1. The Nervous System Chapter 14, pgs. 392-399

2. Function of the Nervous System
It is your body’s communication network and control center.
It coordinates all of your body’s actions and functions
It senses changes not only within the body, but also outside of it in your environment and enables you to respond within fractions of a second.
This information is transmitted throughout your body by means of electrical charges (impulses) at speeds up to 280mph.

3. Neurons (Nerve Cells)
The messengers and receivers of electrical impulses.
They have the memory capability of a thousand CD-ROMs, each one containing the Encyclopedia Britannica

4. Neurons (Nerve Cells)
1. Sensory Neurons – carry signals from sense receptors into the central nervous system.

5. Neurons (Nerve Cells)
2. Motor Neurons – carry signals from the central nervous system to muscles and glands.

6. Neurons (Nerve Cells)
3. Interneurons – form all the electrical connections within the central nervous system itself.

7. The Central Nervous System
The central nervous system is made up of the brain and the spinal cord.

8. The Spinal Cord a downward extension of the brain.
A cylinder of nerve tissue about 18 inches long and about as thick as your index finger.

9. The Spinal Cord
It is protected by the vertebrae, cerebrospinal fluid, and three layers of connective tissue called meniges.

10. The Brain
The largest, most complex part of the nervous system which helps you receive and process messages and coordinate muscular movement.
It is also involved with your emotions and everything you sense.

11. The Brain
It weighs approximately 3 pounds and contains almost 100 billion neurons.
It reaches full size by age 6, and uses more than 20% of the oxygen you inhale.
It does not fully mature until age 25.

12. The Brain
It is protected by eight cranial bones, three layers of cranial meninges, and cerebrospinal fluid.

13. The Brain
The brain cells produce electrical signals and send them along pathways called circuits which receive, process, store, and retrieve information.
The brain creates it’s electrical signals by chemical means and depends on the many complicated chemical substances the brain cells produce.

14. The Cerebrum
The largest, most complex part of the brain which is the site of most conscious and intelligent activities.
It is divided into two halves, called the cerebral hemispheres.

15. The Cerebrum
The right hemisphere controls the muscular activity of and receives sensory input from the left side of the body.
The left hemisphere does the same for the right half of the body.
The left hemisphere is responsible for language, logic, arithmetic calculation, analysis, and critical thinking.
The right hemisphere is concerned with imagination and visual thinking (spatial relationships, form, artistic activities, and emotional responses).

16. The Cerebrum
Frontal Lobe – controls voluntary movements and language. The prefrontal areas of this lobe are believed to be involved with intellect and personality.
Parietal Lobe – involved with sensory information such as heat, cold, pain, touch, and body position in space.

17. The Cerebrum
3. Occipital Lobe – involved with the sense of vision. 4. Temporal Lobe – contains the senses of hearing and smell, as well as being involved with memory, thought, and judgment.

18. The Cerebellum
The second largest part of the brain located below the occipital lobe of the cerebrum.
Concerned with maintaining posture & balance and coordinating muscle movement.

19. The Cerebellum
It receives impulses from the balance organs of the inner ear and from muscles, then refines the orders sent to muscles to coordinate movement and balance.

20. The Brain Stem
A three inch long stalk of nerve cells and fibers that connects the spinal cord to the rest of the brain.
Controls involuntary basic functions of breathing, heart beat, and eye reflexes.

21. The Brain Stem
1. Medulla Oblongata – the lowest part of the brainstem containing vital control centers that regulate heartbeat, breathing, blood pressure, and digestion.
It also controls swallowing, vomiting, sneezing, and coughing; receives and relays taste sensations from the tongue; and is involved with speech and tongue movement.

22. The Brain Stem
2. Pons – The middle portion of the brain stem serving mainly as a pathway for nerve impulses passing to & from the cerebrum.
It also relays sensory information from the ear, face, and teeth as well as signals that control jaw movement and facial expressions.

23. The Brain Stem
3. Midbrain – highest part of the brain stem which controls eye movement and the size and reaction of the pupils.

24. The Brain Stem
4. Thalamus – two egg-shaped lobes about the size of walnuts located above the midbrain which are involved with receiving information from the eyes and ears, and also the touch and pressure receptors of the skin.

25. The Brain Stem
5. Hypothalamus – located behind the eyes and under the thalamus, which controls various body processes (metabolism, sexual development, and emotional responses) & keep the body conditions balanced (body temperature, stimulate appetite, and regulate sleep)

26. Peripheral Nervous System
Composed of the Autonomic Nervous System and the Somatic Nervous System.
Consists of nerves that fan out from the central nervous system to the muscles, skin, internal organs and glands.
Consists of 12 cranial nerves that branch from the brain and 31 pairs of spinal nerves that branch from the spinal cord.

27. Peripheral Nervous System
Autonomic Nervous System
Responsible for controlling the involuntary functions of the body (sweating, digestion & heart rate).
Consists of the sympathetic and parasympathetic nervous systems which have opposing effects on the same organ and act in conjunction & normally balance each other.

28. Peripheral Nervous System
Autonomic Nervous System
Sympathetic Nervous System
Responds to the body’s needs during increased activity and in emergencies (“fight or flight response).
It quickens the heartbeat and breathing rate and increases blood flow to the muscles.
Leads to all the body’s vital organs and glands

29. Peripheral Nervous System
Autonomic Nervous System
2. Parasympathetic Nervous System
Opposes the action of the sympathetic nervous system by slowing body functions.

30. Peripheral Nervous System
Somatic Nervous System
Consists of sensory neurons that relay messages from receptors in the ears, eyes, nose, tongue, and skin to the Central Nervous System and motor neurons that transmit impulses from the Central Nervous System to skeletal muscles which involves voluntary responses

31. Problems of the Nervous System

32. Possible Causes Damage to nerve cells or injury to the head or spine.
Nerve tissue damaged by degenerative diseases.
Use of drugs and alcohol, which destroys brain cells and cause nervous system disorders.
In the U.S. each year, over one million people sustain head injuries and an estimated 11,000 new cases of spinal cord injury occur. These injuries may result from falls, sports or recreational activities, motor vehicle crashes, physical assaults, or gunshot wounds

33. Concussions
The immediate and short-lived impairment of neurological function due to either direct trauma (a blow to the head), or indirect trauma (a fall where vibrations travel up the spinal column to the brain.

34. Concussions

35. Concussions
Because the brain is suspended in fluid, a blow to the head can create an injury either at the point of contact or on the opposite side to it (contracoup).

36. Concussions
Depending on the force of the blow and the person’s tolerance to withstand such a blow, varying degrees of cerebral hemorrhage (bleeding), swelling and tissue laceration may occur which cause pathological changes to occur (blurred vision, dizziness, nausea, loss of consciousness, etc.)
Concussions are cumulative, with each successive concussion causing more severe damage.

37. Concussions
Post Concussion Syndrome may develop with symptoms including impairment of short-term memory and problem-solving ability, attention and concentration difficulties, anxiety, frequent headaches, seizures, muscle weakness, and alteration of emotions and personality.
These symptoms may last for weeks, months, or even years.

38. Concussions
If a person receives a second concussion while still recovering from the initial concussion, a condition known as “Second Impact Syndrome” may occur which results in a failure of the autonomic nervous system, diffuse swelling of the brain, and death.

39. Cerebral Contusions
Bruising of the brain following a blow to the head, which causes internal bleeding from injured blood vessels.

40. Cerebral Contusions
Epidural Hematoma – a hematoma (pocket of blood) in the space between the skull and the meninges which is caused by a rupture of an artery resulting in rapid deterioration of neurological function.

41. Cerebral Contusions
2. Subdural Hematoma – a hematoma (pocket of blood) in the space between the meninges and the brain caused by a ruptured vein. Since veinous bleeding is slower, a person may not show symptoms until hours, days, or even weeks later.

42. Spinal Cord Injuries
Trauma or swelling of the spinal cord or the tissue surrounding it can result in temporary loss of nerve function

43. Spinal Cord Injuries
If the spinal cord has been severed or damaged beyond repair, paralysis usually occurs.
An injury to the upper part of the spinal cord may result in quadriplegia, or paralysis of both upper and lower limbs.

44. Spinal Cord Injuries
An injury to the lower part of the spinal cord may result in paraplegia or paralysis of both lower limbs

45. Degenerative Diseases

46. Parkinson’s Disease
Results in the destruction of nerve cells in an area of the brain that helps coordinate skeletal muscle movement.
It is a progressive disorder, meaning that it gradually involves more and more nerve cells.
As the nerve cells are destroyed, muscle function is impaired.

47. Parkinson’s Disease
Symptoms include uncontrolled muscle tremors and increased muscle rigidity.
There is no known cause or cure at the present time.

48. Multiple Sclerosis
Involves the destruction of the myelin sheath that surrounds the axons of neurons in the Central Nervous System.
The scar tissue that remains on the neuron interferes with the conduction of nerve impulses, and voluntary control of muscles decreases

49. Multiple Sclerosis
With each new attack, loss of nerve function increases.
Multiple Sclerosis is an autoimmune disease in which the body attacks its own tissue.

50. Alzheimer’s Disease Results when neurons in the brain are destroyed.
If neurons become clogged with protein deposits, they are unable to transmit impulses.

51. Alzheimer’s Disease
The result is confusion, loss of memory, and gradual mental deterioration.
There is no known cause or cure for Alzheimer’s disease at the present time.

52. Other Disorders & Problems

53. Epilepsy
A disorder of the nervous system that is characterized by recurrent seizures – sudden episodes of uncontrolled electrical activity in the brain.
It can be caused by brain damage before or during birth, infections, head injury, withdrawal from drugs or alcohol, or exposure to toxins.

54. Epilepsy
Seizures may be slight and brief, involving little body movement, or they can be quite severe, involving muscle contractions throughout the entire body.
Medications can help control seizures so that a person with epilepsy can lead a normal, healthy life.

55. Cerebral Palsy
Refers to a group of non-progressive neurological disorders that are the result of damage to the brain before, during, or just after birth; or in early childhood.
Causes may include infections such as encephalitis or meningitis, head injury, or exposure to radiation before birth.

56. Cerebral Palsy
Physical therapy, braces to enable walking, and medications can help cerebral palsy patients be independent and participate in everyday activities.