Loss of Homeostasis Flashcards
What are the growth hormone disorders?
Gigantism and dwarfism
What causes gigantism?
Excess growth hormone
What causes dwarfism?
A deficiency in growth hormone
What is infantile hypothyroidism?
Hyposecretion of thyroid hormone caused by an external factor (other)
What ca not enough thyroid hormone in newborns lead to?
Low metabolic rate, growth being retarded, cold intolerant (can’t warm up), brain development is inhibited causing mental impairments
What can cause infantile hypothyroidism?
Lack of iodine in a mothers diet so maternal iodine supplementation is recommended to avoid it
What is iodine deficiency disorder known as?
Simple goitre
What happens when someone is iodine deficient?
The thyroid gland is unable to make enough thyroid hormone (TH). When stored TH is depleted, TRH and TSH secretion increase to stimulate the thyroid gland to make more TH. Without iodine the TH is unable to be made
What is the net result of iodine deficiency?
Loss of negative feedback control and overstimulation of the thyroid gland. The excess TSH stimulates growth of the thyroid gland and so a goitre/growth may be formed
What is graves disease?
Hypersecretion of thyroid hormone (too much) caused by an autoimmune disorder
What are the symptoms of graves disease?
High metabolic rate, weight loss, heat intolerant, increased heart rate, nervousness, hair loss, exophthalmos (plugging out of eyes) and thyroid swelling
What does hyperparathyroidism lead to?
Excess PTH secretion (hyper secretion)
What is hyperparathyroidism caused by?
A parathyroid tumour
What is the effects of hyperparathyroidism?
Bones become soft, deformed and fragile. Raises the blood levels of calcium and phosphate ions. Promotes formation of kidney stones composed of calcium and phosphate
What happens when blood calcium concentration is too high?
Hypercalcemia
What is effected by hypercalcemia?
Nerve and muscle cells
How are nerve and muscle cells effected by hypercalcemia?
They become less responsive and excitable because increase in extracellular calcium ions makes the membrane potential further from the threshold
What other effects does hypercalcemia have?
Can lead to depression of the nervous system, emotional disturbances, muscle weakness and sluggish reflexes
What happens if blood calcium concentration is significantly elevated?
Cardiac arrest can occur
What happens when blood calcium concentration is too low?
Hypocalcemia
What is effected by hypocalcemia?
nervous system
How is the nervous system effected by hypocalcemia?
Increased excitability because decrease in extracellular calcium ions makes the membrane potential closer to threshold
What does increased excitability of the nervous system from hypocalcemia do?
Leads to muscle tremors, spasms or cramps
What happens when blood calcium levels are very low?
Get paraesthesia (tingling/burning sensation) in the hands and face, muscle cramps, and in some cases the muscles of the larynx may contract tightly (laryngospasm) which can shut off air flow and cause suffocation
What can hypocalcemia be cause by?
Vitamin D deficiency because the gut doesn’t absorb calcium, diarrhoea, thyroid tumors, underactive or removal of parathyroid glands, pregnancy and lactation
What is diabetes type 1?
Hyposecretion (too little or no) of insulin
What can type 1 diabetes be caused by?
Destruction of pancreatic beta cells by the immune system
What is the outcome/ effects of diabetes type 1?
Glycosuria (glucose in the urine), polyuria (excess volume of urine production) and polydipsia (thirst)
How is type 1 diabetes treated?
Insulin injections or infusion
What is diabetes type 2?
Hyposensitive (too little or no response) to insulin “insulin resistance”
What is the cause of type 2 diabetes?
Desensitisation of insulin receptor. Associated with obesity
What is the outcome/effects of diabetes type 2?
Same as type 1- Glycosuria (glucose in the urine), polyuria (excess volume of urine production) and polydipsia (thirst)
How is type 2 diabetes treated?
Changes in diet and exercise. various medications
How is diabetes mellitus diagnosed?
Because blood glucose concentration fluctuates throughout the day a single blood test isn’t effective. So, responses to glucose (glucose tolerance test) are checked, insulin levels and longer term exposure (HbA1C test)
What happens if there is a problem with glucagon secretion?
Because there are other hormones which can increase blood glucose concentration, if there is a problem with glucagon secretion it doesn’t cause a problem as large.
When may the set point/normal range need to be changed to maintain homeostasis?
Change in altitude, shift to a location with different climate, fever
What needs to change when altitude is changed?
Change in blood count for oxygen carrying capacity
What needs to change when we move to a location with a different climate?
Basal metabolic rate (BMR) which is linked to the thyroid hormone
What needs to change when we get a fever?
The set point for temperature needs to be shifted temporarily
