Brain

Definition

The brain is the central organ of the nervous system, responsible for processing sensory information and controlling bodily functions. It is protected by the skull and the blood-brain barrier.

5 Must Know Facts For Your Next Test

1. The brain is covered by three protective membranes called meninges: dura mater, arachnoid mater, and pia mater.
2. Cerebrospinal fluid (CSF) surrounds the brain and spinal cord, providing cushioning and removing waste.
3. The brain can be affected by various infections such as meningitis, encephalitis, and brain abscesses.
4. The blood-brain barrier restricts passage of most substances from the bloodstream into the brain, making treatment of infections challenging.
5. Microorganisms like bacteria, viruses, fungi, and parasites can breach these defenses to cause nervous system infections.

Review Questions

• What are the three layers of membranes that protect the brain called?
• How does cerebrospinal fluid (CSF) benefit the brain?
• Why is treating infections in the brain particularly challenging?

Related terms

Meningitis:

Inflammation of the protective membranes covering the brain and spinal cord.

Encephalitis: Inflammation of the brain tissue itself.

Blood-Brain Barrier:

A selective barrier that protects the brain from harmful substances in the bloodstream.