Pituitary Gland Flashcards

1
Q

What two lobes form the pit gland?

A

Anterior and posterior

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2
Q

What kind of cells is the anterior pit made up of?

A

Glandular

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3
Q

What kind of cells is the posterior pit made up of?

A

Neuronal (axons mainly)

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4
Q

What hormones does the anterior pit secrete?

A
Growth Hormone
Follicle stimulating Hormone
ACTH
Thyroid stimulating hormone
Prolactin
Luteinizing hormone
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5
Q

What hormones does the posterior pit secrete?

A

ADH

Oxytocin

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6
Q

Where is the pit gland located?

A

In the pit fossa.

Below the hypothalamus and above the sella turcica of the sphenoid bone.

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7
Q

What surrounds the pit gland?

A

Cavernous sinuses (R and L).

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8
Q

What links the R and L cavernous sinuses?

A

Anterior intercavernous sinus

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9
Q

What forms the lateral border of the cavernous sinuses?

A

Dura mater

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10
Q

What is the dura mater?

A

A meningi that forms the floor of the cranial fossae.

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11
Q

What is the diaphragm sellae?

A

Part of the dura mater that coverers the pit fossa

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12
Q

What coverers the pit fossa?

A

Diaphragm sellae from dura mater.

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13
Q

What is the main content of the cavernous sinuses?

A

Venous blood vessels that drain into the internal jugular vein

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14
Q

Where do the venous blood vessels in the cavernous sinus drain into?

A

Internal jugular vein

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15
Q

What six points of interest can be seen in the cavernous sinuses?

A
Internal carotid artery
Oculomotor (CNIII)
Trochlear (CNIV) 
Abducens (CNVI)
Ophthalmic and maxillary divisions of trigeminal (CNV1+2)
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16
Q

List the 4 lateral cranial nerves in the cavernous sinuses from superior to inferior.

A

Oculomotor (CNIII)
Trochlear (CNIV)
Ophthalmic division of trigeminal (CNV1)
Maxillary division of trigeminal (CNV2)

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17
Q

What can be found directly above the pit gland?

A

Optic chiasm

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18
Q

What is the optic chiasm?

A

Where the optic (CNII) nerves cross.

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19
Q

Where is the optic chiasm located?

A

Directly above the pit gland.

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20
Q

What links the posterior pit to the hypothalamus?

A

Infundibulum

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21
Q

What are the two options for approaching the pit gland for surgery?

A

Transcranial- Subfrontal lobe

Transsphenoid- Via nasal cavity and sphenoid sinuses

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22
Q

What bones need broken when accessing the pit gland via the transsphenoid route?

A

Separation of nasal septum (+/- Le Fort 1)

Floor and roof of sphenoid sinuses

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23
Q

What bones make up the nasal cavity?

A

Vomer

Ethmoid

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24
Q

What are the four paranasal sinuses?

A

Frontal
Maxillary
Ethmoid air
Sphenoid

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25
Q

What is the function of the optic chiasm?

A

Conducts AP bilaterally from nasal retinae

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26
Q

How does functional deficit of optic chiasm present?

A

Bitemporal hemianopia

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27
Q

What is the function of the oculomotor nerve?

A

Motor movement of eye

Sphincter of iris

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28
Q

How does a problem with the oculomotor nerve present?

A

Problems with eye movement

Dilated pupils

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29
Q

What does the trochlear nerve do?

A

Depresses eye

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30
Q

How do problems with the trochlear nerve present?

A

Inability to look inferior and laterally

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31
Q

What does the trigeminal do?

A

Sensory to most of face

Motor to muscles of mastication

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32
Q

How does damage to the trigeminal nerve present?

A

Sensory loss of face

Inability to chew

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33
Q

What does the abducens nerve do?

A

Abducts the eye

34
Q

How do issues with the abducens nerve present?

A

Inability to abduct eye

35
Q

What does the cavernous sinuses do?

A

Drain venous blood

36
Q

What can cause problems with the cavernous sinuses?

A

Venous harmorrhage

37
Q

What do the internal carotid arteries do?

A

Supply blood to brain and orbit

38
Q

What can cause issue with the internal carotid arteries?

A

Catastrophic haemorrhage

39
Q

What does the dura mater do?

A

Protects the structures of the cranial cavity

40
Q

What can cause damage to the dura mater?

A

CSF leak

41
Q

What five hormones regulate the anterior pit?

A
Thyrotropin Releasing Hormone
Corticotropin Releasing Hormone
Gonadotropin Releasing Hormone
Growth Hormone Releasing Hormone
Dopamine
42
Q

What does TRH do?

A

Stim TSH release

43
Q

What does CRH do?

A

Stim ACTH release

44
Q

What does GnRH do?

A

Stil LH and FSH release

45
Q

What does GHRH do?

A

Stim GH release

46
Q

What does DA do?

A

Inhibit Prolactin release

47
Q

Where are ADH and OXT produced?

A

Hypothalamus then migrate to post pit

48
Q

On what tissue does TSH act?

A

Thyroid gland

49
Q

What does TSH do?

A

Stim thyroid gland to produce thyroxine

50
Q

On what tissue does ACTH act?

A

Adrenal cortex

51
Q

What does ACTH do?

A

Stim cortisol release

52
Q

On what tissues do LH and FSH act?

A

Testes and ovaries

53
Q

What do FSH and LH do?

A

Stim oestrogen and testosterone production

54
Q

What does GH do?

A

Stimulates growth through IGF-1

55
Q

On what tissues does GH act?

A

All of them

56
Q

On what tissue does prolactin act?

A

Mammary tissue

57
Q

What does prolactin do?

A

Stim milk production

58
Q

On what tissue does ADH work?

A

Kidneys

59
Q

What does ADH do?

A

Stim water retention

60
Q

On what tissues does oxytocin act?

A

Uterus SM
Ductus deferens SM
Prostate SM

61
Q

What are the three broad categories of pathology of the pit?

A

Too little hormone
Too much hormone
Gland is too big

62
Q

How do you test for too much/little hormone?

A

Blood tests

63
Q

How do you test for a pit gland that is too big?

A

Imaging- MRI or US

64
Q

In a dynamic endocrine test for too much hormone what do you do?

A

See if you can suppress the hormone

65
Q

In a dynamic endocrine test for too little hormone what do you do?

A

See if you can stim hormone

66
Q

Give examples of a dynamic endocrine test for too little hormone?

A

Insulin stress test
Water deprivation test
Synacthen test

67
Q

How does the insulin stress test work?

A

Drop blood glucose to <2.2 using insulin to stim cortisol and GH release

68
Q

What is a safer alternative to the insulin stress test?

A

Prolonged glucagon test

69
Q

What should cortisol rise to in the insulin stress test for it to be normal?

A

> 500

70
Q

What should GH rise to in the insulin stress test for it to be normal?

A

> 7 micrograms/l

71
Q

How does the water deprivation test work?

A

Deprive of liquid for 8h and check is Ur/Serum osmol ratio is >2.

72
Q

What does a Ur/Serum osmol ratio of <2 suggest?

A

Diabetes insipidus

73
Q

When do you not need to do a water deprivation test?

A

If the baseline reading is >2

74
Q

What is the second part of the water deprivation test?

A

Give desmopressin. If it improves after DDAVP then problem with pit/hypo if not problem with kidneys.

75
Q

What kind of cells is the anterior pit made of?

A

Acidophils
Basophils
Chromophobes

76
Q

What kind of acidophil cells are present and what do they produce?

A

Somatotrophs- GH

Mammotrophs- PRL

77
Q

What colour do acidophils appear on staining?

A

Red

78
Q

What colour do basophils appear on staining?

A

Blue

79
Q

What kind of basophil cells are present and what do they produce?

A

Corticotrophs- ACTH
Thyrotrophs- TSH
Gonadotrophs- FSL/LH

80
Q

What colour do chromophobes appear on staining?

A

Clear

81
Q

How does the posterior pit appear on T1 MRI scans?

A

Very bright