline
- Cortisol
What does the integrated response produce?
- Increased cardiac output and ventilation
- Diversion of blood flow to muscles and heart
- Mobilisation of glycogen and fat stores ‘fight or flight’
all occurs in the SNS through permissive action of cortisol
What are the actions of cortsiol?
- Metabolic effects
- Anti inflammatory/immunosuppressive effects
- Role in adaptation to stress
What are the metabolic actions of cortisol?
Elevate plasma glucose & build up glycogen stores
- Increased gluconeogenesis and glycogen synthesis
- Decreased glucose uptake
- Increased protein breakdown
- Decreased protein synthesis
What occurs in the permissive action of cortisol in the stress response system?
- Shift from protein & fat stores in favour of expanded glycogen stores and plasma glucose availability
- Amino acids available for tissue repair if physical damage
- In stress-activated immune responses, cortisol protects the body against damage from potential over-activation of immune defence mechanisms
What can prolonged elevated cortisol levels lead to?
- Muscle wasting
- Hyperglycaemia
- GI ulcers
- Impaired immune response
What is Cushing’s syndrome?
Excess glucocorticoid
What are the effects of Cushing’s syndrome?
Primary defect:
-Autonomously secreted adrenal tumour
Secondary defect:
-Excessive production of ACTH which leads to pituitary tumour or ectopic tumour
