-
Autonomic Nervous System
- -System of motor neurons that innervate smooth muscle, cardiac muscle, and glands
- -Regulates visceral functions (HR, BP, digestion, urination)
- -ANS= general visceral motor division
- -Peripheral nerves serve the somatic system; all mixed cranial nerves, all spinal nerves
- -Peripheral nerves serve the autonomic AND somatic: some cranial nerves
-
CNS and PNS
CNS- Brain and Spinal Cord
PNS- Cranila nerves and Spinal Nerves
-
Sensory (Afferent Division)
-Somatic and Visceral
- Somatic Sensory- Touch, pain, pressure, vibration, temperature, and proprioception in skin, body wall, and limbs
- - Hearing, equilibrium, vision, smell
- Visceral Sensory- Stretch, pain, temperature, chemical changes, and irritation in viscera: nausea and hunger
- - Taste
-
Motor(Efferent)
-Somatic and visceral
Somatic Motor- Motor innervation of all skeletal muscles
- Visceral Motor- Mmotor innervation of smooth muscle, cardiac muscle, and glands; equivalent to ANS
- - Parasympathetic and Sympathetic Divisions
-
Autonomic Nervous System
- -Two motor neurons involved with autonomic ganglion
- -Motor Unit- chain of TWO motor neurons (pre-ganglionic and post-ganglionic)
- -Pre= thin, light myelinated
- -Post= thinner, unmyelinated
- -ACh and NE = Neurotransmitters, receptors scattered throughout organs
- -Targets function without neural input; there is a basic level of activity(ANS regulates by inc/dec)
-
Somatic Nervous System
- -One motor neuron runs from CNS to innervated muscle
- -Motor Unit- single motor neuron and muscle fibers innervated
- -Thick myelinated axons
- -Excitatory only
- -ACh=neurotransmitter at endplate
- -Action dependent on motor nerves
-
Sympathetic ANS
- CNS Origin- Thoracic and lumbar spinal nerves "thoracolumbar"
- Functions- "Fight or Flight", active functions- exercise
- Neuron Length- Preganglionic- Short, Postgaglionic- Long
- Location of prepost synapse- Proximal (near spinal cord)
- Neurotransmitter- Preganglionic= ACh, Postganglionic= NE
- Activation- More general activation, all at once
-
Parasympathetic ANS
- CNS Origin- Cranial nerves and sacral spinal nerves, "craniosacral"
- Functions- Housekeeping (resting functions- digestion)
- Neuron Length- Preganglionic= Long, Postganglionic= Short
- Location of prepost synapse- Distal (near target organ)
- Neurotrransmitter- Pre and Post= ACh
- Activation- More selective activation of specific targets
-
Sympathetic and systems
- Respiratory- Dialtes bronchioles, decreased mucous in airways, deeper breaths
- Cardiovascular- Increases HR, increases muscle contraction, strength, vaasoconstriction
- Digestive- Decreases saliva, thickens secretion, decreases GI tract mobility
- Sweat Glands- Increases sweat secretion
- Energy Stores- Releases fuel (catabolic)
- Exercise- Increases activity
-
Parasympathetic and Systems
- Respiratory- Constricts bronchioles, increaaes mucous in airways, shallower breaths
- Cardiovascular- Decreases HR, decrease muscle contraction strength
- Digestive- Increases saliva, thins secretion, increases GI tract motility
- Sweat Glands- NONE
- Energy Stores- Stores fuel (anabolic)
- Exercise- Decreases Activity
-
Adrenal Medulla
- Adrenal gland located on superio side of kidney
- Cortex= outer portion
- Medulla= inner portion (sympathetic ganglion)
- Controlled by sympathetic nervous system
- Secretion- epinepherine (adrenaline), and norepinepherine (catecholamines)
- Target- all sympathetic target organs
- Effects- feinforces sumpathetic mass activation, hormonal effect lasts longer
- Increases HR, dilate coronary vessels, increase mental alertness, increase resp and matabolic rate
-
Visceral Sensory Neurons
- General Visceral Neurons
- Stretch, temp, chemicals, irritation
- Most are free nerve endings
- Referred Pain
- Difficulty pinpointing signals
- People often perceive that pain is comin from somatic areas like skin orouter body
-
Control of ANS
- Brain Stem and Spinal Cord
- Reticular formation- most direct influence
- Hypothalamus
- Main integration center of ANS- directs parasympathetic and sympathetic activities
- Amygalda (part of limbic system)
- Stimulates sympathetic activity- fear
- Cerebral Cortex
- Can overcome responses with relaxation
-
ANS Disorders
- Autonomic dysreflexia (mass reflex reaction)
- -Uncontrolled activation of ANS motor neurons
- -Affects people with spinal cord injuries above T6 level
- -When cord injury first happens- no reflexes, return later
- -Initial trigger causes mass activity of reflexes- body spasms, colon and bladder empty, sweating, high BP
- -Exact mechanism unknown
|
|
