Autonomic Nervous System: Structure, Divisions, and Functions

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

Control of skeletal muscle and somatic sensory functions like vision and touch.

What does the autonomic nervous system (ANS) regulate?

Heart rate, blood pressure, body temperature, and visceral sensory inputs.

What type of neurons extend from the spinal cord to the muscle in the somatic nervous system?

One single lower motor neuron.

What are the two types of neurons in the autonomic nervous system?

Preganglionic neurons (myelinated) and ganglionic neurons.

What is neuronal convergence?

Input coming into a single cell body from several cell bodies.

What is neuronal divergence?

A single axon affecting multiple different cells from one cell body.

What is the primary role of the parasympathetic division of the ANS?

Rest, recovery, and digestion.

Where are the ganglionic neurons located in the parasympathetic division?

Close to target organs.

Which cranial nerve is associated with blinking and dilation of the eyes?

Oculomotor nerve (CN III).

What is the primary role of the sympathetic division of the ANS?

Fight or flight response, preparing the body for emergencies.

What is the thoracolumbar division?

The part of the sympathetic division that originates from T1 to L2 of the spinal cord.

What is an autonomic plexus?

Collections of sympathetic postganglionic axons, parasympathetic preganglionic axons, and visceral sensory axons.

What is autonomic tone?

Sustained activity in parasympathetic and sympathetic divisions that regulates target organs.

What is an example of antagonistic effects in dual innervation?

Parasympathetic activity slows heart rate while sympathetic activity speeds it up.

What is an example of cooperative effects in dual innervation?

Parasympathetic activity leads to erection while sympathetic activity leads to ejaculation.

What are autonomic reflexes?

Involuntary reflexes that help maintain homeostasis, such as smooth muscle contractions and gland secretion.

Which brain structure serves as the integration and command center for autonomic functions?

The hypothalamus.

What role does the brainstem play in the autonomic nervous system?

It acts as a major autonomic reflex center for blood pressure and digestive activities.

What reflex center is responsible for urination and defecation?

The spinal cord.