PHGY 210 Lecture Notes - Lecture 3: Muscle Tone, Brainstem, Preganglionic Nerve Fibers
22 Jul 2018
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Why is it slow: presynaptic: fast transmitter release, postsynaptic: slow, amplified, prolonged response. Binds to gtp and links receptor to effector. G-protein: binds gtp and links receptor to effector. Autonomic nervous system (ans): sympathetic-fight or flight, parasympathetic-rest and digest. Both s and p innervate most organs, control visceral function, little conscious influence: enteric nervous system-in gut, controlled by ans. Both pathways have 2 neurons that synapse in an autonomic ganglion. One exception, ie, no postganglionic neurons: symp input to adrenal glands. Cns origin of preganglionic: thoracic and lumbar spinal cord. Cns origin of preganglionic: brainstem or sacral sc. Preganglionic transmission: both sympathetic and parasympathetic preganglionic neurons release acetylcholine: Ionotropic receptors: sodium ion in and potassium ion out and epsp. Postganglionic transmission: postganglionic neurons release norepinephrine or acetylcholine: slow transmission to muscle or glands, chance biochemistry vm, metabolic receptors (mrs): generate 2nd messengers. Increase calcium ion channel and calcium ion release. Constant sym & para tone at most targets.
