Central Nervous System (CNS)

Overview of the CNS

The central nervous system (CNS) is a major division of the nervous system responsible for integrating sensory information and responding accordingly. It consists of the brain and spinal cord.

• Key Components: Brain and spinal cord

• Function: Processes information and coordinates activity throughout the body

Protection and Support of the CNS

• Cerebrospinal Fluid (CSF): A clear fluid that cushions the CNS and supplies it with nutrients.

• Meninges: Three layers of connective tissue that protect the CNS. From superficial to deep, these are: 1. Dura mater 2. Arachnoid mater 3. Pia mater

• Location of CSF: CSF sits in the subarachnoid space, between the arachnoid mater and pia mater.

Spinal Cord Structure and Function

The spinal cord is a long, thin, tubular structure that connects the brain to the peripheral nervous system.

• Number of Spinal Nerves: 31 pairs

• Characteristics: Contains both gray and white matter; transmits nerve signals between the brain and body

• Epidural Space: Located between the dura mater and the vertebral wall; site for epidural anesthesia

• Spinal Block Location: Occurs in the subarachnoid space

• Gray Matter: Collection of cell bodies and sensory neurons; involved in sensory functions

• White Matter: Contains myelinated axons; involved in motor functions

• Butterfly Shape: The center of the spinal cord looks like a butterfly and contains collections of dendrites and cell bodies

Brain Structures and Functions

Brain Hemispheres

• Left Hemisphere: Responsible for speech, analytical thinking, and math

• Right Hemisphere: Responsible for artistic, creative, and musical ideas

• Surface Features: Elevated ridges are called gyri; shallow grooves are called sulci

Major Brain Lobes and Their Functions

• Temporal Lobe: Involved in auditory processing and memory

• Occipital Lobe: Responsible for visual processing

• Parietal Lobe: Evaluates sensory input such as touch, pain, taste, pressure, and temperature

• Frontal Lobe: Controls voluntary motor functions, aggression, moods, speech, and judgment

Corpus Callosum

• Function: Connects the left and right hemispheres of the brain, allowing communication between them

Longitudinal Fissure

• Function: Deep groove that separates the two cerebral hemispheres

Brainstem and Associated Structures

Components of the Brainstem

• Midbrain

• Pons

• Medulla Oblongata

Brainstem Functions

• Medulla Oblongata: Controls breathing and salivation; continuous with the spinal cord

• Pons: Influences moods, sorts data, and is involved in memory

• Midbrain: Controls the pituitary gland

Other Brain Structures

Hypothalamus

• Functions: Regulates body temperature, hunger, thirst, sleep, and emotional activity

Cerebellum

• Functions: Coordinates voluntary movements, balance, and posture

Cranial Nerves

Overview

• Number of Cranial Nerves: 12 pairs

• Optic Nerve: Responsible for vision

• Olfactory Nerve: Responsible for smell

Nervous System Divisions

Somatic vs. Autonomic Nervous System

• Somatic Nervous System: Controls voluntary movements

• Autonomic Nervous System: Controls involuntary functions such as heart rate, digestion, and respiratory rate

Autonomic Nervous System Divisions

• Parasympathetic Division: Controls the body under normal conditions; stimulates salivary glands, slows heart rate, constricts bronchi

• Sympathetic Division: Controls the body under stressful situations (fight or flight); increases heart rate, blood pressure, and respiration rate

Summary Table: Major Brain Lobes and Functions

Key Equations and Terms

• Equation for Nerve Impulse Transmission:

Where V is voltage, I is current, and R is resistance (Ohm's Law, relevant for understanding electrical properties of neurons).

• Gyri: Elevated ridges on the surface of the cerebrum

• Sulci: Shallow grooves/indentations on the surface of the cerebrum

Additional info:

• Some questions reference labeling worksheets and diagrams; students should review anatomical diagrams for brain labeling practice.

• For exam preparation, focus on understanding the structure-function relationships within the CNS and brain regions.