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BRS 4: Endocrinology > 4.1: The pituitary gland > Flashcards

4.1: The pituitary gland Flashcards

1
Q

What is a hormone?

A

A messenger carried by the blood stream

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2
Q

Two main hormone classifications

A

Peptide and Steroid

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3
Q

Synthesis of Peptide hormones

A

synthesised as prohormones (long inactive chain) requiring further processes to activate

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4
Q

Storage of Peptide hormones

A

Stored in vesicles, released by stimulus

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5
Q

Receptors of peptide hormones

A

On cell membrane, then transducer signal using 2nd messenger (intracellular signal cascade)

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6
Q

Synthesis of steroid hormones

A

Synthesised in series of reactions from cholesterol

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7
Q

Storage of steroid hormones

A

Released immediately (constitutive secretion)

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8
Q

Receptors of steroid hormones

A

Bind to intracellular receptors, change gene expression directly

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9
Q

What bone does the pituitary gland sit in

A

Stella turcica of sphenoid bone

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10
Q

Another name for anterior pituitary gland, and cell type

A

Adenohypophysis
Epithelial

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11
Q

Origin of anterior pituitary gland

A

Upgrowth from oral ectoderm of primitive oral cavity - Rathkes pouch (in embryo)

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12
Q

Another name of posterior pituitary gland and cell type

A

Neurohypophysis
Neural origin

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13
Q

Where is the posterior pituitary gland derived from

A

Down growth of diencephalon that forms floor of the third ventricle (in embryo)

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14
Q

What regulates anterior pituitary function

A

Hypothalamic-pituitary portal system

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15
Q

How is the anterior pituitary gland regulated

A

Parvocellular neurones in the hypothalamus release signals which terminate at the median eminence.
Median eminence released hypothalamic releasing/inhibiting factors into capillary plexus in median eminence.
Factors carried by portal circulation to anterior pituitary.

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16
Q

5 endocrine cells making up anterior pituitary

A

Somatotrophs
Lactotrophs
Corticotrophs
Thyrotrophs
Gonadotrophs

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17
Q

Hypothalamo-pituitary portal system

A

Hypothalamic neurosecretory cells release hormones into hypothalamo-pituitary portal system
RHS and IHs travel in portal system to anterior pituitary
Stimulate or inhibit hormone release from anterior pituitary cells
Anterior pituitary hormones leave gland via blood

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18
Q

Somatotrophs release

A

Growth hormone

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19
Q

Lactotrophs release

A

Prolactin

20
Q

Thyrotrophs release

A

Thyroid stimulating hormone (TSH)

21
Q

Gonadotropins release

A

Luteinising hormone (LH)
Follicle stimulating hormone (FSH)

22
Q

Corticotrophs release

A

Adrenocorticotrophic hormone (ACTH)

23
Q

What regulates growth hormone

A

Releasing - growth hormone releasing hormone
Inhibiting - somatostatin

24
Q

What regulates prolactin

A

Inhibiting- dopamine

25
Q

What regulates thyroid stimulating hormone (TSH)

A

Releasing - thyrotrophin releasing hormone

26
Q

What regulates LH and FSH

A

Gonadotrophin releasing hormone

27
Q

What regulates Adrenocorticotrophic hormone (ACTH)

A

Release - corticotrophin releasing hormone

28
Q

Target of GH

A

General body tissues (liver)

29
Q

Target of prolactin

A

Breasts (lactating women)

30
Q

Target of TSH

A

Thyroid

31
Q

Target of Gonadotrophins (LH & FSH)

A

Testes and ovaries

32
Q

Target of ACTH

A

Adrenal cortex

33
Q

What sits above the pituitary gland

A

Optic chiasm

34
Q

What happens if a pituitary tumour compresses the optic chiasm

A
  • bitemporal hemianopia
    Fibres from nasal retinae which cross at optic chiasm are compressed, preventing transmission of sensory information from lateral (temporal) visual fields to occipital lobe
35
Q

Mechanism of growth hormone action

A

Acts directly on body tissues but also stimulates insulin-like growth factor (IGF-1 and 2) which also acts

36
Q

Excess growth hormone can lead to

A

(ADULTS) - ACROMEGALY Coarsening of facial features (macroglossia and prominent nose)
Prognathism: large jaw
Increased hand and feet size
Sweatiness
Headache
(CHILDREN) GIGANTISM

37
Q

2 posterior pituitary hormones

A

Arginine vasopressin (AVP) : Anti-diuretic hormone
Oxytocin
(Produced by hypothalamus put stored in posterior pituitary)

38
Q

Anatomy of posterior pituitary

A

Continuous with hypothalamus

39
Q

What is controlled in posterior pituitary regulation

A

Hypothalamic magnicellular neurons
Supraoptic - AVP
Paraventicular - oxytocin

40
Q

Regulation of posterior pituitary gland

A

Two sets of hypothalamic neurosecretory cells produce AVP and oxytocin and transport them to posterior pituitary
Excitation of hypothalamic magnocellular neurones stimulates release of AVP or oxytocin, they diffuse into blood

41
Q

Physiological action of vasopressin (AVP / ADH)

A

Stimulation of water reabsorption in renal collecting duct, concentrating urine
Vasoconstrictor, stimulating ACHT release from anterior pituitary

42
Q

How does vasopressin concentrate urine

A

AVP from blood binds to V2 receptor on cells lining lumen of collecting duct,
Triggers intracellular signalling cascade
Allows insertion of aquaporin-2 to membrane
Water reabsorbed unit lumen
Aquaporin-3 added to membrane to allow water to be reabsorbed into blood stream

43
Q

2 physiological actions of oxytocin

A

Uterus at parturition - myometrial cells - contraction - baby delivery
Breast during lactation - myoepithelial cells - contraction- milk ejection

44
Q

2 physiological actions of oxytocin

A

Uterus at parturition - myometrial cells - contraction - baby delivery
Breast during lactation - myoepithelial cells - contraction- milk ejection

45
Q

Role of anterior pituitary in lactation

A

Mechanical stimulation activates afferent pathways
Signals integrated in hypothalamus and inhibit dopamine release from dopaminergic neurons
Less dopamine = less inhibition of anterior pituitary Lactotrophs
Increased plasma prolactin increases milk SECRETION in mammary glands

46
Q

Role of posterior pituitary in lactation

A

Mechanical stimulation activates afferent pathways
Stimulate oxytocin in hypothalamus releasing neuron activity
Action potentials travel down oxytocin neurons and oxytocin into blood
Increased plasma oxytocin increases milk ejection in mammary glands

BRS 4: Endocrinology (10 decks)

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