Autonomic and Somatic Nervous Systems

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Questions and Answers

What hormones are released by the adrenal medulla in the sympatho-adrenal medulla pathway?

Acetylcholine and dopamine

Epinephrine and norepinephrine (correct)

Serotonin and cortisol

Glutamate and histamine

Which neurotransmitter is released by all preganglionic axons in the autonomic nervous system?

Norepinephrine

Acetylcholine (correct)

Epinephrine

Dopamine

What is the primary function of norepinephrine released by most postganglionic sympathetic axons?

It has excitatory or inhibitory effects depending on the receptor. (correct)

It acts solely on sweat glands.

It exclusively promotes digestion.

It only has inhibitory effects.

Which higher brain centers influence autonomic functions?

Cerebrum, hypothalamus, brainstem, and spinal cord Signup and view all the answers

How does acetylcholine affect the effectors when released from postganglionic parasympathetic axons?

It may have either an excitatory or inhibitory effect depending on the receptor. Signup and view all the answers

What is the primary role of the somatic nervous system (SNS)?

Controlling conscious voluntary movements. Signup and view all the answers

Which statement accurately describes the autonomic nervous system (ANS)?

It includes processes that are regulated automatically. Signup and view all the answers

What distinguishes the motor neurons of the ANS from those of the SNS?

ANS includes preganglionic and ganglionic neurons. Signup and view all the answers

In the autonomic nervous system, where is the cell body of the preganglionic neuron located?

In the brain or spinal cord. Signup and view all the answers

What is the primary function of ganglionic neurons in the ANS?

To transmit signals from preganglionic to effector cells. Signup and view all the answers

Which aspect of the ANS allows for greater control and communication?

Neuronal divergence and convergence. Signup and view all the answers

What type of muscle fibers do autonomic motor neurons innervate?

Smooth and cardiac muscle fibers. Signup and view all the answers

Which characteristic is NOT associated with the somatic nervous system?

It is responsible for subconscious actions. Signup and view all the answers

What is the primary function of the parasympathetic division of the autonomic nervous system?

Conservation of energy and maintenance of homeostasis Signup and view all the answers

What anatomical term is used to describe the parasympathetic division of the autonomic nervous system?

Craniosacral division Signup and view all the answers

Where do the preganglionic neurons of the sympathetic division originate?

Between T1 and L2 spinal segments Signup and view all the answers

What is a key anatomical feature of the sympathetic division compared to the parasympathetic division?

More complex organization with synapses in sympathetic chains Signup and view all the answers

Which type of ganglia are associated with the preganglionic neurons of the sympathetic division?

Sympathetic chain ganglia Signup and view all the answers

How does the outflow of the parasympathetic division occur?

Through cranial nerves and sacral nerves Signup and view all the answers

What is the primary role of the sympathetic division during emergencies?

Facilitating 'fight-or-flight' responses Signup and view all the answers

Where do sympathetic preganglionic axons travel after exiting the spinal cord?

With somatic motor neuron axons to anterior roots Signup and view all the answers

Study Notes

Autonomic Nervous System

The autonomic nervous system (ANS) regulates processes subconsciously.
It controls smooth muscle, cardiac muscle, and glands.
The somatic nervous system (SNS) controls skeletal muscle.
SNS processes are consciously perceived or controlled.

Comparison of Somatic and Autonomic Nervous Systems

ANS involves two neurons, a preganglionic and a postganglionic neuron.
SNS involves one neuron.
ANS responses are often involuntary, while SNS responses are voluntary.
ANS neurotransmitters can excite or inhibit effector cells (e.g. smooth muscles, cardiac muscles, and glands).
SNS neurotransmitters always excite their effector cells (e.g., skeletal muscles).

Divisions of the Autonomic Nervous System

The ANS has two divisions: parasympathetic and sympathetic.

Parasympathetic Division

The parasympathetic division is associated with homeostasis, conservation of energy and replenishment of nutrient stores.
It is also called the craniosacral division because the preganglionic neurons are in the brainstem and sacral region.
The synapse in the parasympathetic division is either found in the terminal ganglia close to the target organ or intramural ganglia in the wall of the target organ.

Sympathetic Division

The sympathetic division is activated during emergencies ("fight-or-flight").
It prepares the body for action by increasing alertness and metabolic activity.
It is also called the thoracolumbar division because the preganglionic neurons are in the thoracic and lumbar regions of the spinal cord.
Preganglionic axons typically travel with somatic motor neurons and exit the spinal cord via the anterior roots.
They synapse either in the sympathetic chain or in ganglia located close to the vertebral column.

Neurotransmitters

All preganglionic axons release acetylcholine (ACh).
Most postganglionic sympathetic axons release norepinephrine (NE).
Postganglionic parasympathetic axons release acetylcholine (ACh).
The effect of released neurotransmitters depends on the receptor type.

CNS Control of Autonomic Function

The CNS, specifically the cerebrum, hypothalamus, brainstem, and spinal cord, influence autonomic function.
The hypothalamus plays a crucial role in integrating and controlling autonomic functions, including emotional responses.

Autonomic Plexuses

Autonomic plexuses are networks of nerves that contain both sympathetic and parasympathetic fibers.
They help regulate organs and tissues by coordinating innervation from different sources.

White and Gray Rami

White rami are branches that carry sympathetic preganglionic neurons from the spinal nerve to the sympathetic trunk (located in the lateral column).
Gray rami are branches that carry postganglionic sympathetic neurons back to the spinal nerve, innervating structures in the body wall.

Overview of Sympathetic Pathways

There are three main sympathetic pathways: the spinal nerve pathway, the post-ganglionic sympathetic pathway, and the splanchnic nerve pathway.
The latter involves a preganglionic axon traveling with splanchnic nerves to synapse at a prevertebral ganglion.
There is also the adrenal medulla pathway, where the preganglionic axon synapses directly with cells in the adrenal medulla, releasing norepinephrine into the blood stream.

Comparison of Parasympathetic and Sympathetic Divisions

The parasympathetic division is responsible for rest and digestion, while the sympathetic division is activated for "fight or flight" situations.
The pathways, neurotransmitters, and ganglia associated with each division differ significantly, allowing for localized, specific control of target organs.

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Description

Explore the functions and differences between the autonomic and somatic nervous systems in this quiz. Learn about their structure, responses, and divisions, including the parasympathetic system. Understand how these systems regulate bodily processes and their roles in controlling muscles and glands.