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F1:CEP20/21 > Pituitary gland and disorders > Flashcards

Pituitary gland and disorders Flashcards

1
Q

Where does the pituitary sit?

A

In the mid cranial fossa in the sella turcica of the sphenoid bone

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2
Q

What is the pituitary gland directly attached to? How does this happen through what membrane does this happen?

A

Pituitary is connected. hypothalamus via the infundibulum which pierces through the diaphragma sellae into the sella turcia

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3
Q

What axis does the pituitary form?

A

Hypothamo-pituitary axis

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4
Q

What is the anterior pituitary also known as

A

The adenohypophysis

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5
Q

What does the adenohypophysis comprise of?

A

Pars distalis
Pars intermediate
and the pars tuberalis that wraps around the pituitary stalk

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6
Q

What is the pars distalis?

A

contains glandular endothelial cells that produce anterior pituitary hormones as well as a rich fenestrated capillary network supported by fibroblasts and reticular fibres

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7
Q

What does the neruohypophysis or posterior pituitary comprise of?

A

Infundibular stalk and infundibular process that forms the posterior lobe

Is an extension of the hypothalamus therefore is neural tissue

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8
Q

What does the posterior pituitary contain?

What hormones does it produce?

A

Axons of neurones that originate in the supraoptic (mainly AVP) nuclei and the paraventricular (mainly oxytocin) nuclei of the hypothalamus
axons pass down the supraopticohypophyseal tract into capillary bed where they secrete oxytocin and vasopressin (ADH) via neruosecretion

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9
Q

Chromaphils are the secretory cells in the anterior pituitary what are the subtypes

A

Acidophils pink staining

basophils more blue staining

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10
Q

What cells are the acidophils in the anterior pituitary?

What is their histological apperance?

A

Somatotrophs
very large nuclei most numerous cell in the anterior pituitary produce and secrete GH which is packed in many vehicles in the cytosol

Lacto-mommotropic cells produce prolactin

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11
Q

What are the basophils that are present in the anterior pituitary?

A

Gonadatropic cells
produce LH and FSH
large cells with large nuclei

Corticotropic cells
produce ACTH
sparser secretory granules vesicles located on periphery

Thyrotropic cells
produce TSH
smaller granule contain vesicles located on the periphery

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12
Q

What are the two main blood vessels that bring blood to the pituitary gland?
Where do they stem form?
What part of the pituitary do they supply

A

Superior hypophyseal arteries stem from internal carotid artery bring blood to the median eminence of the hypothalamus and the infundibular stalk

Inferior hypophyseal artery that supplies the posterior pituitary

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13
Q

What is significant about the superior hypophyseal artery?

A

Blood supply to median eminence of the hypothalamus capillaries then region into blood sinusoids down into the pars distalis then branches to form an extensive capillary network

This is known as the hypothalamicHypophyseal portal system and allows hormones produced by the pituitary to reach the anterior pituitary without entering systemic circulation

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14
Q

What is the venous drainage of the pituitary gland

A

The hypophyseal vein

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15
Q

What is significant about the pituitary glands location?

A

Superior is the optic chiasm
surrounded laterally anteriorly and posteriorly by the cavernous sinus
and surrounded inferiorly by the sphenoid sinus

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16
Q

What is significant about the cavernous sinus and the pituitary gland

A

Contains cranial nerves III, IV, VI and V1 and V2 in order from superior to inferior
as well as the internal carotid artery

as such there is a lot to avoid when carrying out pituitary surgery

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17
Q

What are tropic hormones

A

hormones that target other endocrine tissues

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18
Q

What are the tropic hormones produced by the pituitary?

A

FSH
LH
ACTH
TSH

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19
Q

What are the other non-tropic hormones produced by the anterior pituitary

A

Prolactin

Growth hormone

20
Q

What stimulates growth hormone secretion?

A

GHRH growth hormone releasing hormone produce by the hypothalamus

Also stimulated by sleep hypoglycaemia and exercise

21
Q

What is the function of GH, and how does it carry out this role?

A

Cell division
protein synthesis
glucose metabolism
bone growth

It does this indirectly through the production of insulin growth factor one (IGF-1) in the liver which then triggers the mitogenic and metabolic effects of the GH

22
Q

What inhibits GH

A

high GH levels and high IGF-1
hyperglycaemia
somatostatin

23
Q

What does GH deficiency result in

A

Stunted growth and delayed development results in dwarfism in children
decreases muscle strength and exercise capacity
decreases bone mineral density

24
Q

How is GH deficiency diagnosed? What test do you do?

A

Secretion of GH naturally pulsative higher at night

Growth hormone stimulation tests given insulin that results in hypoglycaemia should result in an increase in GH secretion
IGF-1 levels also measured

25
Q

What is GH excess?
What causes this?
What does it cause and what are the symptoms of this disease?

A

Leads to acromegaly or gigantisism in children

Caused by a pituitary adenoma

no reduction or natural drops in GH levels

Acromegaly:
growth of facial skeleton protruded jaw
growth of hands and feet
issues with fertility and heart
thickened skin
difficulty sleeping
inter dental spacing
26
Q

What are the local effects of pituitary adenomas

A

headaches
pressure on the optic chiasm resulting in visual field loss bitemporal hemianopia
lateral expansion can lead to compression of cranial nerves in cavernous sinus

27
Q

Treatment of GH excess?

A

Surgery to remove pituitary adenoma
transsphenoidal surgery

Radiotherapy

somatostatin analogues can be given as long actin preparations

28
Q

LH and FSH

What simulates production?

What is the role of FSH and LH?

A

Produced by gonadtropic cells

Stimulated to produce LH and FSH by GnRH gonadatropin releasing hormone

FSH and LH Peptide hormones with an inactive A subunit and specific B subunit that is activated once cleaved

Role in the development of secondary sex characteristics
production of sex hormones oestrogen and testosterone

29
Q

What inhibits FSH LH

A

high GnRH
high FSH
high LH
and various other sex hormones

30
Q

FSH LH deficiency?
Effects?
Treatment?

A

Leads to delayed puberty in children and poor development of secondary sex characteristics

Leads to decreased fertility and libido in women and osteoporosis

leads to decreased libido and infertility in men as well as loss of muscle mass

Treatment:
FSH and LH replacement therapy

31
Q

FSH LH excess

A

VERY RARE

FSHomas of pituitary
will lead to menstural irregularities as well as enlarged testicles

Treatment is surgery

32
Q

ACTH what does it stand for?

A

Adrenocorticotropic hormone

33
Q

What stimulates ACTH release and what is its role?

A

Stimulated by release of CRH (corticotropin releasing hormone) by the hypothalamus
Also stimulated by stress

controls cortisol production by the adrenal glands which itself has a key role regulating the production of other steroids produced by the adrenal gland

34
Q

What inhibits ACTH

A

high ACTH
high CRH
high levels of many other hormones it results in the production of

35
Q

ACTH excess?

A

results in Cushings disease

central obesity moon face thick skin striae on skin easy bruising osteoporosis

36
Q

Diagnosis

Treatment of ACTH excess?

A

high cortisol leaves loss of diurnal rhythm no significant drop in cortisol level

Transsphenoidal surgery to remove pituitary adenoma

37
Q

TSH
Stimulation
Role
Inhibition

A

Produced by thyrotropic cells

Stimulated by TRH Thyrotropin releasing hormone

Role in thyroid gland and thyroid home regulation

Inhibited by high TSH high thyroid hormone levels

38
Q

TSH excess due to pituitary adenoma

A

Hyperthyroidism
TSH-omas VERY RARE cause

Treatment is transsphenoidal surgery

39
Q

TSH defficency

A

secondary Hypothyroidism

40
Q

Prolactin

A

Produced by lacto-/ mammotropic cells

stimulated by breast feeding and pregnancy

allows mammotropic glands to produce milk following childbirth and inhibits gonadal activity through inhibition of GnRH

Hypothalamus inhibits PRL release via dopamine

41
Q

Prolactin excess?
Cause?
Symptoms?

A

When no pregnant can be caused by drugs (dopamine antagonists) or through pituitary adenomas

Galactorrhoea milky nipple discharge and hypogonadism

Treatment dopamine agonists to degrease PRL levels and the size of the tumour

42
Q

ADH or vasopressin AVP?

Role?

A

Produced and released by neurosecretory cells in the posterior pituitary

Increases the rate of free water reabsorption in the luminal membrane of kidney through V2 receptors causing integration of aquaporins into luminal membrane of collecting duct

Stimulated by hyperosmoregularity of the circulate effective circulating volume

43
Q 
What is AVP 
deficiency 
Causes
how is it diagnosed?
treatment?
A

Diabetes insipidus

Autoimmune destruction of neurosecretory cells
tumors
trauma
infection 
inheritance

have to determine it is not diabetes mellitus measure blood gluc
Water deprivation test urine output should decrease in people who are normal will remain the same for ADH deficiency

Treatment ADH analogues

44
Q

What is inadequate production of pituitary hormones called?

What is inadequate production of hormones from the anterior pituitary called?

A

hypopituitarism

Panhypopituitarism

45
Q

Give three causes of hypopituitarism

A

Trauma to the pituitary
non functional Pituitary adenomas
Pituitary infarction

46
Q

Causes of hyperpituitarism

A

functional pituitary adenomas
hypothalamic disease rare
ectopic production of hypothalamic agents

F1:CEP20/21 (12 decks)

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