1. Endocrinology Introduction

Question 1

What are the 2 categories of hormones?

Answer 1

Steroids (fat-soluble) OR Non-Steroids (water-soluble)

Question 2

Give an example of a fat soluble hormone.

Answer 2

Steroids e.g. cortisol.

Question 3

Are fat soluble hormones stored in vesicles or synthesised on demand?

Answer 3

Fat soluble hormones e.g. steroids are synthesised on demand.

Question 4

What are steroid hormones made of and where?

Answer 4

Made of cholesterol

Made by the adrenal glands and the gonads

Question 5

Where in a cell are steroid cell receptors located?

Answer 5

Steroid cell receptors are located in the cytoplasm.

Question 6

Give examples of non-steroid hormones.

Answer 6

Peptides e.g. insulin, glucagon, TRH, LH, FSH

Proteins/Amino acid hormones from the AA, Tyrosine
e.g. thyroid hormones, adrenaline, noradrenaline

Question 7

How do water soluble hormones e.g. peptides get into a cell?

Answer 7

They bind to cell surface receptors.

Question 8

Where in a cell are peptide cell receptors located?

Answer 8

Peptide cell receptors are located on the cell membrane.

Question 9

Are water soluble hormones stored in vesicles or synthesised on demand?

Answer 9

Water soluble hormones e.g. peptides are stored in vesicles.

Question 10

Name the glands involved in the endocrine system.

Answer 10

• Hypothalamus
• Pituitary glands - anterior and posterior
  -Thyroid and parathyroid glands
• Adrenal glands
• Gonads

Question 11

Describe and structure of the hypothalamus and the pituitary gland.

Answer 11

Hypothalamus: paraventricular + supraoptic nuclei

Hypothalamus -> Pituitary stalk -> Pituitary glands

Pituitary glands -> 1) Anterior lobe - glandular tissue
2) Posterior lobe - axons from 2 nuclei

Question 12

What are the 2 categories of hormones released by the hypothalamus? State the hormones released.

Answer 12

**Stimulatory: **
~ Thyrotropin releasing hormone -> TRH
~ Corticotropin releasing hormone -> CRH
~ Gonadotropin releasing hormone -> GnRH
~ Growth hormone releasing hormone -> GHRH

and

Inhibitory:
~ Growth homrone inhibiting hormone AKA Somatostatin -> GHIH
~ Prolactin inhibiting factor AKA Dopamine

Question 13

Give an example of an amine hormone.

Answer 13

Noradrenaline and adrenaline.

Question 14

Give 5 ways in which hormone action is controlled.

Answer 14

1. Hormone metabolism.
2. Hormone receptor induction.
3. Hormone receptor down-regulation.
4. Synergism e.g. glucagon and adrenaline.
5. Antagonism e.g. glucagon and insulin.

Question 15

Where is the thyroid gland located?

Answer 15

Anteriorly in the neck at the level of C5-T1 vertebrae;
Deep to the sternothyroid and sternohyoid muscles

Question 16

Describe the shape of the thyroid

Answer 16

• 2 lobes: left and right
• Lobes united over the trachea by a thin ‘Isthmus’ (usually anterior to the 2nd + 3rd tracheal rings)
• H-shaped appearance
• Some have a 3rd lobe!
• Covered by a fibrous capsule
• Covered by deep cervical fascia

Question 17

Where are the parathyroid glands located?

Answer 17

Medial half of the posterior surface of each lobe of the thyroid gland inside its fibrous sheath.

Superior parathyroid glands:
- Inferior border of the cricoid cartilage

Inferior parathyroid glands:
- Inferior poles of the thyroid gland

Question 18

Where do the parathyroid glands develop from?

Answer 18

Inferior parathyroid -> 3rd Dorsal pharyngeal pouch

Superior parathyroid -> 4th Dorsal pharyngeal pouch

Question 19

How are the parafollicular cells (C-cells) of the thryroid gland developed?

Answer 19

4th pharyngeal pouch -> Ventral -> Ultimopharyngeal body -> C-cells

Question 20

Where does the thyroid gland develop from?

Answer 20

From the endoderm at the base of the tongue, independent of the pharyngeal apparatus.

Descends down the neck; parathyroid glands latch on; cells from the ultimopharyngeal body migrate + join it; continues to rest at the base of the neck

Question 21

What layer of the trilaminar disc is the anterior pituitary derived from?

Answer 21

Ectoderm (Rathke’s pouch).

Question 22

What is the posterior pituitary derived form?

Answer 22

The floor of the ventricles.

Question 23

What is the anatomical connection between the hypothalamus and the anterior pituitary gland?

Answer 23

Hypothalamo-hypophyseal-portal system

• A system of tiny capillaries that moves hormones quickly from the hypothalamus to the anterior pituitary.