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Flashcards in The Nervous System Deck (131):
1

What are the three main overlapping Functions? Explain.

1) Sensory Input: monitor changes occuring inside and outside of the body using sensory receptors
2) Integration: process and interpret the sensory input to decide on a required action
3) Motor Output: causes a response by activating muscles or glands (effectors)

2

How many types of cells are there in the nervous system? What are they?

2 types
Supporting Cells (Glia)
Neurons

3

What are the functions of Glia?

Functions include support, insulation, and protection

4

Can Glia transport impulses?

No

5

Do Glia lose their ability to divide?

No

6

Do Neurons transport impulses? (Explain why)

Yes. Trasmit impulses in your nervous system from one part of the body to another.

7

What are nerves composed of?

Many individual neurons bundled together.

8

What are neurons made up of?

-cell body
-dendrites
-axon

9

What does the cell body contain?

Nucleus and metabolic center

10

What does the cell body lack? What does this mean?

Lacks centrioles (doesn't divide).

11

What are dendrites?

Projections or extensions that receive signals from other neurons and carry impulses toward the cell body.

12

Are dendrites high or low branched?

High

13

What is the axon?

A single, very thin projection from the cell body

14

Does the axon carry impulses towards or away from the cell body?

Away from the cell body.

15

How does a axon end?

Ends in a series of branches with slight enlargments on their ends.

16

What are the enlargments on the end of axons called?

Axon terminals

17

Neurons conduct electrical impulses taht allow what to detect and respond to stimuli?

Cells, tissues, and organs.

18

What is the myelin sheath?

Schwann cells in the peripheral nervous system form a shiny white fatty protein wrapped around axon.

19

What form myelin in the central nervous system?

Oligodendrocytes

20

What are the three main functions of the myelin sheath?

1) functions in the protection of the nerve fibre
2) serves as a good insulator
3) increases the rate of tranmission of the nerve impulse along the axon

21

Are their gaps between teh sections of teh myelin sheath? If yes, what are they called?

-Yes
-Nodes of Ranvier

22

Do impulses jump from node to node at a fast or slow rate?

Very fast rate

23

Do nerve impulses travel faster along myelinated nerves than nonmyelinated ones?

Myelinated nerves

24

What do sensory neurons carry impulses from? Where do they carry them to?

Specialized nerve endings called receptors to the spinal cord or brain.

25

What can these receptors be specialized for? (sensory neurons).

Heat, light, presure, sound waves, chemicals in food, air, etc.

26

Whare is the cell body of the sensory neuron located? What is it next to?

Clusters called ganglia, next to the spinal cord.

27

Where do the axons terminate?

Interneurons

28

Where are interneurons found?

The central nervous system

29

What is integrative function?

Information is brought together (interpreted to create sensations, thought, add to memory, make decisions, etc.).

30

What body parts might some interpretation of the sensory information have to occur in before an appropriate responce is decided on?

Spinal cord or brain

31

who do sensory neurons and other interneurons stimulate?

Interneurons

32

Interneurons integrate the ___ and relay appropriate ___ to the _____ or other ______.

-date
-impulses
-brain
-motor neurons

33

What are motor neurons?

Muscles or glands cause reactions or responses to stimuli.

34

What are effector organs?

muscles or glands cause reactions or responses to stimuli.

35

What do motor neurons carry?

Impulses from the interneuron in the brain or the spinal cord to an effector that causes a reason in that gland or muscle.

36

Where is the cell body of a motor neuron located?

Within the spinal cord or brain.

37

Do motor neurons have long or short axons? Why?

Long lince the impulses travel away from teh cell bodies.

38

What do individula fibres do?

Very frequently come together to lie side-by-side in collective bundles more commonly known as nerves.

39

Thousands of individual____make up the nerves leading to and from body areas.

-neurons

40

What is a reflex arc?

The most basic of nervous responses by orgamisms having a nervous system

41

What are the five parts of the reflex?

1) the receptor
2) the sensory neuron
3) the interneuron in the spinal cord
4) the motor neuron
5) the effector (muscles)

42

Many reflex arcs are ______or______actions.

-withdrawal
-protective

43

Does the brain have to participate in relex arc?

No, but some interneurons do carry impulses to the brain so that it does become aware of an action.

44

What are some common reflex arcs?

Startle response, blinking, knee jerk, sneezing, coughing, and the changing of pupil size.

45

Nerve ending before the impulse:
Where is an electric potential?

Between the outside surfac e and the inner area of a neuron.

46

Before impulse:
This_____develops when an uneven distribution of_____builds up.

-polarization
-ions

47

On the outside surface, there is a high concentration of what ion?

Sodium (Na+)

48

On the inside surface, there is a high concentration of what ions?

-potassium (K+)
-chlorine (Cl-)
-negatively charged protein molecules

49

Diffusion of ____and ____is happening BUT______pumps within the____membrance actively transport____out and___in are working to conteract diffusion.

-K+
-Na+
-sodium-potassium
-neuron
-Na+
-K+

50

How many Na+ are out for every K+ in?

3 Na+ for every 2 K+.

51

What happends to the nerve membraine to start an impulse?

-stimulatin initiate an action potential in a nerve cell
-stimulation casue a membrance to become more permeable to the sodium ion due to channels in membrance opening
-rapid inward movement of sodium ions causes carge reversal (depolarization) of membrance
-if stimulus is strong enough, activates neuron to transmit signal called action potential
-when impulse occurs, inward movement of sodium ions cause other channels through plasma membrance to open and K+ ions leave the cells restoring the positive charge outside the cell (repolatization)

52

The much greater concentration of positive sodium ions on the outside to the potassium ions inside creates what and between what?

Creates a potential difference (about -70 to -90 millivolts) between the positive outside and the negative inside.

53

The electrochemical reaction or impulse may travel up to how many meters per second in myelinated enrve fivres?

150 m/s

54

How long, after an impulse passes, does it take to regenerate the original potential?

.001 to .002 seconds

55

How many impulses can a nerve fibre conduct in one second?

500 to 1000

56

Once a nerve impulse starts what does it move along? Does it move with stimulation?

-moves along a fibre
-no stimulation

57

What does a change in membrance permeability trigger?

A change in teh adjoining section as te impulse moves along.

58

In a myelinated fibre, depolarization occurs only at the what?

-the nodes of Ranvier

59

What does depolarization of one nerve immediately trigger? Why?

-the next node
-Na+ and K+ cannot diffuse through muelin

60

What does an impulse actually do in a myelinated fibre as opposed to a non-myelinated fibre?

Jumps from node to node instead of moving continuously.

61

How many times faster are movements in myelinated fibres?

4 times faster.

62

What most occur for a neuron to conduct another impulse

Repolarization

63

What is a synaptic cleft?

neurons are not directly connected to other neurons at their ends. Instead a space exists between them--the synaptic cleft.

64

How do impulses get across teh sunaptic space?

When impulse reaches the end of an axon, vesicles release a neurotransmitter which diffuses across the synapse to the membrance of the dendrite of the next cell.

65

What is a neurotransmitter?

chemical released via exocytosis

66

What does the neurotransmitter do?

alter the permeability of the dendrite's membrane to sodium ions and a new impulse in initiated.

67

Where does the neurotransmitter go when its job is finished?

As soon as it is released, some of it is reabsorbed by the dendrite. Enzymes released by the axon terminal break down the rest.
Prevents firing or triggerin gimpulses at the dendrite.

68

Certain features of___and___result in impulses travelling from neuron to neuron in only one direction.

-neurons
-synapses

69

Only______releases the chemical transmitters and only____are sensitive to them?

-axon terminals
-dendrites

70

Impulses only move from_______to______and not the other way around.

-axon terminals
-dendrites

71

The nervous system of a vertebrate organism consists of____major divisions

2

72

What are the two divisions?

-central nervous system
-peripheral nervous system

73

What is the central nervous system made up of?

-brain
-spinal cord
-interneurons carrying info in and out

74

What kind of centres does the central nervous system have?

integrating and command centers

75

What does the central nervous system interpret sensory information based on?

past experience and current conditions

76

What is the peripheral nervous system made up of?

-nerves that carry info between the organs in the body and the central nervous system
-communication lines

77

How many neurons does the brain contain?

-over 100 billion

78

How many hemispheres does the brain have?

2

79

How many protective membrances does the brain have? What are they made up of? What covers the entire organ?

-3
-connective tissue
-meninges

80

What do these membranes provide? What is it helped by?

-cushioning effect
-helped by cerebrospinal bluid between second and third layer

81

What is cerbrospinal fluid secreted by?

clusters of capillaries within the fluid filled cavities of the brain

82

What does the cerbrospinal fluid also function in?

-nutrient distribution
-waste removal
-movment of hormones
-movement of WBC

83

What are the three regions of the brain?

-forebrain
-midbrain
-hindbrain

84

What is the hindbrain made up of?

cerebellum, pons, medulla oblongata

85

What is teh medulla oblongata? What can injury to this area result in?

Nerve impulses controlling some of the vital body brocesses that are involuntary. Heavy blow or injury to this areas can result in quick death?

86

What is the pons?

-relay station passing info between cerebellum and cerebrum
-pathway connecting the catious parts of the brain with each other
-important in breathing

87

What does the cerebellum coordinate?

-muscle actions, balance, posture

88

How doe we maintain balance?

Muscle "instruction" from the cerebrum and nerve impulses from body parts enter cerebellum where they are coordinated so that we can maintain balance

89

What is teh cerebellum vital in?

carrying out such asctions auch as jumping or spinning

90

The cerebellum is also important in____and _____ motor responses?

-learning
-remembering

91

What is teh midbrain?

major function seems to be that of relaying nerve impulses betweent the forebrain and hindbrain. Relays impulses between the forebrain and the eyes and ears.

92

What is the brain stem made up of? What does it serve as and why?

-medulla oblongata, pons, and the midbrain
-all infor must pass through on way to higher brain regions so it serves as a filter

93

What is the largest part of the brain? What makes up most of it? What are the other parts?

-forebrain
-cerebrum
Other parts:
-thalamus
-hypothalamus

94

What does the cerebrum divide into?

-left and right cerebral hemispheres (from outside each is seen to consist of many folds and creases).

95

What does the deepest crease create and what does it extend down to?

the two hemispheres. extends down to the corpus callosum.

96

What is teh corpus callosum?

where nerve bundles cross over from one hemisphere to the other allowing communication betweent the right and left cerebral hemispheres

97

What do the other deep creases or fissures divide?

each hemisphere into four segments or lobes: frontal, parietal, occipital, temporal.

98

What are the 3 basic regions in the cerebrum?

1) cerebral cortex (gray matter)
2) Thalamus
3) Hypothalamus

99

What is the cerebral cortex responsible for?

speech, memory, logic, emotional response, interpretation of voluntary movement, interpretaion of sensation, consciousness

100

What is the thalamus responsible for and where is it?

-below the cerebrum
-areas where sensory messages to cerebrum pass which enable individuals to become aware of such things as pressure, pain, or temperature extremes

101

What is the hypothalamus responsible for and where is it located?

-below the thalamus
-regulates the pituitary gland
-controls water adn salt concentration in blood
-regulates body temp, blood rpessure, thirst, sex drive, figh or flight, helps us experience emotions
-maintaisn daily biorhythmus (sleep and hungar)
-biological clock

102

What is white matter?

fiber tracts (connections)

103

What is basal nuclei?

patches of gray matter that helps regulate the stopping of voluntary motor activities

104

What is the spinal cord?

the other major coordinating center and part of the central nervous system

105

How many way pathway to and from the brain is the spinal cord?

Two-way

106

The spinal cord is a major what center?

Reflex

107

What is the spinal cord surronded by?

meminges

108

How many pairs of spinal nerves arise from the cord? What do they serve as?

-31 pairs
-serve as a link between all the peripheral nerves and brain

109

What can damages to the gray matter result in?

flaccid paralysis (nerve impulses do not reach the muscles affected and muscles will atrophy).

110

What can damage to the white amtter result in?

spastic paralysis (muscles still stimulated by spinal arcs, but movement in involuntary and not controllable and loss of feeling occurs).

111

What is a nerve?

Structure of neuron fivers outside of the CNS.

112

How are nerves classified?

according to which way they transmit impulses.

113

What do mixed nerves contain?

contain both sensory and motor nerurons. All spinal nerves are mixed.

114

What do sensory nerves carry?

only carry impulses towards the CNS.

115

What do motor nerves carry?

carry impulses away from the CNS.

116

What are the two nerves of the peripheral nervous system?

-somatic nerves
-automatic nerves

117

Many of the ____and _____nerves are____ nerves and are part of the_____system.

-cranial
-spinal
-voluntary
-somatic

118

What does the somatic system carry? Does the body have conscience control over these?

-messages for voluntary actions back and forth between the body parts and brain.
-yes

119

What does the somatic system control?

skeletal muscle, bones, and skin

120

Can the actions or responses carried out by the autonomic nervous system be conscieously controlled?

no (happen automatically or involuntarily)

121

What does the autonomic system regulate and how?

conditions in the internal environment inside the body by controlling actions of organs or glands.

122

What kind of muscle is the autonomic nerves known to control?

-smooth muscle (surrounds organs and blood vessels.
-known to control cardiac muscle (heart muscle)

123

What organs does the autonomic nervous system control?

organs of the digestive, circulatory, excretory, adn endocrine systems

124

What does the autonomic system work to maintain?

relative stability of your internal environment (breathing rate, stomach secretions).

125

How many sets of neurons with opposing effects on body organs make up the autonomic nervous system? What are they?

Two:
-sympathetic division
-parasympathetic division

126

Where do nerves of the sympathetic system come from?

-come from thoracic and lumbar vertebrae

127

What is the sympathetic system involved in?

all internal adjustments that prepares the body for action or increased levels of stress

128

How do nerves of the parasympathetic system leave the brain?

directly or from either the cervical or caudal sections of the spinal cord.

129

What do the parasympathetic nerves carry out?

Impulses that return a body to normal funcctioning after a period of stress is over. Allows us to conserve energy.

130

What do sympathetic and parasympathetic nerves do to eachother? What is this an example of?

-counterbalance eachother activities
-homeostasis occuring within the body

131

Why are fin adjustments continually being made? (sympathetic and parasympathetic).

So that glands and organs are functioning at levels appropriate to a body at a particular time.