Organization of the Nervous System

Overview of the

Central (CNS),

Peripheral (PNS),

Autonomic (ANS),

Enteric (ENS)

Nervous Systems

Brain

• Structure– Ventricles– Meninges

• Organization

• Function

Meningial Cell

• Cells that form the meningeal cell layers of the meninges covering the brain and spinal cord

Meninges

• is a three layered covering of brain in which blood vessels travel and cerebrospinal fluid (CSF) is absorbed.

• Meninges means “covering”in Greek

• Dura Mater: hard mother in Latin

• Arachnoid Membrane: spider web like

• Pia Mater : gentle mother in Latin

Dura Mater:

• tough inelastic leather-like membrane covering brain/spinal cord

• Blood vessels cross through it

• Protects brain and spinal cord

Arachnoid Membrane:

• Spider-web like membrane

• Sub-arachnoid space is filled with CSF and the arachnoid villi of blood vessels of the arachnoid re-absorb the CSF

Pia Mater

• closely adheres to brain and spinal cord tissue

• Blood vessels penetrate pia to supply brain

• Separated from arachnoid membrane by the subarachnoid space

blood-brain barrier

• blood vessels have special anatomy that provides blood-brain barrier that prevents toxins, viruses and improper chemical environment from affecting brain cells.

Ventricles

• The brain is hollow, ie there are CSF-filled caverns and canals inside the brain

• Two lateral ventricles, left and right

• 3rd ventricle

• 4th ventricle

Ependymal Cell

• Epithelial cells that line the ventricular system

• Can also secrete CSF in some locations of the ventricles

• CSF cushions & protects brain and provides chemical environment for proper brain function

CSF

• Choroid plexus (epithelial cells) resides in 3rd & 4th ventricle and makes CSF

• Hydrocephalus (water on the brain) results from accumulation of CSF

Microglia

• Smallest glial cell

• No known role in healthy nervous system\

• Involved in repair of nervous system after injury or infection

• Multiply quickly, migrate to injured area and phagocytize dead cells.

• Behave like macrophages

Exam 1

• Cells: Chapter 1-Nolte-Human Brain

• History: Chapter 1- Bear

• Organization of NS: Ch 7 Bear – Or

• any book on reserve has a chapter devoted to general organization