Overview of the Nervous System

Overview of the Nervous System

Introduction to the Nervous System

The nervous system is an intricate communication network that coordinates the activities of the body. It consists of the brain, spinal cord, and nerves, and is responsible for controlling consciousness, movement, and many other bodily functions.

• Central Nervous System (CNS): Composed of the brain and spinal cord. It integrates and processes information, and controls consciousness.

• Peripheral Nervous System (PNS): Consists of nerves outside the CNS, connecting the CNS to limbs and other body parts. It transmits sensory and motor information between the CNS and the rest of the body.

Key Terms:

• Sensory (Afferent): Carries information toward the CNS.

• Motor (Efferent): Carries information away from the CNS to muscles and glands.

Example Applications:

• Feeling worry after an argument is a CNS function.

• Just feeling warmth from holding a cup of coffee involves the PNS.

• Deciding what study time best suits you is a CNS function.

• Digesting a big burger that you ate a few minutes ago involves the PNS.

Nervous Tissue

Types of Nervous Tissue Cells

Nervous tissue makes up the nervous system and consists of two main types of cells: neurons and neuroglia.

• Neurons: The structural and functional units of the nervous system. They conduct electrical signals and respond to stimuli.

• Neuroglia (Glial Cells): Provide support and protection for neurons. They do not conduct electrical signals but play a vital role in maintaining the environment around neurons.

Neuron Structure:

• Dendrite: Receives electrical signals from other cells.

• Axon: Long, slender extension that transmits electrical impulses away from the neuron’s cell body.

Neuroglia Structure:

• Myelin Sheath: Fatty layer that insulates axons and increases the speed of electrical signal transmission.

Key Facts and Examples

• The myelin sheath is a fatty layer that insulates the axon.

• Neurons transmit electrical impulses, while neuroglia provide support.

• Axons conduct signals away from the neuron’s cell body; dendrites receive signals.

Common Misconceptions

• The peripheral nervous system (PNS) consists of nerves outside the CNS.

• Neuroglia do not transmit electrical impulses.

• The brain is responsible for sending and receiving information, not the mind.

Table: Comparison of Neurons and Neuroglia

Feature	Neurons	Neuroglia
Function	Transmit electrical impulses	Support, protect, and nourish neurons
Ability to Divide	Limited	Can divide throughout life
Myelin Sheath	Present on some axons	Formed by specific neuroglia (e.g., Schwann cells, oligodendrocytes)

Additional info: The nervous system is essential for maintaining homeostasis and responding to internal and external stimuli. Damage to neurons can result in loss of function, while neuroglia play a key role in repair and maintenance.