NERVOUS SYSTEM By: Abby & Tessa

TERMS Brain- encephal/o- coordinates all activities of the body and receives and transmits messages throughout the body. Spinal Cord- myel/o- transmits nerve impulses between the brain, limbs and lower part of the body Nerves- neur/i, neur/o- receive and transmit messages to and from all parts of the body

MORE TERMS Central Nervous System (CNS)- includes the brain and spinal cord Peripheral Nervous System (PNS)- includes the 12 pairs of cranial nerves extending from the brain and the 31 pairs of spinal nerves extending the spinal cord Autonomic Nervous System (ANS)- includes the peripheral nerves and ganglia on either side of the spinal cord

DIVIDED INTO TWO SUB-DIVISION Central Nervous system (CNS)  Brain and spinal cord  Integrating and command center of the nervous system Peripheral Nervous System (PNS)  Part of nervous system that extends from the brain and spinal cord  Afferent (sensory)  Efferent (motor) 1.Cranial nerves: carry signals to and from the brain 2.Spinal nerves: carry signals to and from the spinal cord

FUNCTIONS AND ORGANIZATION OF THE NERVOUS SYSTEM  The efferent (motor) division is divided into the somatic nervous system and the automatic nervous system  The automatic nervous system is further divided into the sympathetic and parasympathetic divisions  The activities of the nervous system can be grouped into sensory, integrative and motor functions

NERVE TISSUE  Neurons are the nerve cells that transmit impulses  The conducting cell that transmits impulses  Structural unit of the nervous system  The other type of cell is neuroglia or glial cell  Means “nerve glue”  These cells are nonconductive and provide a support system for the neurons  They are a special type of nerve tissue  Supporting cells are neuroglia, protect and nourish the nerouns and they are capable of mitosis

NERVE IMPULSES  The ability to respond to a stimulus (excitability) and transmit impulses (conductivity)  At rest the outside of a neuron is positive charge and has a higher concentration inside  The cell membrane of non conducting neuron is polarized with an abundance of sodium ions outside the cell and an abundance of potassium ions and negatively charged proteins inside cell  A stimulus alters the permeability of cell membrane  In response to a stimulus the cell membrane becomes permeable to sodium ions  They enter cell and depolarize(sodium diffuses) the membrane Followed by reverse polarization  Saltatory conduction occurs in myelinated fibers where the action potential jumps from node to node  To initiate an impulse is called a threshold (liminal) stimulus

CENTRAL NERVOUS SYSTEM  The brain is surrounded by the cranium and the spinal cord is protected by the vertebrae  In addition to bone the CNS is surrounded by connective tissue membranes called Meninges and cerebrospinal fluid (CSF)  Meninges  The outer layer is tough white fibrous connective tissue  The middle layer is the arachnoid whish resembles a cobweb in looks and contains blood vessel underneath  The innermost layer is pia matter it is delicate and thin and tightly bound to the surface of the brain and spinal cord

CONT.  The spinal cord consist if a central core of gray matter surrounded by white matter  Gray matter consists of neuron cell bodies  White matter is myelinated nerve fibers  Two enlargements of the spinal cord are in the cervical and sacral regions  The primary sensory area of the brain is the post central gyrus in the parietal lobe  Ascending tracts carry sensory impulses to brain  corticospinal tracts are descending tracts that begin in the cerebral cortex

CHAPTER QUIZ RECALL: MATCH THE DEFINITIONS ON THE LEFT WITH THE APPROPRIATE TERM ON THE RIGHT 1.Outermost covering of the CNS 2.Produces cerebrospinal fluid 3.Occurs along myelinated axons 4.Supporting cells of the nervous system 5.White, fatty covering of axons 6.Controls contraction of skeletal muscles 7.Lowest part of the brain stem 8.Contains visual cortex 9.Efferent Process of a neuron 10.Contains somatosensory cortex A. Axon B. Choroid plexus C. Dura mater D. Medulla oblongata E. Myelin F. Neuroglia G. Occipital lobe H. Parietal lobe I. Saltatory conduction J. Somatic nervous system

CHAPTER QUIZ RECALL ANSWERS 1.Outermost covering of the CNS 2.Produces cerebrospinal fluid 3.Occurs along myelinated axons 4.Supporting cells of the nervous system 5.White, fatty covering of axons 6.Controls contraction of skeletal muscles 7.Lowest part of the brain stem 8.Contains visual cortex 9.Efferent Process of a neuron 10.Contains somatosensory cortex Axon Choroid plexus Dura mater Medulla oblongata Myelin Neuroglia Occipital lobe Parietal lobe Saltatory conduction Somatic nervous system

1. NEURONS LOCATED ENTIRELY WITHIN THE CNS ARE a)Motor neurons b)Association neurons c)Efferent neurons d)Sensory neurons

ANSWER: B Association neurons It is a link which conveys impulses in an arc from sensory to motor neurons

2. SELECTED EVENTS IN IMPULSE CONDUCTION ARE GIVEN. ARRANGE THESE EVENTS IN THE ORDER IN WHICH THEY OCCUR 1) SODIUM GATES OPEN 2) POTASSIUM GATES OPEN 3) STIMULUS ALTERS MEMBRANE PERMEABILITY 4) ACTIVE TRANSPORT OF SODIUM AND POTASSIUM 5)REVERSE POLARIZATION 3,1,2,4,5 3,1,5,4,2 3,4,1,5,2 3,1,5,2,4

ANSWER: D 3,1,5,2,4

3. WHITE MATTER a)Forms the cerebral cortex b)Consists of neuron cell bodies c)Forms the outer covering of the brain d)Consists of myelinated fibers

ANSWER D White matter consists of myelinated fibers Not the gray matter

4. THE THREE REGIONS OF THE BRAIN STEM ARE THE a)Thalamus, hypothalamus, pineal body b)Thalamus, pons, cerebellum c)Midbrain, pons, medulla oblongata d)Thalamus, midbrain, cerebral peduncles

ANSWER IS C Midbrain Pons medulla oblongata

5. THREE CRANIAL NERVES THAT HAVE ONLY SENSORY FUNCTIONS ARE a)Optic, olfactory, and trigeminal b)Optic, olfactory, and vestibulocochlear c)Optic, oculomotor, and glossopharyngeal d)Vagus, trigeminal, and facial

ANSWER IS B Three cranial nerves that have only sensory functions are Optic, olfactory, and vestibulocochlear