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MCAT > Biology Ch 4. The Nervous System > Flashcards

Biology Ch 4. The Nervous System Flashcards

1
Q

Neurons

A

Highly specialized cells responsible for the conduction of impulses, communicate using both electrical and chemical forms

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2
Q

Electrical communication neurons

A

Electrical communication occurs via ion exchange in the generation of membrane potential’s down the length of an axon

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3
Q

Chemical communication neurons

A

Chemical communication occurs via neurotransmitters released from the presynaptic cell in the binding of these neurotransmitters to the postsynaptic cell

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4
Q

Dendrites

A

Appendages on the soma that receives signals from other cells

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5
Q

Soma

A

Cell body, the location of the nucleus as well as organelles such as the endoplasmic reticulum and ribosomes

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6
Q

Axon hillock

A

We are the cell body transitions from the soma to the axon and where the action potential’s are initiated

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7
Q

Axon

A

A long appendage down which an action potential travels

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8
Q

Nerve terminal

A

aka synaptic bouton, at the end of an axon from which neurotransmitters are released, enlarged and flattened to maximize transmission and ensure proper release of neurotransmitters

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9
Q

Synaptic bouton

A

aka nerve terminal, the end of an axon from which neurotransmitters are released, enlarged and flattened to maximize transmission and ensure proper release of neurotransmitters

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10
Q

Nodes of Ranvier

A

Exposed areas of myelinated axons that permit saltatory conduction, critical for rapid signal conduction

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11
Q

Synapse

A

Consist of the nerve terminal of the presynaptic neuron, the membrane of the postsynaptic cell, and the space between the two (synaptic cleft)

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12
Q

Synaptic cleft

A

Space between one neurons nerve terminal and the others membrane

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13
Q

Myelin

A

Insulating/fatty substance that prevents signal loss, created by oligodendrocytes in the CNS and Schwann cells in the PNS, prevents dissipation of the neural impulse and crossing of neural impulses from adjacent neurons, increases the speed of conduction in the axon

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14
Q

Oligodendrocytes

A

Creates myelin in the central nervous system

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15
Q

Schwann cells

A

Creates myelin in the peripheral nervous system

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16
Q

Nerves

A

What neurons can be bundled into in the PNS, may carry multiple types of information including sensory, motor, or both, cell bodies of the same type are clustered together into ganglia

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17
Q

Tracts

A

What neurons can be bundled into in the CNS, only contain one type of information, cell bodies of neurons in the same tract are grouped into nuclei

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18
Q

Ganglia

A

Where cell bodies of neurons of the same type on nerves cluster together in the PNS

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19
Q

Nuclei nerves

A

Where cell bodies of individual neurons within a tract cluster together in the CNS

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20
Q

Neuroglia

A

aka glial cells, other cells within the nervous system, include astrocytes, ependymal cells, microglia, oligodendrocytes, and Schwann cells

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21
Q

Astrocytes

A

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

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22
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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23
Q

Microglia

A

Phagocytic cells that ingesting break down waste products and pathogens in the central nervous system

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24
Q

Resting membrane potential

A

Potential for all neurons, approximately -70 mV, maintained using selective permeability of Na+ and K+ and Na+/K+ ATPase

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25
Q

Na+/K+ ATPase

A

Times three sodium ions out of the cell for every two potassium ions pumped in

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26
Q

Excitatory signals

A

Cause depolarization of the neuron

27
Q

Inhibitory signals

A

Cause hyperpolarization of the neuron

28
Q

Temporal summation

A

The integration of multiple signals near each other in time

29
Q

Spatial summation

A

The addition of multiple signals near each other in space

30
Q

Action potential

A

Transmission of electrical impulses down the axon

31
Q

Depolarization

A

Occurs from excitatory stimulation, raises membrane potential above resting, once the cell is depolarized to the threshold voltage, voltage gated sodium channels open

32
Q

Threshold voltage

A

Voltage where voltage gated sodium channels open during cell depolarization

33
Q

Electrochemical gradient during depolarization

A

Causes sodium to continue to flow into neuron, allows for depolarization to continue

34
Q

Peak of the action potential

A

Approximately + 35 mV, the voltage were sodium channels are in activated and potassium channels open

35
Q

Repolarization

A

After the peak of the action potential is reached, potassium channels open and potassium flows out of the cell due to a strong electrochemical gradient, potassium channel stay open long enough to overshoot the action potential resulting in a hyperpolarized neuron, then the potassium channels close

36
Q

Hyperpolarization

A

Potassium channels stay open long enough to overshoot the resting membrane potential before the potassium channels close, Na+/K+ ATPase brings the neuron back to resting potential and restores gradients, causes refractory period

37
Q

Refractory period

A

When the axon is hyperpolarized, causes the action option to propagate down the length of the axon in only one direction

38
Q

Absolute refractory period

A

The cell is unable to fire another action potential

39
Q

Relative refractory period

A

The cell requires a larger than normal stimulus to fire an action potential

40
Q

Neurotransmitter release

A

When the action potential arrives at the nerve terminal, voltage gated calcium channels open, the influx of calcium causes fusion of vesicles filled with neurotransmitters with the presynaptic membrane, resulting in exocytosis of neurotransmitters into the synaptic cleft

41
Q

Neurotransmitter uptake

A

Neurotransmitters bind to receptors on the postsynaptic cell, which maybe ligand gated ion channels or G protein coupled receptors

42
Q

Stopping the propagation of a signal

A

Neurotransmitters must be cleared from the postsynaptic receptors, this can occur via the neurotransmitter being enzymatically broken down, the neurotransmitter being reabsorbed back into the presynaptic cell by reuptake channels, or the neurotransmitter diffusing out of the synaptic cleft

43
Q

Reuptake channels

A

Channels that allow neurotransmitters to be reabsorbed back into the presynaptic cell from the synaptic cleft

44
Q

Central nervous system matter

A

Either white or gray matter

45
Q

White matter

A

Myelinated axons, in the brain deeper than grey matter, in the spinal cord less deep than grey matter

46
Q

Grey matter

A

Unmyelinated cell bodies and dendrites, less deep than white matter in the brain, and deeper than white matter in the spinal cord

47
Q

Three types of neurons

A

Motor/efferent, interneurons, sensory/afferent neurons

48
Q

Reflex arcs

A

The ability of interneurons in a spinal cord to relay information to the source of a stimulus while simultaneously routing it to the brain

49
Q

Monosynaptic reflex arc

A

The sensory neuron (afferent, presynaptic) fires directly onto the motor neuron (efferent, postsynaptic)

50
Q

Polysynaptic reflex arc

A

At least one interneuron between the sensory (afferent) neuron and the motor (efferent) neuron

51
Q

Myelin sheath

A

Coats most axons in mammalian nerve fibers, maintains the electrical signal within one neuron

52
Q

Glial cells

A

aka neuroglia, play both structural and supportive rolls in the nervous system, cells that are not neurons, includes astrocytes, ependymal cells, microglia, oligodendrocytes, and Schwann cells

53
Q

Impulse propagation

A

Uptake of Na in one segment causes depolarization of nearby segment allowing it to reach threshold, because one direction in refractory period, one way signal, CSA increase allows signal to go faster, longer length causes it to be slower

54
Q

Saltatory conduction

A

Myelin insulation so effective that the membrane is only permeable to ion movement at the nodes of Ranvier, signal therefore hops from node to node

55
Q

Effector

A

The postsynaptic cell if a neuron signals to a gland or a muscle

56
Q

Supraspinal

A

Type of circuit that is used when input from the brain or brainstem is required

57
Q

Spinal cord regions

A

Cervical, thoracic, lumbar, and sacral

58
Q

Vertebral column

A

Protects the spinal cord, transmits nerves at the space between vertebrae

59
Q

Dorsal root ganglia

A

Where cell bodies of sensory neurons that enter on the dorsal side of the spinal cord are found

60
Q

Motor neurons and spinal cord

A

Exit the spinal cord ventrally, side closest to the front of the body

61
Q

Autonomic nervous system neurons

A

Two neurons, work in series to transmit messages from the spinal cord, first is the preganglionic neuron (soma in CNS but axon in PNS), second is the postganglionic neuron

62
Q

Somatic nervous system neurons

A

A motor neuron in the SNS goes directly from the spinal cord to the muscle without synapsing

63
Q

Parasympathetic nervous system neurotransmitters

A

Both preganglionic and postganglionic neurons release acetylcholine

64
Q

Sympathetic nervous system neurotransmitters

A

Preganglionic neuron releases acetylcholine, most postganglionic neurons release norepinephrine

MCAT (67 decks)

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