ORGANIZATION OF THE NERVOUS SYSTEM85 to 180 billion neurons in the human brain?! How does anything get done?

CENTRAL NERVOUS SYSTEM Brain and spinal

cord.

PERIPHERAL NERVOUS SYSTEM (PNS) Def: all nerves that

lie outside the brain and spinal cord

Nerves: bundles of neuron fibers

PNS is subdivided into the Somatic Nervous System and Autonomic Nervous System

SOMATIC NERVOUS SYSTEM Def: nerves that

connect to voluntary skeletal muscles and to sensory receptors

Carry info to and from Central Nervous System

2 types of nerve fibers…

AFFERENT AND EFFERENT NERVE FIBERS Afferent nerve

fibers: axons that carry info. inward to the central nervous system from the periphery of the body

Efferent nerve fibers: axons that carry info. outward from the central nervous system to the periphery of the body

AUTONOMIC NERVOUS SYSTEM Def: nerves that

connect to the heart, blood vessels, smooth muscles, and glands

Controls involuntary functions

Subdivided into 2 branches…

SYMPATHETIC AND PARASYMPATHETIC DIVISIONS Sympathetic

division: mobilizes body’s resources for emergencies

Parasympathetic division: conserves bodily resources

CENTRAL NERVOUS SYSTEM Def: brain and the spinal

cord Surrounded by

Cerebrospinal Fluid: nourishes the brain and provides a protective cushion

CSF comes from blood Substances must pass the

Blood-brain barrier: semipermeable membrane-like mechanism that controls which substances pass btwn the blood and brain

SPINAL CORD Connects the brain

to the rest of the body through the PNS

An extension of the brain

Runs from brain to just below the waist

THE BRAIN In the skull Weighs c. 3 lbs Contains billions of

interacting cells Numerous ways to

study…

RESEARCH METHODS FOR THE BRAINBrain function is difficult to examine…Unless someone wants to volunteer to have their brain dissected while they are still living. Technology has helped…

ELECTRICAL RECORDINGS Electroencephalogra

ph (EEG): a device that monitors electrical activity of the brain over time by means of electrodes attached to the scalp

Invented by Hans Berger in 1929

Translates info. into brain waves

LESIONING Def: destroying a

piece of the brain Used to study

cause-and-effect relations btwn brain damage and behavior

Attach an electrode to a specific area and burn the tissue

ELECTRICAL STIMULATION OF THE BRAIN (ESB) Def: ESB involves

sending a weak electrical current into a brain structure to activate it

Used mostly on animals

Used in brain surgery for humans

BRAIN-IMAGING PROCEDURES Computerized

Tomography (CT) scan: X-ray of brain structure

Creates a horizontal “slice” of the brain

Least expensive and widely used

BRAIN-IMAGING PROCEDURES Positron Emission

Tomography (PET) scanning

Used to examine brain function

Maps actual activity Provides color coded

map of brain

BRAIN-IMAGING PROCEDURES Magnetic Resonance

Imaging (MRI) scan Uses magnetic fields,

radio waves, and computerized enhancement to map brain structure

Produces 3-D image of brain

Functional Magnetic Resonance Imaging (fMRI) monitors blood and oxygen flow in the brain