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Biology - Systems > Nervous > Flashcards

Nervous Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

What are neurons

A

The functional unit of the nervous system. It is an elongated cell with three parts

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1
Q

How does the nervous system function? How does the transmission occur?

A

By the almost instantaneous transmission of electrochemical signals. The means of transmission are highly specialized cells knows as neurons.

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2
Q

What are the three major parts of the neuron

A

Dendrites, cell body, axon

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3
Q

How many dendrites does the typical neuron have

A

Many

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4
Q

What do dendrites look like

A

Thin branches extending from the cell body

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5
Q

What does the cell body of the neuron contain

A

Nucleus and organelles

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6
Q

How many times longer is the axon than the rest of the neuron

A

Can be thousands

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7
Q

What is the axon

A

A single, long projection extending from a cell body

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8
Q

What does the axon end in

A

Several small branches known as axon terminals

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9
Q

How are neurons connected/not connected

A

They are often connected in chains and networks, yet they never actually come in contact with one another: the axon terminals of one neuron is separated from the dendrites of an adjacent neuron

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10
Q

What separates the axon terminals of one neurons from the dendrites of an adjacent neuron

A

A small gap known as a synapse

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11
Q

Where does the electrical impulse moving through a neuron begin

A

The dendrites

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12
Q

Where does the electrical impulse move after the dendrites

A

It passes through the cell body and then along the axon

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13
Q

What does the impulse always do

A

Follow the same path from dendrite to cell body to axon

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14
Q

What happens when the electrical impulse reaches the synapse at the end of the axon

A

It causes the release of specialized chemicals known as neurotransmitters

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15
Q

What do the neurotransmitters do after the electrical impulse activated them

A

They carry the signal across the synapse to the dendrites of the next neuron, starting the process again in the next cell

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16
Q

What is the cell at when there is no impulse traveling through a neuron? What is the charge of the cell?

A

The cell is at its resting potential and the inside of the cell contains a negative charge in relation to the outside

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17
Q

To keep the cell negatively charged inside, what does it require

A

Energy: it is an active process

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18
Q

What protein does the cell membrane of the neuron contain

A

Na+/K+ ATPase

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19
Q

What does Na+/K+ ATPase do (the sodium potassium pump)

A

Uses the energy provided by one molecule of ATP to pump three positively charged sodium ions out of the cell, while simultaneously taking into the cell two positively charged potassium ions.

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20
Q

What does the sodium potassium pump build up outside and inside the cell

A

Outside: a high concentration of sodium ions
Inside: an excess of potassium ions

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21
Q

What is one of the special properties of phospholipid cell membranes and what does that mean for the concentrations that the sodium potassium pump created

A

The special property is that they bar passage to ions unless there is a special protein channel that allows a particular ion in or out. This means that all of the ions can’t diffuse across the membrane to regularize the distribution like they want

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22
Q

Does a special protein channel exist for the sodium that is built up

A

For the sodium that is built up outside the cell, there is no channel

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23
Q

Does a special protein channel exist for the potassium that is built up inside the cell

A

Yes- there are potassium leak channels that allow some of the potassium ions to flow out of the cell

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24
Q

What does the difference in ion concentrations create

A

A net potential difference across the cell membrane of approximately -70 mV or millivolts ( the value of the resting potential )

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25
Q

What is the value of the resting potential

A

-70 mV

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26
Q

What do most cells have

A

Some sort of resting potential from the movement of ions across their membranes

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27
Q

Neurons are among only a few types of cells in that they can also form a ____

A

An action potential

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28
Q

What is the action potential

A

The electrochemical impulse that can travel along the neuron

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29
Q

(Comprehensive) what does the neuron membrane contain

A

Sodium potassium pump and potassium leak channel proteins as well as voltage gated proteins

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30
Q

What do voltage gated proteins do

A

Respond to changes in the membrane potential by opening to allow for certain ions to cross that would not normally be able to do so

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31
Q

What channels does the neuron contain

A

Voltage gated sodium channels and voltage gated potassium channels that open under different circumstances

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32
Q

Where does the action potential begin

A

When chemical signals from another neuron manage to depolarize, or make less negative, the potential of the cell membrane in one localized area of the neuron cell membrane, usually in the dendrites

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33
Q

What happens if the neuron is stimulated enough so that the cell membrane potential in that area manages to reach as high as -50 mV (from the resting potential of -70 mV)

A

The voltage gated sodium channels in that region of the membrane open

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34
Q

What is the threshold potential

A

The voltage at which the voltage gated channels open

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35
Q

What happens when the voltage gated channels open and why

A

The sodium ions follow the concentration gradient and Rush into the cell because there is a large concentration of positive sodium ions just outside the cell membrane that have been pumped out by the sodium potassium pump

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36
Q

What happens with the flood of positive ions

A

The cell continues to depolarize, or become less negative

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37
Q

What happens when the membrane potential gets as high as +35 mV

A

The voltage gated sodium channels close and the voltage gated potassium channels open, letting the positive potassium ions concentrated in the cell rush out of the neuron, repolarizing the cell membrane to its negative resting potential

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38
Q

As the potassium ions rush out of the neuron, what happens

A

The membrane potential continues to drop beyond -70 mV until the voltage gated potassium channels close once again around -90 mV

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39
Q

With the voltage gated proteins closed what happens

A

The sodium potassium pump and the potassium leak channels work to restore the membrane potential to its original polarized state of -70 mV.

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40
Q

How long does the whole process with the pump take to occur

A

Approximately one millisecond

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41
Q

The action potential does not occur in one localized area of the neuron and then stop (t/f)

A

True

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42
Q

Describe the action potential traveling down the length of the neuron

A

When one portion of the neuron’s cell membrane undergoes an action potential, the entering sodium atoms not only diffuse into and out of the neuron, they also diffuse along the neuron’s length. These sodium ions depolarize the surrounding areas of the neuron’s cell membrane to the threshold potential, at which point the voltage gated sodium channels in those regions open, creating an action potential. This cycle continues to occur along the entire length of the neuron in a chain reaction

43
Q

What doesn’t happen during the time it takes the neuron to polarize back from +35 mV to -70 mV and what is the result of this

A

The voltage gated sodium channels will not reopen. This lag prevents the action potential from moving backward to regions of the cell membrane that have already experienced an action potential.

44
Q

What are axons of many neurons surrounded by

A

A structure known as the myelin sheath

45
Q

What does the myelin sheath do

A

Helps to speed up the movement of action potentials along the axon

46
Q

What is the sheath made of

A

Schwann cells

47
Q

What do Schwann cells do

A

They wrap themselves around the axon of the neuron

48
Q

What are the small gaps between the Schwann cells known as

A

Nodes of Ranvier

49
Q

Why does the action potential not have to occur along the entire length of the axon

A

Because the sodium and potassium ions that caused the action potential are only able to cross the cell membrane at the nodes of Ranvier

50
Q

What happens when the action potential is triggered at one node

A

The sodium ions that enter the neuron will trigger an action potential at the next node -> causes action potential to jump from node to node, greatly increasing its speed

51
Q

What is the jumping of the action potential called

A

Saltatory conduction

52
Q

What does multiple sclerosis do

A

Damages the myelin sheaths, greatly impeding conduction of impulses along the neurons

53
Q

How is a stronger signal generated when needed

A

Firing action potentials more rapidly -no such thing as stronger or weaker action potential

54
Q

What happens when an action potential reaches a synapse

A

Neurotransmitter vessels are released; they diffuse across gap and bind to receptors

55
Q

What is an excitatory neurotransmitter

A

Cause target neuron to allow positive ions to enter it

56
Q

What is an inhibitory neurotransmitter

A

Cause target neuron to allow negative ions to enter i

57
Q

What are ganglia and what organisms have just the ganglia

A

Simple, organized clusters of neurons. Annelids and mollusks.

58
Q

Which organisms have ganglia and sensory organs and describe them

A

Arthropods - more complex with antennae and compound eyes

59
Q

What does the vertebrate nervous system include

A

A brain and numerous specialized sensory organs

60
Q

What is the CNS and what does it do

A

central nervous system: central command. Receives sensory input from all of the body, integrates info, creates response. Controls most basic functions necessary for survival and complex behavior and consciousness

61
Q

What is the PNS and what does it do

A

Peripheral nervous system - refers to the pathways through which the central nervous system communicates with the rest of the organism

62
Q

What type of systems have three types of neural building blocks

A

Highly evolved systems

63
Q

What are the three types of neural building blocks

A

Sensory motor and interneurons

64
Q

Describe sensory neurons

A

After an organism’s sense organs receive a stimulus from the environment, sensory neurons send that info to the CNS

65
Q

Describe motor neurons

A

In response to some stimulus or as a voluntary action, motor neurons carry information away from the CNS to an organ or muscle

66
Q

What do interneurons do

A

Provide the connection between sensory and motor neurons

67
Q

What does the CNS consist of

A

Brain and spinal cord

68
Q

Describe the spinal cord

A

A long cylinder of nervous tissue that extends along the vertebral column from the head to lower back

69
Q

What is the brain made up of

A

Almost entirely interneurons

70
Q

Describe the cerebrum

A

Largest portion of the brain

71
Q

What does the cerebrum control

A

Voluntary movement, sensory perception, speech, memory, creative thought

72
Q

What does the cerebellum do

A

Fine tunes voluntary movement; coordination and balance

73
Q

What does the brain stem (medulla specifically) do

A

Involuntary functions. Medulla processes info and maintains alertness

74
Q

What does the hypothalamus control

A

Homeostasis, temperature, hunger and thirst, water balance, emotion

75
Q

What types of neurons does the spinal cord have

A

All three types of neurons: the spinal cord is a link between the body and the brain and also regulates simple reflexes.

76
Q

What are the brain and spinal cord bathed in

A

A fluid known as the cerebrospinal fluid that acts as a cushion and is maintained by the glial cells

77
Q

What does the PNS consist of

A

A sensory system and a motor system (which further splits into the somatic system and the autonomic system)

78
Q

What does the sensory system of the PNS do

A

Carries info from senses to CNS

79
Q

What does the motor system do

A

Branches out from CNS to targeted organs and muscles

80
Q

What does the somatic system (division of motor system of PNS) control

A

Voluntary movement

81
Q

What is acetylcholine

A

An excitatory neurotransmitter that causes contraction of skeletal muscles

82
Q

All somatic system neurotransmitters are ___

A

Excitatory

83
Q

What does the autonomic system do (subdivision of motor system of PNS)

A

Controls tissues other than from skeletal muscles

84
Q

What is the sympathetic division of the autonomic system of the motor system of the PNS

A

Prepares body for emergency situations

85
Q

What does the parasympathetic division of the autonomic system of the motor system of the PNS do

A

During sleep, it slows breathing, speeds up digestion, and slows heartbeat

86
Q

Sense organs transmit signals from the environment through the what to the what

A

Through the PNS to the CNS

87
Q

What can the eyes sense

A

Intensity and frequency of light

88
Q

What are two photoreceptors

A

Rods and cones

89
Q

What do rods do

A

Respond to low illumination levels

90
Q

What do cones do

A

Color vision and brighter lights

91
Q

What is the path of action potential impulses

A

From neurons to the occipital lobe of the brain

92
Q

What is the retina

A

What light is focused on

93
Q

What do the lens do

A

Maintain focus by changing shape

94
Q

What do the pupils do

A

Regulate amt of light able to pass to lens

95
Q

What does the cornea do

A

Bends light through pupil

96
Q

What is another name for the ears

A

Tympanic membrane

97
Q

What do the ears do

A

Sense frequency of air molecules

98
Q

What do auditory ossicles do

A

Amplify vibrations and direct them to the cochlea

99
Q

What does the cochlea do

A

Converts vibrations to action potentials

100
Q

What is the auditory nerve

A

What transmits action potentials to brain

101
Q

What do taste buds/chemoreceptors do

A

Create action potentials that travel to the brain

102
Q

What are the four main taste sensations

A

Sour salty bitter sweet

103
Q

What is the olfactory epithelium

A

Where smell originates

104
Q

What do the somatic senses include

A

Touch pressure posture movement temperature pain

Biology - Systems (6 decks)

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