#6: Thyroid & Parathyroid Glands Flashcards
Thyroid
located in the front of the throat
iodine (from diet) necessary to produce all of its hormones
- not enough iodine results in goiter
Parathyroid
Mammals have 4
- 2 on each side of thyroid gland
Thyroxine (T4)
regulating metabolism
accounts for most of thyroid secretions
made in the thyroid from tyrosine (an amino acid) and iodine (4 mol)
Triiodothyronine (T3)
regulating metabolism
more potent than T4 and not produced in the same quantity
made in the thyroid from tyrosine and iodine (3 mol)
T3 and T4 cause…
people to undergo cellular respiration at a faster rate (generates ATP and heat)
the release of T3 and T4 is controlled by a homeostatic control system
Drop in metabolism
detected by receptors in the hypothalamus (sensor)
the hypothalamus releases TRH, which triggers pituitary gland (integrator) to release TSH (effector)
TSH stimulates release of T3 and T4 by the thyroid (increasing metabolism)
T3 and T4 are also released when an individual is exposed to stress or cold
Calcitonin
blood [calcium]
produced by the thyroid gland
lowers [calcium] by decreasing osteoclasts activity while stimulating activity of osteoblasts
also decreases the reabsorption of calcium in nephrons
Parathyroid hormone
blood [calcium]
produced by the parathyroid glands
raises [calcium] by increasing the activity of osteoclasts and increasing the reabsorption of calcium
Importance of Calcium
- enzyme activation
- conduction of nerve signals
- muscle contractions
- blood clotting
Underproduction
results in poor nerve and muscle function
Overproduction
leads to osteoporosis (thin and fragile bones)
Osteoclasts vs Osteoblasts
break down bone vs build up bone
