Chapter 2.3 Other Endocrine Glands ✓ Flashcards
Where is the pineal gland located?
Its a small gland found deep inside the brain
At what stage of life does the pea-sized pineal gland decrease in size?
After puberty
What hormone does the pineal gland secrete and what is its role?
It secretes melatonin and its responsible for the regulation of sleep patterns.
What effect does light and darkness have on the production of melatonin?
Light inhibits melatonin from being produced whereas the darkness stimulates the amount of melatonin produced
Where is the thyroid gland located?
Its located in the neck, just below the larynx.
What does the thyroid gland consist of and how are they connected?
It consists of two lobes that lie on either side of the trachea and they are connected via a narrow piece of tissues.
What does the thyroid gland secrete?
It secretes two hormones:
-Thyroxine (T4) and triiodothyronine (T3).
What hormone needs to be secreted in order for the thyroid to secrete its hormones?
Thyroid stimulating hormone (TSH) needs to be produced via the hypothalamus.
Thyroxine and triiodothyronine are based on what two molecules?
They are based off two molecules of the amino acid, tyrosine.
What and how much molecules does thyroxine have compared to triiodothyronine?
Triiodothyronine or T3 has 3 iodine atoms attached whereas thyroxine or T4 has 4 iodine atoms attached.
What percentage of thyroid hormones produced consists of thyroxine compared to triiodothyronine.
Approximately 80% of the thyroid hormone produced is thyroxine and only 20% is triiodothyronine.
What does thyroxine control?
-Increases metabolic rate and therefore oxygen consumption and heat production.
-Has a role in regenerating levels of calcium and phosphate in the blood.
How does thyroxine control metabolism?
It controls metabolism by controlling the breakdown of complex molecules to release energy and the synthesis of complex molecules from simpler ones. The process releases energy, some of which is converted into heat to help maintain body temperature.
What happens after the thyroid hormones are released and what is the process called?
When thyroxine and triiodothyronine are released, an enzyme converts T4 into T3 which is a process called de -iodination.
How does the thyroid gland assist in regulating the levels of calcium and phosphate in the blood?
They regulate levels of calcium and phosphate through the release of calcitonin by C-cells.
How does calcitonin regulate the levels of calcium and phosphate in the blood? (*)
-When the concentration of calcium in the blood increases, the thyroid gland releases calcitonin, which reduces the reabsorption of calcium by the kidneys and the breakdown of bone.
-If the concentration of phosphate in the blood becomes too high, calcitonin acts to move phosphate into bone and reduces its reabsorption by the kidneys
Where are the parathyroid glands located?
The parathyroid glands are located in the rear surface of the lobes of the thyroid gland.
How many parathyroid glands are there in an average human body?
4
What hormone does the parathyroid gland produce and what is its role?
It secretes parathyroid hormone (PTH or parathormone) which increases calcium levels in the blood and phosphate excretion in the urine.
(write about the cycle of calcium levels on pg 37)
Where is the thymus gland located?
Its located in the chest just above the heart and just behind the sternum.
At what stage of life does the thymus gland begins to shrink?
After puberty
What group of hormones does the thymus secrete?
It secretes a group of hormones called thymosins.
What do thymosins influence?
It influences the maturation of disease-fighting cells called T-lymphocytes
