1. Chapter 10 Goals Page 343 Students will be able to:
Name, locate, & describe the major organs of the nervous system & their functions.
Learn nervous system combining forms & use them with suffixes & prefixes
Define pathologic conditions affecting the nervous system
Describe nervous system-related laboratory tests, clinical procedures, & abbreviations.
Apply your new knowledge to understanding medical terms in their proper contexts, such as medical reports & records.

2. Nervous System
Chapter 10
Pages 343 – 398

3. Page 344
Introduction
Nerves = microscopic nerve cells collected into macroscopic bundles, that carry electrical messages all over the body.
External receptors as well as internal receptors in muscles & blood vessels receive impulses & in turn transmit impulses to the complex network of nerve cells in the brain & spinal cord.
Within this central part of the nervous system, impulses are recognized, interpreted, & finally relayed to other nerve cells that extend out to all parts of the body.
The nervous system is one of the most complex of all human body systems.
More than 100 billion nerve cells operate constantly all over the body to coordinate the activities we do consciously/voluntarily, as well as those that occur unconsciously/involuntarily.

4. General Structure of the Nervous System
Page 344
General Structure of the Nervous System
The nervous system has two major divisions:
central nervous system (CNS) – consists of the brain & spinal cord
peripheral nervous system (PNS) – consists of:
cranial nerves – carry impulses between the brain the head & neck.
spinal nerves – messages between the spinal cord & the chest, abdomen, & extremities.
Plexuses = a large network of nerves in the peripheral nervous system.
peripheral nerves
The one exception is the tenth cranial nerve, called the vagus nerve. vagus nerve – carries messages to & from the neck, chest, & abdomen.
The cervical, brachial, & lumbosacral plexuses are examples that include cervical, lumbar, & sacral nerves.

5. General Structure of the Nervous System: Cont.
Page 344
General Structure of the Nervous System: Cont.
spinal & cranial nerves = nerves that help the body respond to changes in the outside world. They include:
Sense receptors for sight, hearing & balance, smell, & touch & sensory nerves that carry messages related to changes in the environment toward the spinal cord & brain.
Motor nerves travel from the spinal cord & brain to muscles of the body, telling them how to respond.
For example, when you touch a hot stove, temperature & pain receptors in the skin stimulate afferent nerves, which carry messages toward the spinal cord & brain. Instantaneously, the message is conveyed to efferent nerve cells in the spinal cord, which then active voluntary muscles to pull your hand away from the stove.

6. General Structure of the Nervous System: Cont.
Page 345
General Structure of the Nervous System: Cont.
peripheral nervous system contains:
the spinal & cranial nerves – whose functions are mainly voluntary & involved
autonomic nervous system – a large group of nerves that function involuntarily or automatically, without conscious control. This system of nerve fibers carries impulses away from the CNS to the glands, heart, blood vessels, & involuntary muscles found in the walls of tubes like the intestines & hollow organs like the stomach & urinary bladder.
the spinal & cranial nerves – with sensations of smell, taste, sight, hearing, & muscle movements

7. General Structure of the Nervous System: Cont.
Pages 346 – 347
General Structure of the Nervous System: Cont.
autonomic nerves:
sympathetic nerves – stimulate the body in times of stress & crisis. They increase heart rate & forcefulness, dilate (relax) airways so more oxygen can enter, & increase blood pressure. They also stimulate the adrenal glands to secrete epinephrine, while also inhibiting intestinal contractions to slow digestion.
parasympathetic nerves – slow down heart rate, lower blood pressure, & stimulate intestinal contractions to clear the rectum.

8. Neurons, Nerves, & Glial Cells
Page 348
Neurons, Nerves, & Glial Cells
Neuron = an individual nerve cell.
Dendrites = branching fibers; carry impulses toward
Cell body = contains the cell nucleus; grey
Axon = extends from the cell body, carry impulses away
Myelin sheath = insulates the axon & speeds transmission of the impulse; white
Terminal end fibers = where impulses leave the cell
Synapse = the space where impulses jump from one neuron to another. The transfer of the impulse across the synapse depends on the release of a neurotransmitter.
Neuron = an individual nerve cell, a microscopic structure. Impulses pass in one direction.
Demyelination = the loss of the myelin insulating the nerve fiber & is characteristic of multiple sclerosis, an acquired illness affecting the CNS.
Myelin = a fatty tissue that covers axons.
myelin sheath – gives a white appearance to the nerve fiber (that’s why it’s called white matter[as in parts of the spinal cord & most of the PNS]) The Grey matter of the brain & spinal cords is composed of the cell bodies of the neurons. (the are grey because they are not covered by the myelin sheath)
neurotransmitter = chemical substance released by the neuron that brings the impulse to the synapse (examples: acetylcholine, norepinephrine, epinephrine (adrenaline), dopamine, serotonin, & endorphins)
Ganglia = small cell bodies outside the brain & spinal cord.

9. Neurons, Nerves, & Glial Cells: Cont.
Page 349
Neurons, Nerves, & Glial Cells: Cont.
Nerve = consists of a bundle of dendrites & axons that travel together like strands of rope.
Afferent (sensory nerves) = peripheral nerves that carry impulse to the CNS from stimulus receptors
Efferent (motor nerves) = peripheral nerves that carry impulse from the CNS to organs that produce responses
Nerve = able to be seen with the naked eye.
Parenchyma = essential distinguishing tissue of an organ. (neurons & nerves in this system)
Stroma = the connective & supportive tissue of an organ. (glial (neuroglial) cells in this system)

10. Neurons, Nerves, & Glial Cells: Cont.
Page 349
Neurons, Nerves, & Glial Cells: Cont.
Glial (neuroglial) cells = the make a supportive framework & help to ward off infection.
Astrocytes (astroglial cells) = appear star-like; transport water/salts between capillaries & neurons.
Micorglial cells = have many dendrites; phagocytes that protect neurons in response to inflammation
Oligodenroglial cells (oligodendrocytes) = have few dendrites; form the myelin sheath in the CNS.
Ependymal cells = lines membranes within the brain & spinal cord where CSF is produced
Glial (neuroglial) cells – They do not transmit impulses, but are more numerous than neurons & can reproduce.
Glial cells, particularly the astrocytes, are associated with blood vessels & regulate the passage of potentially harmful substances from the blood into the nerve cells of the brain. This protective barrier between the blood & brain cells is called the blood-brain barrier (BBB). This barrier consists of special lining (endothelia) cells, which along with astrocytes separate capillaries from nerve cells. Delivery of chemotherapeutic drugs to treat brain tumors is thus difficult, because the BBB blocks drug access to brain tissue.

11. Page 350
The Brain
Brain = controls body activities, weights 3 lbs. & has many different parts.
Cerebrum = largest part of the brain; the “thinking” area
Cerebral cortex = nerve cell sheets that make up the surface of the cerebrum
Gyri = the folds into which the cerebral cortex is arranged
Sulci = grooves that separate the gyri
Cerebral hemispheres = each of the two parts of the cerebrum (left & right)
Cerebral hemispheres – Each hemisphere is subdivided into four major lobes named for the cranial (skull) bones that overlie them. (frontal, parietal, occipital, & temporal)

12. The Brain: Cont. Page 350 Functions of the cerebrum:
Responsible for thought, judgement, memory, association, & discrimination.
Sensory impulses are received through afferent cranial nerves, & when registered in the cortex, they are the basis for perception
Cranial nerves carry motor impulses from the cerebrum to muscles & glands, & these produce movement & activity

13. Pages 350 – 351
The Brain: Cont.
Ventricles = spaces or canals in the middle of the cerebrum.
Contains cerebrospinal fluid (CSF), a watery fluid that flows throughout the brain & around the spinal cord. It protects the brain & spinal cord from shock by acting like a cushion. CSF is usually clear & colorless & contains lymphocytes, sugar, & proteins.
Spinal fluid can be withdrawn for diagnosis or relief of pressure on the brain through a lumbar puncture (LP).
lumbar puncture (LP) = a hollow needle is inserted into the lumbar region of the spinal column below the region where the nervous tissue of the spinal cord ends, & CSF is withdrawn.

14. The Brain: Cont. Page 351 Two other important parts of the brain:
Thalamus – decides what is important & what is not, selectively processing & relaying sensory information to the cerebral cortex. It also plays a major role in maintaining levels of awareness & consciousness.
Hypothalamus – contains neurons that control body temperature, sleep, appetite, sexual desire, & emotions. It also regulates the release of hormones from the pituitary gland & integrates the activities of the sympathetic & parasympathetic nervous systems
Hypothalamus (below the thalamus)
pituitary gland (at the base of the brain)

15. Page 351
The Brain: Cont.
Structures of the brain that lie in the back & below the cerebrum & connect the cerebrum with the spinal cord:
Cerebellum – coordinates voluntary movements & to maintain balance & posture
Brainstem contains the following:
Midbrain – uppermost portion of the brainstem; contains pathways connecting the cerebrum with lower portions of the brain & structures involved with seeing & hearing.

16. Pages 351 – 352
The Brain: Cont.
Pons – connect the cerebellum & cerebrum with the rest of the brain. Nerves affecting the face & eye movement are located here.
Medulla oblongata – connects the spinal cord with the rest of the brain. Nerve tracts cross from right to left & left to right here. It contains:
Respiratory center – controls muscles of respiration
Cardiac center – slows the heart rate when the heart is beating too rapidly
Vasomotor center – affects the muscles in the walls of blood vessels
Vasomotor center – affects (constricts or dilates) the muscles in the walls of blood vessels (influencing blood pressure)

17. The Spinal Cord & Meninges
Page 353
The Spinal Cord & Meninges
Spinal Cord
A column of nervous tissue extending from the medulla oblongata to the second lumbar vertebra within the vertebral column. It carries all the nerves to & from the limbs & lower part of the body, & is the pathway for impulses going to & from the brain. A cross-sectional view of the spinal cord reveals an inner region of gray matter & an outer region of white matter.
cauda equine = a fan of nerve fibers below the end of the spinal cord.
gray matter (containing cell bodies & dendrites)
white matter (containing the nerve fiber tracts with myelin sheaths)

18. The Spinal Cord & Meninges
Page 354
The Spinal Cord & Meninges
Meninges
3 layers of connective tissue membranes that surround the brain & spinal cord.
dura mater = outermost; thick & tough it has channels that contain blood.
subdural space = below the dural membrane
Arachnoid membrane = second layer; loosely attached to the other meninges by web-like fibers.
subarachnoid space = contains CSF
Pia mater = third layer; it’s a delicate connective tissue with a rich supply of blood vessels
Most physicians refer to the pia & arachnoid membranes together as the pia-arachnoid.

19. Pages 362 – 363
Pathology
Congenital Disorders
hydrocephalus
Abnormal accumulation of fluid (CSF) in the brain
spina bifida
Congenital defects in the lumbar spinal column caused by imperfect union of vertebral parts (neural tube defect).
The bones of the skull, the vertebral column, & the meninges, containing CSF, provide a hard box with a interior cushion around the brain & spinal cord. In addition, glial cells surrounding neurons form a blood-brain barrier that prevents many potentially harmful substances in the bloodstream from gaining access to neurons. However, these protective factors are counterbalanced by the extreme sensitivity of nerve cells to oxygen deficiency (brain cells die in a few minutes when deprived of oxygen).
Neurologic disorders may be classified in the following categories:
Congenital
Degenerative, movement, & seizure
Infectious (meningitis & encephalitis)
Neoplastic (tumors)
Traumatic
Vascular

20. Pages 364 – 365
Pathology
Degenerative, Movement, & Seizure Disorders
Alzheimer disease (AD) (Alzheimer's)
Brain disorder marked by gradual & progressive mental deterioration (dementia), personality changes, & impairment of daily functioning.
amyotrophic lateral sclerosis (ALS)
Degenerative disorder of motor neurons in the spinal cord & brainstem
epilepsy
Chronic brain disorder characterized by recurrent seizure activity

21. Pathology Pages 365 – 366 Degenerative, Movement, & Seizure Disorders
Huntington disease (Huntington's)
Hereditary disorder marked by degenerative changes in the cerebrum leading to abrupt involuntary movements & mental deterioration
multiple sclerosis (MS)
Destruction of the myelin sheath on neurons in the CNS & its replacement by plaques of the sclerotic (hard) tissue.
myasthenia gravis (MG)
Autoimmune neuromuscular disorder characterized by weakness of voluntary muscles

22. Pathology Pages 366 – 367 Degenerative, Movement, & Seizure Disorders
palsy
Paralysis (partial or complete loss of motor function)
Parkinson disease (Parkinson's)
Degeneration of neurons in the basal ganglia, occurring in later life & leading to tremors, weakness of muscles, & slowness of movement.
Tourette syndrome (Tourette's)
Involuntary, spasmodic, twitching movements; uncontrollable vocal sounds; & inappropriate words.

23. Pathology Page 368 Infectious Disorders herpes zoster (shingles)
Viral infection affecting peripheral nerves
meningitis
Inflammation of the meninges; leptomeningitis
human immunodeficiency virus (HIV) encephalopathy
Brain disease & dementia occurring with AIDS

24. Pathology Pages 368 – 369 Neoplastic Disorders
brain tumor
Abnormal growth of brain tissue & meninges

25. Pathology Page 369 Traumatic Disorders cerebral concussion
Type of traumatic brain injury caused by a blow to the head
cerebral contusion
Bruising of brain tissue resulting form direct trauma to the head

26. Pathology Pages 369 – 370 Vascular Disorders
cerebrovascular accident (CVA)
Disruption in the normal blood supply to the brain; stroke.
1) Thrombotic - Blood clot in an artery leadign to the brain.
2) Embolic - a dislodged thrombus blocks a small vessel in the brain
3) Hemorrhagic - a blood vessel breaks.
migraine
Severe, recurring, unilateral, vascular headache.

27. Laboratory Tests & Clinical Procedures
Page 371
Laboratory Tests & Clinical Procedures
Laboratory Tests
cerebrospinal fluid analysis
Samples of CSF are examined

28. Laboratory Tests & Clinical Procedures
Pages 371 – 372
Laboratory Tests & Clinical Procedures
Clinical Procedures
X-Ray Tests
cerebral angiography
X-ray imaging of the arterial blood vessels in the brain after injection of contrast materaial.
computed tomography (CT) of the brain
Computerized x-ray technique that generates multiple images of the brain & spinal cord.

29. Laboratory Tests & Clinical Procedures
Page 372
Laboratory Tests & Clinical Procedures
Clinical Procedures
Magnetic Resonance Techniques
magnetic resonance imaging (MRI)
Magnetic field & pulses of radio wave energy create images of the brain & spinal cord.

30. Laboratory Tests & Clinical Procedures
Page 372
Laboratory Tests & Clinical Procedures
Clinical Procedures
Radionuclide Studies
positron emission tomography (PET) scan
Radioactive glucose is injected & then detected in the brain to image the metabolic activity of cells.

31. Laboratory Tests & Clinical Procedures
Page 372
Laboratory Tests & Clinical Procedures
Clinical Procedures
Ultrasound Examination
Doppler ultrasound studies
Sound waves detect blood flow in the carotid & intracranial arteries

32. Laboratory Tests & Clinical Procedures
Page 373
Laboratory Tests & Clinical Procedures
Clinical Procedures
Other Procedures
Electroencephalography (EEG)
Recording of the electrical activity of the brain
lumbar puncture (LP)
CSF is withdrawn from between two lumbar vertebrae for analysis
stereotactic radiosurgery
Use of a specialized instrument to locate & treat targets in the brain.