Copyright © 2009 Pearson Education, Inc. The Nervous System  The nervous system is divided into the central nervous system and the peripheral nervous system  The central nervous system is the brain and spinal cord  It is concerned with integrating incoming information and coordinating all voluntary and involuntary responses

Copyright © 2009 Pearson Education, Inc. The Nervous System  The peripheral nervous system consists of the nerves branching from the central nervous system and the ganglia  It can be further subdivided on the basis of function

Copyright © 2009 Pearson Education, Inc. The Nervous System  The somatic nervous system  Receives sensory information and directs voluntary movements (e.g., bend my arm)  The autonomic nervous system  Regulates involuntary reactions (e.g., heartbeat)

Copyright © 2009 Pearson Education, Inc. The Central Nervous System  The brain and spinal cord are protected by  The bones of the vertebral column and skull  Three connective tissue membranes that form the meninges  Cerebrospinal fluid

Copyright © 2009 Pearson Education, Inc. The Central Nervous System  Inflammation of the meninges is called meningitis  It is caused by many forms of bacteria and viruses, rarely fungal  It can lead to encephalitis (inflammation of the brain)

Copyright © 2009 Pearson Education, Inc. The Central Nervous System  The blood-brain barrier also protects the central nervous system by permitting certain substances to enter the brain, while inhibiting others from entering  It inhibits many potentially life-saving, infection-fighting, or tumor-suppressing drugs that are not lipid soluble from reaching brain tissue  You are responsible for Figure 8.3

Copyright © 2009 Pearson Education, Inc. The Brain Is the Central Command Center  The cerebrum is the thinking, conscious part of the brain  The cerebrum consists of two hemispheres, which receive sensory information from, and direct the movements of, the opposite side of the body

Copyright © 2009 Pearson Education, Inc. The Brain  The cerebrum consists of  The outer layer of gray matter  Called the cerebral cortex  Not myelinated  The underlying white matter  Made of myelinated nerve tracts  Allows for communication between various areas of the brain

Copyright © 2009 Pearson Education, Inc. The Brain  The sensory, motor, and association areas are in the cerebral cortex  The most complex of these areas is the prefrontal cortex which enables us to reason and think in the abstract

Copyright © 2009 Pearson Education, Inc. The Brain  The thalamus  Serves as the relay station of the brain for all sensory information except smell  Also directs motor activity and memory

Copyright © 2009 Pearson Education, Inc. The Brain  The hypothalamus  Maintains homeostasis by regulating blood pressure, heart rate, breathing rate, digestion and body temperature  The hypothalamus coordinates the nervous and endocrine systems through its connection to the pituitary gland  It is a center for emotions and serves as the master biological clock

Copyright © 2009 Pearson Education, Inc. The Brain  The cerebellum  Integrates information from the motor cortex and sensory pathways to produce smooth, well-timed voluntary movements  Controls equilibrium and posture  Stores memories of learned motor skills

Copyright © 2009 Pearson Education, Inc. Brain Stem  The brain stem consists of  Medulla oblongata  Pons  Midbrain

Copyright © 2009 Pearson Education, Inc. The Brain  The medulla oblongata  Contains reflex centers to regulate the rhythm of breathing, force and rate of the heartbeat, and blood pressure  Serves as the pathway for all sensory messages to the higher brain centers and motor messages leaving the brain

Copyright © 2009 Pearson Education, Inc. The Midbrain  Processes information about sights and sounds and controls simple reflex responses to these stimuli

Copyright © 2009 Pearson Education, Inc. The Pons  Means “bridge”  Connects the spinal cord and cerebellum with the cerebrum, thalamus, and hypothalamus  Has a region that assists the medulla in regulating respiration

Copyright © 2009 Pearson Education, Inc. The Brain  The limbic system, which includes several brain structures, is largely responsible for emotions  It includes parts of several brain regions and the neural pathways that connect them

Copyright © 2009 Pearson Education, Inc. Memory  The limbic system plays a role in forming memory. The storage and retrieval of information takes place in two stages:  Short-term memory, which holds a small amount of information for a few seconds or minutes  Long-term memory, which stores limitless amounts of information for hours, days or years

Copyright © 2009 Pearson Education, Inc. The Spinal Cord Transmits Messages  The spinal cord  Conducts messages between the brain and the body  Serves as a reflex center

Copyright © 2009 Pearson Education, Inc. The Spinal Cord  A reflex action is an automatic response to a stimulus in a pre-wired circuit called a reflex arc  Spinal reflexes are essentially decisions made by the spinal cord that are beneficial when a speedy reaction is important to a person’s safety (i.e., the brain is NOT involved)  E.g., step on broken glass

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The peripheral nervous system consists of spinal nerves and cranial nerves  The body has 31 pairs of spinal nerves, each of which originates in the spinal cord and services a specific region of the body  All spinal nerves carry both sensory and motor fibers

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The body has 12 pairs of cranial nerves, which arise from the brain and service the structures of the head and certain body parts, including the heart and diaphragm  Some cranial nerves carry only sensory fibers, others carry only motor fibers, and others carry both types of fibers.

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The peripheral nervous system includes  The sensory receptors  The peripheral nerves  Specialized motor endings that stimulate the effectors

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The peripheral nervous system is divided  The somatic nervous system governs conscious sensations and voluntary movements  The autonomic nervous system is concerned with our unconscious, involuntary internal activities

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The autonomic nervous system can be divided into the sympathetic and parasympathetic nervous systems, two branches with antagonistic actions (they work opposite each other- e.g., one increases heart rate while the other decreases heart rate)  Work to maintain homeostasis

Copyright © 2009 Pearson Education, Inc. The Peripheral Nervous System  The sympathetic nervous system  Gears up the body for stressful or emergency situations (“fight or flight”)  The parasympathetic nervous system  Adjusts body functioning so that energy is conserved during nonstressful times

Copyright © 2009 Pearson Education, Inc. Disorders of the Nervous System Vary in Health Significance  Headaches are usually caused by tension in the neck or by dilation (widening) of the blood vessels of the head  Migraine headaches are caused by an imbalance in the brain’s chemistry

Copyright © 2009 Pearson Education, Inc. Disorders of the Nervous System  A stroke results when the brain is deprived of blood and nerve cells die  The extent and location of the damage caused by a stroke depends on the affected region of the brain

Copyright © 2009 Pearson Education, Inc. Disorders of the Nervous System  A coma is caused by trauma to neurons in regions of the brain responsible for stimulating the cerebrum  A comatose person is totally unresponsive to all sensory input and cannot be awakened

Copyright © 2009 Pearson Education, Inc. Disorders of the Nervous System  A spinal cord injury results in loss of function below the site of injury (nerves are one-way streets)  Depending on which nerve tracts are damaged, injury may result in paralysis, loss of sensation, or both  If the cord is completely severed there is complete loss of sensation and voluntary movement below the level of the cut