Hormonal Communication (chapter 1 of hormonal communication)

Question 1

What system does the endocrine system work alongside to react to changes?

Answer 1

Neuronal system

Question 2

What is the endocrine system made up of?

Answer 2

Endocrine glands

Question 3

What is an endocrine gland? Examples?

Answer 3

• A group of cells which are specialised to secrete chemicals (hormones) directly into the bloodstream
• e.g. pancreas and adrenal glands

Question 4

How are hormonal and neuronal responses coordinated?

Answer 4

Close proximity of the pituitary gland to the hypothalamus - responses are closely linked and coordinated

Question 5

Pituitary gland

Answer 5

• Produces growth hormone - controls growth of bones and muscles
• ADH (anti-diuretic hormone) - increases reabsorption of water in the kidneys
• Gonadotrophins - control the development of the ovaries and testes

Question 6

Thyroid gland

Answer 6

Produces thyroxine - controls rate of metabolism and rate that glucose is used up in respiration, and promotes growth

Question 7

Adrenal gland

Answer 7

Produces adrenaline - increases heart rate and breathing rate, raises blood sugar level

Question 8

Pineal gland

Answer 8

Produces melatonin - affects reproductive development and daily cycles

Question 9

Thymus

Answer 9

Produces thymosin - promotes production and maturation of white blood cells

Question 10

Pancreas

Answer 10

Produces insulin - converts excess glucose into glycogen in the liver; and glucagon, which converts glycogen back into glucose in the liver

Question 11

Testes

Answer 11

Produces testosterone - controls sperm production and secondary sexual characteristics

Question 12

Ovaries

Answer 12

• Produces oestrogen - controls ovulation and secondary sexual characteristics
• Produces progesterone - prepares the uterus lining for receiving an embryo

Question 13

Exocrine glands

Answer 13

Secrete chemicals through ducts into organs, or to the surface of the body

Question 14

Hormones

Answer 14

• Chemical messengers - carry information from one part of the body to another
• They can be steroids, proteins, glycoproteins, polypeptides, amines or tyrosine derivatives

Question 15

How are hormones released and transported to target cells?

Answer 15

• Secreted directly into the blood when a gland is stimulated - can occur due to a change in concentration of a particular substance (i.e. blood glucose concentration)
• Once secreted, the hormones are transported in the blood plasma all over the body
• The hormones diffuse out of the blood and bind to specific receptors for that hormone (found on the membranes or in the cytoplasm of target cells)
• Once bound to their receptors the hormones stimulate the target cells to produce a response

Question 16

Steroid hormones

Answer 16

• Lipid soluble - pass through the lipid component of the cell membrane and bind to steroid hormone receptors
• Form a hormone-receptor complex - acts as a transcription factor which in turn facilitates or inhibits the transcription of a specific gene
• e.g. oestrogen

Question 17

Non-steroid hormones

Answer 17

• Hydrophilic
• Bind to specific receptors on the cell surface membrane of the target cell - triggers a cascade reaction mediated by chemicals called second messengers
• e.g. adrenaline

Question 18

Hormonal system

Answer 18

• Communication - hormones
• Transmission - in the blood system, relatively slow
• Travel - to all parts of the body, however only target organs respond
• Response - widespread, slow, long-lasting
• Effect - permanent and irreversible

Question 19

Nervous system

Answer 19

• Communication - nerve impulses
• Transmission - neurones, very rapid
• Travel - to specific parts of the body
• Response - localised, rapid, short-lived
• Effect - temporary and reversible

Question 20

Adrenal glands location and size (height and length)

Answer 20

• They are located on top of each kidney

- They measure approximately 3cm in height and 5cm in length

Question 21

Adrenal cortex

Answer 21

• The outer region of the adrenal glands
• This produces hormones that are vital to life (cortisol and aldosterone)
• All production of the hormones released is controlled by the hormones released from the pituitary gland (brain)

Question 22

Adrenal medulla

Answer 22

• The inner regions of the adrenal glands
• This produces non-essential hormones (adrenaline and noradrenaline)
• The hormones are released when the sympathetic nervous system is stimulated, which occurs when the body is stressed

Question 23

Glucocorticoids

Answer 23

• Produced by adrenal cortex
• Cortisol - helps to regulate metabolism by controlling how he body converts fats, proteins, and carbohydrates to energy, as well as helping to regulate blood pressure and cardiovascular function in response to stress
• Corticosterone - works with cortisol to regulate immune response and suppress inflammatory reactions
• ## Release of these hormones is controlled by the hypothalamus

Question 24

Mineralocorticoids

Answer 24

• Produced by the adrenal cortex
• Aldosterone - helps control blood pressure by maintaining the balance between salt and water concentrations in the blood and body fluids
• Release of these hormones is controlled by the hypothalamus

Question 25

Androgens

Answer 25

• Produced by the adrenal cortex
• Small amounts of male and female sex hormones are released - relatively small impact compared to oestrogen and testosterone (larger amounts of hormones), but still important, especially in women after the menopause

Question 26

Adrenaline

Answer 26

• Produced by the adrenal medulla
• Increases heart rate, sending blood quickly to the muscles and brain
• Raises blood glucose concentration levels by converting glycogen to glucose in the liver

Question 27

Noradrenaline

Answer 27

• Produced by the adrenal medulla
• Works with adrenaline in response to stress
• Produced following effects: increased heart rate, widening of pupils and air passages (in the lungs), and the narrowing of blood vessels in non-essential organs (resulting in higher blood pressure)