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Pituitary gland Flashcards

(44 cards)

1
Q

What is a hormone?

A

A messenger carried from organ from where it is produced to the affected organ through the bloodstream

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2
Q

What are the two types of hormones?

A

Steroid and peptide

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3
Q

How are peptides synthesised as first

A

prohormones (long polypeptide chain) then cleaved by regulatory enzymes

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4
Q

how are peptide hormones stored and released?

A

stored in vesicles and released by regulatory (stimulatory secretion)

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5
Q

describe the receptors that peptide hormones bind to and how signal reach target?

A

Bind to receptors on cell membrane and transduce signal using 2nd messenger model

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6
Q

how are STEROID hormones synthesised to at first? I.e precursor to all steroid hormones

A

synthesised from CHOLESTEROL in a series of reaction

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7
Q

how are steroid hormones secreted?

A

Constitutive secretion

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8
Q

what type of receptor does steroid hormone bind to?

A

intracellular receptors- transcription factors

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9
Q

what is the pituitary stalk called?

A

infundibulum

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10
Q

what are the 2 parts of the pituitary gland?

A

anterior (adrenohypohysis) and posterior(neurohypophysis)

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11
Q

what are the 3 sections of the anterior pituitary gland

A

pars tuberalis
pars intermedia
pars distalis

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12
Q

where does the pituitary gland sit

A

sella turcica of the sphenoid bone

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13
Q

what part of the brain is located anterio- superior to the pituitary gland

A

optic chiasm

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14
Q

what neurons regulate the anterior pituitary function?

A

Hypothalamic parvocellular neurons

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15
Q

where does the parvocellular neurons terminate

A

median eminence

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16
Q

How does signals from parvocellular neurons reach anterior pituitary gland?

A

VIA hypothalamo-pituitary portal circulatory system

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17
Q

how is the anterior pituitary anatomically distinct from the hypothalamus?

A

DOES NOT contain neural tissue but contains glandular tissue, that’s why parvocellular neurons terminate in median eminence

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18
Q

what type of endocrine cells make up the anterior pituitary gland?

A
Somatotrophs
Lactotrophs
Gonadotrophs
Corticotrophs
Thyrotrophs
19
Q

Describe in detail how the hypothalamus causes thyrotrophs to release THYROTROPHIN

A

hypothalamus parvocellular cells terminate in median eminece
secrete Thyrotrophin releasing hormone into portal system
goes to anterior pituitary (thyrotrophs) and causes thyotrophin to be released.
thyrotrophin released into the blood to thyroid gland
thyroid gland release thyroxin

20
Q

list the endocrine cells of anterior pituitary and their respective hormones they produced

A
somatotrophs- Growth hormone
Lactotrophs- Prolactin
Gonadotrophs- FSH and LH
Thyrotrophs- thyrotrophin
corticotrophs- Adenocorticotrophic hormone(ACTH)
21
Q

Which hormone produced by the parvocellular cells stimulate or Inhibit production of growth hormone

A

Stimulate- Growth hormone releasing hormone.

Inhibit- Somatostatin

22
Q

What hormone controls release of prolactin from lactotrophs?

A

Dopamine- IT INHIBITS ONLY

23
Q

What hormone controls release of TSH (Thyrotrophin)

A

THYROTROPHIN releasing HORMONE. IT STIMULATES only.

24
Q

What hormone controls release of the following? LH/FSH and corticotrophin(ACTH)?

A

LH/FSH- gonadotropin elapsing hormone

ACTH- corticotrophin releasing hormones

25
Where are the receptors of the hormones produced by the anterior pituitary gland?
``` Growth hormone- bone/muscle or liver Prolactin- lactating breast or uterus Thyrotrophin- thyroid gland LH/FSH- testes or ovaries Corticotrophin- adrenal cortex ```
26
What type of scanning is used to locate the pituitary gland?
MRI
27
What causes BITEMPORAL hemianopia
When optic chiasm is compressed; hence contraletral fibres frommedial retinae cant be passed down to the brain. Hence lose peripheral vision. Caused by pituitary tumour underneath the optic chiasm.
28
Outline the neuroendocrine reflex arc for milk production?
Mechanical stimulation by bay on breast Ascending pathway to hypothalamus where dopamine is produced in lesser amount. Less dopamine flow through portal circulatory system. Less lactotophs inhibited Increased plasma prolactin More milk synthesised in mammary glands
29
What hormone produced by liver stimulate growth of bone and muscle
IGF1- adult | IGF-2 FOETUS
30
What’s the difference between acromegaly and gigantism
Acromegaly -too much growth hormone in adults | Gigantism- in children. There’s increase in height as epiphyseal growth plates haven’t fused yet
31
What are the other symptoms of acromegaly
``` Macroglossus- enlarged tongue Increased size of feet and hand Large jaw prognathism Sweatiness Headaches Prominent nose Intradental space ```
32
What tests could you use to confirm acromegaly
Test for growth hormone or IGF-1 Test for oral glucose tolerance; liver glucagon secretion is affected due to too much growth hormone. I.e. you’re given too much glucose (75g sugary drink) and your growth hormone should drop after 2 hrs with rise in glucose.
33
What hormones are produced by the neurohypophysis?
``` Arginine vasopressin(ADH/AVP) Oxytocin ```
34
What neurones cause release of hormones form the neurohypophysis? Describe the process
Magnocellular neurone. It goes directly to neurohypophysis from hypothalamus as the posterior pituitary gland is made out of neural tissue( anatomically continuous with brain).
35
Describe length and origin of magnocellular neurone that causes release of AVP
Long; supraoptic nuclie
36
Describe the length and origin of the magnocellular neurone that causes release of oxytocin?
Long; paraventricular nuclei
37
What causes release of AVP or oxytocin
Excitation ONLY of magnocellular neurones
38
Describe and explain the function of AVP (ADH)?
Stiumulate water reabsorption into renal collecting duct; hence concentrates urine
39
What receptor does ADH bind to in the collecting duct
V2
40
What is the other function of AVP
``` A vasoconstrictor (binds via V1 receptor.) Stimulate ACTH release from adrenohypophysis ```
41
Describe the action of oxytocin in the uterus in parturition
Binds to receptors in myometrial cells and causes contraction Baby delivered
42
Describe the action of oxytocin in breast during lactation?
Bind to receptors on myoepithelial cells and causes contractiion Milk ejection
43
What hormone does the adrenal cortex release after being stimulated by ACTH
CORTISOL.
44
What is the peptide precursor for ACTH?
PRO OPIOMELANOCORTIN