lecture 29 - loss of homeostasis Flashcards
What disorder is caused by excess GH?
Gigantism
What disorder is caused by a deficiency of GH?
Dwarfism
What is infantile hypothyroidism?
Insufficient secretion of thyroid hormone in new born babies.
What is infantile hypothyroidism generally caused by?
Lack of iodine in the mother’s diet
What are the effects of infantile hypothyroidism?
Low metabolic rate, cold intolerance, retarded growth, inhibited brain development
What condition is caused by iodine deficiency?
Simple goitre
What causes simple goitre?
Iodine deficiency means the thyroid gland is unable to make enough thyroid hormone, which causes TRH and TSH secretion to increase to stimulate the thyroid gland, causing more thyroid tissue to grow.
What is Grave’s disease?
Condition caused by the hyper-secretion of thyroid hormone.
What is Grave’s disease caused by?
An auto-immune disorder
What are the symptoms of Grave’s disease?
High metabolic rate, weight loss, swollen thyroid, heat intolerance
What is hyperparathyroidism?
Excessive release of PTH, causing very large release of Ca2+ into the blood.
What is hyperparathyroidism generally caused by?
A tumour on the parathyroid gland.
The levels of what substances are elevated in hyperparathyroidism?
Ca2+ and phosphate plasma concentrations
What are the effects of hyperparathyroidism on bones?
They become soft, fragile and deformed as increased osteoclast activity results in bone Ca2+ resorption into the blood.
What hormone disorder causes kidney stones, and why?
Hyperparathyroidism - elevated calcium and phosphate levels result in calcium phosphate crystallisation in the kidneys
What is hypercalcemia?
Excess plasma [Ca2+] caused by overacting of the parathyroid.
What are the symptoms of hypercalcemia?
Nerve and muscle cells less excitable, depression of the nervous system, emotional disturbance, weakness, sluggish reflexes, cardiac arrest (extreme)
What is hypocalcemia?
low [Ca2+] concentration, caused by an under active parathyroid
What are the symptoms/effects of hypocalcemia?
Increased excitability of the nervous system, muscle spasms, paraesthesia, laryngospasm.
What is paraesthesia, and what is it caused by?
Tingling/burning in hands and face, often caused by hypocalcemia.
What is laryngospasm, and what is it caused by?
Contraction of the larynx, potentially resulting in suffocation. Caused by hypocalcemia
What are causes of hypocalcemia?
Vitamin D deficiency, diarrhoea, thyroid tumors (unregulated C-Cells producing calcitonin), under active parathyroid, preganancy and lactation.
What is type 1 diabetes mellitus?
Hyposecretion (insufficient secretion) of insulin
What is type 1 diabetes caused by?
Destruction of pancreatic beta cells by the immune system
What are the outcomes of diabetes (type 1 and 2)?
Glucosuria (glucose in urine), polyuria (excessive urination), polydipsia (excessive thirst)
What is glucosuria?
Presence of glucose in the urine.
What is polyuria?
Excessive urination
What is polydipsia?
Excessive thirst
What is the treatment for type 1 diabetes?
Insulin injections/infusion
What is Type 2 diabetes mellitus?
Hyposensitivity to insulin - ‘insulin resistance’
What is type 2 diabetes mellitus caused by?
Desensitisation of insulin receptors - associated with obesity
In what way does hypercalcemia lead to decreased sensitivity of excitatory tissue?
Membranes are hyperpolarised.