Principles of neuroendocrinology Flashcards

1
Q

neuroendocrinology

A

study of physiological processes involved in integrating neural and endocrine functions
brain produces neurohormones

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2
Q

neuroendocrine systems

A

set of neurons, glands, non-endocrine tissues and neurochemical, hormones, humoral signals they produce and receive, that function in an integrated manner to collectively regulate a physiological or behavioural state

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3
Q

neuroendocrine integration

A

process by which neuroendocrine signals register/transduce/interpret important signals/internal and external environment & direct adaptive changes in prevailing physiological and behavioural states

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4
Q

what do NTs/neurohormones/hormones cause

A

AP cause depolarisation of the nerve terminal
increase permeability
Ca2+ influx
NT release via exocytosis

hormones released by endocrine cells into bloodstream act at a distance to target cells

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5
Q

neurosecretion

A

production and secretion of neurohormones by neurons into the bloodstream
vesicles are larger (100-400um) longer AP duration = more Ca2+ influx per AP

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6
Q

neurosecretory cells

A

posterior pituitary (cell bodies in SON/PVN)
similar structure to other neurons/dendrites/perikarya/axons
different morphology for specialised function

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7
Q

peptidergic

A

peptides with varying size 3-50AA chains
peptide synthesised in cell body (larger inactive precursor polypeptide) on RER
golgi packages precursor material into granules, transported to terminals by axonal transport - copackaged peptidase enzyme processes the final secretory product within vesicles
e.g magnocellular neurons in PVN/SON product OT/AVP

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8
Q

neuropeptide processing

A

neuropeptide - prepro - pro - hormone

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9
Q

evidence for neuropeptide processing

A

cysteine (aa) associated with OT/AVP
radiolabelled cysteine injected in rat cerebral ventricles
radioactivity accumulates in SON/PVN of hypothalamus - radioactivity in pituitary stalk and posterior lobe
rat given hypertonic salt solution (for AVP secretion) causes faster accumulation and cysteine transport
axonal transport via radioactive phosphorus is identical

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10
Q

excitation/secretion coupling

A

depolarisation (AP) causes AVP secretion
depolarisation by increasing K+ concentration
increase in Ca2+ conc causes hormone release, agents which block Ca2+ interfere with secretory response

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11
Q

define homeostasis

A

process requiring co-ordinated control over endocrine, behavioural, autonomic nervous responses to the environment
hypothalamus at the base of the brain - sends projections to circulatory system and higher brain centres

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12
Q

what is the circumventricular organ

A

present in many sites in the ventricular system
lacks the BBB - endothelial cells are fenestrated allowing diffusion
hormones out/circulating factors in (median eminence)

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13
Q

types of nuclei in the hypothalamus

A

feeding: ARC/VMH/LH
drinking: PVN/SON
sexual behaviour: pre optic/VMH
stress response: PVN
electrolyte and water balance: SON/PVN
centre concept is outdated - fine tuning

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14
Q

what are the tissues which form the neurohypophysis and adenohypophysis

A

invagniation of FB (diencephalon) which form the posterior lob (neurohypophysis) - SON/PVN
outgrowth of the buccal cavity (rathke’s pouch) - forms anterior lobe (adenohypophysis) - glandular
pars intermedia forms MSH (not in adult humans)

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15
Q

secretion of the anterior and posterior pituitary

A

anterior: LH/FSH/TSH/ACTH/PRL/GH
posterior: AVP/OT

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16
Q

appetite hormones

A

leptin - secreted from adipose, decreases food intake
PYY3-36 - decreases food intake
GLP-1 - releases insulin
ghrelin - increases food intake

17
Q

hypothalamo-hypopysial portal system

A

anterior pituitary passes via long/short hypophyseal portal vessels
superior hypophyseal artery supplies the median eminence and stalk
inferior hypophyseal artery supplies the posterior lobe and anterior lobe via short portal vessels
both lobes drain into venous sinuses

18
Q

milk reflex

A

suckling activates the afferent nerves
activates efferent nerves in hypothalamus
neurosecretion of oxytocin
oxytocin mediated milk ejection

19
Q

nipple innervation

A

contains mechanosensory nerves and sends an AP
increased OT via posterior P milk ejection via contraction
increased prolactin decreased DA (negative feedback)

20
Q

neuronal reflex

A

similar to neuromuscular reflex
transient fixed pattern response to a stimulus
e.g. Posterior P OT milk ejection

21
Q

homeostatic control mechanisms

A

restrict physiological/behavioural variable around a set point
use negative feedback
hypo-pituitary-endocrine organ axis
food intake

22
Q

homeostatic neuroendocrine axis 3 Tier

A

HPT/HPA/HPG
hypothalamus to anterior pituitray via hypothalamus releasing/inhibiting factors
anterior pituitary to end organ by adenohypophysis hormone
end organ signals back to hypothalamus and pituitary
negative feedback via long/short loop feedback

23
Q

Homeostatic neuroendocrine axis 2 tier

A

GH/PRL release - acts at multiple target organs, feedback from pituitary more important
hormone secretion mainly under control of short feedback loop (from anterior pituitary)