Lecture 1- Introduction To Endocrinology

Question 1

Primary endocrine glands

Answer 1

Their main function is to secrete hormones e.g. pituitary, thyroid, adrenal glands and the pancreas

Question 2

Secondary endocrine glands

Answer 2

Their main function is not to secrete hormones, but contain cells which to e.g. kidneys, stomach and liver

Question 3

Exocrine glands

Answer 3

Secrete products into ducts that carry secretions unto body cavities, lumen of organ or to outer surface of body i.e. target organ

Question 4

Endocrine hormone

Answer 4

Secrete hormones directly into the blood that act on distant cells

Question 5

Paracrine hormone

Answer 5

Acts locally on neighbouring cells

Question 6

Autocrine hormones

Answer 6

Acts on the same cell that secreted the hormone

Question 7

Diurnal

Answer 7

Secreted daily

- cortisol is an example which is high in the morning and low at night

Question 8

Melatonin

Answer 8

Secreted with a daily (circadian) rhythm

• secretion peaks at night
• controls sleep patterns

Question 9

Positive feedback

Answer 9

Rate of process increased and product increases

E.g. oxytocin which stimulates and enhances labour contractions

Question 10

Negative feedback

Answer 10

Rate of process decreased as the formation of the product increases

Question 11

Acromegaly

Answer 11

Excess of growth hormone during adulthood
-symptoms include swollen hands/feet (squashed nerves = carpal tunnel syndrome); abnormal periods and erectile dysfunction; sleep apnoea

Question 12

Down regulation

Answer 12

If a hormone is present in excess the number of target cells may decrease, decreasing sensitivity to hormone

Question 13

Upregulation

Answer 13

If a hormone is deficient, the number of target cell receptors may increase, to increase sensitivity to hormone

Question 14

Hypothyroidism

Answer 14

Low T3 and T4; high TSH

Question 15

Hyperthyroidism

Answer 15

High T3 and T4; low TSH

Question 16

Cushing’s syndrome

Answer 16

• Overproduction of ACTH from pituitary

- Overproduction of cortisol from the adrenal glands

Question 17

Addison’s disease

Answer 17

Lack of cortisol and aldosterone

• due to autoimmune destruction of adrenal gland
• symptoms include weight loss; dizzy spells; hyperpigmentation due to build up to ACTH which stimulates production of melanin by melanocytes); frequent urination due to lack of aldosterone (less sodium reuptaken in the kidneys)

Question 18

Cholesterol

Answer 18

Precursor to steroid hormones

Question 19

Thyrotoxicosis

Answer 19

Excess thyroxine (T4) production

Question 20

Hypoglycaemia

Answer 20

Insulin excess, low blood sugar

Question 21

Insulin and cytokines act via which kind of receptor?

Answer 21

Intracellular (phosphorylation of intracellular proteins)

Question 22

Steroid, thyroid hormones and vitamin D act via which type of receptor?

Answer 22

Intracellular (nuclear receptors)

Question 23

Catecholamines, NO and peptide hormones act via which type of receptor?

Answer 23

Extracellular (g protein coupled receptors GPCRs)

Question 24

What is the main action of intracellular receptors for hormones?

Answer 24

Phosphorylation of intracellular proteins

Question 25

What is the main action of a GPCR leading to the specific hormone response?

Answer 25

Increase of intracellular cAMP

Question 26

What is the effect to of insulin on glucose uptake?

Answer 26

Increased into fat and muscle

Question 27

Hormone

Answer 27

A regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action

Question 28

Catecholamines

Answer 28

Water soluble e.g. adrenaline/ noradrenalin/ melatonin

Question 29

Peptides

Answer 29

Water soluble e.g. insulin/ PTH

Question 30

Steroids

Answer 30

Lipid soluble e.g. cortisol/ sex steroids/ vitamin D

Question 31

Action of lipid soluble hormones

Answer 31

1. Diffuses through the blood and plasma membrane into a cell 2. Hormone binds to receptor in cystic or nucleus 3. Alters gene expression 4. Activates or suppresses the production of protein

Question 32

Action of water soluble proteins

Answer 32

1. Diffuses through blood and binds to receptor on exterior plasma membrane of target cell 2. Hormone receptor compels activates the membrane protein (G protein) 3. Activated G protein activates adenylyl cyclise 4. This converts ATP to cAMP in the cystol (Ca 2+ is another secondary messenger) 5. cAMP activates protein kinases (phosphorylates target cellular proteins) 6. Produces physiological response- activation/suppression 7. Phosphodiesterase deactivates cAMP 8. Works with low concentration of hormone as second messenger causes cascade effect

Question 33

Permissive effect

Answer 33

The response only occurs when there is a recent or simultaneous presence of a second hormone

Question 34

Synergistic effect

Answer 34

Effect of two hormones acting together is greater than the sum of their individual effects

Question 35

Antagonistic effect

Answer 35

When one hormone opposes the actions of another hormone

Question 36

Gigantism

Answer 36

Caused by an adenoma (tumour of the pituitary gland) - excessive growth hormone in children - symptoms include large hands/feet; prominent jaw and forehead; flat nose/larger head/lips

Question 37

What is insulin’s effect on glycogen?

Answer 37

Increase in glycogen synthesis

Question 38

What is insulin’s effect on triglycerides?

Answer 38

Increase storage in adipose tissue

Question 39

What is insulin’s effect on proteins?

Answer 39

Increased protein synthesis

Question 40

What is insulin’s effect on the liver?

Answer 40

Decreases hepatic gluconeogenesis

Question 41

What are the two main disorders associated with insulin deficiency?

Answer 41

Type I and type II diabetes

Question 42

Excess insulin causes what condition?

Answer 42

Hypoglycaemia

Question 43

Ghrelin

Answer 43

Increases food uptake

Question 44

Where is ghrelin produced?

Answer 44

Stomach