Autonomic Nervous System
motor neurons innervate smooth and cardiac muscle and glands
make adjustments to ensure optimal support for body cavities
operate via subconscious control(of basal functions)
relatively limited sensory function to autonomic nervous system
Sympathetic and Parasympathetic
divisions of the ANS
both principally motor but have opposite affects with some exceptions where parasympathetic does not affect this area
How Somatic and Autonomic Nervous system differs:
effectors, efferent pathways(and neurotransmitters), target organ responses to neurotransmitters
very specific targets. they both leave the medulla/spinal cord and go to the target organs where they exert their effect
Effectors
Somatic: skeletal muscles
ANS: cardiac muscle, smooth muscle, glands
Somatic Neurons
voluntary motor neuron. takes two motor neurons to exert effect. exits go directly to the target. Highly mylenated
Class A fibers
Autonomic Neurons (sympathetic)
takes either two or one neuron to reach the target(depending on circumstances). slow than voluntary
class b and c fibers here.
B: the neuron comes off the spinal cord (preganglionic fiber)
C: postganglionic fiber
Autonomic Neurons (parasympathetic)
galglion between the two motor neurons.
both b and c fibers. most originate from cranial nerves
Exceptions: sacral spinal nerves
Dual Innervation
almost all visceral organs are served by both divisions, but they cause opposite effects
Parasympathetic Division Roles
Promotes maintenance activities and conserves body energy
relaxation(blood pressure, heart rate, and respiration low)
"rest and digest"
Sympathetic Division Role
Fight or Flight response
promotes adjustments during exercise/threatened(raised blood pressure, respiration and liver releases glucose)
Parasympathetic(craniosacral) division outflow
all have preganglionic neurons that fire onto postganglionic neurons that then fire onto the muscle
cranial nerve lengths vary in postganglionic fibers
Oculomotor (III)
cranial outflow
effector: eye
Facial (VII)
cranial outflow
effector: salivary, nasal and lacrimal glands
Glossophrayngeal (IX)
cranial outflow
effector: parotid salivary gland
Vagus(X)
cranial outflow
effector: heart, lungs, and most visceral organs
important for heart rate
S2S4
sacral outflow
effector: large intestine, urinary bladder, uterus, and reproductive organs
maintains blood flow to genetalia (erection cannot occur without this)
Sympathetic Division
strictly spinal nerves.
runs from t1 to l2
fairly clean.
all nerves leave spinal cord and come to a ganglionic trunk
can travel up or down the trunk and synapse onto a postganglionic fiber
can also pass right through and travel to another ganglion
Distinction between Sympathetic and Parasympathetic
blood vessels are the exception to the rule. sympathetic control blood vessels. parasympathetic has very little to do with blood vessels with one exception: genetalia
(both parasympathetic and sympathetic regulate blood flow in the genetalia)
location of sympathetic trunk
leave from the ventral root
don't simply follow nerve. travel to the ganglionic trunk
two clusters of nerve that travel from the spinal nerve to the ganglionic trunk
White ramus is the neuron that is coming off the ventral root and comes out to the ganglionic trunk(preganglionic fiber)
gray raums comes from the ganglionic trunk(postganglionic fibers)
"Special Ganglia"
isolated ganglia. goes to the ganglionic trunk and keeps going to another ganglia where it can synapse onto its postsynaptic fiber
always leaves through the ventral root
separates through the nerve through the white ramus(because its mylenated)
ganglionic trunk it has three options to get to the postganglionic fiber which then goes to the target organ
Neurotransmitters
ACH and NE
ACH(acetocholine)
lowers heart rate. preganglionic fiber always secrets
only thing secreted with parasympathetic at both the pre and postganglionic fibers
has 12-15 receptors it can bind to
most abundant neurotransmitter in the nervous system
NE(norepinephrine)
causes increased heart rate
only the sympathetic system can secrete NE parasympathetic system cant do anything with NE
has 5 receptors
Cholinergic Receptors
Nicotinic and muscarinic(named after the drugs that activated them)
Nicotinic
found in skeletal. universally excitation
will stimulate EPSP(excitatory postsynaptic potential)
Muscarinic
sweat glands.
large variety
in some cases excitatory and in other inhibitory
Adrenergic Receptors
Five distinct
two subcategories(Alpha and Beta)
Beta Receptors
B1: found in the muscle of the heart(increase heart rate when bound to NE)
B2: found in the heart's blood vessels(coronary) inhibitory causes smooth muscles in blood vessels to relax and dilate to allow more blood flow
B3: activate fat tissue from adipose
Alpha Receptors
A1: blood vessels in the systemic parts of the body(kidneys, liver, stomach, muscles) excitatory constriction within the arteries
True/False: A neurotransmitter is excitatory/inhibitory based on the receptor not the specific neurotransmitter
True
Sympathetic Tone (Vasomotor Tone)
controls blood pressure even at rest.
keeps the blood vessels in continual state of partial constriction
as long as its firing it will continue to constrict. if it slows down, the relaxation will start
Parasympathetic Tone
slows the heart, dictates normal activity levels of the digestive and urinary tracts
associated with when we are at rest(below 100 bpm)
dominant when at rest; still sympathetic regulation during this time
frequency of firing allows changes in heart rate in the parasympathetic system
Cooperative Effects of Parasympathetic and Sympathetic System
for reproduction to occur you have to have both systems
parasympathetic increases blood flow for erection
sympathetic: ejaculation
Unique Roles of Sympathetic Division
metabolism, mobilizing the nutrients, sympathetic mobilizes fat
thermoregulatory response to heat
releases of renin from the kidneys
Localized Verses Diffuse Effects
parasympathetic: short-lived and localized
sympathetic: long-lasting, body wide effects)