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PA10315 2nd semester > Neuroendocrine regulation and pituitary > Flashcards

Neuroendocrine regulation and pituitary Flashcards

1
Q

Overview of neuroendocrine regulation

A

Hypothalamus secretes stimulating factors (on) or inhibiting factors (off) which act on the anterior and posterior pituitary gland
Pituitary gland secretes trophic factors/hormones which act on gonads, thyroid and adrenal. These release primary hormones into circulation that target tissues

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2
Q

How does hypothalamus act on the pituitary gland

A

Synapses with the posterior pituitary gland and releases adh and oxytocin

Causes the anterior pituitary gland (by release of regulatory hormones) to release primary hormones including GH and prolactin (during pregnancy makes mammary glands develop milk ducts)
The anterior pituitary gland targets endocrine glands

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3
Q

Where is the hypothalamus located

A

at the base brain

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4
Q

What does the hypothalamus use the pituitary gland as

A

output organ

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5
Q

Hypo to posterior

A

Hypothalamus has modified neurosecretory cells, modified nerve endings which release ADH directly into circulation and act on the posterior pituitary gland

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6
Q

Hypo to anterior and

A

Hypo releases trophic hormone into median eminence and the Hypothalamo-pituitary portal vessel to anterior pituitary
Blood flow 1 direction, only hypo signals to anterior pituitary
Means small amounts of hormone needed to bring about response in anterior
Anterior v vascularised- easily secrete hormones into blood

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7
Q

Hypothalamic nuclei

A 
have diverse functions
Areas for neuroendocrine control: 
paraventricular nucleus (oxytocin release- lactation) 
Supraoptic (vasopressin/release)
Arcuate nucleus and periventricular zone (neuroendocrine control)
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8
Q

Cells in the periventricular zone

A

They are suprachiasmatic neurones- receive retinal innervation and synchronize circadian rhythms (based on daylight). Light/dark cycle drives neuroendocrine signals

Send output to sympathetic and parasympathetic output neurones in spinal cord to control activity of ANS

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9
Q

Neurosecretory cells

A

responsible for release of regulatory hormones to control pituitary gland

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10
Q

Hypo regulatory hormones: releasing/stimulating factors

A 
CRF- corticotropin releasing factors
TRH- thyrotropin releasing hormone
GHRH- growth hormone releasing hormone
GnRH- gonadotropin releasing hormone
PRF- prolactin releasing factor
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11
Q

Hypo regulatory hormones: Inhibiting factors

A

GHIH- growth hormone inhibiting hormone
PIH- prolactin inhibiting hormone
MSH-IH- melanocyte stimulating hormone inhibiting hormone

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12
Q

Anatomy of pituitary gland

A

Different sorts of tissues
Pars nervosa- posterior, nerve like
Pars distalis- anterior, has secretory vesicles with hormones
Pars intermedia in the middle, has neither anterior nor posterior, releases MSH

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13
Q

Anterior pituitary hormones, four trophic hormones

A

Thyroid Stimulating hormone
AdrenoCorticoTrophic Hormone
Follicle Stimulating Hormone
Lutenizing hormone

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14
Q

Anterior pituitary hormones: two primary hormones

A

Growth Hormone
PRoLactin

caps intentional

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15
Q

GnRH from hypo triggers release of

A

LH, FSH from pituitary

Which acts on testes, ovary

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16
Q

TRH

A

TSH

Thyroid

17
Q

CRF

A

ACTH

adrenal

18
Q

GHRH

A

GH (somatotropin)

multiple tissues

19
Q

SRIF

A

GH

multiple tissues

20
Q

PRF and PIH

A

Prolactin

Breast

21
Q

Negative feedback control

A

In loops

Hormone released from endocrine gland switches off its own production and feeds back onto anterior pituitary- inhibits release of pituitary hormones

Pituitary hormones feed back onto anterior pituitary and hypothalamus to switch off production of hormones

hypo- releasing hormone- AP-Pituitary hormone- endocrine gland- hormone

22
Q

Effects of growth hormone (somatotropin,/somatotrophin)

A

Incr cell size, number and differentiation
Stimulate proteinsynthesis
incr bone growth
Stimulate fat utilization (breakdown)
Alter carbohydrate metabolism (growth requires energy, release of glucose)

23
Q

GH main role

A

Regulator of post natal growth

24
Q

GH acts at … and how?

A

receptor tyrosine kinase

Binds, triggers phosphorylation of TK residues inside the cell, activates kinase cascade (activation of MAP kinases etc)

25
Q

Effects of GH on proteinsynthesis

A

First GH acts on liver to bring about production of somatomedins (insulin-like growth factors)
GH and somatmedins act on the nucleus to incr transcription, and acts on ribosomes to incr translation. They also incr uptake of amino acids via transporters into the cell- building blocks

Overall incr PS

26
Q

Somatomedins

A

small proteins produced by the liver in response to GH
At least 4 produced- somatomedin C most important
Long half life vs GH (20h vs <20 mins)

27
Q

GH released in response to

A

GHRH

28
Q

Release of GH decr by

A

GHIH or somatostatin

29
Q

GH secretion control

A

GHIH and GHRH released from ventromedial hypothalamus

GH regulated by short feedback loop

30
Q

What factors is GH controlled by

A

sleep, exercise, stress

31
Q

somatomedins feed back onto

A

GHIH production positively

GHRH production negatively

32
Q

Deficit of GH

A

dwarfism, may be:

  • anterior pituitary dysfunction
  • GH deficit
  • normal GH by hereditary somatomedin deficit

Accelerated ageing- loss of GH after adolescence
- decr PS

33
Q

Excess GH

A

Gigantism- early life pituitary tumour

Acromegaly- pituitary tumour after adolescence

34
Q

Acromegaly

A 
excess production GH
Most affects middle aged
Premature death
Slow onset so freq incorrectly diagnosed
Most common symptoms are abnormal growth of hands and feet
35
Q

Acromegaly: treatment

A

Aim to reduce GH production:
- surgical removal of tumour
drug therapy: octrotide and lanreotide (somatostatin analogues), bromocriptine
-Radiation therapy

36
Q

Daily Pattern of GH release

A

Surge overnight

Shows circadian rhythm

37
Q

GH secretion is episodic

A

in bursts
surge at birth, puberty
Stable at adulthood
Decline in old age

38
Q

insulin induced hypoglycaemia

A

stimulated GH secretion
decr glucose, FAs, AAs
Incr GH

PA10315 2nd semester (27 decks)

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