6a - Autonomic Nervous System

Enteric sensory neurons stretch chemical composition

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Unformatted text preview: tain homeostasis by detecting ^ 2. Enteric motor neurons – smooth muscle, glands stimulate or inhibit ^ 3. Enteric interneurons – connect sensory and motor creates reflex loops - rapid responses 16-10 Neurotransmitters • Sympathetic and parasympathetic neurons secrete either: • Acetylcholine (cholinergic) • Norepinephrine (adrenergic) Sympathetic Parasympathetic Preganglionic neurons Preganglionic neurons Cholinergic Postganglionic neurons Adrenergic Cholinergic Postganglionic neurons Cholinergic sweat glands exception 16-11 Receptors Cholinergic Receptors • 2 classes: located in cell bodies on postg neurons , and neuromuscle junction • Nicotinic receptors – excitatory – bind Na+ channels • Muscarinic receptors – excitatory or inhibitory – G-protein smooth muscle, cardiac, glands • Postganglionic neurons in autonomic ganglia and muscle cell membranes – nicotinic receptors • effector cells that respond to acetylcholine from postganglionic neurons – muscarinic receptors 16-12 Receptors Adrenergic Receptors • 2 classes: • Alpha receptors (A1, A2) • Beta receptor (B1, B2) inhibit • Diverse actions – dependent on the receptor and the tissue 16-13 (a) Nicotinic receptors Location of nicotinic receptors Fig. 16.6 ACh released Preganglionic neuron Postganglionic neuron (b) Muscarinic receptors Location of muscarinic receptors Location of nicotinic receptors ACh released ACh released Cell of effector Preganglionic neuron (c) Adrenergic receptors Postganglionic neuron Location of nicotinic receptors Cell of effector Location of adrenergic receptors NE released ACh released Preganglionic neuron Postganglionic neuron ANS Regulation • ANS – homeostasis use of • Autonomic reflexes viseral sensory input and autonomic sensory responses • Baroreceptors detect stretch and changes in b.p. 16-15 Glossopharyng...
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