Chapter 9 Nervous System PDF

THE BRAIN THE NERVOUS SYSTEM: A BASIC BLUEPRINT  FUNCTION OF THE NERVOUS SYSTEM gather and process information produce responses to stimuli coordinate the workings of different cells Regulates and coordinates all body activities Center of all mental activity, including thought, learni...

THE BRAIN THE NERVOUS SYSTEM: A BASIC BLUEPRINT  FUNCTION OF THE NERVOUS SYSTEM gather and process information produce responses to stimuli coordinate the workings of different cells Regulates and coordinates all body activities Center of all mental activity, including thought, learning, and memory. TWO(2) PARTS, CENTRAL NERVOUS SYSTEM (CNS) AND THE PERIPHERAL NERVOUS SYSTEM (PNS) THE CNS WHICH INCLUDES THE brain AND spinal cord. receives, processes, interprets, stores information & sends messages destined for muscles, glands, & organs Controls consciousness  The PNS transmits information to & from the CNS by way of Sensory & motor nerves. 12 pairs of cranial nerves 31 pairs of spinal nerves  PERIPHERAL NERVOUS SYSTEM Afferent (sensory) Efferent (motor) nerves nerves Carry impulses from the central nervous Carry impulses system to muscles and from the body to glands the central nervous Cause the target system organs to do something in response to commands  PERIPHERAL NERVOUS SYSTEM Somatic Nervous Autonomic Nervous System System (SNS) (ANS) Provides voluntary Provides involuntary control over skeletal control over smooth muscle contractions muscle, cardiac muscle, and glandular activity and secretions in response to the commands of the central nervous system.  AUTONOMIC NERVOUS SYSTEM Sympathetic nerves Parasympathetic Increase heart rate nerves Constrict blood Slow heart rate vessels Increase peristalsis of intestines Raise blood Increase glandular pressure secretions Dilate pupils Relax sphincters “Fight-or-flight” Constrict pupils response “Rest and digest” Communication in the Nervous System Neurons are the basic units of the nervous system. Base unit that has very simple function – “decide” whether to transmit signal or not NEURON CONSISTS OF: 1. DENDRITES 2. CELL BODY 3. AXON 4. AXONAL TERMINAL 5. SYNAPSE  Dendrites Receive information from axon terminals of another neuron Cell Body Contains the nucleus and is the site of synthesis of all neuronal proteins and membranes. Axon Carry information “long” distances Conducts impulses away from the cell body Some axons are covered with a myelin sheath Axon Terminals Transmit information Synapse Space between two nerves which the impulse must cross STRUCTURE OF A NEURON AREAS OF THE BRAIN  MENINGES OF THE BRAIN (COVERINGS) Dura Mater Outermost covering of the brain Tough, white connective tissue Epidural space (cushion of fat and connective tissue) Subdural space (cavity is filled with serous fluid) Arachnoid Mater middle covering Subarachnoid space contains cerebrospinal fluid (CSF) Pia Mater innermost covering Tightly bound to the surface of the brain and spinal cord  STRUCTURES OF THE BRAIN Cerebrum Largest and uppermost portion of the brain Controls consciousness, memory, sensations, voluntary movements Cortex Gyri – elevations Sulci – grooves Longitudinal fissure divides cerebrum into two hemispheres  STRUCTURES OF THE BRAIN Cerebellum Attached to the brain stem Maintains muscle tone Coordinates normal movement and balance Diencephalon Located between cerebrum and midbrain Consists of thalamus, hypothalamus, and pineal gland STRUCTURES OF THE BRAIN Brain Stem Region between diencephalon and spinal cord Consists of midbrain, pons, and medulla oblongata Serves as pathway for impulses between brain and spinal cord Controls respiration, blood pressure, and heart rate FOREBRAIN HIND & MIDBRAIN LIMBIC SYSTEM CEREBRAL CORTEX CORTEX FUNCTION Cerebellum balance & coordination Thalamus directs sensory messages to appropriate higher centers. Hypothalamus emotion sends out chemicals that tell the pituitary gland limbic system emotions pathways involved in pleasure. amygdala evaluating sensory information Hippocampus "gateway to memory“ formation of long-term memories for facts and events. THE LIMBIC SYSTEM  Cerebrum divided into 2 cerebral hemispheres and is covered by thin layers of cells known collectively as the cerebral cortex. THE TWO HEMISPHERES OF THE BRAIN LOBES OF THE CEREBRUM CRANIAL NERVES  OLFACTORY(Sensory) FACIAL (Both) OPTIC (Sensory) ACOUSTIC (Sensory) OCCULOMOTOR GLOSSOPHARYNGIAL (Motor) (Both) VAGUS (Both) TROCHLEAR (Motor) SPINAL ACCESORY TRIGEMINAL (Both) (Motor) ABDUCENS (Motor) HYPOGLOSSAL (Motor)  Cranial nerves The cranial nerves are arranged in 12 pairs, so the two nerves on a pair are identical in function and structure. These nerves serve both sensory and motor functions. The cranial nerves are generally named after the area or function they serve, and are identified with Roman numerals: I, II, III, IV, V, VI, VII, VIII, IX, X, XI, XII Cranial nerves I. Olfactory nerve: sensory for the sense of smell. II. Optic nerve: sensory for the sense of sight. III. Oculomotor nerves: nerves controls muscle of the eye. IV. Trochlear nerves controls muscles of the eye.  Cranial nerves v. Trigeminal nerves: each divide into 3 branches: 1.Ophthalmic branches go to the eyes & forehead. 2.Maxillary branches go to the upper jaw & innervate the teeth & surrounding tissues. 3.Mandibular branches go to the lower jaw & innervate the teeth & surrounding tissues. Cranial nerves VI. Abducens nerves control muscles of the eyes. VII. Facial nerves innervate the muscles of facial expression, salivary glands, lacrimal glands & sense of taste on the anterior 2/3rd of the tongue.  Cranial nerves VIII. Acoustic nerves: each divide into two branches a. Cochlear branches, which are concerned with the sense of hearing. b. Vestibular branches, which are concerned with the sense of balance. IX. Glossopharyngeal nerves: innervate the parotid glands, sense of taste on the posterior third of the tongue, and part of the pharynx.  X. Vagus nerves innervate part of the pharynx, larynx and vocal cords, part of the thoracic and abdominal viscera. XI. Spinal accessory nerves innervate the shoulder muscles. XII. Hypoglossal nerves: innervate the muscles concerned with movements of the tongue. THE SPINAL CORD  Spinal cord transmits impulses to and from the brain and controls some reflex actions. Like the brain, the spinal cord is also cushioned and protected by meninges. 31 segments with pairs (left & right) nerves carrying sensory and efferent information VERTEBRA & SPINAL CORD SPINAL NERVES NERVOUS SYSTEM DISORDERS  Alzheimer's disease deterioration of memory, thinking, and reasoning.  Amyotrophic lateral sclerosis ▪resulting in the loss of ability to move any of the muscles in the body.  Carpal tunnel syndrome ▪compression at the wrist of the median nerve supplying the hand, causing numbness & tingling.  Epilepsy marked by seizures that often involve convulsions or the loss of consciousness.  Huntington's disease: uncontrollable physical movements and mental deterioration. Poliomyelitis Contagious viral disease cause by damage to the central nervous system, resulting in paralysis & loss of muscle tissue.  Migraine particularly intense form of headache  Parkinson's disease: cells in one of the movement-control centers of the brain begin to die, resulting in a loss of control over speech and head & body movements.  GUILLAIN-BARRE SYNDROME an ascending limb weakness and numbness in the extremities that can progress, in some cases, to paralysis. Cerebrovascular Accident (CVA) Commonly called a stroke The result of a ruptured blood vessel supplying a region of the brain Brain tissue supplied with oxygen from that blood source dies Loss of some functions or death may result