12 - Intro to Endocrine System

Question 1

What are the general characteristics of a control system?

Answer 1

Question 2

What are two important control centres in the brain?

Answer 2

• Hypothalamus: endocrine system
• Medulla oblongata: ventilation and CVS

Question 3

Describe the HPA axis as an example of negative feedback.

Answer 3

• Response to stress

Question 4

What are biological rhythms?

Answer 4

• Set point of control centre varies, following circadian rhythm
• Biological clock in brain in small group of neurones called suprachiasmatic nucleus

- Zeitgebers keep body on cycle, e.g light, temperature

- Melatonin release from pineal gland sets clock

Question 5

What causes jet lag?

Answer 5

• Mismatch between environmental cues, Zeitgebers, and body clock.
• As you move across time zones

Question 6

Explain how osmolality is regulated.

Answer 6

Reference: 275 - 295 mOsm/kg, useful to investigate hyponatraemia

Question 7

Explain how plasma glucose is regulated.

Answer 7

Question 8

What is neurocrine control?

Answer 8

Question 9

What are the similarities and differences between the endocrine and the nervous system for control?

Answer 9

Question 10

What are the different classes of hormones?

Answer 10

• Catecholamines stored in vesicles in cell
• Steroid hormones not stored but precursor cholesterol is

Question 11

How are hormones transported around the blood?

Answer 11

Question 12

What factors determine hormone levels?

Answer 12

• Rate of production
• Rate of delivery e.g high blood flow more hormone
• Rate of degradation

Question 13

What cells do hormones act on?

Answer 13

Question 14

What is a tropic and trophic hormone?

Answer 14

- Tropic: other endocrine glands as their target, mainly released from anterior pituitary gland

- Trophic: stimulate growth in target tissue

Question 15

How are hormones inactivated?

Answer 15

• In liver and kidney
• Steroid inactivated by small change in chemical structure increasing their water solubility so they can be excreted
• Protein degraded to amino acids and reused for protein synthesis

Question 16

Where does the control of appetite originate from?

Answer 16

• Sateity centre of the hypothalamus called arcuate nucleus
• Contains primary neurones that sense metabolite levels and sends inputs to secondary neurones to coordinate response via vagus nerve

Question 17

What are the two types of primary neurone in the arcuate nucleus, and what do they release?

Answer 17

- Orexigenic: NPY and AgRP to stimulate appetite

- Anorexigenic: Pro-opiomelanocortin which can be cleaved to b-endorphin, ACTH, a-MSH, to supress appetite

• a-MSH acts on melanocortin 4 receptors to supress and the b-endorphin from POMC makes you happy

Question 18

What hormone outside of the hypothalamus stimulates appetite?

Answer 18

Question 19

What hormones suppress appetite?

Answer 19

PYY: short peptide hormone from ileum and colon in response to feeding. Inhibits excitatory neurones and stimulates inhibitory ones

Question 20

What can be used to treat early type 2 diabetes?

Answer 20

Pramlintide, analogue of amylin

Question 21

What is the overall control of appetite system?

Answer 21

Question 22

What happens if you have a loss of funcyion leptin gene mutation and how can it be treated?

Answer 22

• Obesity, cannot stop eating so inject them with leptin
• Cannot inject leptin into normal obese people, appear to be resistant