Intro and Hypothalamus Flashcards
What is the primary hormone sequence in the hypothalmic/ pituitary gonadal axis
hierachial arrangement. amplification, propagation, integration(feedback)
CNS Hypo: GnRH Pituitary: FSH/LH To ovary and testis (gonads) testosterone end estradiol
Describe the connections of the hypothalamus with the anterior and posterior pituitary
Anterior: Humoral, is a vascular connection (gonadotrophins)
Posterior: Neural (e,g oxytocin)
Inputs to the hypothalamus from other brain centres
Light- seasonal breeding
Smell- pheromones??
Touch- oxytocin, when baby touches nipple, senses.
Sound- oxytocin, crying can stimulate lactation
Psycho social- pain (can decrease cycles), stress i.e amenorrhea
Nutritional status <47kg- shut down of axis
What is neurosecretion
Release of hormones and like substances by neurons. Unlike neurotransmission
Receptor specificity
Only specific cells exhibit receptors for the particular hormone. Means it does not affect entire body
Feed back loops
Will learn in more detail, but idea of short and long loops where the gonadal hormones cause feedback on the (ant) pituitary, hypothalamus or CNS
What can be said about pulsatile secretion
Can be diurnal, nocturnal.
Main one for reproductive hormones is pulses every few hours (crichorial). Amplitude and frequency will determine how it works on cells.
Origin and location of the hypothalamus
Important anatomical parts
Develops from the hindmost part of the fore brain, the diencephalon
Diencephalon, base of the brian. Funnel shaped, Posterior part has mamillary bodies, is inferior to the thalamus. Optic chiasm is anterior. Surrounded by CSF (third ventricle). Start of stalk is median (BV’s)
Hypothalamus composition
Cell bodies and axons of hypothalamic neurons.
Other axons, axons passing through, glial cells, BV’s
Cell body clusters of neurons are where particular hormones are produced.
What hypothalamic nuclei must we know
Magnocellular: The paired supraoptic and paraventricular nuceli produce Vasopressin and oxytocin. Axons travel to the pars nervosa, PP. Direct inlfuence.
Parvicellular nuclei: The two arcuate/infundibular nuclei. Axons link INDIRECTLY to AP through portal vessels. (Portal vessels in upper and lower infundibular stalk to the pars distalis in the AP) Leak out in pars distalis cells
What hormones are produced by parvicellular nuclei
GnRH; TRH; GHRH and GHRIH; prolactin inhbiting factor; Corticotrophin releasing factor
