Chapter 5

Question 1

Myelin sheath

Answer 1

nerve conduction is determined by diameter of the nerve and the myelin sheath

multi layer lipid that insulates and protects the nerve fibers. Produced by cells called oligodendroglial cells in the cns

Question 2

Neurons are similar to other cells in the body because:

Answer 2

Neurons are surrounded by a cell membrane.
Neurons have a nucleus that contains genes.
Neurons contain cytoplasm, mitochondria and other organelles.
Neurons carry out basic cellular processes such as protein synthesis and energy production.

Question 3

neurons differ from other cells in the body because:

Answer 3

Neurons have specialize cell parts called dendrites and axons. Dendrites bring electrical signals to the cell body and axons take information away from the cell body.
Neurons communicate with each other through an electrochemical process.
Neurons contain some specialized structures (for example, synapses) and chemicals (for example, neurotransmitters).

Question 4

the nervous system contains two kinds of cells:

Answer 4

neurons are the cell type (primarily) responsible for communication and integration in the nervous system.
glia, which protect the neurons, but also modify their action.

Question 5

Neurons (nerve cells) have three parts that carry out the functions of communication and integration:

Answer 5

dendrites, axons, and axon terminals.

Question 6

Neurons have a fourth part the ____________, which carries out the basic life processes of neurons.

Answer 6

cell body or soma

Question 7

synapse

Answer 7

In the nervous system, a synapse is a structure that permits a neuron (or nerve cell) to pass an electrical or chemical signal to another neuron. Some authors generalize this concept to include the communication from a neuron to any other cell type, such as to a motor cell

Question 8

Neuron Types

Answer 8

bipolar (interneuron), unipolar sensory neuron, multipolar neuron (motoneuron), pyramidal cells

Question 9

bipolar (interneuron)

Answer 9

A bipolar cell is a type of neuron which has two extensions. Bipolar cells are specialized sensory neurons for the transmission of special senses. As such, they are part of the sensory pathways for smell, sight, taste, hearing and vestibular functions.

Question 10

unipolar sensory neuron

Answer 10

A unipolar neuron is a type of neuron in which only one protoplasmic process (neurite) extends from the cell body. Most neurons are multipolar, generating several dendrites and an axon and there are also many bipolar neurons.

Question 11

multipolar neuron (motoneuron)

Answer 11

A multipolar neuron (or multipolar neurone) is a type of neuron that possesses a single axon and many dendrites (and dendritic branches), allowing for the integration of a great deal of information from other neurons. These processes are projections from the nerve cell body. Multipolar neurons constitute the majority of neurons in the central nervous system. They include motor neurons and interneurons and are found mostly in the cortex of the brain, the spinal cord, and also in the autonomic ganglia.

Question 12

pyramidal cells

Answer 12

Pyramidal neurons (pyramidal cells) are a type of multipolar neuron found in areas of the brain including the cerebral cortex, the hippocampus, and the amygdala. Pyramidal neurons are the primary excitation units of the mammalian prefrontal cortex and the corticospinal tract.

Question 13

Neuroglial cells

Answer 13

Located in the gray and white matter of the brain and support and protect the nerve cells. There are 40 to 50 times as many glial cells as nerve cells. They are small and do not participate in generation and transmission of nerve impulses. They maintain homeostasis, form myelin, and provide support and protection for neurons in the central and peripheral nervous systems

Question 14

Four types of Neuroglial Cells

Answer 14

Four types astrocytes, oligodendrocyte, ependymal and microglia

Question 15

Astrocytes

Answer 15

Astrocytes (Astro from Greek astron = star and cyte from Greek “kyttaron” = cell), also known collectively as astroglia, are characteristic star-shaped glial cells in the brain and spinal cord. Astrocytes, function as connective tissue and provide skeletal support for the brain cells and their processes and contribute to the blood brain barrier and can degrade released neurotransmitters. (Fight or Flight- astrocytes help you degrade) Astrocytes will migrate to the site of a brain lesion (a stroke) (form a cavity to place ethe debris in).

Question 16

Oligodendrocytes

Answer 16

Oligodendrocytes (from Greek, meaning cells with a few branches), or oligodendroglia, are a type of neuroglia. Their main functions are to provide support and insulation to axons in the central nervous system of some vertebrates, equivalent to the function performed by Schwann cells in the peripheral nervous system.

Question 17

ependymal

Answer 17

Ependyma is the thin epithelial lining of the ventricular system of the brain and the central canal of the spinal cord, made up of ependymal cells. Ependyma is one of the four types of neuroglia in the central nervous system (CNS). It is involved in the production of cerebrospinal fluid (CSF), and is shown to serve as a reservoir for neuroregeneration.

Question 18

microglia

Answer 18

Microglia are a type of neuroglia (glial cell) located throughout the brain and spinal cord.Microglia account for 10–15% of all cells found within the brain. As the resident macrophage cells, they act as the first and main form of active immune defense in the central nervous system (CNS).Microglia (and other neuroglia including astrocytes) are distributed in large non-overlapping regions throughout the CNS. Microglia are key cells in overall brain maintenance—they are constantly scavenging the CNS for plaques, damaged or unnecessary neurons and synapses, and infectious agents

Question 19

Schwann

Answer 19

Glial cells of the PNS are called Schwann acting as connective tissue

Question 20

Action potential

Answer 20

Excitability is a cells response to various stimuli
Conversion of this response into a nerve impulse is called an action potential
Stimuli include chemical or temperature changes, electrical pulses, and mechanical stimulation

Question 21

Neuronal responses to brain injuries

Answer 21

Nerve cells in the brain are less capable fo regeneration
This restricts the recovery of sensorimotor functions and higher mental functions including language after lesions in the brain
Process of spontaneous recovery after trauma and vascular accidents
Axonal regeneration 10-18 days

Question 22

neurotransmitters

Answer 22

Neurotransmitters, also known as chemical messengers, are endogenous chemicals that enable neurotransmission. They transmit signals across a chemical synapse, from one neuron (nerve cell) to another “target” neuron, muscle cell, or gland cell. Neurotransmitters are released from synaptic vesicles in synapses into the synaptic cleft, where they are received by receptors on the target cells. Neurotransmitters play a major role in shaping everyday life and functions.

Question 23

Types of neurotransmitters

Answer 23

There are many different ways to classify neurotransmitters. Dividing them into amino acids, peptides, and monoamines is sufficient for some classification purposes.

Question 24

Major neurotransmitters

Answer 24

acetlychloline, dopamine, GABA, Glutamate, Glycine, Norephinephrine, Serotonin.

Question 25

acetylcholine

Answer 25

Primary neurotransmitter of the PNS Regulates muscular activities and muscle contraction Also found in the CNS Regulates forebrain activity Inhibits basal ganglia activity Cycle of sleep and wakefulness Voluntary movement of motor fibers of the spinal and cranial nerves Myasthenia gravis, Alzheimer disease (decreased production) Probably most important

Question 26

What neurotransmitter is mysathenia gravis associated with?

Answer 26

Mysathenia gravis autoimmune neuro muscular disease that results from growth of antibodes to acetylcholine receptors

Question 27

monoamines

Answer 27

``` Norepinephrine Dopamine Serotonin Y-amino butyric acid GABA glutamate ``` All lie in the brainstem Project to areas of the brain and participate in regulating the activity of large portions of the CNS

Question 28

norepinephrine

Answer 28

Flight or fight reaction Regulates sleep attention and mood Found in pons and medulla Linked to ADD, narcolepsy, mood disorders

Question 29

dopamine

Answer 29

Prefrontal functions (cognition, motivation and emotion) Regulates basil ganglia motor functions Upper midbrain and project ipsilaterally Reduced production causes Parkinson's disease Drug abuse directly or indirectly cause dopamine release Excessive dopamine production in the forebrain contributes to schizophrenia Thorazine blocks dopamine receptors

Question 30

serotonin

Answer 30

95% found in blood platelets and the GI tract Overall level of arousal sleep Regulates emotion Regulates pain perception May be associated with severe depression and mental illness Suicide low levels of serotonin

Question 31

GABA

Answer 31

``` Derivative of glutamate Major inhibitory neurotransmitter for the CNS Widespread in the nervous system Regulates excitability of neurons Regulates pain perception Inhibits basil ganglia movements Pharmaceutical agents that interact with GABA are used for epilepsy, anxiety, insomnia and anesthesia Implicated in Huntington chorea ```

Question 32

glutamate

Answer 32

Main excitatory neurotransmitter in the CNS Mediates fast synaptic transmission in the CNS Excessive glutamate may cause stroke or degenerative disorders

Question 33

Large molecules

Answer 33

Peptides Endorphins, enkephalins and substance P Regulates pain perception

Question 34

Clinical correlates

Answer 34

Brain tumors Multiple sclerosis Myasthenia gravis

Question 35

brain tumors

Answer 35

Neoplasm (tumor) Primary or metastatic Malignant or benign Primary arise from glial cells or meninges within the CNS

Question 36

Malignant tumors

Answer 36

Malignant tumors of the brain include astrocytoma's, ependymal, oligodendrogliomas

Question 37

What is the most malignant brain tumor?

Answer 37

Glioblastoma a type of astrocytoma is the most malignant brain tumor half of patients die within 18 months

Question 38

MS stats

Answer 38

``` 2-3x more women then men Usually occurs between ages 20-50 8-10,000 people under age 18 or over 75 2.3 million worldwide More common in Caucasians of northern European ancestry ```

Question 39

MS cause

Answer 39

Antibodies attack the myelin sheath Form plaques in the brain Decreased speed of nerve conduction Progressive neurological symptoms

Question 40

4 different disease courses (Diagnosis) of MS

Answer 40

Relapsing-remitting MS Primary-progressive MS Secondary-progressive MS Progressive-MS

Question 41

Relapsing-Remitting MS

Answer 41

Clearly defined attacks (relapses) of worsening neurologic functions Followed by flare-ups (exacerbations) Followed by partial repeat recovery (remission) 85% initially diagnosed with relapsing-remitting

Question 42

Primary-progressive ms

Answer 42

Slowly worsening neurologic functions with not relapses or remissions Rate of progression varies 10%

Question 43

Secondary-Progressive MS

Answer 43

Initial period of relapsing-remitting MS Then develop a secondary progress MS where the disease worsens more steadily with or without flare ups remissions or plateau Prior to disease modifying medications, 50% of people with relapsing-remitting MS develop SP within 10 years

Question 44

Progressive relapsing MS

Answer 44

Rare 5% Clear attacks of worsening disease from the beginning No remission

Question 45

Symptoms of MS

Answer 45

``` Early symptoms are vision loss Double vision Vertigo Loss of balance weakness Numbness in the limbs ```

Question 46

Speech disorders of MS

Answer 46

``` Dysarthria Dysphonia Dysphagia Slurred speech Nasal sounding speech ``` Speech and voice disorders in 25-40%

Question 47

Treatment

Answer 47

Treatment is symptomatic Corticosteroids B-interferon Copaxone injections

Question 48

Myasthenia Gravis

Answer 48

Neuromuscular junction disorder Characterized by progressive fatigue and muscle weakness Worsens with exercise and improves with rest Caused by under activity of acetylcholine Autoimmune Symptoms appear at any age

Question 49

Myasthenia Gravis Prevalence

Answer 49

Most prevalent in females during the first 30 years of life | After 30 more prevalent in men

Question 50

Myasthenia Gravis symptoms

Answer 50

Onset is gradual First signs of disease often appear in constantly used muscles such as eye muscles or muscles of respiration Ptosis diplopia

Question 51

Myasthenia Gravis speech disorders

Answer 51

Involvement of cranial nerves Altered facial expression Hypernasality Prognosis is good for those who do not have a progressive form Progressive course may result in respiratory paralysis

Question 52

ptosis

Answer 52

drooping of the eyelid

Question 53

diploplia

Answer 53

double vision