Chapter 17: The Nervous System Part II

1. Chapter 17: The Nervous System Part II HST III Spring 2009

2. Nervous System • Complex • Highly organized system • Coordinates all the activities of the body • Enables the body to respond and adapt to changes that occur both inside and outside the body

3. In the previous discussion we learned: • Neuron • Central Nervous System • Spinal Cord • Cranial Nerves • Motor Pathways • Sensory Pathways • Spinal Reflexes • Common concerning symptoms

4. In this section we will discuss: • Peripheral Nervous System • Diseases and Abnormal Conditions

5. Peripheral Nervous System • Includes spinal and peripheral nerves that carry impulses to and from the spinal cord • 31 pairs of peripheral nerves attach to the spinal cord • Each nerve has an anterior (ventral) root containing motor fibers, and a posterior (dorsal) root containing sensory fibers

6. Peripheral Nervous System • Divided into 2 sections: • 1) Somatic • 2) Autonomic

7. Somatic Nervous System • Consists of 12 pairs of cranial nerves and their branches • 31 pairs of spinal nerves and their branches • Each nerve goes directly to a particular part of the body or networks with other spinal nerves to form a plexus that supplies sensation to a larger segment of the body

8. Sensory Neurons • Relay sensory information from skin, skeletal muscles, and joints to the central nervous system

9. Motor Neurons • Relay motor impulses from the Central Nervous System to skeletal muscles

10. Autonomic Nervous System • Helps to maintain balance in the involuntary functions of the body and allows the body to react in times of emergency • There are two divisions of this system: 1) Sympathetic and 2) Parasympathetic

11. Sensory Neurons • Relay information from visceral organs to Central Nervous system

12. Motor Neurons • Relay impulses from the Central Nervous System to smooth muscles, cardiac muscle and glands

13. Sympathetic Division • In times of emergency, this system prepares the body to react by increasing heart rate, respiration, and blood pressure, and slowing activity in the digestive tract • “Fight or Flight” response

14. Parasympathetic Division • After the emergency, this part of the peripheral nervous system counteracts the actions of the sympathetic nervous system, slowing heart rate, decreasing respiration, reducing blood pressure, and increasing activity in the digestive tract

15. Diseases and Abnormal Conditions

16. Amyotrophic Lateral Sclerosis or Lou Gehrig’s Disease • Chronic • Degenerative neuromuscular disease • Cause is unknown • Genetic or viral-immune factors are suspected as causes • Nerve cells in the CNS that control voluntary movement degenerate, resulting in a weakening and atrophy (wasting away) of the muscles they control

17. Symptoms • Muscle weakness • Abnormal reflexes • Tripping and falling • Impaired hand and arm movement • Difficulty speaking or swallowing

18. Symptoms • As the disease progresses, more muscles are affected, resulting in total body paralysis • In the later stages, the patient loses all ability to communicate, breathe, eat, and move • Mental acuity is unaffected, so an active mind is trapped inside a paralyzed body

19. Treatment • No cure • Drugs such as Riluzole may slow the progression of the disease • Usually fatal within 4 to 6 years of symptom onset, but some patients with slower rates of progression have survived 10-20 years

20. Carpal Tunnel Syndrome • A condition that occurs when the medial nerve and tendons that pass through a canal on their way from the forearm to the hands and fingers is pinched • Repetitive movement of the wrist causes swelling around this canal, which puts pressure on the nerves and tendons

21. Symptoms • Pain • Muscle weakness in hand • Impaired movement of hand • Pain, numbness, and tingling in the thumb, ring finger, or middle finger are classic symptoms

22. Treatment • Initially with anti-inflammatory medications, analgesics for pain, and splinting to immobilize joint (typically at night) • Severe cases that do not respond to these therapies may require surgery to enlarge the canal and relieve the pressure on the nerves and tendons

23. Cerebral Palsy • A disturbance in voluntary muscle action and is caused by brain damage • Lack of oxygen to the brain, birth injuries, prenatal rubella (German measles), and infections are causes • There are 3 forms: spastic, athetoid, and atactic; spastic is the most common

24. Symptoms • Exaggerated reflexes • Tense muscles • Contracture development • Seizures • Speech impairment • Spasms • Tremors • Mental retardation

25. Treatment • No cure • Physical, occupational, and speech therapy • Muscle relaxants, anti-convulsive drugs, casts, braces, and/or orthopedic surgery (for severe contractures) are used

26. Transient Ischemic Attack(TIA) Precursor to Stroke • Sudden focal neurological deficit defined as lasting less than 1 hour and without any underlying structural defects • In the first 3 months after a TIA, 15% of patients will progress to stroke, especially those with diabetes, age older than 60 years, or changes in speech or motor function • Risk for stroke is highest in the first 30 days after a TIA

27. Cerebrovascular Accident (CVA) or Stroke • Occurs when the blood flow to the brain is impaired, resulting in a lack of oxygen and a destruction of brain tissue • Can be caused by cerebral hemorrhage resulting from hypertension, an aneurysm, or a weak blood vessel; or by a an occlusion, or blockage, caused by atherosclerosis or a thrombus (blood clot).

28. CVA or Stroke • 3rd leading cause of death in US • Higher incidence in African Americans • One year mortality rate after Transient Ischemic Attack is approximately 25% • Public awareness of CVA warning signs is high, but only 17% of people state they would call 911 if they thought someone was experiencing a CVA

29. Smoking High fat diet Hyperlipidemia Hyperglycemia Obesity Sedentary lifestyle Hypertension Alcohol use (heavy) Atrial fibrillation Coronary artery disease Cardiac emboli Vascular disease Blood-clotting disease Factors that increase risk for CVA:

30. Stroke Risk Factors: Primary Prevention • Targets modifiable risk factors, namely hypertension, smoking, hyperlipidemia, diabetes, obesity, alcohol use, and sedentary lifestyle

31. Stroke Risk Factors: Secondary Prevention • Once a patient has experienced a TIA, heath care professionals should focus on addressing any secondary risk factors, depending on etiology

32. Stroke Warning Signs • Sudden numbness or weakness of the face, arm, or leg • Sudden confusion, trouble speaking or understanding • Sudden trouble walking, dizziness, or loss of balance or coordination • Sudden trouble seeing in one or both eyes • Sudden severe headache

33. Symptoms • Vary depending on the amount of brain tissue damaged Include: • Loss of consciousness • Weakness or paralysis on one side of the body (hemiplegia) • Dizziness • Dysphagia (Difficulty swallowing) • Visual disturbances

34. Symptoms • Mental confusion • Aphasia (speech and language impairment) • Incontinence (Involuntary loss of bowel or bladder function) • Severe headache

35. Treatment • Immediate care within the first 3 hours can prevent brain damage • Thrombolytic or “clot busting” drugs such as TPA (tissue plasminogen activator) or angioplasty of the cerebral arteries can dissolve a blood clot and restore blood flow to the brain

36. Treatment • Computerized tomography (CT scans; computerized non-invasive X-rays that show cross-sectional views of body tissue), are used to determine the cause of the CVA. • Clot busting medications cannot be used if the CVA is caused by hemorrhage

37. Treatment • Neuroprotective agents, or drugs that help prevent injury to neurons, are also used initially to prevent permanent brain damage • Additional treatment depends on symptoms and is directed toward helping the person recover from or adapt to the symptoms that are present • Physical, occupational, and speech therapy are the main forms of treatment

38. Encephalitis • Inflammation of the brain • Caused by virus, bacterium, chemical agent, or a complication of measles, chicken pox, or mumps • Frequently contracted from mosquito bite because they carry the virus

39. Fever Extreme weakness Lethargy Visual disturbances Headaches Seizures Coma Disorientation Vomiting Stiff neck and back Symptoms

40. Treatment • Supportive (treat symptoms) • Antiviral medications • Maintenance of fluid and electrolyte balance • Anti-seizure medication • Monitoring of respiratory and kidney function

41. Epilepsy • Seizure syndrome • Brain disorder associated with abnormal electrical impulses in the neurons of the brain • Can be caused by brain injury, birth trauma, tumors, toxins such as lead or carbon monoxide, and infections

42. Absence or Petit Mal Seizures • Milder • Characterized by a loss of consciousness lasting several seconds • Common in children and frequently disappear by late adolescence • Appear as if they are staring off into space

43. Generalized Tonic – Clonic Seizures • Grand mal seizures • Most severe • Characterized by a loss of consciousness lasting several minutes; convulsions accompanied by violent shaking and thrashing movements; hypersalivation, causing foaming of the mouth; and loss of body functions • Some individuals experience an aura, which is a pre-cursor to the seizure

44. Treatment • Anticonvulsant drugs are effective in controlling epilepsy

45. An excessive accumulation of cerebrospinal fluid in the ventricles of the brain, and in some cases, the subarachnoid space. Usually caused by congenital defect, infection, or tumor that obstructs the flow of cerebrospinal fluid out of the brain Hydrocephalus

47. Symptoms • Abnormally enlarged head • Prominent forehead • Bulging eyes • Irritability • Distended scalp veins • Retardation when the pressure prevents proper development of the brain

48. Treatment • Surgical implantation of a shunt or tube between the ventricles and the veins, heart, or abdominal peritoneal cavity to provide for drainage of the excess fluid

50. Meningitis • Inflammation of the meninges of the brain and/or spinal cord • Caused by a bacterium, virus, fungus, or toxin such as lead or arsenic