Loss Of Homeostasis Flashcards
What are the 2 growth hormone diseases
Excess growth hormone - gigantism
Deficient growth hormone levels - primordial dwarfism
What causes gigantism
A tumour in the anterior pituitary. Unregulated growth results in unregulated growth hormone secretion
What is infantile hypothyroidism causes and symptoms
Causes: lack of iodine in mothers diet during gestation, breast feeding
Symptoms: Low metabolic rate, cold intolerant, retarded growth, brain development inhibited
Outline simple goitre/iodine deficiency disorder
Iodine deficiency, thyroid gland unable to make TH. When TH depleted, TRH and TSH secretion increases to stimulate thyroid gland production of TH. Without iodine, TH cannot be made
Loss of negative feedback control, and overstimulation of thyroid gland
Excess TSH stimulates growth of thyroid gland
What is Graves’ disease, its causes and symptoms
Too much thyroid hormone. Antibodies bind receptors, triggering over production of thyroid hormone
Causes: autoimmune disorder
Symptoms: High metabolic rate. Weight loss
What is Hyperparathyroidism
Too much parathyroid hormone
Leads to excess PTH, usually causes by a parathyroid tumour.
Bones become soft, reformed, fragile - too much calcium removed from bone
Raises calcium and phosphate blood concentrations
Promotes formation of calcium phosphate kidney stones (high mineral concentrate during crystallises)
What is Hypercalcaemia
Too much blood calcium
Nerve and muscle cells less responsive and excitable
Can lead to depression of the nervous system, emotional disturbance, muscle weakness, sluggish reflexes
If plasma levels are significantly elevated, can lead to cardiac arrest
What are the causes and symptoms of hypocalcemia
Caused by: vitamin D deficiency, diarrhoea, thyroid tumours (unregulated C cells producing calcitonin - reduces blood Ca2+ levels), under reactive or removed parathyroid glands, Pregnancy and lactation
Symptoms: increased excitability of the nervous system, muscle tremors, spasms, cramps,
What happens when blood Ca2+ levels get very low
Paraesthesia - tingling/burning sensation in hands and face
Muscle cramps,
Muscle of larynx contract tightly - suffocation
Outline the hypercalcemic effects on resting membrane potential and thus neural activation
Hypercalcemia = high extracellular Ca2++ levels
+20mV outside cell
Resting membrane potential -90mV (opposed to 70mV)
Much greater potential required to reach threshold for action potential generation
Outline the hypocalcemic effect on the resting membrane potential of a cell and thus neural activation
Hypocalcemia = low extracellular Ca2+ levels
Resting membrane potential = -60mV (opposed to -70mV)
Much smaller local potential required to reach threshold and thus to give rise to action potentials
Outline type 1 diabetes mellitus
Hyposecretion - minimal/no insulin secretion
Cause: Can be caused by autoimmune distraction of beta cells
Symptoms: glucosuria (glucose in urine), polyuria (excess urine volume)
Treatments: insulin injections or infusions
Why can’t insulin be oral taken e.g in a tablet
Insulin is a peptide hormone, hence digestive system would break down into constitutive components (amino acids)
Outline type 2 diabetes mellitus
Hyposensitive receptors - too little/no responce to insulin “insulin resistance”
Cause: desensitisation of insulin receptor - associated with obesity
Symptoms: Glycosuria (glucose in urine), polyuria (excess urine)
Treatment: Changes in diet and exercise, various medications
What is primary action of glucagon, and what else carries out this function
Primary action is increase blood glucose
Growth hormone, Adrenaline
