Chapter 7 Peripheral Nervous system: efferent Flashcards
Efferent Division
carries info from the CNS to effector organs in the body
Somatic system
axons of motor neurons that innervate skeletal muscle (voluntary movement)
Autonomic System
axons that innervate smooth muscle, cardiac muscle, and glands
sympathetic system
fight or flight
Parasympathetic
rest
Enteric system
network of nerves in the digestive tract partially controlling digestive activities
Autonomic pathways consist of a two-neuron chain. What does each target?
preganglionic fiber and postganglionic fiber
pre-ganglionic fiber targets CNS
post-ganglionic fiber targets PNS
What two neurotransmitters does the autonomic nervous system use?
acetylcholine and norepinephrine
What is the difference between nicotonic ACh receptors and muscarinic ACh receptors?
nicotinic ACh receptor—an ACh-gated channel
muscarinic receptor—G-protein-coupled receptor for ACh
Why do we often see different types of receptors on one organ?
Diversity of receptors on effector organs means same neurotransmitters can be used to produce different effects on different organs
In the sympathetic nervous system, where are preganglionic cell bodies primarily located? What about postganglionic cell bodies?
- Preganglionic cell bodies in thoracic and lumbar regions of the spinal cord
- Most postganglionic cell bodies within the sympathetic ganglion chain
In the parasympathetic nervous system, where are preganglionic cell bodies primarily located? What about postganglionic cell bodies?
- Preganglionic cell bodies in brain (cranial nerves) or lumbar region of spinal cord
- Postganglionic cell bodies in terminal ganglia near the effector organs
What is dual intervention? What state does it typically maintain?
Most organs innervated by both sympathetic & parasympathetic fibers
- Usually both are active and balance each other out—a state called sympathetic tone
In what situations does sympathetic dominance usually occur? How about parasympathetic dominance?
-sympathetic dominance: Promotes responses that prepare body for strenuous activity in stressful situations (“fight-or-flight”)
-parasympathetic dominance: Promotes “general housekeeping” activities of body during restful situations (“rest-and-digest”)
What does a motor neuron innervate? Is the connection one-to-one? Where is its cell body? Is it a part of the somatic nervous system or the autonomic nervous system?
-innervates multiple muscle fibers
-Each muscle fiber innervated by only one motor neuron
-cell body in spinal cord
-somatic
