Hypothalamus & Posterior Pituitary Flashcards
what is a magnocellular neuron?
neurons in the hypothalamus that signal to hte posterior pituitary and is involved in oxytocin and AVP.
what is a parvicellular neuron?
a neuron that signaling from the hypo to the anterior pit via the median eminence to deliver hormones such as CRH, TRH, DA to the portal veins.
where does TRH come from within the hypo?
the PVN
where does LHRH come from in the hypo?
ant/medial hypo
what does CRH come from?
portion of PVN
where does GHRH come from
acruate nucleus
where does somatostatin come from?
PVN
where does DA come from?
arcuate nucleus
what hormones come from the posterior pit?
oxytocin and vasopressin/ADH/AVP
what does oxytocin do?
uterine contractions and milk ejection
where is ADH found?
V1r: smooth muscle
v2r: kidney collecting ducts
when is oxytocin released?
feeling secure, privacy, people you know, relaxation, dim lighting, comfortable environment, being touched
when is oxytocin release inhibited?
feeling scared, watched, being uncomfortable, around strangers, bright lights, and thinking
what is the oxytocin signaling cascade?
- oxytocin binds to Gprc
- GTP G protein activates PLC to increase it
- PIP2 intxts with DAG to increase IP3
- IP3 causes the ER to release Ca++
- Ca++ intxts with calmodulin
- ca++/calmodulin, Ca++, and PKC all act to cause target cell responses
how does Ca++ cause muscle contractions?
As Ca++ increases in the cell it binds to Calmodulin. This acts on MLCK (myosin light chain kinase). MLCK phosphorylates myosin to induce a muscle contraction.
