CH 18 Flashcards
Autonomic nervous system
Autonomic nervous / Autonomic motor/ Visceral motor system (ANS)
Motor system which initiates and transmits nerve impulses from the CNS to the cardiac muscle, smooth muscle, and glands
Includes processes regulated below the conscious level
Often reflexively responds to input from visceral sensory components like carbon dioxide concentration in blood or pressure by measuring stretch in smooth muscle of visceral walls
Two divisions of ANS
- Parasympathetic
- Sympathetic
The function of the ANS is to maintain _____________
homeostasis: constant stable internal environment
Thus the ANS regulates all physiological processes that keep us alive, including regulation of heart rate, blood pressure, body temperature, sweating, digestion
Sympathetic division
Fight or flight
Maintains homeostasis during exercise or times of stress or emergency
Releases nutrients from stores
Increases HR, BP, respiratory rate, activity of sweat glands, inhibits digestion, inhibits defecation and urination reflexes, dilates pupils
Parasympathetic division
Rest and digest
Conserves energy and replenishes nutrients from stores
Lowers HR, BP, respiratory rate; stimulates digestion, stimulates defecation and urination reflexes, constricts pupil
Somatic nervous system (SNS)
Includes processes that are perceived or consciously controlled
Divisions of SNS
- Somatic sensory
- Somatic motor
Somatic sensory
Includes detection of stimuli and transmission of nerve impulses from special senses (vision, taste, hearing, equilibrium, smell) and proprioceptors (receptors in joints and muscles that detect body position)
Somatic motor
Involves initiation and transmission of nerve impulses from CNS to control skeletal muscles
Preganglionic nerve
First neuron in ANS pathway whose cell body lies in the brain or spinal cord
Have myelinated axons, small in diameter, always results in release in ACh to excite second neuron
The preganglionic nerve extends from the cell body and exits the CNS in either a spinal or cranial nerve.
The preganglionic nerve’s axon extends to a second cell body housed in an ______________ in the PNS
autonomic ganglion
Ganglionic neuron
Second neuron in ANS pathway
Cell body resides in autonomic ganglion
Have unmyelinated axons, even smaller diameter, releases either ACh or NE, which can excite or inhibit an effector
Postganglionic nerve
Neuron whose axon extends from the cell body to an effector (cardiac muscle, smooth muscle, gland)
The parasympathetic division in nicknamed __________ division
Why?
craniosacral
Because preganglionic neurons exit from brainstem and S2-S4 spinal cord segments
Ganglia for parasympathetic division
- Terminal ganglia
- Intramural ganglia
Terminal ganglia
Close to target organ/ effector
Intramural ganglia
Located within wall of target organ/ effector
Axons of preganglionic neurons travel with which cranial nerves? (Cranial nerves of parasympathetic division)
- Oculomotor (CN III)
- Facial (CN VII)
- Glossopharyngeal (CN IX)
- Vagus (CN X)
Oculomotor nerve (CN III)
Parasympathetic neurons control intrinsic (smooth) muscle of eye
Facial nerve (CN VII)
Parasympathetic neurons control lacrimal gland and two major salivary glands
Glossopharyngeal nerve (CN IX)
Parasympathetic neurons control one major salivary gland
Vagus nerve (CN X)
Parasympathetic neurons control smooth muscle and glands of organs in thoracic and abdominal cavities
Sympathetic division is also termed __________ division because preganglionic neuron cell bodies are in ________ of gray matter between __________ of cord
thoracolumbar
lateral horns
T1-L2
Ganglia for sympathetic division
- Sympathetic trunk
- Collateral/ prevertebral ganglia
- Adrenal medulla
