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Neuroendocrine

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imissyou419's version from 2017-04-01 01:56

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Hypothalamus-anterior pituitary & hormoneParvicellular neurons are short, hypophyseal portal system carry hormones to anterior pituitary; i.e. anterior pituitary release trophic hormones - FLATPAG (adrenal, thyroid, liver, ovary)
Hypothalamus-posterior pituitary & hormoneMagoncellular neurons are long, direct release in posterior pituitary (they don't use blood system) i.e. posterior pituitary release vasopressin & oxytocin (affect kidney, uterus, mammary gland)
What are the 3 hypothalamic neuronsmagnocellular neuron, parvicellular neuron, hypothalamic projection neuron (neuronal targets e.g. sympathetic preganglionic neuron in spinal cord)
Where is magnocellular and parvicellular neurons located?paraventricular nucleus (hormones produced by magno and parvicellular overlap with hormones produced from arcuate nucleus (non-endocrine section))
Episodic endocrine secretion complex
Male vs female
Most hormones display more than 1 pattern of secretion - important in terms of strategy to regulate growth hormone to treat growth hormone deficiency (different treating males and females b/c hormone released differently)
Endocrine rhythm - lightSuprachiasmatic nucleus of hypothalamus - regulate intrinsic CIRCADIAN pattern of secretion and neuronal activity, involves coordinated expression of "clock" genes [Cryptochromes (Cry) and Period (Per)], light "entrains" or reset the pattern to correspond to day/night cycle;

Direct input from non-visual region of retina onto SCN, SCN activated, clock genes (Cry & Per) activated, produce hormones
Endocrine rhythm - darkDirect input from non-visual region of retina onto SCN, SCN inactivated, non-visual information from retina to SCN relayed via spinal cord to pineal gland, pineal gland produce melantonin which reset SCN [clock genes (Cry & Per)] - no hormones produced, decreases body temp, lead to drowsiness
HP-Adrenal Axis - Systemic Stress (e.g. cold, hypoglycemia, fear)Parvicellular neurons in hypothalamus detect change in temp, hypoglycemia, fear;
CRH released go to anterior pituitary through hypophyseal portal system;
ACTH released into blood circulate throughout body and act on adrenal cortex (zona fasciculata and reticularis) to produce cortisol;
Cortisol bind to glucocorticoid receptor which increase blood glucose through gluconeogenesis, muscle catabolism (a.a), inhibition of GLUT4 activity;
Cortisol negatively feedback on hypothalamus and anterior pituitary
ACTHPOMC (265 a.a. precursor of many hormones) with N-terminal fragment, ACH and beta-lipoprotein;
ACTH over time is broken down into alpha-MSH and CLIP;
beta-lipoprotein over time is broken down into gamma-lipoprotein and beta-endorphin
Addison's Diseaseform of hypocortisolism, leads to high level of ACTH;
Causes: autoimmune disease, adrenal cancers.
Symptoms: fatigue, weakness, WEIGHT LOSS (hyperinsulin secretion), hypoglycemia, hyperpigmentation (alpha-MSH), low blood pressure, depression
In some cases: nausea, diarrhea, vomiting, hypotension, salt craving
HP-Thyroid AxisParvicellular neurons from hypothalamus release TRH;
TRH go to anterior pituitary through hypophyseal portal system;
TSH released into blood stream act on thyroid follicles which make thyroid hormones throxyine - T4 and triiothyronine - T3 (increase metabolism and HR days/weeks/months);
high levels of T3/T4 shut down production of TRH and TSH
GrowthParvicellular cells from hypothalamus release GhRH;
GhRH go to anterior pituitary through hypophyseal portal system;
Anterior pituitary release GH into blood stream which act on:
LIVER to produce IGF-I which stimulate growth,
BONE for growth, repair,
ADIPOSE TISSUE to produce leptin (↓ appetite/food intake, ↑ energy output, ↑ puberty, ↑ GH release, ↓ bone formation - obese patients have osteoporosis b/c of high leptin);
high levels of IGF-I shut down production of GhRH and GH
SRIFreleased from the hypothalamus inhibits TSH and GH release from anterior pituitary directly but weakly
ProlactinParvicellular neurons from hypothalamus release TRH/PRF,
TRF/PRFgo to anterior pituitary through hypophyseal portal system;
Anterior pituitary releases prolactin,
prolactin: ↑ secretory cell differentiation and ↑ milk production;
Suckling ↑ E2 (estrogen) which feedforward to hypothalamus and anterior pituitary to release more TRH/PRF and prolactin;
HP-Gonadal AxisParvicellular cells from hypothalamus release GnRH,
GnRH go to anterior pituitary through hypophyseal portal system;
LH and FSH released which act on gonads (gametogenesis and maturation, steroidogenesis);
Testosterone, estrogen, progesterone, inhibin negatively feedback to hypothalamus and anterior pituitary decreasing GnRH and LH, FSH; LH and FSH negatively feedback on hypothalamus decreasing GnRH
Hypothalamusinvolved in energy homeostasis, a sensing organ (pariventricular/magnocellular sense changes in fear, temp, nutrients and respond via pituitary)
4 ways to pituitary hormone failuregenetic (disease), receptor (receptor mediated defects), structural (too few or too many pituitary cells), transcription factor defect (that make pituitary hormone development)
Vasopressinhigh osmolarity is detected by magnocellular neurons in hypothalamus,
acts on posterior pituitary to produce ADH,
ADH increase water reabsorption and Na+ retention;
Low BP also stimulate ADH release, Low BP activate RAAS
DopamineDopamine release from hypothalamus directly inhibit ADH release from posterior pituitary, Prolactin release from anterior pituitary
OxytocinSuckling and Vaginal/cervical stimulation detected by magnocellular neurons increases oxytocin release,
Oxytocin act on breast tissue for milk "let-down" and act on vagina for further uterine contraction during labour, approperiate maternal behaviour
Other roles:
feeding behaviour and satiety, gastric acid secretion, BP, temp, HR regulation, stimulation of glucagon secretion, gonadotropin secretion, stress responses, tubule contraction and sperm transfer in testis
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