Nervous System

Responsible for coordinating the many activities performed inside

and outside the bodyEvery square inch of the human body is supplied with fine fibers known as nerves; there are over 100 billion nerve cells, known as

neurons, in the body

Neurology

The study of the nervous system and its disordersThe nervous system is one of the most important systems of the body; controls and coordinates the function of all other systems, making them work harmoniously and efficiently

Divisions of Nervous System

Principal parts are the brain, spinal cord and nerves

Cerebrospinal System Also known as the central nervous systemConsists of the brain, spinal cord, spinal nerves & cranial nervesIt controls consciousness and all mental activities, voluntary functions of the five senses

Seeing, hearing, feeling, smelling & tasting

Controls voluntary muscle actions, including all body movements and facial expressions

Peripheral Nervous System

Made up of sensory and motor nerve fibers that connect the peripheral (outer) parts of the body to the central nervous systemIt has both sensory and motor nerves and carries messages to and from central nervous system

Autonomic Nervous System

Controls the involuntary musclesRegulates the action of the smooth muscles, glands, blood vessels and heart

Brain Spinal Cord

Brain is largest mass of tissue in the bodyAverage weight is 44-48 ouncesCentral power station of the body

Brain Spinal CordContains 12 pairs of cranial nerves

All of which originate in the brain & reach various parts of the head, face & neck

Spinal cord originates in the brainEnclosed & protected by spinal column

31 pairs of spinal nervesExtend from spinal cord to muscles & skin of trunk & limbs

Nerve Cell Structure & Function

Neuron or nerve cellPrimary structural unit of nervous system; composed of cell body & nucleus

DendritesTree-like branching of nerve fibers extending from the nerve ell that receive impulses from other neurons

Nerve Cell Structure & Function

Axon & Axon terminalSend impulses to other neurons, glands & muscles

NervesLong, whitish cords made up of bundles of fibers held together by connective tissue, through which impulses are transmitted

Types of NervesSensory nerves (afferent)

Carry impulses or messages from sense organs to the brain, where sensations of touch, cold, heat, sight, hearing, taste, smell, pain & pressure are experienced

Motor (efferent) nervesCarry impulses from brain to muscles; the transmitted impulses produce movement

Types of NervesMixed nerves

Contain both sensory and motor fibers and have the ability to both send and receive messages

ReflexAutomatic response to a stimulus that involves movement of an impulse from a sensory receptor along an afferent nerve to the spinal cord, and a responsive impulse along an efferent neuron to a muscle causing a reaction

Example: the quick removal of a hand from a hot object

Reflexes do not have to be learned