Week 6 - Endocrine System

Question 1

What are the 3 major components of the endocrine system? Briefly describe each

Answer 1

1) Glands - specialized cells that produce and secrete hormones
2) Hormones - substances that are secreted by glands into the circulatory system
3) Receptors - bind to specific hormones to result in physiological changes.

Question 2

What hormones are secreted by the posterior pituitary gland and what is there function?

Answer 2

• Anti diuretic hormone (ADH) - Fluid regulation

* Oxytocin - child birth and breast feeding

Question 3

What hormones are secreted by the anterior pituitary gland and what is there function?

Answer 3

• Growth hormone - growth
• Prolactin - Milk production
• FSH & LH - regulate the reproductive system
• TSH - stimulates the thyroid
• Adrenocorticotrophic hormone (ACTH) - adrenal glands

Question 4

What hormones are secreted by the thyroid gland and what is there function?

Answer 4

• Thyroxine and triiodothonine - control basal metabolic rate

Question 5

What hormones are secreted by the parathyroid gland and what is there function?

Answer 5

Parathyroid hormone - Regulates calcium, magnesium and phosphate ions in the blood stream.

Question 6

What hormones are secreted by the adrenal gland and what is there function?

Answer 6

• Adrenaline & Noradrenaline - involved in the fight flight response
• Cortisol and aldosterone - Helps maintain hydration and electrolyte balance

Question 7

What hormones are secreted by the pancreas and what is there function?

Answer 7

• Insulin & glucagon - regulate blood sugar levels

Question 8

What hormones are secreted by the gonads and what is there function?

Answer 8

• Testosterone & Estrogen - Control growth and function of reproductive organs and are associated with the development of secondary sexual characteristics.

Question 9

Define hormone

Answer 9

A hormones a chemical messenger that is released into the bloodstream by endocrine glands.

Question 10

Identify the two classes that most hormones can be classified into

Answer 10

• Amino acid bases

* Steroids

Question 11

What is the solubility of amino acid based hormones?

Answer 11

Water soluble

Question 12

How do amino acid based hormones travel in the blood stream?

Answer 12

Travel in plasma

Question 13

Where are the receptors for amino acid based hormones? Why?

Answer 13

Plasma membrane of the cell - they are polar and thus can diffuse directly across the cell membrane into a cell

Question 14

List 3 examples of amino acid based hormones

Answer 14

• glucagon
• insulin
• adrenaline
• oxytocin

Question 15

What are steroid based hormones derived from?

Answer 15

cholesterol

Question 16

What is the solubility of steroid based hormones?

Answer 16

lipid soluble

Question 17

How are steroid based hormones transported in the blood?

Answer 17

1) Specialized steroid hormone carriers

2) non-selectively by the protein albumin

Question 18

Where are the receptors for steroid based hormones? why?

Answer 18

In the cytoplasm as they are able to diffuse directly across the plasma membrane.

Question 19

List some examples of steroid bases hormones

Answer 19

• testosterone
• oestrogen
• progesterone
• cortisol

Question 20

What are the three methods of controlling hormone release? Describe.

Answer 20

1) Humoral stimuli - hormones are secreted in response to direct changes in blood levels of ion & nutrients.
2) Neural stimuli - nerve fibres directly stimulate hormone release
3) Hormonal stimuli - hormones release is triggered by the hormones released by another endocrine organ.

Question 21

Using the effect of parathyroid on calcium levels, explain the role of humoral stimuli on hormone secretion.

Answer 21

• When calcium levels are low it stimulates the parathyroid to secrete more PTH
• When calcium levels are high the secretion of PTH is inhibited.

Question 22

Use the effect of sympathetic innervation of the adrenal glands as an example of neural stimuli on hormone release

Answer 22

• Sympathetic nerve fibres stimulate the adrenal glands to release adrenaline and noradrenaline

Question 23

Describe the hypothalmic-pituitary axis and the different hormones released.

Answer 23

The hypothalamus releases hormones that stimulate the anterior pituitary gland to release hormones such as TSH, ADTH and GH that go on and effect the release of other hormones in various organs of the body.

Question 24

Steroid hormones have a __________ mechanism on cell whereas amino acid based hormones use a _________?

Answer 24

• Direct effect - gene expression

* Indirect - second messenger

Question 25

Why is hormone signalling rather slow compared to the nervous system?

Answer 25

• Hormone signalling required the binding of hormones to receptors located on distance cells, whereas neurotransmitters only have to diffuse directly across the synapse.
• Similarly, the NS involves electrical transmission of signals along the cell, whereas hormone signalling requires the binding of chemical to trigger intracellular responses.

Question 26

What are tropic hormones?

Answer 26

Hormones that have other endocrine glands as their target.