Endocrine system

Question 1

What is the endocrine system?

Answer 1

It involves a series of endocrine glands that secrete hormones into the blood. These act as chemical messengers, as they are transported around the body in the blood and act on target cells or organs. This regulates bodily functions.

Question 2

What is the endocrine system involved in?

Answer 2

• Regulation of growth and development
• Regulation of the reproductive system
• Homeostasis: the regulation of the internal environment of the body.

Question 3

What are the components of the endocrine system?

Answer 3

• Hypothalamus
• Pituitary gland
• Thyroid and parathyroid
• Adrenals
• Ovaries
• Testes
• Pancreas

Question 4

What is the location and function of the hypothalamus?

Answer 4

• It’s located in the base of the brain.
• It is responsible for the control of body temperature, water balance, BP and secretion of hormones.
• It secretes hormones that stimulate or suppress the release of a hormone in the pituitary gland.

Question 5

What is the location and function of the pituitary gland?

Answer 5

• It is divided into the anterior and posterior parts or lobes. Hormones produced in the hypothalamus are stored in the posterior lobe before secretion. The hypothalamus also produces releasing factors that stimulate the anterior lobe to secrete various hormones.
• It controls the functions of other glands.

Question 6

What is the location and function of the thyroid and parathyroid gland?

Answer 6

• In the front of the neck.

• Thyroid: responsible for the regulation of metabolic rate. It is controlled by the releasing factor TRH, secreted by the hypothalamus.

• Parathyroid: works with the thyroid to control the levels of calcium in the body. Parathyroid hormone (PTH) is secreted by the parathyroid and increases the concentration of calcium ions in the blood, while calcitonin, which is secreted by the thyroid, reduces the concentration of calcium ions in the blood.

Question 7

Define metabolism.

Answer 7

This describes all the chemical reactions that take place in the body.

Question 8

Define metabolic rate.

Answer 8

The rate at which the energy stored in food is transferred by all the metabolic reactions that take place in the body.

Question 9

What is the location and function of the adrenal glands?

Answer 9

• They’re located at the top of each kidney and have two parts:
- Adrenal medulla
- Adrenal cortex

Question 10

What is the role of the adrenal medulla?

Answer 10

It is the central part of the adrenal half and produces the hormone adrenaline that prepares the body to respond to threat or danger. This is known as fight or flight.

Question 11

What is the role of the adrenal cortex?

Answer 11

It produces several steroid hormones involved in the regulation of different aspects of metabolism including carbohydrates and mineral ions.

The name for these hormones is corticosteroids.

Question 12

What are the 2 classes of corticosteroids?

Answer 12

• Glucocorticoids (e.g cortisol) which helps regulate carbohydrates metabolism.
• Mineralocorticoids help regulate the balance of mineral ions like sodium and potassium.

Question 13

What is the location and function of the ovaries?

Answer 13

• They’re located at both sides of the uterus.
• Release egg cells.
• Produce female sex hormones like oestrogen and progesterone, which are involved in the regulation of the menstrual cycle.

Question 14

What is the location and function of the testes?

Answer 14

• They’re underneath the penis, enclosed in the scrotum.
• They secrete the male sex hormone testosterone and produce sperm.

Question 15

What is the location and function of the pancreas?

Answer 15

• It’s located at the back of the abdomen, behind the stomach.
• It produces digestive enzymes. It endocrine function is carried out by the islets of Langerhans which produce the hormones insulin and glucagon. These regulate blood glucose concentration.

Question 16

What are the two types of hormones?

Answer 16

This is based on their chemical structure.

• Steroid hormone: These are based on cholesterol and include sex hormones and corticosteroid hormones.
• Other hormones are amino acid derivatives, peptides or proteins.

Question 17

What is the hormone thyroxine secreted by and what is its function?

Answer 17

• It’s secreted by the thyroid.
• It acts on most body cells to regulate metabolism, temperature, heart rate and growth and tissue development.

Question 18

What is the hormone cortisol secreted by and what is its function?

Answer 18

• It’s secreted by the adrenal cortex.
• It is produced in response to stress. It acts on the liver and muscle cells and increases the blood glucose concentration.

Question 19

What is the hormone oestrogen secreted by and what is its function?

Answer 19

• It’s secreted by the ovaries.
• It acts on the pituitary gland and the uterus and is involved in the regulation of the menstrual cycle, supports the growth of the uterine lining and maintains bone density.

Question 20

What is the hormone testosterone secreted by and what is its function?

Answer 20

• It’s secreted by the testes.
• It acts on muscle and bone cells, the anabolic action of testosterone increases the muscle mass and bones density.
• It acts on sex organs, the androgenic action of testosterone stimulates the development of the male sex organs and secondary sexual characteristic like facial hair.
• It also required for the production of sperm cells.

Question 21

What is the hormone gastrin secreted by and what is its function?

Answer 21

• It’s secreted by the gastric cells of the stomach lining.
• It acts on the stomach and has several actions in digestion involving the stomach and small intestine. It stimulates the release of gastric acid to aid digestion.

Question 22

What is the growth hormone (GH) secreted by and what is its function?

Answer 22

• It’s secreted by the pituitary gland.
• Most body cells respond to GH which is responsible for normal growth during infancy and childhood. Therefore it stimulates cell reproduction and regeneration.

Question 23

What is the follicle-stimulating hormone (FSH) secreted by and what is its function?

Answer 23

• It’s secreted by the pituitary gland.
• It acts in the ovaries, stimulating the growth and development of the egg follicle during the first half of the menstrual cycle. The egg follicles are in the ovaries and contain the developing egg cell. It also stimulates the production of sperm.

Question 24

What is the result of too much and too little thyroxine?

Answer 24

• Too much: Weight loss, rapid HR and anxiety.
• Too little: Fatigue, weight gain and low mood.

Question 25

What is the result of too much and too little cortisol?

Answer 25

• Too much: Cushing’s syndrome (weight gain, high BP and bone loss).
• Too little: Fatigue, weight loss, low BP and vomiting.

Question 26

What is the result of too much and too little oestrogen?

Answer 26

• Too much: weight gain and low mood. In women it can cause severe premenstrual syndrome and in men it can cause erectile dysfunction.
• Too little: irregular periods, hot flashes, painful sex, headaches and mood swings.

Question 27

What is the result of too much and too little testosterone?

Answer 27

• Too much: increased irritability, changes in libido, irregular menstrual cycle and increased muscle mass.
• Too little: erectile dysfunction, lower bone mass and reduced sex drive.

Question 28

What is the result of too much and too little gastrin?

Answer 28

• Too much: It causes the stomach to produce too much acid, resulting in peptic ulcers. It can also result in diarrhoea and belly pain.
• Too little: increased risk of gut infection and limited ability of the stomach to absorb nutrients.

Question 29

What is the result of too much and too little growth hormone?

Answer 29

• Too much: body tissues and bones grow more quickly leading to abnormally large hands and feet. This is a condition called acromegaly.
• Too little: reduced energy levels, osteoporosis (reduced bone mineral density), reduced muscle strength, insulin resistance and impaired cardiac function.

Question 30

What is the result of too much and too little follicle-stimulating hormone?

Answer 30

• Too much: menopause (hot flashes, weight gain, vaginal dryness, irregular menstruation and bone loss).
• Too little: poor ovarian and testicular function, which can lead to infertility.

Question 31

What are hormones transported in?

Answer 31

The bloodstream.

Question 32

What are hormones transported in?

Answer 32

The bloodstream.