neuroendocrinology Flashcards
neuroendocrinology
branch of the biological sciences dealing with neurosecretion and the physiological interaction between the central nervous system and the endocrine system
what do neuroendocrine cells receive ?
neuronal input and secrete hormones in response to that input – the sites where this occurs are the hypothalamus and the pituitary gland
what homeostatic functions are controlled by the neuroendocrine system?
1.blood pressure and electrolyte composition
2.body temperature
3.energy metabolism
4.reproduction
5.stress response
6.growth
Blood pressure and electrolyte composition
control of drinking and salt appetite and control of blood osmolality and vasomotor tone
Body temperature
metabolic thermoregulation and behaviours like seeking an appropriate environment
3 processes in energy metabolism
1.feeding
2.digestion
3.metabolic rate
Reproduction
hormonal control of mating, pregnancy and lactation
Stress response
adrenal stress hormones
Growth
growth hormone
what is does the hypothalamus function?
integrate autonomic nervous system signals and endocrine function with behaviour, especially behaviour concerned with basic homeostatic requirements of every day life
what 3 ways can the homeostasis be controlled through?
1.Behavioural responses
2.Neuronal control through the autonomic nervous system
3.Hormonal control through hormone release from the pituitary gland
what are the 2 main mechanisms by which the hypothalamus can regulate the pituitary gland?
- parvocellular neurones
2.magno cellular neurones
parvocellualar neurones
small neurones and small axons which signal to the anterior pituitary(which links to the hypothalamus) via the hypothetical portal system which involves the portal vein
portal vein
comes from 1 capillary bed to another capillary bed , links directly to other areas of the body
what do Parvo cellular neurones release
release hormones into the portal system - these hormones make a direct route through the blood to the pituitary
what happens when the Parvo cellular neurones release hormones and the go through the blood to the pituitary ?
bind to the target receptors in the anterior pituitary cells and signal to the anterior pituitary which responds to those signals by releasing other hormones
in parvo cellular neurones cell when the hormones are released, where are they released to?
general circulation
magno cellular neurones
bigger neurones and longer axons(these are In the hypothalamus
in magno cellular neurones where do the longer axons project?
-directly into the posterior pituitary -theres no portal system here
in the magno cellular neurones, where do the axons project to ?
general circulation
once hormones have reached the general circulation phase where do they signal?
to the downstream gland
what are the 3 downstream glands?
1.thyroid
2.gonads-overies or testes
3.adrenal
access
when the hormones in general circulation are signalled to a down stream gland
what is one example of three things would make an axis ?
1.hypothalamus
2.pituitary
3.gonand
what 2 things does the infundibulam link?
the pituitary and the hypothalamus
what 4 main groups have the nuclei of the hypothalamus been divided into?
1.pre optic area
2.anterior o super optic region
3.middle region or tubule
4.posterior region
where is the para ventricular nucleus
this is in the anterior region
what is para ventricular nucleus involved in?
stress hormone, hormone Thyroid releasing hormone(TRH)
what 3 things is TRH involved in ?
1.metabolism
2.osmo regulation
3.blood pressure
what 2 things is arcuate nucleus involved in?
1.reproduction
2.growth
3.lactation
super optic nucleus
releases ADH hormones involved in osmoregulation and blood pressure and maternal control via oxytocin
where is the pituitary glands located?
cavity within the sphenoid bone at the base of the brain called the sella turcica
how many lobes does the pituitary gland consist
two lobes of relevance to human physiology – the middle lobe is insignificant
what type of blood does capillary bed in the hypothalamus deliver?
oxygenated blood
what type of blood does the posterior pituitary blood take back to the circulatory system ?
deoxygenated blood
what do releasing hormones do?
comes from the hypothalamus and signals further release of something downstream in the pituitary gland
what are the 5 different target cell types within the anterior pituitary
1.Corticotropin releasing hormone (CRH)
2.Thyrotropin releasing hormone (TRH)
3.Gonadotropin releasing hormone (GnRH)
4.Growth hormone releasing / inhibiting hormones (GHRH/GHIH)
5.Prolactin inhibiting hormone (dopamine)
what hormones do each of these release ?
1.Corticotropin releasing hormone (CRH)
2.Thyrotropin releasing hormone (TRH)
3.Gonadotropin releasing hormone (GnRH)
4.Growth hormone releasing / inhibiting hormones (GHRH/GHIH)
5.Prolactin inhibiting hormone (dopamine)
1.ACTH
2.TSH
3.LH, FSH
4.Growth hormone
5.Prolactin
what does HPA axis include?
-cortical dropping
-releasing hormone signalling in the anterior pituitary releasing ACTH in response to that then goes to the adrenal glands
what happens after the ACTH goes to the adrenal glands?
theres a negative feedback loop from cortisol to the hypothalamus and the anterior pituitary to down regulate for CRH and ATCH due to inhibition of both of these
what hormone is in the reproductive axis ?
gonadotrophin releasing hormone (GnRH) which signals to the anterior pituitary
in the reproductive system what 2 things does the gonadotrophin releasing hormone, inhibit?
-LH-lutenzining hormone
-FSH-follicule stimulating hormone
when the gonadotrophin releasing hormone sends signalling to the ovaries and testes what hormones do they release?
steroid sex hormones
what are 2 growth hormones?
1.prolactin
2.growth hormone
what is the release of growth hormones determined by?
balance between the releasing hormone and the inhibits hormone
what is an alternative name for growth hormone ?
somatostatin
what does prolactin enhance but what does it inhibit ?
dopamine secretion and inhibits prolactin release
what type of neurones are super optic nucleus and ventricular neurones called?
cellular neurones
what types of axons does the posterior gland include?
myelinated axons
what 2 nuclies does the myelinated axons come from?
1.para ventricular nucleus
2.super optic nucleus
pituicytes
-contains astrocyte-like neuroglial cells
-cytoplasmic processes that surround the axons
-found in the posterior pituitary gland
what 2 things are released in the posterior pituitary gland?
antidiuretic hormone (arginine vasopressin)
-oxytocin
what are both antidiuretic and oxytocin hormones produce by?
hypothalamic nuclei (to some extent), but they are produced by separate cell types
what are both antidiuretic and oxytocin hormones ?
small peptide hormones synthesised as larger precursors in cell bodies in the hypothalamus
what are antidiuretic and oxytocin hormones , packaged and processed into?
mature hormone and bound to carrier proteins
where is the hormone-carrier complex transported along?
neuronal axon and temporarily accumulates at Herring bodies
what do the hormone containing vesicles fuse with?
cell membrane in response to action-potential associated Ca2+ influx, releasing the hormone
what does the hormone dissociate from ?
carrier protein, which has no further function
what do the antidiuretic hormone increase in the kidneys ?
water reabsorption and causes constriction of arterioles , raising blood pressure
what does oxytocin cause
uterine contraction during labour and milk ejection- during breastfeeding
what do oxytocin- releasing terminals do?
project into other parts of the brain, producing cognitive and behavioural effects related to social bonding
Neuroendocrine cells
present in the peripheral nervous system - in the peripheral nervous system -particularly the sympathetic branch of the autonomic system
what do the sympathetic neurones supply with nerves
the adrenal medulla
what forms in the adrenal medulla ?
form synapses with Chromaffin cells that resemble post-synaptic neurons
upon receiving neuronal stimulation, what do the cells release?
adrenaline and noradrenaline as part of the ‘fight or flight’ response
