Endocrine System

Question 1

What is a hormone?

Answer 1

A hormone is a signalling molecule which enables an event in one part of the body to have an effect elsewhere. They travel in the blood to target tissues.

Question 2

Where may hormones be produced?

Answer 2

Hormones may be produced in the endocrine glands, or in cells distributed around the body.

Question 3

What is the endocrine system involved in the regulation of?

Answer 3

The endocrine system is involved in the regulation of homeostasis, cellular metabolism, growth and development, stress response, reproduction and the production of immune cells.

Question 4

A particular hormone usually affects only a limited number of cells. What are these known as?

Answer 4

The cells affected by a hormone are known as the hormone’s target cells.

Question 5

What makes a cell a target for a hormone?

Answer 5

A cell is a target for a hormone if it has a specific receptor for that hormone. Receptors may be intracellular or on the cell surface.

Question 6

What is the hypothalamus?

Answer 6

The hypothalamus is a small region of the brain which contains clusters of neurons. It regulates pituitary gland activity.

Question 7

What does the pituitary gland regulate?

Answer 7

The pituitary gland regulates many body functions as well as other glands.

Question 8

The posterior pituitary is actually an extension of…

Answer 8

The posterior pituitary is actually an extension of the hypothalamus.

Question 9

Which hormones are synthesised in the hypothalamus and stored in the posterior pituitary?

Answer 9

The antidiuretic hormone and oxytocin are synthesised in the hypothalamus and stored in the posterior pituitary.

Question 10

What is the anterior pituitary made up of?

Answer 10

The anterior pituitary is made up of epithelial cells.

Question 11

What is the function of the anterior pituitary?

Answer 11

The anterior pituitary synthesises and secretes several peptide hromones.

Question 12

What is the target organ and action of the adrenocorticotropic hormone (ACTH)?

Answer 12

ACTH targets the adrenals and causes secretion of other hormones.

Question 13

What is the target organ and action of the thyroid-stimulating hormone (TSH)?

Answer 13

TSH targets the thyroid gland and causes secretion of thyroid hormones.

Question 14

What is the target organ and action of the follicle-stimulating hormone (FSH)?

Answer 14

FSH targets the gonads and is involved in the growth and maintenance of the reproductive system.

Question 15

What is the target organ and action of the luteinising hormone (LH)?

Answer 15

LH targets the gonads and is involved in sex hormone production.

Question 16

What is the target organ and action of the growth hormone (GH)?

Answer 16

GH targets the liver and adipose tissue, and promotes growth.

Question 17

What is the target organ and action of prolactin?

Answer 17

Prolactin targets the mammary glands and promotes milk production.

Question 18

Neurons in the hypothalamus release…

Answer 18

Releasing/inhibiting hormones which travel in a portal blood system to the anterior pituitary gland

Question 19

What happens to releasing hormones at the anterior pituitary gland?

Answer 19

The anterior pituitary secretes releasing hormones into the blood where they travel to their target to produce a response.

Question 20

What happens to inhibitory hormones at the anterior pituitary gland?

Answer 20

In response to an inhibitory hormone, the anterior pituitary stops secreting the relevant hormone, causing a knock-on effect on the target tissue.

Question 21

Describe the negative feedback loop of the hypothalamic-pituitary-thyroid axis.

Answer 21

Thyrotrophin-releasing hormone (TRH) is released from the hypothalamus and stimulates production and secretion of the thyroid stimulating hormone (TSH) from the anterior pituitary. TSH stimulates production of thyroid hormones (T3 and T4) from the thyroid. T3 and T4 have a negative feedback on the pituitary and hypothalamus so reduce production of TRH and TSH when they reach the correct level.

Question 22

Most hormone levels decline with age. Levels of which hormones increase with age?

Answer 22

The follicle stimulating hormone, luteinising hormone and norepinephrine levels increase with age.

Question 23

How does ageing affect target cells?

Answer 23

Target cells become less sensitive to hormones as we age.

Question 24

The metabolism and excretion of hormones may be affected by which kind of diseases?

Answer 24

Chronic diseases, such as those affecting the liver and kidney, can affect the metabolism and excretion of hormones.

Question 25

What is somatopause?

Answer 25

Somatopause is a gradual, progressive decline in growth hormone secretion with age. This is primarily caused by reduced secretion of the growth hormone-releasing hormone by the hypothalamus.

Question 26

What are the effects of somatopause?

Answer 26

Somatopause leads to decreased production of insulin-like growth factor 1 (IGF-1) and metabolic changes such as increased body fat, decreased protein synthesis, reduced bone mass and decreased immune function.

Question 27

What effect does exercise have on somatopause?

Answer 27

Regular physical activity has been shown to slow the decline in growth hormone secretion, improving body composition, bone density and metabolic health.

Question 28

What are some of the risks of growth hormone replacement?

Answer 28

Risks of GH replacement include insulin resistance, oedema, joint pain and increased risk of cancer.

Question 29

Which hormones are importanrt for maintaining the Basal Metabolic Rate?

Answer 29

T3 and T4 (thyroxine) are important for maintaining BMR.

Question 30

A decrease in thyroid activity as we age leads to a reduction in the production of which hormone?

Answer 30

T3 production decreases as we age.

Question 31

Risk of autoimmune thyroiditis increases in elderly females. What is a dietary risk factor for this?

Answer 31

A lack of dietary iodine may increase risk of autoimmune thyroiditis.

Question 32

When is menopause recognised to have occured?

Answer 32

Menopause is recognised to have occurred after 12 consecutive months of amenorrhea for which there is no other obvious pathological or physiological cause.

Question 33

What causes menopause?

Answer 33

Menopause is caused by the depletion of primordial follicles in the ovaries and a decline in oestrogen levels.

Question 34

What is the hallmark of ovarian ageing?

Answer 34

The progressive loss of follicles is the hallmark of ovarian ageing. As the number of follicles declines, ovaries produce less oestrogen resulting in a weaker negative feedback signal to the hypothalamus and pituitary. This causes the pituitary to increase secretion of the follicle-stimulating hormone (FSH).