Chapter 12Chapter 12The Nervous SystemThe Nervous System

By: Norma GongoraBy: Norma Gongora

Organs of the Nervous Organs of the Nervous SystemSystem

BrainBrain NervesNerves Spinal CordSpinal Cord

The BrainThe Brain It is one of the largest organs in the body, It is one of the largest organs in the body,

and coordinates most body activities.and coordinates most body activities. It is the center for all thought, memory, It is the center for all thought, memory,

judgment, and emotion.judgment, and emotion. Each part of the brain is responsible for Each part of the brain is responsible for

controlling different body functions, such as controlling different body functions, such as temperature regulation and breathing.temperature regulation and breathing.

There are 4 sections to the brain: cerebrum, There are 4 sections to the brain: cerebrum, cerebellum, diencephalon and brain stem.cerebellum, diencephalon and brain stem.

CerebrumCerebrum It is the largest section of the brainIt is the largest section of the brain It is located in the upper portion of the It is located in the upper portion of the

brain and is the area that processes brain and is the area that processes thoughts, judgment, memory, problem thoughts, judgment, memory, problem solving, and language. solving, and language.

The outer layer of the cerebrum is the The outer layer of the cerebrum is the cerebral cortex, which is composed of cerebral cortex, which is composed of folds of gray matter.folds of gray matter.

The cerebrum is subdivided into the left The cerebrum is subdivided into the left and right halves called cerebral and right halves called cerebral hemispheres. Each hemisphere has 4 hemispheres. Each hemisphere has 4 lobes.lobes.

Lobes of the CerebrumLobes of the Cerebrum 1.1. Frontal lobeFrontal lobe: Most anterior portion of the : Most anterior portion of the

cerebrum, controls motor function, personality, and cerebrum, controls motor function, personality, and speechspeech

2.2. ParietalParietal lobelobe: The most superior portion of : The most superior portion of the cerebrum, receives and interprets nerve the cerebrum, receives and interprets nerve impulses from sensory receptors and interprets impulses from sensory receptors and interprets language.language.

3.3. Occipital lobeOccipital lobe: The most posterior portion of : The most posterior portion of the cerebrum, controls vision.the cerebrum, controls vision.

4. 4. Temporal lobeTemporal lobe: The left and right lateral : The left and right lateral portion of the cerebrum, controls hearing and smellportion of the cerebrum, controls hearing and smell

The CerebellumThe Cerebellum Second largest portion of the brainSecond largest portion of the brain Located beneath the posterior part of Located beneath the posterior part of

the cerebrumthe cerebrum Aids in coordinating voluntary body Aids in coordinating voluntary body

movements and maintaining balance movements and maintaining balance and equilibriumand equilibrium

Refines the muscular movement that Refines the muscular movement that is initiated in the cerebrumis initiated in the cerebrum

Brain StemBrain Stem

MidbrainMidbrain——acts as a pathway for impulses acts as a pathway for impulses to be conducted between the brain and to be conducted between the brain and the spinal cord. the spinal cord.

Pons Pons means bridge—connects the means bridge—connects the cerebellum to the rest of the brain.cerebellum to the rest of the brain.

Medulla oblongataMedulla oblongata——most inferior most inferior positioned portion of the brain; it connects positioned portion of the brain; it connects the brain to the spinal cord. the brain to the spinal cord.

Spinal CordSpinal Cord Protected by cerebrospinal fluid. Protected by cerebrospinal fluid. Inner core of the spinal cord contains gray Inner core of the spinal cord contains gray

matter. matter. The outer portion of the spinal cord is The outer portion of the spinal cord is

myelinated white matter. myelinated white matter.

Peripheral Nervous SystemPeripheral Nervous System Includes both the 12 pairs of cranial nerves and Includes both the 12 pairs of cranial nerves and

the 31 pairs of spinal nerves. the 31 pairs of spinal nerves. A nerve is a group or bundle of axon fibers A nerve is a group or bundle of axon fibers

located outside the central nervous system that located outside the central nervous system that carries messages between the CNS and the carries messages between the CNS and the various parts of the body. various parts of the body.

Whether a nerve is cranial or spinal is Whether a nerve is cranial or spinal is determined by where the nerve originates. determined by where the nerve originates.

Cranial nerves arise from the brain, mainly at Cranial nerves arise from the brain, mainly at the medulla oblongata. the medulla oblongata.

Autonomic Nervous SystemAutonomic Nervous System Involved with the control of involuntary or Involved with the control of involuntary or

unconscious bodily functions. unconscious bodily functions. It is divided into two branches: sympathetic It is divided into two branches: sympathetic

branch branch and parasympathetic branch. and parasympathetic branch. The sympathetic nerves stimulate the body The sympathetic nerves stimulate the body

in times of stress and crisis. in times of stress and crisis. The parasympathetic nerves serve as a The parasympathetic nerves serve as a

counterbalance for the sympathetic nerves. counterbalance for the sympathetic nerves.

Somatic NervesSomatic Nerves Serve the skin and skeletal muscles.Serve the skin and skeletal muscles. These are also the nerves that carry These are also the nerves that carry

motor commands to skeletal muscles.motor commands to skeletal muscles. Large variety of sensory receptors Large variety of sensory receptors

found in the dermis layer of the skin found in the dermis layer of the skin use somatic nerves to send their use somatic nerves to send their information, such as touch, information, such as touch, temperature, pressure, and pain, to the temperature, pressure, and pain, to the brain. brain.