Ch 16: Autonomic Nervous System

functions of the autonomic nervous system (ANS)

16.1: Overview of the Autonomic Nervous System

maintains homeostasis of the body by regulating heart rate, breathing rate, body temp., and digestive and urinary function.

sympathetic division

• the division of the ANS that has more influence on effectors under conditions of increased physical activity or stress, like sweating

• fight-or-flight response

• preganglionic cell bodies are in the lateral horns of the spinal cord gray matter from T1 to L2

• preganglionic axons pass through the ventral roots to the white rami communicantes to the [term part] chain ganglia

• ganglia are located near the spinal column

parasympathetic division

• the division of the ANS that has more influence under conditions of rest

• preganglionic cell bodies are in nuclei in the brainstem or the lateral parts of the spinal cord gray matter from S2 to S4

  • preganglionic axons from the brain pass to ganglia through cranial nerves

  • preganglionic axons from the sacral region pass through the pelvic splanchnic nerves to the ganglia

• preganglionic axons pass to terminal ganglia within the wall of or near the organ that is innervated

• effects are more localized

• long preganglionic and short postganglionic fibers

somatic nervous system (SNS)

16.2: Contrasting the Somatic and Autonomic Nervous Systems

the cell bodies of [term part] motor neurons are located in the CNS, and their axons extend to skeletal muscles, where they have an excitatory effect, which is usually consciously controlled.

• consciously controlled movements

• innervated skeletal muscle

autonomic nervous system (ANS)

16.2: Contrasting the Somatic and Autonomic Nervous Systems

the cell bodies of the preganglionic neurons of the [term] are located in the CNS and extend to ganglia, where they synapse with postganglionic neurons. The postganglionic axons extend to smooth muscle, cardiac muscle, or glands and have an excitatory or inhibitory effect, which is usually unconsciously controlled.

• involuntarily controlled

• innervates smooth muscle, cardiac muscle, and glands

preganglionic neuron

16.2: Contrasting the Somatic and Autonomic Nervous Systems

Autonomic neuron that has its cell body located within the central nervous system and sends its axon through a nerve to an autonomic ganglion, where it synapses with postganglionic neurons.

postganglionic neuron

16.2: Contrasting the Somatic and Autonomic Nervous Systems

Autonomic neuron that has its cell body located within an autonomic ganglion and sends its axon to an effector organ.

sensory neurons

16.2: Contrasting the Somatic and Autonomic Nervous Systems

• not classified as somatic or autonomic

• propagate action potentials from sensory receptors to the CNS

• can provide information for reflexes mediated through the SNS or the ANS

• some primarily affect somatic functions and other primarily influence autonomic functions

• functional overlap makes attempts to classify these as either somatic or autonomic meaningless

dual innervation

16.4: Physiology of the Autonomic Nervous System

• means that the ANS innervates most organs by both sympathetic and parasympathetic neurons

• Ex: GI tract, heart, urinary bladder, and reproductive tract

cholinergic neuron

16.4: Physiology of the Autonomic Nervous System

a nerve fiber that secretes acetylcholine as a neurotransmitter substance

adrenergic neuron

16.4: Physiology of the Autonomic Nervous System

a nerve fiber that secretes norepinephrine (or epinephrine) as a neurotransmitter substance

nicotinic receptor

16.4: Physiology of the Autonomic Nervous System

• A class of cholinergic receptor molecule that is specifically activated by nicotine and by acetylcholine

• excitatory

• found in all postganglionic neurons

muscarinic receptor

16.4: Physiology of the Autonomic Nervous System

• A class of cholinergic receptors that is specifically activated by muscarine in addition to acetylcholine

• either excitatory or inhibitory

• found in all parasympathetic and some sympathetic effectors)

adrenergic receptors

16.4: Physiology of the Autonomic Nervous System

• Receptor molecules to which epinephrine or norepinephrine binds

• alpha and beta receptors

  • epinepherine has a greater effect than norepinephrine on most of these receptors

• either excitatory or inhibitory

• found in most sympathetic effectors

alpha and beta receptors

16.4: Physiology of the Autonomic Nervous System

• adrenergic receptors subdivisions

• epinepherine has a greater effect than norepinephrine on most of these receptors

terminal ganglia

parasympathetic ganglia are called…