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MCAT Biology > The Nervous System > Flashcards

The Nervous System Flashcards

(57 cards)

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1
Q

Neurons

A

Specialized cells capable of transmitting electrical impulses and then translating those electrical impulses into chemical signals

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2
Q

Cell body (Soma)

A

Contains the nucleus and processes incoming signals

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3
Q

Dendrites

A

Receive signals from other cells

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4
Q

Axon hillock

A
  • Located between the cell body and the axon.
  • Plays a critical role in the transmission of nerve signals
  • Where action potentials are initiated
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5
Q

Action potential

A

Transmission of electrical impulses down the axon

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6
Q

Axon

A

Carries electrical signals away from the cell body to other neurons or muscles

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7
Q

Nerve terminal / Synaptic bouton

A

End of the axon from which neurotransmitters are released

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8
Q

Nodes of Ranvier

A

Exposed areas of myelinated axons that permit saltatory conduction (Where electrical signal jumps from one node to the next)

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9
Q

Synapse

A
  • Junction between two neurons
  • Presynaptic neuron
  • Synaptic cleft
  • Postsynaptic cell
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10
Q

Presynaptic neuron

A

The neuron sending the signal

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11
Q

Synaptic cleft

A

They tiny gap between the two cells

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12
Q

Postsynaptic cell

A

The cell receiving the signal

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13
Q

Myelin

A

An insulating substance that prevents signal loss

  • Created by oligodendrocytes in CNS
  • Created by schwann cells in PNS
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14
Q

Individual axons are bundled into

A

nerves or tracts

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15
Q

Single nerve

A

May carry multiple types of information, including sensory, motor, or both

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16
Q

Tracts

A

Contain only one type of information

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17
Q

Ganglia

A

where the Cell bodies of neurons (same type) within a nerve cluster together in PNS

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18
Q

Nuclei

A

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

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19
Q

Glial Cells

A

Support and protect neurons. They are important for the health and function of the nervous system

  • Astrocytes
  • Oligodendrocytes
  • Schwann cells
  • Ependymal cells
  • microglia
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20
Q

Astrocytes

A

Support neurons, maintain the blood-brain barrier, and help with nutrient transport

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21
Q

Ependymal Cells

A

Line the ventricles of the brain and help circulate cerebrospinal fluid (Supports the brain serves as a shock absorber)

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22
Q

Microglia

A

Immune cells of the nervous system, cleaning up debris and fighting infection

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23
Q

Resting membrane potential

Study These Flashcards
A
  • -70 mV
  • Maintained using selective permeability of ions as well as the Na+/K+ ATPase
  • The Na+/K+ ATPase pumps 3 Na out and 2 K in
24
Q

Incoming signals can be

Study These Flashcards
A

Excitatory or Inhibitory

25
Excitatory signals
cause depolarization of the neuron
26
Inhibitory signals
Cause hyperpolarization of the neuron
27
Temporal summation
integration of multiple signals near each other in time
28
Spatial summation
Addition of multiple signals near each other in space
29
Resting Potential
- The neuron is at rest - Inside of the cell is more negative then the outside - Na outside , K inside - Maintained by the sodium-potassium pump and leak channels - -70mV
30
Depolarization (Rising Phase)
- Voltage-gated sodium channel open - Sodium rushes into the cell, making the inside more positive - Peaks around 30 - 40 mV
31
Repolarization (Falling Phase)
- Sodium channels close and voltage-gated potassium channels open - Potassium flows out the cell, making the inside of the more negative again
32
Hyperpolarization (Undershoot)
- Potassium channels stay open a bit too long - The membrane becomes more negative than the resting potential
33
Return to resting potential
- Potassium channels close, and the sodium potassium pump restores the original ion balance - cell returns to -70 mV, ready to fire again
34
Threshold
- 50 mV must be reached to trigger an action potential
35
When do action potentials fire?
at around 30 to 40 mV
36
While the axon is hyperpolarized
It is in the refectory period
37
Refractory periods
Phases during and after an action potential when a neuron cannot or is less likely to fire another action potential
38
Absolute refractory period
- No firing possible; No new action potential can be triggered - Occurs during depolarization and most of repolarization - Ensures that the action potential only travels in one direction and prevents overlapping signals
39
Relative Refractory Period
A period when a new action potential can occur but only if the stimulus is stronger than usual - Occurs during late repolarization and hyperpolarization - Allows for precise timing between signals and prevents rapid firing
40
What happens when an action potential reaches the nerve terminal?
- Arrival of the action potential depolarizes the nerve terminal, which opens calcium channels - The increase in calcium triggers synaptic vesicles to move forward and fuse with the presynaptic membrane. - Neurotransmitters are released in to the synaptic cleft - The neurotransmitters bind to the synaptic cleft and bind to specific receptors on the postsynaptic membrane these receptors can either be ligand-gated ion channels or G-protein coupled receptors -Neurotransmitters must be cleared from the postsynaptic cell. Otherwise a new action potential can be triggered.
41
How can neurotransmitters be cleared from the postsynaptic receptors?
- The neurotransmitter can be enzymatically broken down - It can be absorbed back into the presynaptic neuron by reuptake channels - The transmitter can diffusion away from the the synaptic cleft
42
What are the 3 types of neurons ?
- Motor (Efferent) - Interneurons - Sensory (Afferent)
43
Motor (Efferent)
Carry signals from the CNS to muscles or glands to cause movement or secretion - Ex- telling muscles to contract to move your hand
44
Sensory Neurons (Afferent neurons)
Carry signals from sensroy receptors (Skin, eyes, and ears) toward the CNS - Ex - detecting pain, temperature, or light
45
Interneurons
Connect sensory and motor neurons within CNS. Help process information and coordinate responses - Found only in brain and spinal cord
46
Central nervous system
Brain and spinal cord
47
Peripheral nervous system
Cranial and Spinal nerves
48
White matter
Myelinated axons
49
Grey matter
Unmyelinated axons
50
Matter in the brain
White matter is deeper than dark matter
51
Matter in the spinal cord
Grey matter is deeper than the white matter
52
The PNS consist of what 2 nervous system ?
- Somatic (Voluntary) - Autonomic (Automatic)
53
Automatic nervous system
- Parasympathetic - Rest and digest - Sympathetic - Fight or flight
54
Reflex arcs
Use the ability of interneurons in the spinal cord to relay information to the source of a stimulus while simultaneously routing it to the brain
55
What are the two reflex arcs
- Monosynaptic reflex arc - Polysynaptic reflex arc
56
Monosynaptic reflex arc
The sensory neuron fires directly onto the motor neuron
57
Polysynaptic reflex arc
The sensory neuron may fire onto a motor neuron as well as interneurons that fire onto other motor neurons

MCAT Biology (4 decks)

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