Intro to ANS Flashcards
Function of Autonomic Nervous System
regulation of involuntary physiologic process
Give examples of involuntary physiologic processes
heart rate, blood pressure, respiration, digestion, sexual arousal
Anatomically distinct divisions of ANS
sympathetic, parasympathetic, enteric
Type of nerves/action of ANS
Visceral motor; motor fibers (multipolar) carry info toward targets in PNS
sensory ANS “associated”
pseudo unipolar fibers that provide a mechanism to monitor activities of ANS
Is the ANS primarily sensory or motor
Simply - viceromotor
Somatic
structures associated with outer body wall, derived from ectoderm, paratial mesoderm, and somatic LP of mesoderm). Conscious motor and sensation
Visceral
structures associated with inner organs; derived from splanchnic layer of lateral plate mesoderm, intermediate mesoderm, endoderm. Includes glands, cardiac muscle, and smooth muscle. Unconscious and involuntary movement of your viscera
How many neurons make up the ANS unit?
2 neuron-system in periphery
Visceral afferents
pseudo-unipolar fibers that transmit info that we cannot perceive (osmolality, pain of viscera) to the CNS. Located in dorsal root ganglia
Visceral efferents
multipolar motor fibers from ANS relay info toward targets in 2 neuron peripheral connection; functions: organ movement, vasoconstriction, airway diameter. Control of cardiac and smooth muscle, glandular tissue
preganglionic axons
originate from neurons in CNS and travel to peripheral ganglion
postganglionic axons
axons originating from the cell bodies making up ganglia, travel to target tissue
List the similarities between the parasympathetic and sympathetic nervous system
- both efferent systems
-both involve regulation of the internal environment
-both involve 2 neurons that synapse at peripheral ganglia
-Innervate glands, smooth muscle, cardiac muscle
Target tissues of the sympathetics
-Organs of head, neck, trunk, external genitalia
-adrenal medulla
-sweat glands
-arrector pili
-all vascular smooth muscles
»>ALL TISSUES
Target tissues of parasympathetics
-organs of head, neck, trunk, external genitalia
»» “INTERNAL ONLY”
Function/anatomical characteristics of the sympathetics
“fight of flight”
preganglionic neurons in thoracic and lumbar spinal cord. Chain ganglia alongside vertebral colum
Sympathetic tone is “always on”
Function/anatomical characteristics of the parasympathetics
“feed and breed” & “rest and digest”
preganglionic from cranium through cranial nerves, some in sacral spinal cord
Effectors receiving sympathetic innervation only
adrenal medulla, arrector pili muscles, sweat glands, many blood vessels
Sympathetic vasomotor tone
baseline action potential
increase in firing frequency = vasoconstriction
decrease in firing frequency= vasodilation
can shift blood supply to organs as needed
Sympathetic stimulation ______ blood to skeletal/cardiac muscles while ____ blood flow to skin
Increases; Decreases
Where are sympathetic postganglionic cell bodies located?
In paravertebral ganglia (sympathetic chain) OR preaortic (prevertebral) ganglia
Where are parasympathetic postganglionic cell bodies located?
in, on, or near the walls of their target organs
Where are sympathetic preganglionic cell bodies?
Located in lateral horn of T1 to L2 spinal cord. Axons go to sympathetic chain
