Origin-Endoderm
Location-Four parathyroid gland located at the back of the thyroid gland but functionally independent of thyroid.
Structure-Yellow coloured compactly solid mass of cell and the secretory cell called principal or chief cell.
-This gland secrete a peptide hormone called parathyroid hormone (PTH) or parathormone.
-Its secretion is controlled by circulatory plasma level of Ca++.
-It is a hypercalcemic hormone and increase Ca++ level of blood in the following ways-
1.It stimulate bone resorption or dissolution or demineralisation.
2.Increases Ca++ absorption from renal tubules.
3.Increases Ca++ absorption from intestine.
-PTH together with TCT regulates calcium balance of the body.
-Hyperparathyroidism causes osteitis fibrosa cystica disease where demineralised bone become soft and prone to fracture.
Facts about Coma
Coma is a prolonged period of unconsciousness. Unconsciousness is the lack of appreciation of (or reaction to) a stimulus. Coma differs from sleep in that one cannot be aroused from a coma.
Coma involves two different concepts:
1.) Reactivity: Reactivity refers to the innate (or inborn) functions of the brain, i.e., the telereceptors (eyes and ears), the nociceptors (responses to pain), the arousal reaction (wakefulness) and the orienting response (turning one's head toward the source of sound or movement). We could also refer to these as reflexive movements.
2.) Perceptivity: Perceptivity refers to the responses of the nervous system to stimuli, which have been learned or acquired, i.e., language, communication skills, individual methods of movement such as gestures, etc. Perceptivity also refers to less complex learned or acquired reactions such as flinching when threatened. We can also think of these as conscious movements.
