2. 1 PowerPoint ® to accompany Second Edition Ramutkowski  Booth  Pugh  Thompson  Whicker Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Medical Assisting Chapter 27

3. 2 Objectives: 27-1Explain the difference between the central nervous system and the peripheral nervous system. 27-2 Describe the functions of the nervous system. 27-3Describe the structure of a neuron. 27-4Describe the function of a nerve impulse and how a nerve impulse is created. 27-5Describe the structure and function of a synapse. 27-6Describe the function of the blood-brain barrier. The Nervous System

4. 3 Objectives: 27-7Describe the structure and functions of meninges. 27-8Describe the structure and functions of the spinal cord. 27-9Define reflex and list the parts of a reflex arc. 27-10List the major divisions of the brain and give the general functions of each. 27-11Describe the differences between the somatic nervous system and autonomic nervous system. The Nervous System

5. 4 Objectives: 27-12 Explain the two divisions of the autonomic nervous system. 27-13Explain the functions of the cranial and spinal nerves. 27-14Describe the location and function of cerebrospinal fluid. 27-15Describe various disorders of the nervous system and how they are diagnosed and treated. The Nervous System

6. 5 Introduction  Nervous system is a highly complex system divided into two major parts;  Central nervous system (CNS)  Peripheral nervous system.  Controls all other organs systems and is important for maintaining balance within those systems. Disorders of the nervous system are numerous and often very difficult to diagnose and treat because of the complexity of this system.

7. 6 General Functions of the Nervous System  Detect and interpret sensory information,  Make decisions about the sensory information that is received,  Carry out motor functions based on the decisions made. For example, if you feel pain, your brain might decide you need to move away from the painful stimulus.

8. 7 Neuron Structure  Transmit electrochemical messages called nerve impulses to other neurons and effectors (muscles or glands)  Neurons lose their ability to divide  When destroyed by disease, they cannot be replaced

9. 8 Neuron Structure (cont.) Neurons Neurons have cell body processes called nerve fibers that extend from the cell body.  Dendrites  Dendrites - short - function is to receive information (nerve impulses) for the neuron  Axons  Axons - long - function is to send information (nerve impulses) away from the cell body.

10. 9 Nerve Impulse  Nerve impulse is the flow of electric current along the axon membrane  At rest, or in its polar state, more sodium (Na + ) is on the outside of the membrane, which makes the outside positive and the inside negative.  When sodium moves into the cell, the membrane depolarizes, which means that the inside becomes more positive.  The membrane repolarizes when potassium (K + ) and later sodium move to the outside of the cell membrane.

11. 10 Synapse  Synaptic knobs contact dendrites, cell bodies and the axons of other neurons  Synaptic knob is contacting is called a postsynaptic structure.  Within synaptic knobs are vesicles or small sacs that contain chemicals called neurotransmitters. When the nerve impulse reaches the synaptic knobs, the neurotransmitters are released onto postsynaptic structures.

12. 11 Neurotransmitters  Functions:  Causes muscles to contract or relax  Causes glands to secrete products  Activates neurons to send nerve impulses, inhibiting neurons from sending nerve impulses.

13. 12 Apply Your Knowledge What is the function of a dendrite?

14. 13 Answer Apply Your Knowledge - Answer Dendrite’s function is to receive information (nerve impulses) for the neuron. What is the function of a dendrite?

15. 14 Central Nervous System  Includes the spinal cord and brain.  Has a blood-brain barrier:  Barrier prevents certain substances from entering the tissues of the CNS  Tight capillaries form the blood-brain barrier.  Meninges are membranes that protect the brain and spinal cord.  Includes the spinal cord and brain.  Has a blood-brain barrier:  Barrier prevents certain substances from entering the tissues of the CNS  Tight capillaries form the blood-brain barrier.  Meninges are membranes that protect the brain and spinal cord.

16. 15 Cerebrospinal fluid  Location:  Between the arachnoid mater and pia mater is an area called the subarachnoid space  Function:  Cushions the CNS

17. 16 Spinal Cord  Slender structure that is continuous with the brain  Descends into the vertebral canal and ends around the level of the first or second lumbar vertebra.  31 spinal segments:  8 cervical segments  12 thoracic segments  5 lumbar segments  5 sacral segments  1 coccygeal segment

18. 17 Spinal Cord (cont.) Name the spinal segments and tell how many of each segment are present on the spinal cord.  8 cervical segments  12 thoracic segments  5 lumbar segments  5 sacral segments  1 coccygeal segment

19. 18 Spinal Cord – Gray and White Matter  Gray matter - inner tissue with darker color  contains neuron cell bodies and their dendrites  divisions are called horns and the divisions of the white matter are called columns (funiculi)  columns contain groups of axons called nerve tracts  central canal runs down the entire length of the spinal cord through the center of the gray matter  White matter - the outer tissue  contains myelinated axons  Gray matter - inner tissue with darker color  contains neuron cell bodies and their dendrites  divisions are called horns and the divisions of the white matter are called columns (funiculi)  columns contain groups of axons called nerve tracts  central canal runs down the entire length of the spinal cord through the center of the gray matter  White matter - the outer tissue  contains myelinated axons

20. 19 Spinal Cord - Ascending and Descending Tracts  Function of the spinal cord is to carry sensory information to and from the brain  Ascending tracts - carry sensory information up to the brain  Descending tracts - carry motor information down from the brain to muscles and glands

21. 20 Spinal Cord Reflexes  Function of the spinal cord is to participate in reflexes  Reflex - a predictable, automatic response to stimuli Receptor Sensory Neurons Effectors Motor Neurons Interneurons

22. 21 Apply Your Knowledge What are the descending tracts of the spinal cord?

23. 22 Answer Apply Your Knowledge - Answer Descending tracts carry motor information down from the brain to muscles and glands What do the descending tracts of the spinal cord do?

24. 23 The Brain Four Parts:  Cerebrum  Diencephalons  Brain stem  Cerebellum

25. 24 The Brain - Cerebrum  Largest part of the brain  Two halves cerebral hemispheres  Thick bundle of nerve fibers called the corpus callosum connect the two hemispheres  Lobes  Frontal  Parietal  Temporal  Occipital  Cortex  Ventricles

26. 25 The Brain - Diencephalons  Thalamus - relay station for sensory information that heads to the cerebral cortex for interpretation  Hypothalamus - maintains balance by regulating many vital activities such as heart rate, blood pressure, and breathing rate. Located between the cerebral hemispheres and is superior to the brain stem

27. 26 The Brain - Brain stem  Midbrain  Midbrain - controls both visual and auditory reflexes  Pons  Pons - regulates breathing  Medulla oblongata  Medulla oblongata - controls many vital activities such as heart rate, blood pressure, and breathing Connects the cerebrum to the spinal cord

28. 27 The Brain - Cerebellum  Inferior to the occipital lobes of the cerebrum  Posterior to the pons and medulla oblongata  Inferior to the occipital lobes of the cerebrum  Posterior to the pons and medulla oblongata  Coordinates complex skeletal muscle contractions that are needed for body movements

29. 28 Apply Your Knowledge The patient has had trauma to the pons of the brain. What type of problems would you see in the patient?

30. 29 Answer Apply Your Knowledge - Answer The patient could not breath without assistance. The patient has had trauma to the pons of the brain. What type of problems would you see in the patient?

31. 30 Preventing Brain and Spinal Cord Injuries  Always wear appropriate protective gear while playing any sport.  Avoid diving headfirst into unknown waters.  Always wear your safety belt.  Follow safety rules on playgrounds.  Make sure children use car seats that are appropriate for their age and weight.  Be familiar with ways to get help quickly in emergencies.  Follow traffic rules and signs while walking, biking, or driving.

32. 31 Peripheral Nervous System  Consists of nerves that branch off the CNS.  These nerves are called peripheral nerves and are classified in 2 types:  Cranial nerves  Spinal nerves

33. 32 Cranial Nerves – 12 Sets Olfactory nerves I. Olfactory nerves carry smell information to the brain for interpretation. Optic nerves II. Optic nerves carry visual information to the brain for interpretation. Oculomotor nerves III. Oculomotor nerves are found within the muscles that move the eyeball, eyelid and iris. Trochlear nerves IV. Trochlear nerves act in the muscles that move the eyeball.

34. 33 Cranial Nerves (cont.) Trigeminal nerves V. Trigeminal nerves carry sensory information from the surface of the eye, the scalp, facial skin, the lining of the gums, and the palate to the brain for interpretation. They also are found within the muscles needed for chewing. Abducens nerves VI. Abducens nerves act in the muscles that move the eyeball.

35. 34 Facial nerves VII. Facial nerves are found in the muscles of facial expression as well as in the salivary and tear glands. These nerves also carry sensory information from the tongue. Vestibulocochlear nerves VIII. Vestibulocochlear nerves carry hearing and equilibrium information from the inner ear to the brain for interpretation. Cranial Nerves (cont.)

36. 35 Glossopharyngeal nerves IX. Glossopharyngeal nerves carry sensory information from the throat and tongue to the brain for interpretation. They also act in the muscles of the throat. agus nerves X. Vagus nerves carry sensory information from the thoracic and abdominal organs to the brain for interpretation. These nerves are also found within the muscles in the throat, stomach, intestines and heart. Cranial Nerves (cont.)

37. 36 Accessory nerves XI. Accessory nerves are found within the muscles of the throat, neck, back, and voice box. Hypoglossal nerves XII. Hypoglossal nerves are found within the muscles of the tongue. Cranial Nerves (cont.)

38. 37 Spinal Nerves  Spinal nerves are peripheral nerves that originate from the spinal cord.  31 pairs of spinal nerves:  8 pairs of cervical nerves (C1 through C8)  12 pairs of thoracic nerves (T1 through T12)  5 pairs of lumbar nerves (L1 through L5)  5 pairs of sacral nerves (S1 through S5)  One pair of coccygeal nerves (Co)  Spinal nerves are peripheral nerves that originate from the spinal cord.  31 pairs of spinal nerves:  8 pairs of cervical nerves (C1 through C8)  12 pairs of thoracic nerves (T1 through T12)  5 pairs of lumbar nerves (L1 through L5)  5 pairs of sacral nerves (S1 through S5)  One pair of coccygeal nerves (Co)

39. 38 Somatic and Autonomic Nervous Systems  Consists of nerves that connect the CNS to skin and skeletal muscle.  Somatic nervous system - “voluntary” nervous system because it controls skeletal muscles, which are under voluntary control.  Autonomic nervous system consists of nerves that connect the CNS to organs and other structures such as the heart, stomach, intestines, glands, blood vessels, and bladder (among others) - “involuntary” nervous system.

40. 39 Neurologic Testing  Typical neurologic examination:  State of consciousness  Reflex activity  Speech patterns  Motor patterns

41. 40 Diagnostic Procedures  Lumbar Puncture  Magnetic Resonance Imaging (MRI).  Positron Emission Tomography (PET) Scan  Computerized Tomography (CT) Scan  Electroencephalogram (EEG)  X Ray Common diagnostic procedures

42. 41 Reflex Testing  Biceps reflex  Biceps reflex - The absence of this reflex may indicate spinal cord damage in the cervical region.  Knee reflex  Knee reflex - The absence of this reflex may indicate damage to lumbar or femoral nerves.  Abdominal reflexes  Abdominal reflexes - These reflexes are used to evaluate damage to thoracic spinal nerves.  Biceps reflex  Biceps reflex - The absence of this reflex may indicate spinal cord damage in the cervical region.  Knee reflex  Knee reflex - The absence of this reflex may indicate damage to lumbar or femoral nerves.  Abdominal reflexes  Abdominal reflexes - These reflexes are used to evaluate damage to thoracic spinal nerves.

43. 42 Apply Your Knowledge What is the somatic nervous system?

44. 43 Answer Apply Your Knowledge - Answer Somatic nervous system (“voluntary”) nervous system because it controls skeletal muscles, which are under voluntary control What is the somatic nervous system?

45. 44 Diseases and Disorders of the Nervous System  Alzheimer's Disease  Alzheimer's Disease - a progressive, degenerative disease that occurs in the brain. Amyotrophic Lateral Sclerosis (ALS)  Amyotrophic Lateral Sclerosis (ALS) - a fatal disorder characterized by the degeneration of neurons in the spinal cord and brain.  Bell's Palsy  Bell's Palsy is a disorder in which facial muscles are very weak or totally paralyzed.

46. 45 Diseases and Disorders of the Nervous System (cont.)  Brain Tumors and Cancers  Brain Tumors and Cancers - abnormal growths in the brain  Epilepsy and Seizures -  Epilepsy and Seizures - occur when parts of the brain receive a burst of electrical signals that disrupt normal brain functioning.  Guillain-Barré Syndrome  Guillain-Barré Syndrome - a disorder in which the body's immune system attacks part of the peripheral nervous system.

47. 46 Diseases and Disorders of the Muscular System Headaches affect almost everyone at some point in their life  Tension Headaches  Cluster  Migraine Headaches affect almost everyone at some point in their life  Tension Headaches  Cluster  Migraine Multiple Sclerosis (MS) Multiple Sclerosis (MS) - a chronic disease of the central nervous system in which myelin is destroyed. Stroke Stroke - brain cells die due to an inadequate blood flow.

48. 47 Diseases and Disorders of the Muscular System (cont.)  Meningitis  Meningitis is an inflammation of the meninges.  Neuralgias  Neuralgias are a group of disorders commonly referred to as nerve pain  Parkinson's Disease  Parkinson's Disease is a motor system disorder  Sciatica  Sciatica occurs when the sciatic nerve is damaged.

49. 48 Apply Your Knowledge The doctor has told your patient she has had a stroke. How would you explain this to the family?

50. 49 Answer Apply Your Knowledge - Answer A stroke happens when brain cells are damaged or die due to an inadequate blood flow. The doctor has told your patient she has had a stroke. How would you explain this to the family?

51. 50 Summary Medical Assistant Functions of the nervous system include detecting and interpreting sensory information, making decisions about that information, and responding to and carrying out motor functions based on those decisions. Knowledge of this system is essential when assisting the physician during a neurologic exam.

52. 51 End of Chapter