Autonomic Motor System

Overall Function

• regulate involuntary function of organs to maintain homeostasis

  • operates involuntarily and quickly

What are the two motor systems

Somatic and Autonomic

Which motor system is voluntary and controls skeletal muscle?

Somatic

What does the Autonomic Motor System control?

Nearly all organs are directly influenced by the AMS

Do the somatic and autonomic motor systems work in tandem?

Yes

Ex. you go on a run

• somatic initiates and regulates skeletal muscle contractions to produce movement

• The autonomic works behind the scenes to support voluntary movement by increasing heart rate, breathing, ect.

Parasympathetic Division

Regulates homeostasis at rest, helps conserve and store chemical energy

“Rest and digest” chill response.

Sympathetic Division

Regulates homeostasis during physical and psychological stress, uses chemical energy to alleviate stress

“fight, flight, or think” stress response

What is in the Central Crisis Management Center

Brain and spinal cord

What is in the Regional Crisis Management Center

Sympathetic Division

What alerts does the sympathetic division recieve

It receives high priority alerts and instructions from the CNS of how to respond to crisis

What happens after the Sympathetic Crisis management receives the alerts and instructions

It sends commands to organs. Either a “go” command to essential compartments, or a “no go” command to non-essential compartments

The no-go command is meant to conserve or divert resources

What is the Regional Crisis Recovery and Maintenance Center

Parasympathetic Division

What is the job of the parasympathetic division of crisis management

Recieves “all-clear” or “maintenance request” from CNS, sends commands to specific departments, “go” commands sent to a few essential departments (specific expertise with crisis recovery or maintenance, “no go” commands to non-essential departments to conserve resources

What does the AMS depend on the CNS for?

• recieve and process sensory information from visceral senses, special senses, and general senses

• issuing go commands

  • needs to be told what to change and where change is needed

What do the motor neurons innervate in the autonomic motor system

-smooth muscle

-the heart

-glands

Where is smooth muscle found

walls of hollow organs and walls of blood vessels

Somatic Motor System Motor Neurons

• single lower motor neuron

• dendrites and cell body in gray matter spinal cord

• myelinated axon

  • forms synapse with myofibe

1st Neuron- Preganglionic Neuron

• dendrites and cell body in gray matter of brain and spinal cord

  • forms synapse with 2nd neuron in ganglion

2nd Neuron- Postganglionic Neuron

• dendrites and cell body in ganlion

• forms synapse with cells in smooth muscle, heart, and glands

Ganglia

clusters of cell bodies of neurons of AMS, location of synapse between pre and post ganlionic neurons

Function of Ganglion

mini processing center, receives incoming information and directs outgoing traffic, amplifies outgoing traffic

Advantages of Two-Neuron System

reduces the total number of neurons in the brain and spinal cord

• provides a mini-processing center in PNS

• divergence and convergence allow the PNS to “sum up” or “confirm” incoming information to ensure an organ response is needed, and send commands to organs

Autonomic Ganglia: Processing

ratio between pre and postganglionic neurons and synaptic transmission

Divergence

1 preganlionic to 2-30 postganglionic

Convergence

2-30 preganglionic to one postganglionic

Sympathetic division divergence

high divergence, 1:20-30, during a stress resonse, the body blast go commands to multiple organs at once

Parasympathetic division divergence

low divergence, 1:2-3, a chill response that only send go commands to specific organs

Sympathetic division convergance

high convergance- 20-30:1

Parasympathetic convergence

low convergence, 2-3:1, ganglia are near or inside the target organ, there is less opportunity for convergence

Characteristic of Preganglionic Neurons: Parasympathetic

Dendrites and cell bodies- in gray matter, in the brainstem or sacral region of the spinal cord

axons- bundle and enter PNS through cranial and spinal nerves, myelynated, long, few to no axon collaterals

Synapse- with postganglionic neurons in ganglia

Location of Parasympathetic ganlia

Cranial Ganglia- near skull or deep in neck and head

• motor aspects of special senses

Terminal Ganglia

• within or close to organs, serves a specific organ

Characteristics of Postganglionic Neurons: Parasympathetic

Dendrites- in cranial and terminal ganglia near or inside the target organ

Axons- unmyelynated and short (travel short distance)

Synapse- with target cells within groups

Characteristic of Preganlionic: Sympathetic

Dendrites- in the gray matter of the spinal cord, thoracic and lumbar regions

Axons- bundled and enter PNS via spinal nerves, myelinated, short, with many collaterals

Synapse- w/ postganglionic neurons in ganglia, each collateral can enter a different ganlia and synapse with a postganglionic neuron

Location of Ganglia in sympathetic division

Sympathetic trunk and collateral ganglia

How do Sympathetic Trunk Ganglia Work

They synapse between pre and post ganglionic neurons for organs above the diaphragm

Collateral ganglia

some preganglionic neurons pass through trunk ganglia to the collateral ganglia, synapse below the diaphragm

Characteristics of Postganlionic Neurons: Sympathetic Division

Dendrites- in sympathetic trunk ganglia or collateral ganglia

Axon- unmyelinated, long, many collaterals

Synapse with target cells within organs

Neurotransmitters

Two synapses

preganglionic to postganglionic

Postganlionic to target cell

What are the two major neurotransmitters

acetylcholine and norepinephrine

What is the job o fneurotransmitters?

binding to receptors and directly or indirectly opening Na+, K+ or Ca+ ion channels

What stimulus do they provide?

excitatory or inhibitory stimulus, in target cellss

What channels do excitatory vs inhibitory open

excitatory- open Na+ channel or Ca+

inhibitory- opening of K+ channels

Is the neurotransmitter the excitatory or inhibitory stimulus?

No, the opening of the channels is the stimulus

Acetylcholine (ACH)

they release from all preganglionic neurons, and all postganglionic neuron from parasympathetic

What are the receptors that bind to ACH called?

Cholinergic receptors

what are the two kinds of cholinergic receptors?

Nicotinic receptors- excitatory stimulus

Muscarinic receptors- excitatory or inhibitory stimulus

Where are nicotinic receptors

in all postganglionic neurons and target cells

What is the function of nicogenic receptors

They are a binding site for ACH and as chemically gated Na+ channel. The binding allows for Na+ to diffuse into a postganlionic neuron or target cell

Where are muscarinic receptors located

target cells

What do muscarinic receptors do

ACH binding initiates a cascade of reactions that regulate ion channels indirectly through a secondary messenger

Inhibitory stimulus of muscarinic

pacemaker of the heart, ACH binds to M2 muscarinic receptors and indirectly opens K+ channels, which slows heart rate

Excitatory stimulus of muscarinic receptors

stomach or intestines, ACH binds to M3 and indirectly opens Ca+ channel which causes smooth muscle to contract

Noepinephrine

Released postganglionic neurons of sympathetic division

What are receptors that bind to norepiniephrine called

adrenergic receptors, they regulate ion channels indirectly

Adrenergic receptors are

alpha and beta receptors, they provide excitatory or inhibitory stimulus in target cells

Excitatory adregenic stimulus

pacemaker of the heart, NE binds to b1 receptors and indirectly open Ca+ channels, which increase heart rate

Inhibitory Stimulus of adrenergic

bladder, NE binds to B2 and B3 receptors and indirectly opens K+ channels, slows contraction of smooth muscle

what is the involuntary movement of the AMS dependent on

innervation by neurons of the parasympathetic and/or sympathetic divisions

Processes that are not innervated by neurons of the parasympathetic or sympathetic divisions

skeletal muscle tissue, bone tissue, some endocrine glands, brian tissue

Innervated by only the sympathetic system

blood vessels, adrenal medulla, sweat glands, adipose tissue,

Innervated only by parasympathetic

very few things, some cells in stomach and eye muscles

Dual Innervation

most organs, provides a finer degree of control of organ fucntion through antagonistic effectors, which have opposite actions

Dual Innervation: The heart

the heart is not dependent on the nervous system becuase it has its own ability to contraction and regulate blood

The nervous system does regulate heart rate: Para:vagus nerve, other:cardiac tissue