ORGANIZATION OF THE NERVOUS SYSTEM 85 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 BRAIN Brain 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 Electroencephalograp h (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