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?
Thyroxine or T3 has 3 iodine atoms attached whereas triiodothyronine 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
Where are the adrenal glands located?
It is located on top of each kidney
What does each adrenal gland contain?
It contains an inner adrenal medulla and an outer adrenal cortex
What hormones are produced by the adrenal medulla?
adrenaline and noradrenaline
What is the role of adrenaline?
Adrenaline helps to prepare the body for a reaction to a threatening situation (fight or flight response)
What is the role of noradrenaline?
Noradrenaline has similar affects to adrenaline in particular it increases the rate and force of the heartbeat.
What are the hormones produced by the adrenal cortex collectively called?
Corticosteroids
What are the two main corticosteroids?
Aldosterone and cortisol
What is the role of aldosterone?
Aldosterone acts on the kidney to reduce the amount of sodium and increase the amount of potassium in the urine.
What is the role of cortisol?
With related hormones, promotes normal metabolism, helping the body to withstand stress and to repair damaged tissues.
Where is the pancreas located?
It lies just below the stomach and alongside the duodenum (first part of small intestine).
Is pancreas an endocrine gland or exocrine gland?
Both
What does the endocrine part of the pancreas secrete?
It secretes digestive enzymes into the small intestine through the pancreatic duct.
What is the endocrine part of the pancreas made up of?
Islets of Langerhans
What hormones does the islets of langerhans secrete?
It secretes insulin and glucagon
What role does insulin have overall in the body?
Insulin reduces the amount of glucose in the blood.
What is a beta cells?
Beta cells are cells that secrete insulin
Where are beta cells located?
They are located in the islets of Langerhans
How does insulin reduce the amount of glucose in the blood?
It does that by promoting the uptake of glucose from the blood by the cells of the body
What effect does insulin have on the liver?
Insulin causes the convention of glucose to glycogen and fat in the liver.
How does insulin affect skeletal muscles?
Insulin promotes the formation of glycogen from glucose in skeletal muscles
What does insulin do in fat storage tissues?
Insulin stimulates the conversion of glucose into fat in fat storage tissues
How is insulin secretion regulated?
It is regulated by the pancreas which determines how much insulin should be secreted by the amount of glucose in the blood.
What type of feedback system controls insulin secretions?
Negative feedback system.
What are alpha cells?
Alpha cells are cells that secrete glucagon
Where are alpha cells located?
In the Islets of Langerhans
What is the role of glucagon?
Glucagon acts the opposite way to insulin. It works to increase the blood glucose level, mainly by promoting the breakdown of glycogen to glucose in the liver.
Apart from increasing the blood glucose levels, what else does glycogen do?
It also stimulates the breakdown of fat in the liver and in fat storage tissues.
What are the two gonads?
testes and ovaries
Define androgens and its role.
Androgens are a group of sex hormones that affect sexual development, reproductive health, and body development in both males and females
What is the main androgen hormone for males and where is it produced?
Testosterone produced from the testes
What is the role of testosterone?
Testosterone is responsible for the development and maintenance of the male sex characteristics.
What are the female sex hormones and where are they produced?
oestrogen and progesterone produced from the ovaries
What is the role of oestrogen in females?
Oestrogen stimulates development of female sex characteristics and regulate the menstrual cycle
What is the role of progesterone in females?
Progesterone regulates the menstrual cycle and pregnancy. It prepares the mammary glands for milk secretion.
What hormone does the kidney secrete and its role?
The kidney secretes erythropoietin (EPO) which stimulates production of red blood cells by the bone marrow.
Why does the heart secrete a hormone?
It secretes a hormone to reduce blood pressure
Why does the placenta secrete hormones during pregnancy?
Because it helps to maintain the pregnancy, stimulate development of the foetus and stimulate the mother’s mammary glands.
What is the target cell for thyroxine and triiodothyronine?
most body cells
What is the target cell for calcitonin?
Bones and kidney
What is the target cell for the parathyroid hormone?
Bones and kidney
What is the target cell for thymosins?
T-lymphocytes
What is the target cell for cortisol?
Most body cells
What is the target cell for corticosteroids (including aldosterone)?
Kidneys
What is the target cell for adrenaline and noradrenaline?
Most body tissues
What is the target cell for insulin?
Most body cells
What is the target cell for glucagon?
Liver and fat storage tissues
What is the target cell for androgens (e.g. testosterone)?
Many tissues
What is the target cell for oestrogen?
Many tissue
What is the target cell for progesterone?
Uterus and mammary glands.
