BIOL 2160 Chapter : Chapter 5 Chemical Messengers (Fall 2012)
Document Summary
Chapter 5 chemical messengers: mechanisms of intercellular communication, direct communication through gap junctions, indirect communication through chemical messengers. -released by cell, moves to target cell by diffusion. -paracrines act on neighboring cells (the messenger cannot enter the cell; it is too big) -histamines released with tissue damage and cause dilation of local vessels. -testosterone moves from the leydig cells into the seminiferous tubules. Very potent in small amounts regulate cellular responses to hormones can activate or inhibit adenylyl. Messengers of nervous system: released from neuron by exocytosis, diffuses to very close target cell across a synapse. Messenger of endocrine system: released from endocrine gland into blood, transported in blood to target. Target cell = cells in body with receptors specific to the hormone. Neurohormones: hormones released from the axons of neurons in the hypothalamus, adh & oxytocin, inhibiting & releasing hormones into the portal system going into the anterior pituitary. Involved in cell development, differentiation, and **immune response.
