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Year 2 Medicine > Introduction to the Hypothalamic-Pituitary Axis > Flashcards

Introduction to the Hypothalamic-Pituitary Axis Flashcards

1
Q

Autocrine signalling is a form of cell signalling in which a cell secretes a hormone or chemical messenger that binds to autocrine receptors on …

A

that same cell, leading to changes in the cell

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2
Q

Paracrine signalling is a form of cell-to-cell communication in which a cell produces a signal to induce changes in …

A

nearby cells, altering the behaviour of those cells.

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3
Q

Endocrine action is where the hormone is …

A

distributed in blood and binds to distant target cells.

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4
Q

… action: the hormone is distributed in blood and binds to distant target cells.

… action: the hormone acts locally by diffusing from its source to target cells in the neighborhood.

… action: the hormone acts on the same cell that produced it.

… action: neuronal cells that secrete chemicals which enter the bloodstream and flow to a distant site and act on target cell receptors.

A

Endocrine action: the hormone is distributed in blood and binds to distant target cells.

Paracrine action: the hormone acts locally by diffusing from its source to target cells in the neighborhood.

Autocrine action: the hormone acts on the same cell that produced it.

Neuroendocrine action: neuronal cells that secrete chemicals which enter the bloodstream and flow to a distant site and act on target cell receptors.

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5
Q

Where does the pituitary lie?

A

in the brain, just behind the eyes

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6
Q

The pituitary has two parts, the … pituitary and the … pituitary

A

anterior pituitary

posterior pituitary

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7
Q

Anatomy of the pituitary:

The pituitary gland is a pea-sized oval structure, suspended from the underside of the brain by the pituitary … (known as the infundibulum). It sits within a small depression in the … bone, known as the sella turcica (‘’Turkish saddle’’).

It consists of how many parts? Where are they derived from?

It has it’s own pituitary … which protects it inside the skull

A

stalk

sphenoid bone

2 parts - posterior derived from hypothalamus and anterior derived from roof of pharynx, called Rathke’s pouch

pituitary fossa

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8
Q

Pituitary gland blood supply:

  • It has a … sinusoidal circulation
  • circulation is lined by …
  • … … is above the pituiatry = linked to pituitary tumours
A
  • portal sinusoidal circulation
  • circulation lined by sinusoids
  • optic chiasm is above the pituitary
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9
Q

What is shown in this image?

A

Pituitary gland anatomy

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10
Q

What is shown in this image?

A

Bottom - pituitary tumour pressing on the optic chiasm

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11
Q

Anatomy of pituitary image

A
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12
Q

What is shown in the image?

A

Drawings by Leonardo de Vinci - showing relationship between the third ventricle and hypothalamus

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13
Q

The hypothalamus

  • Integrates functions that maintain chemical and temperature …
  • Functions with the … system
  • Controls the release of … from the anterior and posterior pituitary
A
  • Integrates functions that maintain chemical and temperature homeostasis
  • Functions with the limbic system
  • Controls the release of hormones from the anterior and posterior pituitary
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14
Q

Hypothalamic releasing hormones

  • The median … secretes small peptides and …
  • These hormones control the secretion of gonadotropes, somatotropes, lactotropes, corticotropes and thyrotropes
  • Discovery of the hypothalamic releasing hormones and the blood supply connecting the hypothalamus and pituitary led to the Nobel Prize physiology/medicine in … for Andrew Schally and Roger Guillemin.
A
  • The median eminence secretes small peptides and dopamine
  • These hormones control the secretion of gonadotropes, somatotropes, lactotropes, corticotropes and thyrotropes
  • Discovery of the hypothalamic releasing hormones and the blood supply connecting the hypothalamus and pituitary led to the Nobel Prize physiology/medicine in 1977 for Andrew Schally and Roger Guillemin.
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15
Q

Gonadotropes cells are endocrine cells in the anterior pituitary that produce the gonadotropins, such as the … hormone and … hormone

A
  • Follicle stimulating hormone - FSH
  • Luteinizing hormone - LH
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16
Q

Somatotrophs are the cells in the anterior pituitary that release … … hormone (also called somatotropin). They constitute about …-…% of the anterior pituitary cells.

A
  • pituitary growth hormone
  • 30-40% of anterior pituitary cells
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17
Q

A lactotropic cell is a cell in the anterior pituitary which produces … in response to hormonal signals including dopamine which is … and thyrotropin-releasing hormone which is stimulatory.

A
  • produces prolactin
  • dopamine is inhibitory
  • thyrotropin-releasing hormone is stimulatory
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18
Q
  • … is made in the corticotroph cells of the anterior pituitary gland, where it is released in bursts into the bloodstream and transported around the body.
A
  • ACTH
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19
Q

Thyrotropes (also called thyrotrophs) are endocrine cells in the anterior pituitary which produce … …. hormone in response to … … hormone. Thyrotropes consist around …% of the anterior pituitary lobe cells

A

Thyrotropes (also called thyrotrophs) are endocrine cells in the anterior pituitary which produce thyroid stimulating hormone in response to thyrotropin releasing hormone. Thyrotropes consist around 5% of the anterior pituitary lobe cells

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20
Q

Who discovered the hypothalamic releasing hormones?

A

Andrew Schally and Roger Guillemin - led to Nobel prize in 1977

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21
Q

Hypothalamic releasing hormones

  • GnRH (… releasing hormone)
    • … AA, isolated in 1971
    • Stimulates secretion of … and …
A
  • GnRH (Gonadotropin releasing hormone)
    • 10 AA, isolated in 1971
    • Stimulates secretion of FSH and LH
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22
Q

Hypothalamic releasing hormones

  • SS, known as (…)
  • Inhibits … hormone secretion
A
  • SS (Somatostatin)
  • Inhibits growth hormone secretion
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23
Q

Hypothalamic releasing hormones

  • Dopamine
    • Inhibits … secretion
A
  • Dopamine
  • Inhibits prolactin secretion
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24
Q

Hypothalamic releasing hormones

  • … releasing factor (CRF)
  • … AA, isolated in 1981
  • stimulates secretion of …
A
  • Corticotropin releasing factor (CRF)
  • 41 AA, isolated in 1981
  • stimulates secretion of ACTH
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25
Q

Hypothalamic releasing hormones

  • … releasing hormone (TRH)
  • … AA, isolated in 1969
  • Stimulates … secretion
A
  • thyrotropin releasing hormone (TRH)
  • 3 AA, isolated in 1969
  • Stimulates TSH secretion
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26
Q

Hypothalamic releasing hormones

  • GHRH (… … releasing hormone)
  • … AA … protein receptor secretin family
  • Stimulates … secretion
A
  • GHRH (growth hormone releasing hormone)
  • 44 AA, G protein receptor secretin family
  • Stimulates GH secretion
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27
Q

Structure of pituitary and release of hypothalamic releasing hormones

  • hypothalamus has neurosecretory cells that secrete … hormones
  • these travel down the … circulation in the pituitary … to the … pituitary (where they have their action)
  • neurosecretory cells also secrete posterior pituitary hormones
  • posterior pituitary has more … tissue
A
  • hypothalamus has neurosecretory cells that secrete releasing hormones
  • these travel down the portal circulation in the pituitary stalk to the anterior pituitary (where they have their action)
  • neurosecretory cells also secrete posterior pituitary hormones
  • posterior pituitary has more neurological tissue
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28
Q

Hormones from the hypothalamus are delivered to the … pituitary via the hypothalamic-… portal system. It is … and has … which allows free access and movements of these peptides.

A

Hormones from the hypothalamus are delivered to the anterior pituitary via the hypothalamic-hypophyseal portal system. It is sinusoidal and has pores which allows free access and movements of these peptides.

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29
Q

Hypothalamic–hypophyseal portal system

  • hypothalamus cells - … and … hormones - flow down … system - to the … pituitary - cause this to produce or inhibit … pituitary hormones
  • enter … circulation and travel to distal … tissues and have affect
  • cells in hypothalamus also have … (ADH) and … - into … pituitary - directly into … circulation
A
  • hypothalamus cells - releasing and inhibiting hormones - flow down portal system - to the anterior pituitary - cause this to produce or inhibit anterior pituitary hormones
  • enter systemic circulation and travel to distal target tissues and have affect
  • cells in hypothalamus also have vasopressin (ADH) and oxytocin - into posterior pituitary - directly into systemic circulation
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30
Q
  • The …-… axis (HPA axis) is an interactive neuroendocrine unit comprising of the …, the … gland, and the … glands.
  • The HPA axis plays key roles in basal … and in the body’s response to …
A

The hypothalamic-pituitary axis (HPA axis) is an interactive neuroendocrine unit comprising of the hypothalamus, the pituitary gland, and the adrenal glands.

  • The HPA axis plays key roles in basal homeostasis and in the body’s response to stress
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31
Q

Adrenal-Pituitary Axis

  • For … Regulation (the main …)
  • …-releasing hormone (CRH) is secreted by the hypothalamus
  • CRH travels in the blood to anterior pituitary - to corticotrophs
  • Production of …
  • This is released into the bloodstream and travels to the adrenal glands, where it binds to specific receptors on the adrenal ….
  • The binding of ACTH to the receptors on the adrenal cortex stimulates the release of … into the bloodstream.
  • involves what mechanism?
A
  • For Cortisol Regulation (main glucocorticoid)
  • Corticotropin-releasing hormone (CRH) is secreted by the hypothalamus
  • CRH travels in the blood to anterior pituitary - specifically to corticotrophs
  • These produce ACTH
  • This is released into the bloodstream and travels to the adrenal glands, where it binds to specific receptors on the adrenal cortex.
  • The binding of ACTH to the receptors on the adrenal cortex stimulates the release of cortisol into the bloodstream.
  • Negative feedback mechanism
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32
Q

Thyroid Axis

  • …-releasing hormone (TRH) is released from the hypothalamus
  • TRH travels in the blood to anterior pituitary - to thyrotrophs
  • Production/release of …
  • This is released into the bloodstream and travels to the thyroid gland
  • Stimulatory effect to promote production of both … and …
  • involves what mechanism?
A
  • Thyrotropin-releasing hormone (TRH) is released from the hypothalamus
  • TRH travels in the blood to anterior pituitary - to thyrotrophs
  • Production/release of thyroid stimulating hormone - TSH
  • This is released into the bloodstream and travels to the thyroid gland
  • Stimulatory effect to promote production of both T3 and t4
  • negative feedback mechanism
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33
Q

​__Gonodal axis

  • GnRH (… releasing hormone) is released from the hypothalamus
  • flows through the gonadotropes in pituitary
  • … and … are both produced
  • direct effect to stimulate either testes to produce … and … or the ovaries to make … and …
A
  • GnRH (gonadotropin releasing hormone) is released from the hypothalamus
  • flows through the gonadotropes in pituitary
  • FSH and LH are both produced
  • direct effect to stimulate either testes to produce testosterone and sperm or the ovaries to make oestrogen and eggs
34
Q

Growth hormone axis

  • GHRH (known as…)
  • Somatostatin is the … (these both act in concert to have a tonic control of secretion of growth hormone)
  • Causes secretion of growth hormone
  • Acts on the … (part of body?) to make a hormone called …-1
  • mediates it’s effects
A
  • GHRH (known as growth hormone releasing hormone)
  • Somatostatin is the inhibitor (these both act in concert to have a tonic control of secretion of growth hormone)
  • Secretion of growth hormone
  • Acts on the liver (part of body?) to make a hormone called IGF-1
  • mediates it’s effects
35
Q

Prolactin axis

  • … is the main controller of prolactin secretion and acts in a … manner
  • The … agonist cause … in prolactin whereas … antagonist … prolactin levels
A
  • dopamine is the main controller of prolactin secretion and acts in a negative manner
  • The dopamine agonist cause reduction in prolactin whereas dopamine antagonist raise prolactin levels
36
Q

Negative-feedback controls - Long and short loop reflexes

  • stimulus on the …
  • causing … hormone to be released
  • flows to … pituitary
  • … hormone produced
  • travels in … to a distal endocrine system/target tissue
  • creates additional hormones
  • long loop negative feedback from hormone and also the short loop negative feedback from hormone (e.g long = … acting on anterior pituitary and hypothalamus, also short = … acting on hypothalamus in addition)
A
  • stimulus on the hypothalamus
  • causing trophic hormone to be released
  • flows to anterior pituitary
  • trophic hormone produced
  • travels in bloodstream to a distal endocrine system/target tissue
  • creates additional hormones
  • long loop negative feedback from hormone and also the short loop negative feedback from hormone (e.g long = cortisol acting on anterior pituitary and hypothalamus, also short = ACTH acting on hypothalamus in addition)
37
Q

What hormones does the anterior pituitary make? (6 hormones)

A
  1. Thyroid stimulating hormone (TSH) - affects thyroid
  2. Adrenocorticotropic hormone (ACTH) - affects adrenals - only affects cortisol production (aldosterone etc not effected by ACTH)
  3. Growth hormone (GH) - multitude of effects but direct effect on liver to make IGF-1
  4. Follicle stimulating hormone (FSH) - act on gonads in girls and boys
  5. Luteinizing hormone (LH) - act on gonads in girls and boys
  6. Prolactin (Prl) - acts on the breasts and also acts as contraceptive - dampens down the ovaries
38
Q

What hormones does the posterior pituitary make? (2 hormones)

A
  1. Arginine Vasopressin (AVP) - ADH
  2. Oxytocin
39
Q

There are 5 phenotypically distinct cells in the anterior lobe of the pituitary:

  1. Somatotropes (…% of anterior lobe cells) - these synthesize … hormone - a polypeptide
  2. Lactotropes (…-…% of cells) - these synthesize … - a polypeptide
  3. Corticotropes (…-…% of cells) - these synthesize … - endorphin, peptide varying from 31-20 AA
  4. Thyrotropes (…% of cells) - Produce …, known as … - a glycoprotein
  5. Gonadotropes (…-…% of cells) - Produce … hormone and … … hormone - both glycoproteins
A
  1. Somatotropes (50% of anterior lobe cells) - these synthesize growth hormone - a polypeptide
  2. Lactotropes (10-20% of cells) - these synthesizeprolactin - a polypeptide
  3. Corticotropes (5-10% of cells) - these synthesize ACTH - endorphin, peptide varying from 31-20 AA
  4. Thyrotropes (5% of cells) - Produce thyrotropin known as TSH - a glycoprotein
  5. Gonadotropes (10-15% of cells) - Produce Luteinizing hormone and Follicle stimulating hormone - both glycoproteins
40
Q

What is shown in this image? (pituitary)

A

Structure of anterior lobe cells

41
Q

What is shown in this image? (anterior pituitary cell type)

A

Electron micrograph of a somatograph (growth hormone secreting cell)

42
Q

3 levels of integration - Endocrine control

  • hypothalamus - … hormones produced
  • … hormones
  • … site - hormones secreted here
A
  • hypothalamus - precursor hormones produced
  • pituitary hormones
  • distal site - hormones secreted here
43
Q

Growth hormone

  • Molecular weight of …
  • bound to … … bound protein and … … bound protein
  • half life varies from … to … minutes
  • … to … secretion
  • predominantly secreted at …
  • acts on … to produce …
A
  • Molecular weight of 22,000
  • bound to high affinity bound protein and low affinity bound protein
  • half life varies from 6 to 20 minutes
  • pulse to pulse secretion
  • predominantly secreted at night
  • acts on liver to produce IGF1
44
Q

As well as acting on the liver, … hormone also has a major effect on a lot of bones and structural tissues. It also plays a role in adults to keep … in good shape and for regeneration after …

A

As well as acting on the liver, growth hormone also has a major effect on a lot of bones and structural tissues. It also plays a role in adults to keep muscle in good shape and for regeneration after exercise

45
Q

Prolactin

  • Prolactin is a … amino acid peptide, synthesised in the … cells of the anterior pituitary
  • major function of prolactin is … production - what stimulates it’s ejection?
  • release is tonically inhibited by …
  • inhibits … function (nature is contraceptive)
  • Prolactin control is a … influence
A
  • Prolactin is a 199 amino acid peptide, synthesised in the lactotrophe cells of the anterior pituitary
  • major function of prolactin is milk production - what stimulates it’s ejection? - oxytocin
  • release is tonically inhibited by dopamine (PIH)
  • inhibits gonodal function (nature is contraceptive)
  • negative influence
46
Q

Thyroid and TSH

  • Regulation of thyroid synthesis and secretion via hypothalamic-pituitary-thyroid axis
  • Hypothalamus - … released - goes to the … pituitary - secretion of … - travels to thyroid - … and … produced - also growth of thryoid - … feedback on the hypothalamus and the anterior pituitary
A
  • Regulation of thyroid synthesis and secretion via hypothalamic-pituitary-thyroid axis
  • Hypothalamus - TRH released - anterior pituitary - TSH - thyroid - T3 and T4 produced - also growth of thyroid - negative feedback on the hypothalamus and the anterior pituitary
47
Q

ACTH and the Adrenal Glands

  • Adrenal medulla - does ACTH affect it?
  • Adrenal cortex
    • 3 specific zones and each produces a specific class of steroid hormone
  • list the zones and hormones they produce

ACTH only controls … production, not the others

A
  • Adrenal medulla - does ACTH affect it? - NO
  1. Zona glomuerulosa - mineralocorticoids
  2. Zona fasciculata - glucocorticoids
  3. Zona reticularis - androgens
  • ACTH only affects glucocorticoid production (cortisol)
48
Q
  • Cortisol has a … variation - usually high in the … and low at …
  • Stressful stimulus causes … of cortisol
A

Cortisol has a diurnal variation - usually high in the morning and low at night

  • stressful stimulus causes cortisol release
49
Q

Glycoproteins LH/FSH and the Gonodal axis

  • Long polypeptides (>… AA) bound to one or more … group
A
  • Long polypeptides (>100 AA) bound to one or more carbohydrate group
50
Q

FSH/LH in females

  • control the menstrual cycle
  • … formation and formation of …
  • LH more to do with production of … and FSH more to do with production of …
  • both needed to develop these things
A
  • control the menstrual cycle
  • oestrogen formation and formation of eggs
  • LH more to do with production of oestrogen and FSH more to do with production of eggs
  • both needed to develop these things
51
Q

Menstrual cycle

  • The menstrual cycle is orchestrated by the … system through the complex interaction of the hypothalamus, pituitary and gonads (known as the …-…-… axis). The entire menstrual cycle lasts around … days, with the cycle beginning on the first day of menstruation and … occurring at approximately day 14.
  • Surge of FH & LH around …
A
  • The menstrual cycle is orchestrated by the endocrine system through the complex interaction of the hypothalamus, pituitary and gonads (hypothalamic-pituitary-gonadal axis). The entire menstrual cycle lasts around 28 days, with the cycle beginning on the first day of menstruation and ovulation occurring at approximately day 14.
  • Surge of FH & LH around ovulation
52
Q

FSH/LH in males

  • FSH and LH affects production of … and …
  • LH more to do with production of …
  • FSH more to do with production of …
A
  • FSH and LH affects production of sperm and testosterone
  • LH more to do with productioo of testosterone
  • FSH more to do with production of sperm
53
Q

Posterior pituitary

  • Comprised of the endings of … from cell bodies in the … (… and …)
  • Axons pass from the … to the posterior pituitary via the … tract
  • Posterior pituitary hormones are synthesized in the cell bodies of neurons in the … and … nuclei
A
  • Comprised of the endings of axons from cell bodies in the hypothalamus (supraoptic and paraventricular)
  • Axons pass from the hypothalamus to the posterior pituitary via the hypothalamohypophysial tract
  • Posterior pituitary hormones are synthesized in the cell bodies of neurons in the supraoptic and paraventricular nuclei
54
Q
  • Hormones synthesized in the hypothalamus are transported down the axons to the endings in the … pituitary
  • Hormones are stored in … in this part of the pituitary until release into the circulation
  • Principal hormones are … and …
A
  • Hormones synthesized in the hypothalamus are transported down the axons to the endings in the posterior pituitary
  • Hormones are stored in vesicles in this part of the pituitary until release into the circulation
  • Principal hormones are vasopressin (ADH) and oxytocin
55
Q

What is shown in this image?

A

Synthesis, storage and release of posterior pituitary hormones

56
Q

Two embryological origins for the pituitary gland - the … and the …

A

​Two embryological origins for the pituitary gland - the adenohypophysis and the neurohypophysis

57
Q

Neurohypophysis

  • outgrowth from the …
  • median … - nerve endings and capillaris
  • … … (posterior or nerual lobe) - contains nerve endings and capillaries
A
  • outgrowth from the hypothalamus
  • median eminence - nerve endings and capillaris
  • pars nervosa (posterior or nerual lobe) - contains nerve endings and capillaries
58
Q

What is shown in this image? (posterior lobe of pituitary)

A

Neurosecretory nerve terminals in contact with a capillary in the posterior lobe

59
Q

The two posterior hormones are small … that are really structural in nature

A

The two posterior hormones are small peptides that are really structural in nature

60
Q

Antidiuretic Hormone (ADH)

  • Antidiuretic actions
    • … permeability of the … ducts to water
    • V… receptors
  • Vasopresser actions
    • … vascular … muscle cells
    • V… receptors, non-…
A
  • Antidiuretic actions
    • increases permeability of the collecting ducts to water
    • V2 receptors
  • Vasopresser actions
    • constricts vascular smooth muscle cells
    • V1 receptors, non-hormonal
61
Q

Kidney - ADH

  • ADH causes urine to become more …
  • more water is brought into …
A
  • ADH causes urine to become more concentrated
  • more water is brought into circulation
62
Q

Vasoconstricting action of ADH

  • … BP/circulating volume
  • … production
  • increase water …, increase …
A
  • Low BP/circulating volume
  • ADH then produced
  • increases water production, increase BP
63
Q

Oxytocin

  • Important in Breast-feeding
    • contracts the … cells of the …
    • classic … reflex
  • childbirth (…)
    • in late pregnancy, uterine smooth muscle (…) becomes sensitive to …
    • … feedback mechanism
A
  • Breast-feeding
    • contracts the myoepithelial cells of the alveoli
    • classic neuroendocrine reflex
  • childbirth (parturition)
    • in late pregnancy, uterine smooth muscle (myometrium) becomes sensitive to oxytocin
    • positive feedback mechanism
64
Q

What mechanism is shown here?

A

Positive feedback mechanism

65
Q
  • Oxytocin is a … protein linked receptor
  • causes … influx - causes contraction of smooth muscle in … or ….
A

Oxytocin is a G protein linked receptor

causes calcium influx - causes contraction of smooth muscle in endometrium or breast

66
Q

Lesions of Hypothalamic Pituitary Axis

  • Hypothalamic (hypothalamic or pituitary stalk disease) vs. primary pituitary disease
  • … defects: Tumors (inc pit …), trauma, inflammatory/infiltrative, vascular (inc. Apoplexy) - most common
  • … … defects: … syndrome, pituitary Aplasia, Anencephaly, Midline defects (rare)
  • … Defects: Hypothalamic/Pituitary Hormone gene defects and hormone receptor gene defects (Very rare)
A
  • Hypothalamic (hypothalamic or pituitary stalk disease) vs. primary pituitary disease
  • Acquired defects: Tumors (inc pit adenomas), trauma, inflammatory/infiltrative, vascular (inc. Apoplexy)
  • Congenital embryopathic defects: Killman’s syndrome, pituitary Aplasia, Anencephaly, Midline defects (rare)
  • Genetic Defects: Hypothalamic/Pituitary Hormone gene defects and hormone receptor gene defects (Very rare)
67
Q

Clinical Manifestations of Lesions of Hypothalamic Pituitary Axis - Tumours

  • Mass effects include … and changes in … field leading to defects
  • Endocrine effects:
    • …pituitarism: TSH/ACTH/GH/LH-FSH/Prolactin
    • …pituitarism: TSH/ACTH/GH/LH-FSH/Prolactin
A
  • Mass effects include headaches and changes in visual field
  • Endocrine effects:
    • hypopituitarism:
    • hyperpituitarism:
68
Q

Syndrome of Panohypopituitarism

  • progressive loss of … … function: first hormones to usually go = … and …, also …; …; …
  • Hypopituitarism with … … is suggestive of hypothalamic etiology
A
  • progressive loss of anterior pituitary function: first hormones to go = FSH/LH and GH; TSH; ACTH
  • Hypopituitarism with Diabetes Insipidus is suggestive of hypothalamic etiology
69
Q

What diagnosis is present in the image below?

A

Pituitary tumour

70
Q

Prevalence of pituitary tumours: (6 types in total)

  • What is most common?
  • Second most common?
  • What is relatively common? (2 types)
  • least common?
  • very rare?
A
  • most common = prolactin tumours
  • second most common = non-functioning tumors
  • relatively common = GH tumours, ACTH tumors
  • least common = FSH/LH
  • Very rare = TSH tumors
71
Q

Pituitary Adenoma

  • Microadenomas are
  • Macroadenomas are >and including …mm
  • majority are monoclonal and not …
  • may or may not be …
  • … effects and … may be present irrespective of functional status
  • Functioning (Secretes …) vs. non-functioning
A
  • Microadenomas are <10mm
  • Macroadenomas are >and including 10mm
  • majority are monoclonal and not malignant
  • may or may not be functional
  • mass effects and hypopituitarism may be present irrespective of functional status
  • functioning (Secretes hormones) vs. non-functioning
72
Q

Types of Pituitary Adenoma

  • … : Produce too much prolactin
    • Produces galactorreah, reduced … function
  • … secreting tumours: produce too much ACTH - too much cortisol = … syndrome
    • centropetal …, … skin, osteoporosis, dia…
  • … secreting: produce too much growth hormone - leading to …
  • FSH/LH secreting: rare
    • … syndromes
  • TSHomas: TSH secreting - very rare
    • leads to …
A
  • Prolactinomas: Produce too much prolactin
    • Produces galactorreah, reduced gonodal function
  • ACTH secreting tumours: produce too much ACTH - too much cortisol = cushing’s syndrome
    • centropetal obesity, thin skin, osteoporosis, diabetes
  • GH secreting: produce too much growth hormone - acromegaly
  • FSH/LH secreting: rare
    • hypersecretion syndromes
  • TSHomas: TSH secreting - very rare
    • leads to thyrotoxicosis
73
Q

Clinical Assessment - Pituitary

  • … - symptoms of … excess or deficiency
  • … - signs of hormone excess or deficiency
  • basal hormone result - pituitary hormones e.g. …, ACTH, GH and downstream hormones e.g. …, IGF-1
  • … secretion - to distinguish normal from abnormal
  • … fields
  • … MRI (CT)
A
  • History - symptoms of hormone excess or deficiency
  • examination - signs of hormone excess or deficiency
  • basal hormone result s- pituitary hormones e.g. prolactin, ACTH, GH and downstream hormones e.g. cortisol, IGF-1
  • Stimulated secretion - to distinguish normal from abnormal
  • Visual fields
  • Imaging e.g. MRI (CT - first way historically, MRI better)
74
Q

Stimulating secretion results: Insulin Hypoglycaemia test

  • Give …
  • Blood glucose … - below … = pituitary churns out … to raise this level
  • If you induce … episode = max response from pituitary, checks it’s ….
A
  • Give insulin
  • Blood glucose fall - below 2 = pituitary churns out hormones to raise this level
  • If you induce hypoglycaemic episode = max response from pituitary, checks it’s response
75
Q

Simultaneous Bilateral Inferior Petrosal Sinus and Peripheral Vein Sampling for ACTH

  • 2 catheters into … supplying pituitary, either side
  • give …. - cortisol releasing hormone
  • Causes ACTH production from pituitary
  • …. secreting adenoma = … release of ACTH
  • See in figures if much brisker response on either side of the pituitary - shows what …. the tumour is on
A
  • 2 catheters into vein supplying pituitary, either side
  • give CRH - cortisol releasing hormone
  • Causes ACTH production from pituitary
  • ACTH secreting adenoma = greater release of ACTH
  • See in figures if much brisker response on either side of the pituitary - shows what side the tumour is on
76
Q

Pituitart Tumour Visual Field Defect

  • ​Optic … - nerves cross above … - lesion pressing on this means you get a … …
  • lose vision on …. of both eyes
  • only place that causes this - characteristic of a pituitary tumour pressing on optic chiasm
  • tells you exactly where lesion is
A
  • ​Optic chiasm - nerves cross above pituitary - lesion pressing on this means you get a Bitemporal hemianopsia
  • lose vision on outside of both eyes
  • only place that causes this - characteristic of a pituitary tumour pressing on optic chiasm
  • tells you exactly where lesion is
77
Q
  • What is shown in this image?
A
  • CT scan of pituitary
78
Q

What is shown in this image?

A

MRI of pituitary

79
Q

What is shown in this image?

A

MRI of pituitary adenoma touching the optic chiasm

80
Q
A

Year 2 Medicine (162 decks)

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