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Biology MCAT > Nervous System > Flashcards

Nervous System Flashcards

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1
Q

Neurons

A

A specialized cell capable of transmitting electrical impulses and then translating those electrical impulses into chemical signals

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2
Q

Cell Body

A

A portion of the neuron where the nucleus, endoplasmic reticulum, and ribosomes are located, also known as the soma.

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2
Q

Soma

A

Neuron cell body

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3
Q

Dendrites

A

The portion of a neuron that receives stimuli from other cells and conveys them toward the cell body

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4
Q

Axon Hillock

A

Transition point between the cell body (soma) and the axon of a neuron; the site of action potential intiation

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5
Q

Action Potentials

A

Is when an abrupt change in the membrane potential of a nerve or muscle caused by changes in membrane ionic permeability; results in conduction of an impulse in nerves or contraction in muscles

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6
Q

Axon

A

The long fiber of a neuron; it conducts impulses away from the cell body toward the synapse

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7
Q

Myelin

A

what most mammalian nerve fibers are insulated by

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8
Q

Myelin sheath

A

The white, lipid containing material surrounding the axons of the many neurons in the central and peripheral nervous systems.
-Maintains the electrical signal within one neuron and increases the speed of conduction in the axon.

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9
Q

Oligodendrocytes

A

Myelin producing cells in the CNS

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10
Q

Schwann Cells

A

Myelin producing cells in the PNS

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11
Q

Nodes of Ranvier

A

Points on a myelinated axon that are not covered by myelin

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12
Q

Nerve Terminal

A

End of the axon from which neurotransmitter molecules are released

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13
Q

Synaptic Bouton (Knob)

A

Nerve terminal

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14
Q

Neurotransmitters

A

The chemicals that transmit information from one neuron to another

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15
Q

Synaptic Cleft

A

Space between the neurons into which the terminal portion of an axon releases neurotransmitters which bind to the dendrites of the postsynaptic neuron

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16
Q

Synapse

A

The junction between two neurons into which neurotransmitters are released

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17
Q

What is a nerve?and the three types?

A

A bundle of neurons in the PNS
1.) Sensory
2.) Motor
3.) Mixed

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18
Q

Sensory Nerve

A

Nerves that carry sensory information (afferent)

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19
Q

Motor Nerve

A

Nerves that carry motor information (efferent)

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20
Q

Mixed Nerve

A

Nerves that carry both motor and sensory information

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21
Q

Tracts

A

AXONS bundled together in the CNS

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22
Q

Multiple NEURONS bundle together to form a _____________.

A

Nerve in the PNS

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23
Q

Axons bundled together in CNS form ________________.

A

tracts

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24
Q

Cell bodies of neurons of the same type within a NERVE cluster together in _______________________.

A

ganglia in the PNS

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25
Q

Cell bodies of the individual neurons within a TRACT clustr together in ________________.

A

Nuclei in the CNS

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26
Q

Axon bundles in CNS: Multiple neuron blundles
PNS:

A

Tracts
Nerves

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27
Q

Nuclei

A

The cell bodies of neurons in the SAME TRACT in CNS

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28
Q

Gilial Cells

A

Neuroglia

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29
Q

Neuroglia cells

A

(Glial Cells) play supportive and structural roles for neurons; responsible for functions such as holding neurons in place, supplying neurons with oxygn and nutrients, insulating neurons from other neurons, destroying pathogens, and removing dead neurons

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30
Q

Astrocytes

A

Nourish neurons and form the blood brain barrier, which controls the transmision of solutes from the bloodstream into nervous tissue

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31
Q

Ependymal Cells

A

Line the ventricles of the brain and produce cerebrospinal fluid, which physically supports the brain and serves as a shock absorber

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32
Q

Microglia

A

Are phagocytic glial cells that ingest and break down waste products and pathogens in the CNS

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33
Q

Mylenating glial cells in CNS and PNS?

A

In CNS = oligodendrocytes
In PNS = schwann cells
both produc myelin around axons

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34
Q

Resting Membrane Potential

A

Net electric potential difference that exists across the cell membrane, created by movement of charged molecules across that membrane

  • for neurons this potential is about -70mV with the inside of neuron being (-) and outside being (+)
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35
Q

What are the two most important ions involved in generating maintaining the resting potential?

A

Potassium (K+) and sodium (Na+)

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36
Q

Na+/K+ ATPase (important)

A

Sodium-Potassium Pump
Pumps out 3 sodium for every 2 potassium pumped in
Maintains gradient resting membrane potential.
A greater concentration of Na+ is found outside neuron and a greater concentration of K+ found inside a neuron
-ATP required for each transport since both are moved against the gradient

37
Q

Mnemonic of the direction of ion movement by Na/K ATPase

A

pumpKin
-K=potassium into the cell
therefore, sodium out of the cell

38
Q

Sodium and Potassium concentration inside and outside the cell

A

Outside the cell (net positive): sodium»potassium inside the cell (net negative charge):
potassium»sodium

39
Q

Potassium leak channels

A

Facilitate the outward movement of potassium, which allows the slow leak of potassium out of the cell

40
Q

Neurons can receive both excitatory and inhibitory input

A

-excitatory input causes depolarization
-inhibitory input causes hyperpolarization

41
Q

Depolarization

A

Raising the membrane potential (Vm) from its resting potential; more positive and likely to fire an action potential

42
Q

Hyperpolarization

A

Lowering the membrane potential from its resting potential –more negative on inside

43
Q

Threshold

A

The lowest magnitude of stimulus strength that will induce a response– -55 to -40mV

44
Q

Summation

A

The additive effect of multiple signals.
two types of summations:
-spatial
-temporal

45
Q

Temporal Summation

A

Same or nearby presynaptic neuron firing multiple times in close succession a relatively short period of time (temporary)

46
Q

Spatial Summation

A

Several different synaptic neurons firing at the same time at different synapses (multiple neurons)

47
Q

Electrochemical Gradient

A

A gradient consisting of a difference in electrical potential as well as chemical concentration

48
Q

Inactivated Sodium Channels

A

When Vm approached +35mV (peak of AP), potassium channels open.

49
Q

Deinactivated Sodium Channels

A

When Vm is brought back near -70mV after sodium channels have been inactivated

50
Q

Closed Sodium Channels

A

Sodium Channels before the cell reeaches threshold and after inactivation has been reversed

51
Q

Open Sodium Channels

A

Sodium Channels from threshold -70mV to approximately +35mV

52
Q

Inactive Sodium Channels

A

Sodium Channels from approx +35mV to the resting potential -70mV aka the repolarization/refractory period

53
Q

Repolarization

A

Restoration of the resting membrane potential in neurons from being depolarized by both active and passive processes

54
Q

What are the two refractory periods?

A

Absolute and Relative

55
Q

Absolute Refractory Period

A

No amount of stimulation can cause another action potential to occur
-absolutely can’t occur

56
Q

Relative Refractory Period

A

Greater than normal stimulation can cause an action potential to occur because the membrane is starting from a potential that is more negative than its resting value

57
Q

Impulse Propagation

A

Movement of an action potential down an axon resulting in neurotransmitter release at the synaptic bouton and transmission of the impulse to the target neuron or organ

58
Q

Increased length of axon increases/decreases conduction rate?

A

Longer axons would decrease conduction rate because it increases the resistance

59
Q

Greater cross sectional area of axon increases or decreases rate of transmission?

A

Increases transmission due to decreased resistance

60
Q

How does mylen speed up conduction rate?

A

Myelin is an extraordinarily good insulation,preventing the dissipation of the electric signal

61
Q

Saltatory Conduction

A

Process by which an electrical signal jumps across the nodes of Ranvier to travel down an axon

62
Q

Presynaptic Neuron

A

Neuron before the synaptic cleft

63
Q

Postsynaptic Neuron

A

The neuron after the synaptic cleft

64
Q

Effector

A

If a neuron signals to a gland or muscle rather than a neurons, the postsynaptic cell is termed an effector

65
Q

How does an action potential result in neurotransmitter release?

A

When an action potential reaches the nerve terminal, the voltage gated calcium channels open, allowing Calcium to flow into the cell. This sudden increased in intracellular CALCIUM triggers fusion of the membrane-bound vesicles with cell membrane at the synapse, CAUSING EXOCYTOSIS of the NT into the synapse

66
Q

Difference between electrical and chemical transmission

A

Within a single neuron, ELECTRICITY is used to pass signals down the length of the axon.
-Between other neurons, CHEMICALS (neurotransmitters) are used to pass signals to the subsequent neuron (or gland or muscle)

67
Q

Types of neurotransmitter receptors and results?

A

-Ligand-gated ion channels = results in either a stimulation (depolarize) or inhibitory (hyperpolarization) response
-G protein coupled receptors (GPCR) = change levels of cAMP or influx of calcium

68
Q

What are 3 ways neurotransmitter is removed from synapse?

A
  1. broken down by enzymes
  2. reuptake carriers
  3. Diffusion out of synapse
69
Q

Acetylcholine (ACh)

A

A neurotransmitter found throughout the nervous system; broken down by the enzyme acetylcholinesterase

70
Q

Reuptake Carriers

A

Brings neurotransmitters back into presynaptic neuron.
An autoreceptor will signal the presynaptic cell to stop releasing and start teh reuptake process

71
Q

Sensory Neurons (Afferent Neurons)

A

A neuron that picks up impulses from sensory receptors and transmits them toward the central nervous system

72
Q

Motor Neurons (Efferent Neurons)

A

A neuron that transmits nervous impulses from the CNS to an effector

73
Q

Mnemonic: Afferent and Efferent neurons

A

(A)fferent neurons (A)scend in the spinal cord toward the brain; (E)fferent neurons (E)xit the spinal cord on their way to the rest of the body

74
Q

Interneurons

A

are found between other neurons and are the most numerous of the three types. Interneurons are located predominantly in the brain and spinal cord. Linked to reflexive behavior.

75
Q

Central Nervous System (CNS)

A

The brain and spinal cord

76
Q

What does the brain consist of?

A

White matter is deeper than grey matter in the brain. Opposite in the spine.

77
Q

White Matter

A

Consists of axons encased in myelin sheaths
- in the brain, the white matter lies deeper than the grey matter.

78
Q

Grey Matter

A

Any region in the central nervous system that consists of unmyelinated cell bodies, dendrites, and synapse. Gray matter is on the outside of the brain.

79
Q

4 parts of spinal cord

A

From head to toe:
1) Cervical
2) Thoracic
3)Lumbar
4) Sacral

80
Q

Vertebral Column

A

protects spinal cord

81
Q

Dorsal Root Ganglia

A

Where the cell bodies of sensory neurons (dorsal root) can be found in the spine

82
Q

Peripheral Nervous System (PNS)

A

Includes all neurons outside the central nerovus system, including sensory and motor neurons; it is subdivided into the somatic and autonomic nervous system.
-transmit info to and from CNS

83
Q

Somatic Nervous System

A

Subdivision of the peripheral nervous system that governs all voluntary action

84
Q

Divisions of NERVOUS SYSTEM

A

Central Nervous System (CNS) and Peripheral Nervous System (PNS)

85
Q

Autonomic Nervous System (ANS)

A

Subdivision of the PNS responsible for involuntary activities, which is further subdivided into the parasympathetic and sympathetic nervous systems

86
Q

Parasympathetic Nervous System

A

The subdivision of the autonomic nervous system involved in rest and homeostasis; it is generally antagonistic to the sympathetic nervous system
- “rest and digest”

87
Q

Sympathetic Nervous System

A

The subdivision of the autonomic nervous system that produces the fight or flight response

88
Q

Sympathetic NS activation

A

-increased HR
-increased BP
-increases blood glucose concentration
-relaxes bronchi
-dilates eyes
-release of epinephrine*
-In SNS

89
Q

Parasympathetic NS activation

A

-decrease HR
-constricts bronchi and pupils
-increase digestion
-contract bladder

90
Q

Reflex

A

An involuntary nervous pathway consisting of sensory neurons, interneurons, motor neurons, and effectors; it occurs in response to a specific stimulus

Biology MCAT (5 decks)

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