Lessons 7–8 · 2 lessons · O. Mavlonov, T. Tilavov, B. Aminov. Biology (Human body and health), Grade 8. Revised and expanded 6th edition. “O‘qituvchi” Publishing and Printing Creative House, Tashkent, 2019
7
Parathyroid, pituitary, thymus and adrenal glands: structure and function
Textbook: pp. 22–23
GoalDescribe the location and hormones of the parathyroid, pituitary, pineal, thymus and adrenal glands.
The four parathyroid glands lie behind the thyroid; their hormone, parathormone, regulates calcium and phosphorus in the blood. The pituitary is a pea-sized gland under the brain, linked to the hypothalamus; its hormones control other glands, and growth hormone affects height (too much or too little in childhood can lead to very tall or very short stature). The pineal gland lies deep in the brain; its hormone melatonin is linked to the sleep–wake rhythm. The thymus lies in the chest behind the sternum, is larger in childhood and takes part in the maturing of immune cells – T lymphocytes – then shrinks. The adrenal glands sit on top of the kidneys: the cortex makes hormones affecting water–salt and other metabolism, the medulla makes adrenaline, which in stress speeds the heartbeat and breathing and readies the body for quick action.
Worked examples
When suddenly frightened the heart beats fast and breathing quickens – adrenaline has been released.
If calcium is off, nerve and muscle work is disturbed; parathormone keeps blood calcium normal.
Class activity
Fill a table: gland – location – hormone – function (5 glands). Hide the gland names and ask a friend to identify them from location.
Practice
1
Where are the parathyroid glands and which hormone do they make?
Behind the thyroid, four of them; parathormone – regulates calcium and phosphorus.
2
What is the position and importance of the pituitary?
Under the brain; controls other glands, and its growth hormone affects height.
3
Where is adrenaline made and what does it do in stress?
In the adrenal medulla; it speeds heartbeat and breathing, raises blood pressure and readies the body for action.
4
Why is the thymus large in childhood and smaller later? Link with immunity.
Immunity is being built in childhood, and many T lymphocytes mature in the thymus; after puberty the gland slowly shrinks and is replaced by fat, but the matured T lymphocytes keep working in the body.