A and P 2 Module One

What does ANS stand for?

Autonomic Nervous System

The autonomic nervous system is considered which arm of the nervous system?

The involuntary arm of the peripheral nervous system (PNS)

What other name is used for the autonomic nervous system?

Visceral (internal organ) motor division

What type of control does the autonomic nervous system operate under?

Involuntary control

The ANS primarily regulates organs rather than what type of structures?

Skeletal muscles

Into how many divisions is the autonomic nervous system divided?

$2$ divisions

What are the two divisions of the autonomic nervous system?

Sympathetic and parasympathetic nervous systems

How do the sympathetic and parasympathetic systems typically function relative to each other?

They work together but in opposite (antagonistic) directions

What term describes the opposing actions of sympathetic and parasympathetic divisions?

Antagonistic

What is the primary goal of the opposing actions of the ANS divisions?

To maintain homeostasis

What does homeostasis mean in the context of the ANS?

Balance

What happens when parasympathetic and sympathetic activity is balanced?

Normal physiological function is maintained

The autonomic nervous system oversees most bodily functions automatically without what?

Conscious control

Name one vital function regulated by the autonomic nervous system.

Heart rate

Name another vital function regulated by the autonomic nervous system.

Blood pressure

Which digestive processes are regulated by the autonomic nervous system?

Digestive and urinary processes

Does the autonomic nervous system require conscious effort to function?

No

Both the somatic and autonomic nervous systems belong to which system?

Peripheral nervous system (PNS)

Which motor division innervates skeletal muscle?

Somatic motor division

What type of muscle contractions are controlled by the somatic motor division?

Voluntary muscle contractions

Are somatic motor actions initiated consciously or unconsciously?

Consciously

Which motor division innervates smooth muscle, cardiac muscle, and glands?

Autonomic motor division

Actions produced by the autonomic motor division are classified as what?

Involuntary actions

What cell types are innervated by autonomic motor neurons?

Smooth muscle cells, cardiac muscle cells, and glands

How many neurons are involved in the somatic motor pathway to a target?

$1$ neuron

Does the autonomic motor system directly innervate its target tissues?

No

How many neurons are required in the autonomic motor pathway?

$2$ neurons

What is the name of the first neuron in the autonomic pathway?

Preganglionic neuron

Where is the cell body of a preganglionic neuron located?

In the central nervous system (CNS)

What direction does a preganglionic neuron carry signals?

From the CNS toward an autonomic ganglion

What neurotransmitter is released by all preganglionic autonomic neurons?

Acetylcholine (ACh)

What is the second neuron in the autonomic motor pathway called?

Postganglionic neuron

Where is the cell body of a postganglionic neuron located?

In an autonomic ganglion in the PNS

What do postganglionic axons innervate?

Target cells (smooth muscle, cardiac muscle, glands)

What neurotransmitters can be released by postganglionic neurons?

Acetylcholine or norepinephrine

Are postganglionic neuron effects always excitatory?

No, they can be inhibitory or excitatory

How does the autonomic motor pathway differ structurally from the somatic pathway?

It requires a $2$-neuron chain instead of $1$ neuron

Which system uses a single neuron from CNS to muscle?

Somatic motor system

Which system requires synapses in peripheral ganglia?

Autonomic nervous system

Do somatic motor neurons synapse in peripheral ganglia?

No

Do autonomic motor neurons synapse in peripheral ganglia?

Yes

Both the somatic and autonomic nervous systems are subdivisions of what?

The peripheral nervous system (PNS)

Are the somatic and autonomic nervous systems part of the CNS?

No

What are the two main divisions of the autonomic nervous system?

Sympathetic and parasympathetic

Which ANS division typically has short preganglionic axons?

Sympathetic nervous system

Which ANS division typically has long postganglionic axons?

Sympathetic nervous system

Which ANS division typically has long preganglionic axons?

Parasympathetic nervous system

Which ANS division typically has short postganglionic axons?

Parasympathetic nervous system

What structural feature explains differences in axon length between ANS divisions?

Location of autonomic ganglia relative to target organs

What is a ganglion?

A cluster of neuronal cell bodies

What does the prefix “pre-” mean?

Before

What does the prefix “post-” mean?

After

Why is a preganglionic neuron named as such?

It comes before the ganglion

Why is a postganglionic neuron named as such?

Its cell body is located within a ganglion

The axon of a postganglionic neuron travels where?

From the ganglion to the target organ

Where are parasympathetic preganglionic cell bodies located?

Brainstem nuclei and sacral spinal cord

What name reflects the origin of the parasympathetic division?

Craniosacral division

Which structures are innervated by parasympathetic cranial nerves?

Head, neck, thoracic viscera, and most abdominal viscera

Which nerves innervate structures in the pelvic cavity?

Sacral nerves

Where are parasympathetic postganglionic neuron cell bodies usually located?

Near or within the target organ

Why are parasympathetic postganglionic axons short?

Because ganglia are close to target organs

The parasympathetic nervous system is known as what type of division?

“Rest and digest” division

What is the primary role of the parasympathetic nervous system?

Digestion and maintenance of homeostasis at rest

Which ANS division is termed the craniosacral division?

Parasympathetic nervous system

Parasympathetic preganglionic neurons originate in which regions?

Brainstem and $S2-S4$ spinal cord

Which ANS division is termed the thoracolumbar division?

Sympathetic nervous system

Sympathetic preganglionic neurons originate in which spinal levels?

$$T1-L2$$

What do ganglionic neurons innervate in both ANS divisions?

Muscles or glands

Which ANS division has longer preganglionic axons?

Parasympathetic

Which ANS division has shorter postganglionic axons?

Parasympathetic

Which ANS division has shorter preganglionic axons?

Sympathetic

Which ANS division has longer postganglionic axons?

Sympathetic

Which division has fewer preganglionic axons?

Parasympathetic

Parasympathetic ganglia are located where relative to effectors?

Close to or within effector organs

Where are sympathetic ganglia typically located?

Near the spinal cord

What two ganglion groups house sympathetic neurons near the spinal cord?

Sympathetic trunk ganglia and prevertebral ganglia

Injury near the spinal cord most likely damages which fiber?

Preganglionic fiber

What nickname is given to the sympathetic nervous system?

Fight-or-flight system

Where are most sympathetic postganglionic cell bodies found?

Sympathetic chain ganglia

How do sympathetic chain ganglia appear anatomically?

Chainlike structures

Where do sympathetic chain ganglia run?

Parallel on both sides of the vertebral column

Which ganglion terminates the chain above the thoracic spinal cord?

Superior cervical ganglion

Which ganglion terminates the chain below the lumbar spinal cord?

Inferior sacral ganglion

Where do sympathetic preganglionic neurons originate?

Lateral horns of thoracic and lumbar spinal cord

Through which spinal root do sympathetic preganglionic axons exit?

Anterior root

After exiting, preganglionic axons form which structure?

White rami communicantes

Are white rami communicantes myelinated or unmyelinated?

Myelinated

White rami communicantes connect spinal nerves to what structure?

Sympathetic chain ganglia

How many possible synapse locations exist in the sympathetic pathway?

$$3$$

First sympathetic synapse option?

Synapse at same spinal level where axon exited

Second sympathetic synapse option?

Ascend or descend to synapse at a different spinal level

Third sympathetic synapse option?

Pass through chain ganglion to synapse in collateral ganglia

What are collateral ganglia also known as?

Prevertebral ganglia

Postganglionic sympathetic axons exit ganglia as what?

Gray rami communicantes

Are gray rami communicantes myelinated?

No

Gray rami communicantes reunite with what structure?

Spinal nerves

Where do postganglionic axons travel after rejoining spinal nerves?

To target cells

Sympathetic synapses may occur at same or different what?

Spinal levels

What neurotransmitter do all ANS preganglionic neurons release?

Acetylcholine (ACh)

Parasympathetic postganglionic neurons release which neurotransmitter?

Acetylcholine