Pituitary hormones

Question 1

Where is the pituitary gland located?

Answer 1

In the sella turcica.

In the midline - between the two eyes.

Question 2

How many parts does the hypophysis have?

Answer 2

2 parts.
Adenohypophysis - anteriorly.

Neurohypophyisis - posteriorly.

Connected to hypothalamus by the stalk (infundibulum).

Question 3

The pituitary gland can extend in what directions?

Answer 3

Superiorly
Inferiorly
Laterally

Question 4

The infundibulum goes through what?

Answer 4

The diaphragma sellae

Question 5

What is the anterior border of the cavernous sinus?

Answer 5

Superior orbital fissure

Question 6

What is the posterior border of the cavernous sinus?

Answer 6

Petrous part of the temporal bone.

Question 7

What is the medial border of the cavernous sinus?

Answer 7

Body of the sphenoid bone

Question 8

What is the lateral border of the cavernous sinus?

Answer 8

Meningeal layer of the dura mater running from the roof to the floor of the middle cranial fossa.

Question 9

What is the roof of the cavernous sinus?

Answer 9

Meningeal layer of the dura mater that attaches to the anterior and middle clinoid processes of the sphenoid bone.

Question 10

What is the floor of the cavernous sinus?

Answer 10

Endosteal layer of the dura mater that overlies the base of the greater wing of the sphenoid bone.

Question 11

What travels through the cavernous sinus?

Answer 11

Abducens nerve (CN VI).

Carotid plexus (post-ganglionic sympathetic nerve fibres).

Internal carotid artery (cavernous portion).

Question 12

What travels through the lateral wall of the cavernous sinus?

Answer 12

Oculomotor nerve (CN III)

Trochlear nerve (CN IV)

Ophthalmic (V1) and maxillary (V2) branches of the trigeminal nerve

Question 13

What is unique about the cavernous sinus?

Answer 13

The cavernous sinus is the only site in the body where an artery (internal carotid) passes completely through a venous structure. This is thought to allow for heat exchange between the warm arterial blood and cooler venous circulation.

Question 14

Mnemonic to remember contents of cavernous sinus:

Answer 14

OTOM CAT

Oculomotor nerve
Trochlear nerve
Ophthalmic branch
Maxillary branch

These are the lateral wall contents from superior to inferior.

Internal carotid artery
Abducens nerve
Trochlear nerve

Medial to lateral.

Question 15

How does the anterior pituitary get its blood supply?

Answer 15

Through the portal venous circulation from the hypothalamus.

Question 16

Describe the hypothalamo-pituitary-target organ axis

Answer 16

Hypothalamus secretes releasing hormone (TRH)

Pituitary secretes stimulating hormone (TSH)

Target organ (thyroid) secreted hormones (T3;T4)

Question 17

What molecule inhibits GH?

Answer 17

Somatostatin

Question 18

In response to GH the liver secretes what?

Answer 18

IGF-I

Question 19

Why is prolactin production different?

Answer 19

It is constantly produced and inhibited by dopamine. (The dopaminergic neurone goes down the stalk and directly releases dopamine to the anterior pituitary).

Question 20

List examples of diseases of the pituitary gland

Answer 20

Benign pituitary adenoma (functional or non)

Craniopharygioma

Trauma (structural or functional problems)

Apoplexy/Sheehans (rapid expansion due to bleeding or acute infarct.
Sheehans: major post-partum haemorrhage = hypoperfusion).

Sarcoid/TB

Question 21

What are the 3 vital points of tumours?

Answer 21

Pressure on local structures.

Pressure on normal pituitary.

Functioning tumour.

Question 22

Describe pressing on local structures more in details:

Answer 22

Push upwards against the optic nerve = bitemporal hemianopia.

The diaphragma sellae can be stretched = headaches.

Lateral expansion (medio-lateral temporal lobe) = seizures.

Downward = no problem, however if all the way down = abnormal connection - CSF rhinorrhoea and infection leading to meningitis.

Question 23

What are the signs and symptoms of pressure on the normal pituitary gland?

Answer 23

Hypopituitarism
Pale
No body hair
Central obesity

Question 24

Functioning tumours of the pituitary

Answer 24

Prolactinoma.

Acromegaly and gigantism.

Cushing’s disease.

Question 25

What is the cut off for a prolactin microadenoma?

Answer 25

1cm

Question 26

Prolactinomas can cause

Answer 26

Expressable galactorrhoea (physical provocation).

Spontanous.

More common in women.

Present with galactorrhoea, amenorrhoea, infertility, loss of libido and visual field defects.

Question 27

How are prolactinomas treated?

Answer 27

Dopamine agonist (cabergoline and bromocriptine).

Question 28

If someone is GH deficient

Answer 28

Short stature (dwarfism)

Question 29

GH excess

Answer 29

Acromegaly and gigantism (depending on age of onset).

Question 30

Cushing’s syndrome

Answer 30

Too much cortisol present in the body.

Most commonly iatrogenic (glucocorticoid treatment).

Pituitary tumour secreting too much ACTH = Cushing’s disease.

Tumour of adrenal gland secreting too much cortisol = Cushing’s syndrome.

Ectopic= lung CA produced ACTH

Question 31

What are the characteristic features of Cushing’s?

Answer 31

Thin legs, thicker trunk.

Abdominal striae (thick pigmented abdominal striae - increased melanin through thin skin makes it red).

Skin is very fragile, difficult to recover from infections (ulcers do not heal).