Adrenal, thyroid and stress adaptations Flashcards
What processes occur within glucose production? (3)
Glycogenolysis
Gluconeogenesis
Glucagon
What processes occur within glucose utilisation?
Insulin
Other than insulin and glucose, what are the other 3 factors for fuel metabolism?
Adrenaline - emergency energy (hypoglycaemia)
Cortisol - mobilisation of fuels during stress adaptation (hyperg)
Growth hormone - promotion of growth (hyperg)
What is synergism in metabolism?
glucagon, adrenaline and cortisol working together to produce a larger combined effect
What is stress? (3)
a state of threatened homeostasis or disharmony
- physiological
- behavioural
What is a stressor? (2)
A stimulus that induces state of stress
- psychological/emotional
- physiological
What is involved in the integrated response, stress response system? (2)
Sympathetic NS & adrenaline
CRH-ACTH-cortisol
What is the effect of SNS and adrenaline in the stress response system? (3)
> Increase cardiac output and ventilation
Diversion of blood flow to the muscles and heart
Mobilisation of glycogen and fat stores
What are the actions of cortisol?
- metabolic effects
- anti-inflammatory/immunosuppressive effects
What are the metabolic actions of cortisol? (2)
Elevate plasma glucose
Build up glycogen stores
What can prolonged elevated cortisol levels lead to? (4)
- Muscle wasting
- Hyperglycaemia
- GI ulcers
- Impaired immune response
What is the key component of Cushing’s syndrome and what does this lead to?
Exogenous glucocorticoid
Excess cortisol
What are the primary and secondary defects of excess cortisol? (2)
Autonomously-secreted adrenal tumour
Excessive production of ACTH (pituitary/ectopic tumour)
What are the steps involved of producing cortisol? (7)
- Hypothalamus
- CRH
- Anterior pituitary
- ACTH
- Adrenal cortex
- Cortisol
- Target cell response
What are the physical effects of Cushing’s syndrome? (6)
- depression
- truncal obesity
- hypertension diabetes
- osteoporosis
- poor wound healing/easy bruising
- skinny arms and legs
What is Addison’s disease caused by, give examples (2)?
Lack of adrenal steroids from the adrenal cortex
- aldosterone
- androgens
What are the consequences of Addison’s disease? (4)
- Hyponatraemia (low blood Na+)
- Hyperalaemia (high plasma K+)
- Muscle weakness
- Postural hypotension
Where is the thyroid gland located?
Round the trachea
What is the structure of the thyroid gland? (5)
follicle:
- capillary
- cuboidal follicular cells
- microvilli
- colloid
- parafollicular cells
What are the thyroid hormones? (3)
Thyroxine (T4)
Tri-iodothyronine (T3)
Calcitonin
What are the steps involved in regulation of thyroid hormone secretion and what is it called? (7)
Endocrine axis:
- hypothalamus
- Thyrotropin-releasing hormone
- Anterior pituitary
- Thyroid-stimulating hormone
- Thyroid gland
- T3/T4
- Target cell response
What are the actions of thyroid hormones? (2)
- Increase metabolism in the body
- Stimulate growth and development
What is a sign of hypothyroidism (2) and what is the treatment?
- Reduction in metabolic activity
- Cretinism
- hormone replacement: synthetic thyroxine
What is a sign of hyperthyroidism?
- Increased tissue metabolism
- Enhancement of b-adrenoreceptor responses
What is the most common cause of hyperthyroidism?
Graves’ disease
What are the causes (1) and symptoms (4) of Graves’ disease?
Causes:
- autoimmune: thyroid stimulating immunoglobulins cause release of thyroid hormones
Symptoms:
- nervousness
- palpitations
- goitre (enlarged thyroid gland)
- exophthalmos
What are the 3 ways to manage the diseases?
- Anti-thyroid drugs - decrease production of thyroid hormones
- Radioactive iodine - destroy follicular cells
- Thyroidectomy - remove part of the thyroid
