Endocrinology

Question 1

Where is the pituitary gland? - How big is it?

Answer 1

Master gland - 4 to 4.8 x 1 to 1.8 x 0.8 to 1.6 cm in size only 7-10 ml sonographic volume
found in the Sella Turkica of the sphenoid bone below the hypothalamus

Question 2

What is a hormone?

Answer 2

A chemical messenger carried from organ by the blood stream

Question 3

Types of hormones

Answer 3

Peptide and steroid hormones

Question 4

Differencing between two types of hormone

Answer 4

Peptide hormones initially are a long precursor
need to be cleaved to be activated
Stored in vesicle
Binds to Cell surface membrane
Activate secondary system

Question 5

How many parts of the pituitary gland? Embryological origin

Answer 5

2 Parts Anterior (grows upwards from oral ectoderm) posterior (originates from the diencephalon)

Question 6

What regulates the anterior pituitary gland? What is the pathway that it communicates down? (I.e. start with the hypothalamus)

Answer 6

Hypothalamus - releases inhibitory factors / activation factors
Parvocellular neurons
Median eminence
Hypothalamo- pituitary - Portal circulation
Anterior pituitary

Question 7

What makes up the anterior pituitary gland?

5 Types of these cells are?

Answer 7

Endocrine cells

• Somatotrophs
• Lactotrophs
• Corticotrophs
• Thyrotrophs
• Gonadotrophs

Question 8

Hormones released by the Anterior pituitary gland and which cells produce them

Answer 8

SOMATOTROPHS - Growth hormone

LACTOTROPHS - Prolactin

THYROTROPHS - Thyroid stimulating hormone (TSH)

GONADOTROPHS - Luteinising hormone & Follicle stimulating hormone

CORTICOTROPHS - Adrenocorticotrophic hormone

Question 9

What happens if somatostatin is not released by the hypothalamus?

Answer 9

Growth hormone is released in large amounts if growth hormone releasing hormone is present

Question 10

What happens when their is a large pituitary tumour?

Answer 10

Pressure on the optic chiasm causes Bitemporal hemianopia

Question 11

Why do adults not get taller even if they have too much growth hormone?

Answer 11

Causes acromegaly - end plates have fused so the long bones do not respond to GH. BUt only the Jaw, hands etc. increase in size

Question 12

What are the hormones released by the posterior pituitary

Answer 12

Arginine vasopressin (AVP) Portal (also known as Anti-diuretic circulation hormone) ADH

Oxytocin

Question 13

Where does arginine vasopressin act?

Answer 13

V2 receptor on collecting cells in the kidneys as well as slight stimulation of the adrenal glands

Question 14

Where does Oxytocin act?

Answer 14

Contraction of the mammary glands to expel the milk formed by the prolactin
Also in the uterus