Anatomical Divisions of the Nervous System

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

The two main anatomical divisions are the Central Nervous System (CNS) and the Peripheral Nervous System (PNS).

What are the components of the Central Nervous System (CNS)?

The CNS is composed of the brain and spinal cord.

What are the primary functions of the CNS?

The CNS is responsible for:

• Integration and processing of sensory input.
• Coordination of motor output.
• Higher functions such as thought, memory, learning, and emotions.

Give an example of the CNS in action.

If you trip, the CNS interprets sensory signals about your body’s position, decides how to restore balance, and sends rapid commands to muscles.

What are the components of the Peripheral Nervous System (PNS)?

The PNS includes all neural tissue outside the CNS, consisting of cranial nerves (to/from the brain) and spinal nerves (to/from the spinal cord).

What are the functions of the PNS?

The PNS:

• Delivers sensory input to the CNS.
• Carries motor output to tissues and organs.

What are the subdivisions of the PNS?

The PNS has two main subdivisions:

• Somatic Nervous System (SNS): Connects to skeletal muscles.
• Autonomic Nervous System (ANS): Regulates smooth muscle, cardiac muscle, glands, and adipose tissue.

From a functional perspective, what are the two main divisions of the nervous system?

The two main functional divisions are the Afferent Division (Sensory) and the Efferent Division (Motor).

What is the role of the Afferent Division?

The Afferent Division brings information into the CNS using receptors that detect stimuli from the external and internal environments (e.g., eyes, ears, skin, stretch receptors, pH sensors).

Provide an example of the Afferent Division's function.

Touching a hot pan activates skin receptors, which then send signals to the spinal cord via the afferent division.

What is the role of the Efferent Division?

The Efferent Division sends commands from the CNS to effectors such as muscles, glands, and adipose tissue.

What are the two major parts of the Efferent Division?

The two major parts are the Somatic Nervous System (SNS) and the Autonomic Nervous System (ANS).

What does the Somatic Nervous System (SNS) control within the Efferent Division?

The SNS controls skeletal muscle contractions, responsible for both voluntary control (e.g., raising your arm) and involuntary reflexes (e.g., pulling your hand from a hot surface).

What does the Autonomic Nervous System (ANS) control within the Efferent Division?

The ANS controls smooth muscle, cardiac muscle, glands, and adipose tissue.

What are the subdivisions of the Autonomic Nervous System (ANS)?

The ANS has three subdivisions:

• Sympathetic Division: Responsible for "fight or flight" responses (e.g., speeds up heart, dilates pupils).
• Parasympathetic Division: Responsible for "rest and digest" functions (e.g., slows heart, promotes digestion).
• Enteric Nervous System (ENS): Controls digestive tract functions independently, though influenced by sympathetic and parasympathetic input.

How do the nervous system divisions work together when you stumble?

When you stumble:

1. Receptors in the inner ear detect imbalance, sending afferent signals to the CNS.
2. The CNS processes this information and sends efferent commands.
3. The somatic system then activates leg and arm muscles to recover balance.

How do the nervous system divisions work together during a stress response?

During a stress response:

1. Seeing a threat sends afferent vision signals to the CNS.
2. The CNS processes the threat.
3. The efferent autonomic sympathetic system then increases heart rate, breathing, and redirects blood flow to muscles.