Ch. 15 Sensory Pathways and the Somatic Nervous System Flashcards
(24 cards)
Autonomic nervous system regulates activity of…
smooth muscle, cardiac muscle, and certain glands
Operation of the ANS to maintain homeostasis
depends on a continual flow of sensory afferent input, from receptors in organs, and efferent motor output to the same effector organs
Structural components of ANS
autonomic sensory neurons, integrating centers in CNS, and autonomic motor neurons
The ANS is regulated by…
centers in the brain, mainly the hypothalamus and medulla oblongata, which receive input from limbic system
The somatic nervous system contains both…
sensory and motor neurons
Where do somatic sensory neurons receive input from?
receptors of the special and somatic senses
Somatic motor neurons
innervate skeletal muscle to produce conscious, voluntary movements
What is the effect of a motor neuron
always excitation
What type of neurons do the ANS contain?
autonomic sensory and motor neurons
The ANS also receives input from…
somatic senses and special sensory neurons
How do autonomic responses regulate visceral activities?
by either increasing (exciting) or decreasing (inhibiting) ongoing activities of cardiac muscle, smooth muscle, and glands
What do all autonomic motor pathways consist of?
two motor neurons in series
Autonomic motor pathway series
- The axon of the first motor neuron of ANS extends from CNS and synapses in a ganglion with the second neuron
- second neuron synapses on an effector
- efferent part of the ANS is divided into sympathetic and parasympathetic divisions
What do preganglionic fibers release?
acetylcholine
What do postganglionic fibers release?
acetylcholine and norepinephrine
Dual innervation
when organs receive impulses from both sympathetic and parasympathetic fibers
Where is the cell body of a preganglionic neuron?
in the brain or spinal cord
Myelinated axon of a preganglionic neuron
called a preganglionic fiber, passes out of the CNS as part of a cranial or spinal nerve
Where is postganglionic neuron?
it lies entirely outside the CNS
Where is cell body and dendrites of postganglionic neuron?
in an autonomic ganglion where it makes synapses with one or more preganglionic fibers
The axon of a postganglionic neuron
unmyelinated and terminates in a visceral effector
Where are the cell bodies of sympathetic preganglionic neurons?
in the lateral gray horns of the 12 thoracic and first 2 or 3 lumbar segments
Parasympathetic ganglia
the terminal or intramural ganglia that are located very close to or actually within the wall of a visceral organ
Examples of parasympathetic ganglia
ciliary, pterygopalatine, submandibular, and otic ganglia
