Endocrine System Flashcards
Examples of amino acid-based hormones
Protein and peptide hormones (e.g., insulin, glucagon)
Amines and amino acids (e.g., adrenaline)
Examples of steroid hormones
Cortisol, oestrogen, testosterone
How do amino acid-based hormones act?
Water soluble
Travel in blood freely
Bind to cell surface receptor (polar so can’t cross lipid membrane)
How do steroid hormones act?
Lipid soluble
Therefore, have to travel in blood bound to a carrier
Bind to intracellular receptor
3 types of hormone regulation and what they do? Examples?
- Hormonal stimuli – hormones stimulate other endocrine glands to secret hormones.
- Neural Stimuli – nerve fibres stimulate hormone release.
E.g., SNS stimulating adrenaline and noradrenaline - Humoral Stimuli – changes in ion or nutrients in the blood stimulate secretion of hormones.
E.g., Calcium in the blood
Define primary disorder: example?
Originate in target organ releasing the hormone
E.g., thyroid gland
Define secondary/tertiary disorder: example?
Defect in hypothalamus-pituitary system
E.g., thyroid gland will involve altered levels of TSH
Hypofunction causes?
- Congenital defects resulting in absence or impaired development of a gland
- Absence of an enzyme
- Destruction of a gland (due to infection, autoimmune response, neoplastic growth and decreased blood flow)
- Atrophy of a gland (due to medication)
- Defective receptor sites
- Response to hormone is diminished
Hyperfunction causes?
- Excessive hormone production due to overstimulation of a gland
- Hormone producing tumour
- Autoimmune disorder
What is a stimulation test?
Tests for HYPOFUNCTION
Stimulating hormones administered to test ability of an endocrine organ to increase hormone production
E.g., ACTH stimulation test
What is a suppression test?
Tests for HYPERFUNCTION
Give external stimulus for the endocrine organ
E.g., Dexamethasone suppression test
What are the tests used to examine endocrine function?
Suppression test
Stimulation test
Blood
Imaging
Causes of hyperthyroidism?
Graves’ Disease common.
Hypermetabolic state
Increase in SNS activity
Cause of primary hypothyroidism?
Autoimmune disorder
E.g. Hashimotos, thyroidectomy, ablation, iodine deficiency
Insulin stimulates:
Uptake, use and storage of glucose Glycogenesis ATP Lipogenesis Protein synthesis
Insulin inhibits:
Glycogenolysis
Gluconeogenesis
Lipolysis
Protein breakdown
Type 1 Diabetes:
Absolute deficiency of insulin
Autoimmune – cell-mediated destruction of pancreatic beta cells
Non-immune – no immune responses / antibodies
Type 2 Diabetes:
Body is resistant to insulin
Characterised by: insulin resistance, B-cell dysfunction, hyperglycaemia
What is Intermediate hyperglycaemia?
Biochemical state where a person has impaired fasting glucose and/or impaired glucose tolerance
HbAc1 level = 41-49mmol/mol
What is Metabolic Syndrome?
Have 3 out of the 5 following:
- Abdominal obesity
- Increased fasting plasma glucose
- Increased BP
- Increased serum triglycerides
- Decreased high-density cholesterol levels
Complications of diabetes mellitus?
- Hypoglycaemia
- Diabetic ketoacidosis
- Hyperosmolar hyperglycaemia state
- Microvascular disease
- Macrovascular disease
- Infection
- Impaired wound healing
What is diabetic ketoacidosis?
Hyperglycaemia, ketosis and metabolic acidosis
The correct sequence of events leading up to the secretion of T3 is
Hypothalamus releases TRH, anterior pituitary releases TSH, thyroid releases T4, T4 converts to T3
