The Nervous System Flashcards
(105 cards)
1
Q
What is neurology?
A
Neurology is the study or knowledge of the branch of medicine that deals with the nervous system and its disease.
2
Q
What are the functions of the nervous system?
A
The nervous system is the chief co-ordinator in the body, necessary so the stable body conditions (homeostasis) can be maintained.
3
Q
How does the body adapt itself to new conditions?
A
Conditions within and outside the body are constantly changing. The nervous system responds to these changes, which are known as stimuli, and causes the body to adapt itself to new conditions.
4
Q
What is a functioning nervous system necessary for?
A
A functioning nervous system is necessary for survival.
5
Q
What organs make up the nervous system?
A
The brain, spinal cord and nerves make up the nervous system.
6
Q
How is the nervous system divided up?
A
The nervous system is divided into the central nervous system and the peripheral nervous system.
7
Q
What does the central nervous system include?
A
The central nervous system includes the brain and the spinal cord.
8
Q
How is the peripheral nervous system divided?
A
The peripheral nervous system is divided into cranial nerves (12 pairs) and the spinal nerves (31 pairs).
9
Q
What does the peripheral nervous system include?
A
The peripheral nervous system includes all the nerves (cranial and spinal) outside the central nervous system.
10
Q
What do cranial nerves carry?
A
Cranial nerves carry impulses to and from the brain.
11
Q
What do spinal nerves carry and how are spinal nerves distributed?
A
Spinal nerves carry impulses to and from the spinal cord. They are distributed evenly in segments down the spinal cord.
12
Q
How much does the brain weigh approximately?
A
Weighs about 3 pounds, and it is a jelly like consistency.
13
Q
When do neutrons of the brain undergo mitosis?
A
Neurons of the brain undergo mitosis only before birth and a few months after birth. Although they grow in size they do not increase in number.
14
Q
When does the brain reach its full size?
A
The brain attains its full size by 18 years of age, but grows rapidly only in the first 9 years.
15
Q
What are neurons?
A
Neurons are nerve cells or conducting cells of the nervous system.
16
Q
What are the three main parts of the brain?
A
1) Cerebrum 2) Cerebellum 3) Brain Stem
17
Q
What is the cerebrum?
A
The cerebrum is the major portion of the brain occupying almost the entire portion of the skull above the eyes. It contains many neurons which are concentrated in the small space.
18
Q
What divides the cerebrum?
A
A fissure divides the cerebrum into two hemispheres, which are linked by nerve fibres.
19
Q
How is the brain organized?
A
The brain is organized so that the left side controls the right side of the body and vice versa.
20
Q
What are the two hemispheres of the cerebrum?
A
The left cerebrum hemisphere (logical side) and the right cerebrum hemisphere (artistic side).
21
Q
What are some things that the left cerebrum hemisphere is responsible for?
A
The left cerebrum hemisphere is responsible for speech, handwriting, reading, mathematics, and recognition of body parts. (Usually dominate in right handed people).
22
Q
What are some things that the right cerebrum hemisphere is responsible for?
A
The right cerebrum hemisphere is responsible for music, geographic sense, and recognition of face.
23
Q
What are the four visible lobes that the hemispheres are divided into and what are they responsible for?
A
1) Occipital (back) - vision
2) Parietal (upper) - distance, sizes, shapes, touch
3) Frontal (front) - movement, speech
4) Temporal (side) - smell, hearing
24
Q
What is the function of the cerebellum?
A
The cerebellum maintains balance, posture, and muscular co-ordination.
25
What is the brain stem?
The brain stem connects the brain with the spinal cord - deals with important basic and involuntary functions.
26
What are the four parts of the brain stem?
1) Hypothalamus
2) Mid brain
3) Pons
4) Medulla Oblongata
27
What is the hypothalamus responsible for?
Hormones, temperature, water balance, cravings and appetite - thus linking the nervous and endocrine systems together.
28
What does the midbrain control?
The midbrain controls visual and auditory reflex centres.
29
What is the pons responsible for?
The pons controls eye and facial movements and regulates breathing.
30
What is the medulla oblongata responsible for?
The medulla oblongata is responsible for breathing, swallowing, intestinal activity. It controls the involuntary actions of the respiratory and circulatory systems and some reflux actions (i.e. sneezing, coughing and vomiting)
31
What encloses the spinal cord?
The spinal cord is enclosed in the bony vertebral column of the back.
32
How many pairs of nerves are in the spinal cord?
31 pairs of nerves.
33
How do nerves enter or leave the spinal cord?
Except for the 12 pairs of cranial nerves that connect directly with the brain, all nerves enter or leave the spinal cord through the openings in the vertebrae.
34
What do sensory impulses do?
Sensory impulses of many kinds enter the outside white matter of the spinal cord and travel upward far enough to trigger spinal reflexes at various levels or travel to the brain.
35
What do motor impulses do?
Motor impulses travel downwards from the nerve cells in the brain to reach spinal cells which relay messages to various muscles, organs, glands and blood vessels.
36
What is the structure of the spinal cord?
The spinal cord is an H shaped area, of grey matter surrounded by white matter.
37
What are the functions of the spinal cord?
1. Reflex activities, which involve the transfer and integration of messages that enter the cord, so that sensory (afferent) impulses may enter and motor (efferent) messages may leave the cord without involving the brain.
2. Conduction of sensory impulses - from afferent (sensory) nerves upward through ascending tracts to the brain.
3. Conduction of motor (efferent) impulses from the brain down through decending tracts to the nerves that supply muscles or glands.
38
What does the peripheral nervous system include?
The peripheral nervous system (P.N.S) includes all the nerves outside the central nervous system (C.N.S)
39
How are the 12 pairs of cranial nerves numbered and where are they located?
The 12 pairs of cranial nerves are numbered according to their connection with the brain, beginning at the front and proceeding back.
40
What do the first 9 pairs and the 12th pair of cranial nerves supply?
The first 9 pairs and the 12th pair supply structures in the head.
41
What are the functions of cranial nerves?
1. Special sensory impulses
2. General sensory impulses
3. Voluntary motor impulses
4. Involuntary motor impulses
42
What are special sensory impulses?
Special sensory impulses, (coming into the brain) such as those for smell, taste, vision, and hearing.
43
What are general sensory impulses?
General sensory impulses (coming into the brain) such as those for pain, touch, temperature, deep muscle sense, pressure, and vibration.
44
What do voluntary motor impulses do?
Voluntary motor impulses (going out of brain) resulting in voluntary control of skeletal muscles.
45
What do involuntary motor impulses produce?
Involuntary motor impulses (going out of the brain) producing involuntary control of glands and involuntary muscles (cardiac muscle and smooth muscle). These motor pathways are part of the involuntary nervous system, parasympathetic division.
46
What are meninges?
Meninges are three layers of connective tissue that surround the brain and spinal cord to form a complete enclosure.
47
What is cerebral spinal fluid?
Cerebral spinal fluid is a clear watery liquid similar to blood plasma, formed inside the ventricles of the brain, by filtration of blood and cellular secretions. CSF flows from ventricle to ventricle, and around the brain and cord. Mich of the fluid layer returns to the blood.
48
What are the functions of cerebral spinal fluid?
1. Cushion shocks to the central nervous system.
2. Carries nutrients to the cells of the central nervous system.
3. Transports wastes from the cells of the central nervous system.
49
How else can the peripheral nervous system be divided?
The peripheral nervous system can be divided into the voluntary (somatic) nervous system and the involuntary (autonomic) nervous system.
50
What does the voluntary (somatic) nervous system do?
The voluntary (somatic) nervous system supplies skeletal muscles - muscles we can consciously move and conducts impulses from the CNS to skeletal muscle.
51
What does the involuntary (autonomic) nervous system do?
The involuntary (autonomic) nervous system supplies smooth muscle (organs). (i.e. cardiac muscle and glands only.) The activities of the above 3 are largely involuntary. This means that they are not under our conscious control.
52
How is the involuntary nervous system divided?
The involuntary nervous system subdivides into the sympathetic nervous system and the parasympathetic nervous system.
53
What does the sympathetic nervous system do?
The sympathetic nervous system acts as an accelerator for those organs needed to meet a stressful situation. It promotes what is called "fight or flight response."
54
What does the parasympathetic nervous system do?
The parasympathetic nervous system acts as a balance for the sympathetic once the crisis has passed. Therefore the effects are opposite to those of the sympathetic nervous system.
55
What does the involuntary nervous system control?
The involuntary nervous system controls the glands, smooth muscle, and cardiac muscle.
56
What does the involuntary nervous system regulate?
The involuntary nervous system together with the endocrine system regulates our response to stress.
57
What does the voluntary nervous system consist of?
The voluntary nervous system consists of all the nerves that control skeletal muscle action, which is under conscious control.
58
What is a nerve cell called?
The nerve cell is called the neuron.
59
What encloses a neuron?
A plasma membrane encloses the entire neuron.
60
What do neurons consist of?
Each neuron consists of a cell body containing the nucleus, and of nerve fibres (axons and dendrites), which are thread like projections of cytoplasm.
61
Why are axons and dendrites called nerve fibres?
Axons and dendrites are called nerve fibres because they are thread like extensions.
62
How many dendrites and axons do neurons typically consist of?
Each neuron generally consists of many dendrites but only one axon.
63
What are the two types of nerve fibres?
Dendrites and axons.
64
What do dendrites do?
Dendrites carry impulses to the cell body.
65
What do axons do?
Axons carry impulses away from the cell body.
66
What are the special structures in the dendrites and what are they responsible for?
Each dendrite has a special structure called the receptor, where stimulus is received and sensory impulses begins.
67
What do sensory neuron dendrites do?
Sensory neuron dendrites pick up sensations of pain, touch, hearing, sight, etc.
68
What does the word dendrite mean?
The word dendrite means resembling tree roots.
69
What are some axons covered with and what does it do?
Some axons in the central and peripheral nervous systems are covered with fatty insulating material called myelin that makes for faster transmission.
70
What colour is myelin and why?
Because of the high fat content of myelin, myelinated fibres have a creamy-white colour.
71
What are axons covered with myelin called and where are they found?
Axons covered with myelin are called white fibres and are found in the "white matter" of the brain and spinal cord, as well as the nerves in all parts of the body.
72
What are myelinated axons of some of the peripheral nervous system covered by?
Myelinated axons of some of the peripheral nervous system are covered by a thin outer sheath, called the neurilemma.
73
What does neurilemma do?
Neurilemma aid in repair of damaged nerve fibres.
74
Why can't myelinated axons regenerate in the central nervous system but can regenerate outside of the central nervous system?
Because neurilemma are not present in the central nervous system myelinated axons can't regenerate, but outside the central nervous system nerves can regenerate, but it is a slow and uncertain process.
75
What does the thickness of an axon determine?
The thicker an axon is the faster the transmission will be?
76
What are clusters of neuron cell bodies called?
Clusters of neuron cell bodies have a grey colour and thus are called grey matter.
77
Are clusters of neuron cell bodies covered with myelin?
No, they are not covered with myelin.
78
What are clusters of cell bodies called when they are within the brain and spinal cord?
When clusters of cell bodies are within the brain and spinal cord, they are called nuclei.
79
What are clusters of cell bodies called when they are outside the brain and spinal cord?
When clusters of cell bodies are outside the brain and spinal cord they are called ganglia.
80
What are the functions of ganglia?
- Muscle coordination
| - Secrete neurotransmitters
81
What is a nerve?
A nerve is a mixed bundle of axons and dendrites.
82
What are bundles of nerve fibres within the central nervous system called? Where are they located and what do they do?
Bundles of nerve fibres within the central nervous system are called tracts. Tracts are located within the brain and spinal cord to conduct impulses to and from the brain.
83
What are nerve cell fibres held together by?
Nerve cell fibres are held together by connective tissue.
84
What is each fibre the extension of?
Each fibre is the extension of a cell body that may live a great distance away in ganglia or spinal cord. For example the static nerve is several feet long. (runs from the spine to the toes)
85
How are neurons classified according to function?
1. Sensory
2. Motor
3. Inter-neurons (or central neurons)
86
What are sensory neurons?
Sensory neurons are neurons that are connected with receptors (for receiving stimuli) and that conduct impulses to the brain and spinal cord, are called sensory and afferent nerves.
87
What are motor neurons?
Motor neurons are fibres that carry impulses away from the central nervous system out to the muscles and glands form the motor or efferent neurons.
88
What are interneurons? (or central neurons)
Interneurons or central neurons conduct impulses from afferent (sensory) neurons toward or to efferent (motor) neurons. Interneurons lie entirely within the central nervous system (brain and spinal cord)
89
What happens when nerve cells die?
When nerve cells die they are not replaced. The generous supply of neurons we have initially allows for. millions to be lost without much impairment, as long as these are not all concentrated in a particular nerve centre.
90
What are all metabolic processes of a neuron directed by and what happens if a nerve fibre is cut or injured?
All metabolic processes of a neuron are directed by the cell body. As long as this vital part is intact, the neuron functions. If a nerve fibre is cut or injured, the part attached to the cell body lives, but the part beyond dies.
91
What do nerve cells specialize in?
Nerve cells specialize in impulse conduction.
92
What does a nerve impulse do?
A nerve impulse spreads along a nerve cell membrane like an electric current. A myelinated nerve fibre conducts impulses more rapidly than an unmyelinated fibre of the same size. In general, the larger the diameter of the axon, the more rapid the impulse conduction.
93
Is there any anatomical connection between neurons?
Each neuron is a separate unit and there is no anatomical connection between them.
94
What is a synapse?
A synapse is an incredibly small gap or junction between the axon of one neuron and the dendrite of another neuron.
95
What do neurotransmitters do that is crucial to the synapse?
Certain chemicals called neurotransmitters or transmitter substances are released from the axon endings to enable the impulse to cross the synapse, to the dendrite of the next neuron.
96
What are some examples of neurotransmitters and what nervous system are the released by?
Epinephrine (adrenalin), norepinephrine (noradrenalin), and acetylcholine. There are many others. These neurotransmitters are released by the involuntary nervous system, other types are secreted by the voluntary nervous system.
97
What is a reflex arc?
The route travelled by many nerve impulses is called a reflex arc. A reflex arc is an impulse conduction route to and from the central nervous system (the brain and the spinal cord)
98
What is the simplest form of a reflex arc?
The simplest form of a reflex arc consists of afferent sensory neurons - and - efferent motor neurons. This is called a two neuron arc.
99
What is the most common form of a reflex arc?
The most common form of a reflex arc is the three neuron arc. It consists of afferent neurons, interneurons and efferent neurons.
100
What happens in a three neuron arc?
Afferent (sensory) neurons conduct impulses to the central nervous system from the periphery (any part outside the CNS). Efferent neurons (motor neurons) conduct impulses from the central nervous system to effectors. Interneurons conduct impulses from sensory (afferent) neurons to motor (efferent) neurons.
101
What is a reflex arc in essence?
In essence a reflex arc is an impulse conduction route from receptors to the central nervous system and out to effectors. (i.e. knee jerk)
102
Do all impulses that terminate in effectors start in receptors?
Not all impulses that terminate in effectors start in receptors. Many being, for example in the brain. (I.e. lifting your hand to wave goodbye.)
103
What are neurotransmitters?
Neurotransmitters are chemical substances that make it possible for a impulse to jump across a synapse from one neuron to another.
104
What is an effector?
An effector is a muscle tissue or glandular tissue that responds to a stimulus (axon)
105
What is a receptor?
A receptor is a specialized cell or ending of a sensory neuron that can be excited by a stimulus (dendrite).
