5.1.4 - Hormonal Communication

Question 1

What is the endocrine system?

Answer 1

It is made up of glands that secrete chemical messengers called hormones into the blood stream to bring about a designated response

Question 2

What hormones does the pituitary gland secrete?

Answer 2

• Growth hormone (controls growth of bone and muscle)
• Anti-Diuretic Hormone (increases reabsorption of water in kidneys)
• Gonadotropins (controls development of ovaries/testes)

Question 3

What hormones does the hypothalamus secrete?

Answer 3

Located near the pituitary gland
Secretes hormones (tends to be releasing hormones) to tell pituitary gland to start/stop making hormones
Links nervous system with the endocrine system
Keeps body balanced in stable state

Question 4

What hormone does the pineal gland secrete?

Answer 4

Melatonin - affects reproductive development and daily cycles

Question 5

What hormone does the thyroid gland secrete?

Answer 5

Thyroxine - controls metabolic rate and the rate of glucose use in respiration + promotes growth

Question 6

What hormone does the thymus secrete?

Answer 6

Thymosin - promotes production and maturation of white blood cells

Question 7

What hormone does the adrenal gland secrete?

Answer 7

Adrenaline - increases heart + breathing rate and blood sugar levels

Question 8

What hormones does the pancreas secrete?

Answer 8

Insulin - converts excess glucose into glycogen in the liver

Glucagon - converts glycogen into glucose in the liver

Question 9

What hormone does the testes secrete?

Answer 9

Testosterone - controls sperm production and secondary secular characteristics

Question 10

What hormones does the ovary secrete?

Answer 10

Oestrogen - controls ovulation and secondary sexual characteristics
Progesterone - prepares uterus lining for receiving and embryo
Oestrogen + Progesterone - controls ovulation and secondary characteristics

Question 11

Name all of the endocrine glands

Answer 11

• Hypothalamus
• Pituitary Gland
• Pineal Gland
• Thyroid gland
• Thymus
• Adrenal Gland
• Pancreas
• Ovary
• Testes

Question 12

Why are hormones chemical messengers?

Answer 12

They carry information from one body part to another

Question 13

What form can hormones be?

Answer 13

• Steroids
• Proteins
• Glycoproteins
• Polypeptides
• Amines
• Tyrosine Derivatives

Question 14

Why can hormones be secreted?

Answer 14

Due to:

• Change in concentration of a particular substance (e.g. blood glucose concentration)
• Another hormone
• Nerve impulse

Question 15

Once a hormone is secreted, what happens after?

Answer 15

1. It is transported in the blood plasma all over the body
2. The hormone diffuses out of the blood
3. Bind to specific receptors for it (found on membrane/in cytoplasm of target cell in target organ)
4. Once bound, hormone stimulates target cell to produce a response

Question 16

What are the two types of hormones that determines the way it causes its effect on a target cell?

Answer 16

Steroid Hormone

Non-Steroid Hormone

Question 17

How does a steroid hormone work?

Answer 17

1. Since it is lipid soluble, it can pass through the lipid layer of a membrane
2. Binds to steroid hormone receptors to form a hormone-receptor complex (found in cytoplasm/nucleus - depends on hormone)
3. HRC acts as a transcription factor which facilitates/inhibits the transcription of a specific gene

Question 18

Steps of the function of a steroid hormone

Answer 18

1. Lipid-soluble steroid hormone passes through membrane
2. Received by receptor protein in cytoplasm forming HRC
3. HRC attaches to DNA
4. Instructions for synthesis of polypeptide
5. Polypeptide synthesised by ribosomes and mRNA

Question 19

What is an example of a steroid hormone?

Answer 19

Oestrogen

Question 20

How does a non-steroid hormone work?

Answer 20

1. Since it is hydrophilic, it cannot pass through the cell membrane
2. It binds to receptors on the cell surface membrane of the target cell
3. This triggers a cascade reaction mediated by second messengers

Question 21

What is an example of a non-steroid hormone?

Answer 21

Adrenaline

Question 22

Why is hormonal communication slower?

Answer 22

Hormones are not directly released onto target cells therefore it is slower and a less specific form of communication

Question 23

How is hormonal communication longer lasting?

Answer 23

Hormones are not broken down as quickly as neurotransmitters therefore they have a longer lasting and widespread effect

Question 24

What is the difference in communication between hormonal and neuronal communication?

Answer 24

Hormonal: hormones
Neuronal: nerve impulses

Question 25

What is the difference in transmission between hormonal and neuronal communication?

Answer 25

Hormonal: by bloodstream + relatively slow
Neuronal: by neurones + fast

Question 26

What is the difference in travelling between hormonal and neuronal communication?

Answer 26

Hormonal: hormone travels to all body parts but only target organs respond
Neuronal: nerve impulses travel to specific part of the body

Question 27

What is the difference in response between hormonal and neuronal communication?

Answer 27

Hormonal: slow + widespread + often long lasting
Neuronal: fast + localised + short-lived

Question 28

What is the difference in the effect between hormonal and neuronal communication?

Answer 28

Hormonal: may be permanent + irreversible
Neuronal: temporary + reversible