Chapter 11: Efferent Division: Automatic and Somatic Motor control
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38 terms
Terms | Definitions |
|---|---|
 what is the efferent division of the peripheral nervous system divided into? | somatic motor neurons and autonomic neurons |
| what do somatic motor neurons control? | skeletal muscles |
| what do autonomic neurons control? | smooth muscle, cardiac muscle, many glands, lymphoid tissue and some adipose tissue |
| what is the autonomic division subdivided into? | sympathetic and parasympathetic branches |
| what does the sympathetic branch do? | prepares the body for stress and intense activities |
| what is the maintenance of homeostasis in the body a balance of? | autonomic control, endocrine control, and behavioral responses |
| what controls the autonomic division? | centers in the hypothalamus, pons and medulla |
| what are some autonomic responses? | spinal reflexes, which can be modulated by input from the brain |
| what do the two autonomic branches demonstrate? | Cannon's properties of homeostasis |
| what are Cannon's properties of homeostasis? | maintenance of the internal environment, tonic control, antagonistic control, and variable tissue responses |
| what is an autonomic pathway composed of? | preganglionic neuron from the CNS that synapses with a postganglionic neuron in the autonomic ganglion |
| what can autonomic ganglia do? | modulate and integrate information passing through them |
| where do most synpathetic pathways originate? | in the thoracic and lumbar regions of the spinal cord |
| where do most sympathetic ganglia lie? | either close to the spinal cord or along the descending aorta |
| where do parasympathetic pathways originate? | in the brain stem or the sacral region of the spinal cord |
| where are parasympathetic ganglia located? | on or near target organs |
| what are the primary autonomic neurotransmitters? | acetylcholine and norepinephrine |
| what do preganglionic neurons secrete? and onto what? | Ach onto nicotinic cholinergic receptors |
| what do postganglionic sympathetic neurons secrete? and onto what? | norepinephrine onto adrenergic receptors |
| what do postganglionic parasympathetic neurons secrete? and onto what? | Ach onto muscarinic cholinergic receptors |
| what is the neuroeffector junction? | the synapse between an autonomic neuron and its target cell |
| what do autonomic axons end with? | varicosities from which neurotransmitter is released |
| what does the adrenal medulla secrete? | epinephrine |
| what controls adrenal meduula? | sympathetic preganglionic neurons |
| what are adrenergic receptors? | G protein-coupled receptors |
| what do alpha receptors respond most strongly to? | norepinephrine |
| what do B1-receptors respond to? | they respond equally to norepinephrine and epinephrine |
| what receptors are not associated with sympathetic neurons? | B2-receptors |
| what do B2 receptors respond most strongly to? | epinephrine |
| what are muscarinic receptors? | G-protein-coupled receptors |
| what do somatic motor pathways have? | a single neuron that originates in the CNS and terminates on a skeletal muscle |
| what are somatic neurons? | always excitatory and cause muscle contraction |
| what does a single somatic motor neuron control? | many muscle fibers at one time |
| what is the neuromuscular junction? | the synapse of a somatic motor neuron on a muscle fiber |
| what is the muscle cell membrane modified into? | a motor end plate that contains a high concentration of nicotinic Ach receptors |
| what opens cation channels? | Ach binding to nicotinic receptors |
| what depolarizes the fiber? | Net Na+ entry into the muscle fiber |
| what breaks down acetylcholine in the synapse? | the enzyme acetyl cholinesterase |
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