12.1 Endocrinology: Basic Concepts And Mechanisms

Question 1

Basic functions of endocrine system

Answer 1

• Glands produce & secrete hormones.
• Hormones chemical substances that regulate the activity of cells or organs.
• Regulate the body’s growth, metabolism, sexual development and function.
• Influences nearly all cells, organs and functions of the human body

Question 2

What are the three classes of hormones

Answer 2

• Peptides and polypeptides
• amino acid derivatives
• steroids

Question 3

Biosynthesis of steroids

Answer 3

Cholestrol + {ACTH, FSH, LH, Angiotensin} ➡️ Pregnenolone ➡️ Progesterone:
-> Aldosterone
-> Cortisol
-> Sex hormones

Question 4

Biosynthesis of peptides

Answer 4

• Pre-prohormone ➡️ Prohormone ➡️ Active hormone
• Glycoproteins: Common α-chain / Unique β- chain
  (FSH, LH, TSH, HVG)

Question 5

Hormone secretion two types

Answer 5

• Continuous – Little variation Thyroid
• Intermittent- Big variation Gonadotrophs – Think menstrual cycle / insulin release

Question 6

Patterns of hormone secretion

Answer 6

Chronic
- maintenance of relatively constant concentration hormone
- thyroid hormone

Acute
- epinephrine in response to stress

Episodic (Cyclic)
- female reproductive hormones

Question 7

Which factors influence hormone release

Answer 7

1. Biological rythms
- Circadian (Day/night) e.g Cortisol
- Menstrual (28day)

2. Stress/Excercise
- ACTH and Cortisol
- Growth hormone
- Prolactin
- Adrenaline and noradrenaline

3. Feeding and fasting
- Insulin; GLP1; Glucagon
- Growth hormone

4. Regulators
- Stimulate / Downregulate
➡️metabolites / products ( eg.⬇️Ca++ ⬆️ PTH)
➡️trophic hormones: hypothalamic; Ptuitary

5. Feedback
- negative (long, short, ultrashort)
- positive

Question 8

How does the hormones act in the endocrine system

Answer 8

Carried in bloodstream or thru lymph to target cells in organs

Question 9

Biotransformation of Vit D

Answer 9

• get in early form form sunshine or diet (fish)
• goes to liver
• goes to kidney (when this don’t work = vit D deficiency)
• need liver and kidney to activate Vit D otherwise it is not going to work at all

Slide 30

Question 10

Difference between hormone classes

Answer 10

Slide 42

Question 11

Endocrine testing

Answer 11

• If you have to much of hormone = measure when hormone would have been at it lowest
• If you think a hormone is too low = measure when hormone should be at it highest (you expect it to be high, if it is low the = deficiency)

Question 12

Pathogenesis of endocrine disorders

Answer 12

• Disease due to hyperfunction or hypofunction (Congenital/ Acquired)
• Genetic/Chromosomal
• Autoimmunity
• Drug-induced
• Receptor defects
• Tumours/Hyperplasia
• Iatrogenic

Question 13

Lifestyle RF and endocrine disorders

Answer 13

• obesity
• osteoporosis