Lecture 9 (Part 2) - Appetite

Question 1

What nucleus in the brain controls the biological clock? What hormones are involved in it?

Answer 1

• Suprachiasmatic nucleus

- Melatonin and pineal gland

Question 2

Desc:

1. Autocrine
2. Paracrine
3. Endocrine
4. Neurocrine

Answer 2

1. Hormones signal acts on origin
2. Hormones signal carried to adjacent cell via IF
3. Endocrine: Hormones released into blood stream act on distant target cell
4. Hormone in neurone released to blood

Question 3

What are the similarities and differences of endocrine and nervous system?

Answer 3

• Both neurons and endocrine cells depolarised
• Both work to maintain homeostasis (dynamic process)
  Endocrine System:
  i) Signal: Hormones————Neurotransmitters
  ii) Convey: Bloodstream——-Chem & electrical
  iii) Speed: Slow————–Fast

Question 4

Desc. classification of hormones

1. Peptide
2. Glycoprotein
3. A.A
4. Steroids

Answer 4

1. Peptide: Insulin & Glucagon
   - Water sol
2. Glycoprotein: LH and FSH
   - Water sol
3. A.a: Tyrosine, noradrenaline, T3,T4
   - Thyroid hormones: lipid sol
   - Adrenal: water sol
4. Steroids: cortisol (transcortin), aldosterone, oestrogen
   - All lipid sol

Question 5

Role of carrier protein

Answer 5

• Increase sol. of hormone in plasma
• Increase half life
• Readily accessible

Thyroxine-binding globulin (TBG)

Question 6

Where is the appetite control centre located in? Which nucleus plays central role?

Answer 6

• Hypothalamus
• Arcuate nucleus:
  i) Stimulatory (promote hunger) - neuropeptide Y and AgRP
  ii) Inhibitory neurones (promote satiety)- POMC

Question 7

What is ghrelin, where is it released from? Function

Answer 7

• Peptide hormones released from stomach wall

- Stimulates excitatory primary neurones in arcuate nucleus –> stimulates appetite

Question 8

What is PPY (Peptide Tyrosine Tyrosine), where is it released from? Function

Answer 8

• Peptide hormone released by ileum and colon

- Inhibits appetite

Question 9

What is leptin, where is it released from? Function

Answer 9

• Peptide hormone released by adipocytes
• Stimulates inhibitory (POMC) neurones and inhibits excitatory (AgRP/NPY)
• Suppress appetite
• ⬆️expression of uncoupling proteins in mitochondria –> energy as heat

Question 10

What is insulin, where is it released from? Function

Answer 10

• Suppresses appetite

- Less than leptin

Question 11

What is amylin, where is it released from? Function

Answer 11

• Peptide hormone secreted by B cells in pancreas
• Suppress appetite
• Pramlintide treatment for type 2 DM

Question 12

Effect of defect in leptin gene in humans. Is it effective in curing obesity?

Answer 12

• Rare loss of func. in humans (massive weight loss when injected w leptin)
• No effect on common obesity due to ‘leptin resistance’

Question 13

What is a hormone?

Answer 13

Chemical signals produced in endocrine gland or tissues that travel in the bloodstream to target tissues or organs