 |
| Pineal, Thyroid and Parathyroid Glands |
|
|
 It is a small round gland in the brain. |
| |
|
It secretes melatonin that regulates the sexual cycle. |
| |
|
| It is a butterfly-shaped, bilobed gland that is situated at the base of the larynx. The two lobes are joined by an isthmus. The hormone secreted is thyroxine. |
| |
| Functions of Thyroxine |
| |
|
Thermoregulation - it regulates the production of body heat by regulating respiration |
| |
|
regulates metabolic rate |
| |
|
regulates mental and physical development |
| |
|
helps in absorption of glucose from intestine |
| |
| Result of Undersecretion of Thyroxine |
| |
|
Simple goitre in which there is enlargement of thyroid due to lack of iodine |
| |
|
Cretinism which is dwarfism and mental retardation due to imperfect development of thyroid |
| |
|
Myxoedema in which the thyroid does not function properly and the person becomes sluggish with swollen face and hands |
| |
| Result of Oversecretion of Thyroxine |
| |
| Oversecretion results in exophthalmic goitre in which the person shows a marked increase in metabolic rate, protrusion of eyes, rapid heart rate and shortness of breath. |
| |
| |
|
| They are present as two pairs at the back of the thyroid. They secrete parathormone which is important in calcium and phosphorus metabolism. |
| |
|
Deficiency of parathormone causes brittle bones. |
| |
|
Oversecretion of parathormone softens the teeth and bones. |
| |
