Overview of Endocrinology

Question 1

What are the major endocrine glands?

Answer 1

Hypothalamus
Pituitary gland
Thyroid, adrenal cortex, gonads
Pancreas
Parathyroid glands

Question 2

What is the endocrine role of the hypothalamus?

Answer 2

They hypothalamus releases activating and inhibitory hormones

Question 3

What hormones is the pituitary responsible for secreting?

Answer 3

Anterior lobe - trophic (growth) hormones

Posterior lobe – oxytocin & vasopressin (ADH)

Question 4

What are the 2 major hormone secreted by the thyroid gland?

Answer 4

Thyroxine

Triiodothyronine

Question 5

What hormones are released via the adrenal glands?

Answer 5

Cortex:
Cortisol, aldosterone

Medulla: Adrenaline/noradrenaline

Question 6

Which hormones do the gonads secrete?

Answer 6

Oestrogens, androgens, progestogens

Question 7

What is the role of the endocrine pancreas?

Answer 7

Secretes Insulin and glucagon for regulating BGL

Question 8

What hormone is secreted by the Parathyroid gland?

Answer 8

Parathyroid hormone

Question 9

What other organs secrete significant hormones in the body?

Answer 9

Kidney (Vit. D, EPO- increases RBC), 
CVS (ANP, endothelins)             
Pineal gland (melatonin)
Thymus gland (thymic hormones)
Bone (phosphate)
Adipose tissue (leptin)

Question 10

What are the different signalling mechanisms of the endocrine system?

Answer 10

Endocrine
Paracrine
Autocrine
Intracrine

Question 11

What is endocrine secretions?

Answer 11

hormones released by an endocrine cell into the general circulation and acting on distant target sites

Question 12

What is meant by Paracrine secretions?

Answer 12

hormones released into an endocrine cell which act locally on adjacent cell

Question 13

What is autocrine secretion?

Answer 13

hormones released by a cell which act back on the same cell

Question 14

What are intracrine secretions?

Answer 14

conversion of an inactive hormone that acts within that cell

Question 15

What are the functions of hormones?

Answer 15

Reproduction, growth and development
- Sex Steroids, thyroid hormones, prolactin, growth
hormone

Maintenance of internal environment
- Aldosterone, parathyroid hormone, vitamin D

Energy production, utilization and storage
- Insulin, glucagon, thyroid hormones, cortisol, growth
hormone

Question 16

What are the protein/peptide hormones?

Answer 16

• Hypothalamic hormones
• Pituitary hormones
• Insulin
• PTH
• Calcitonin

Question 17

Name the steroid hormones (cholesterol)

Answer 17

• Cortisol
• Aldosteorne
• Oestrogens
• Androgens
• Progestagens
• Vitamin D

Question 18

Name the amino acid derivatives (tyrosine / tryptophan)

Answer 18

• Nor/Adrenaline (tyrosine)
• Thyroid hormones (tyrosine)
• Melatonin (tryptophan)

Question 19

Which hormone are derived from fatty acids?

Answer 19

• Prostaglandins
• Thromboxanes
• Prostacyclin

Question 20

What form are hormones usually released in?

Answer 20

Predominantly released as prohormones and then cleaved for activation in the golgi apparatus
E.g.
Pre-proInsulin –> Proinsulin -> Insulin

Question 21

What is the precursor of all steroid hormones?

Answer 21

Cholesterol - all steroid hormone share the steroid nucleus (structure)

Question 22

What is the effect of plasma proteins on hormones?

Answer 22

Plasma proteins alter the solubility of hormones that otherwise couldn’t be transported

Question 23

Describe the half life and circulation of protein / peptide hormones

Answer 23

Half life - minutes

transported mainly unbound to plasma proteins

Question 24

What is the half life and circulation of thyroid hormones?

Answer 24

Half life - Seconds (CA’s)
- Hours (thyroid hormones)

Thyroid hormones transported bound to plasma proteins

Question 25

What is the half life and circulation of steroid hormones?

Answer 25

Half life - hours to days | transported bound to plasma proteins to make them soluble

Question 26

What is the significance of the neuro-endocrine integration?

Answer 26

The Anatomy and functional connections of the hypothalamic–pituitary axis and the hormones secreted by the anterior and posterior lobes of the pituitary gland all work in conjunction with one another

Question 27

Describe the mechanism of action of hormones secreted directly into the blood

Answer 27

Magnocellular neurons within the hypothalamus are neurosecretory cells responsible for releasing oxytocin and ADH directly into bloodstream

Question 28

What is the 3 tier hormone secretory system?

Answer 28

Hormone secreted via Hypothalamus to Pituitary to Target organ via parvocellular neurons

Question 29

Describe the mechanism of action of parvocellular neurons

Answer 29

1. Release and synthesize inhibitory hormones in hypothalamus 2. Hormones enter bloodstream and act on anterior lobe of pituitary gland 3. Then act on pituitary which releases growth hormones, prolactin, sex steroids etc. to act on their target organs

Question 30

What are trophic hormones?

Answer 30

growth hormones

Question 31

Describe the negative feedback control of hormones

Answer 31

When increased they act to upstream regulators within hypothalamic-pituitary axis to decrease further synthesis and release

Question 32

What is the significance of the negative feedback of hormone release?

Answer 32

hormonal concentration need to be regulated to modulate their effects

Question 33

What can effect the negative feedback of hormones?

Answer 33

external stimuli

Question 34

What is the pattern of hormone secretion?

Answer 34

All hormones secreted in a pulsatile pattern

Question 35

What daily rhythms effect hormone secretions?

Answer 35

``` Daily rhythms : - Circadian (24hr body clock) - Diurnal (day/night) Monthly cycles (females) Annual cycles (seen mainly in animals) ```

Question 36

What causes disorders of the endocrine system?

Answer 36

Excess or deficiency Impaired synthesis Transport and metabolism of hormones Resistance to hormone action

Question 37

What is the consequence of decreased ACTH?

Answer 37

Decreased cortisol causing Addison's disease

Question 38

What is the effect of excess ACTH?

Answer 38

Increased cortisol levels leads to Cushing's disease