T1 L1: Intro to the endocrine system

Question 1

How were hormones discovered?

Answer 1

The effects of castration were observed. Castrated chicken wouldn’t develop secondary characteristics. If the testicles were transplanted into the abdomen then the secondary characteristics would still develop indicating that the testes were releasing something needed for development

Question 2

Which gland is important for control of metabolic rate and calcium homeostasis?

Answer 2

The thyroid and Parathyroid

Question 3

What is Myxedema?

Answer 3

A condition caused by severe hypothyroidism

Symptoms: Thickening of skin, fatigue, weight gain, depression, dry skin, and brittle hair

Question 4

What is Cretinism?

Answer 4

A condition characterized by physical deformity and learning difficulties that is caused by congenital thyroid deficiency

Question 5

What is the endocrine function of the pancreas?

Answer 5

Secrete insulin and glucagon into the blood to control blood glucose concentration and glucose utilisation

Question 6

What is the exocrine function of the pancreas?

Answer 6

Secretes digestive enzymes directly into the GI tract

Question 7

Where is the pancreas located in terms of the stomach?

Answer 7

Behind the stomach

Question 8

What is the medulla of the adrenal glands responsible for?

Answer 8

The stress response

Question 9

What is the cortex of the adrenal glands responsible for?

Answer 9

Stress, sodium, and glucose homeostasis

Question 10

How much does the Pituitary gland weigh?

Answer 10

0.5g

Question 11

What is the Pituitary gland responsible for?

Answer 11

It secretes hormones responsible for:

• growth
• blood pressure
• energy management
• All functions of the sex organs
• Thyroid gland activity
• Childbirth
• Pain relief
• Temperature regulation

Question 12

What are the testes and ovaries responsible for?

Answer 12

The development of secondary characteristics

Question 13

What are the 2 divisions of hormones?

Answer 13

Peptide hormones 
Steroid hormones (+Thyroid hormones)

Question 14

What are the characteristics of peptide hormones?

Answer 14

• Chain of amino acids that’s highly water soluble
• Susceptible to protease attack so can’t be ingested
• Unable to cross the cell membrane
• Act on cell-membrane receptors
• Rapid onset of action
• Short half-life and duration of action

Question 15

What are the characteristics of steroid and thyroid hormones?

Answer 15

• Highly lipid soluble
• Poorly water soluble so have to be carried by proteins in the blood
• Only unbound hormones is biologically active
• Able to cross the cell membrane
• Act on intracellular receptors
• Orally active
• Long half-life and duration of action
• Slow onset

Question 16

How is Thyroxine (T4) administered?

Answer 16

Orally as a tablet

Question 17

How do G-protein couples receptors work?

Answer 17

A hormone binds to the 7 transmembrane helices receptor, activating a G-protein to cause synthesis of a second messenger (cAMP or Inositol Triphosphate)

The second messengers phosphorylate intracellular, regulatory proteins to influence cellular activity

Question 18

How do Tyrosine kinase receptors work?

Answer 18

It’s a membrane-bound protein.

Often 2 receptors need to be present for hormone activation because it’s a dimerised receptor. One hormone binds to each receptor, the receptor will then act as an enzyme to phosphorylate Tyrosine

Question 19

Which type of receptor do Insulin and Prolactin use?

Answer 19

Tyrosine Kinase Receptors

Question 20

How do steroid hormone receptors work?

Answer 20

The hormone crosses the cell membrane and binds to the receptor in the cytoplasm. The hormone-receptor complex travels to the nucleus where it binds to the hormone-response element of DNA to influence gene transcription

Question 21

What does the pituitary gland secrete that controls the secretion of other glands?

Answer 21

Stimulating (Trophic) hormones

Question 22

What is Pseudohypoparathyroidism?

Answer 22

PHP is a genetic disorder in which the body fails to respond to parathyroid hormone

Question 23

Describe the process through which the pituitary gland stimulates the production of T3 and T4

Answer 23

The hypothalamus will release Thyrotrophin releasing hormone (TRH) which stimulates the anterior pituitary gland to produce Thyroid stimulating hormone (TSH) which stimulates the thyroid to secrete T3 and T4

Question 24

What does the hypothalamus release to stimulate the posterior pituitary gland?

Answer 24

Releasing hormones

Question 25

What effect does taking T4 supplements have on the negative feedback loop?

Answer 25

The thyroid will stop producing it because the negative feedback loop will be signalling that the body already has enough

Question 26

What is Leptin and what does it do?

Answer 26

A hormone released by cells in adipose tissue. It acts of the hypothalamus to inhibit appetite

Question 27

How can defects in Leptin be linked to obesity?

Answer 27

When the Leptin pathway doesn’t work properly, appetite isn’t inhibited so the person will over eat and gain weight