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Psych 270 > Ch. 1 - Nerve Cells & Nerve Impulses > Flashcards

Ch. 1 - Nerve Cells & Nerve Impulses Flashcards

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1
Q

Neurons

A
  • Neurons receive information and transmit it to other cells

- Approximately 86 billion neurons in adult human brain

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2
Q

Membrane

A

-The surface of a cell which separates the inside of the cell from the outside environment

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3
Q

Nucleus

A

-Structure that contains the chromosomes

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4
Q

Mitochondria

A
  • The structure that performs metabolic activities, providing the energy that the cell uses for all activities
  • Mitochondria have genes separate from those in the nucleus of the cell, and mitochondria differ from one another genetically
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5
Q

Ribosomes

A
  • The sites within a cell that synthesize new protein molecules
  • Some ribosomes float freely in the cell, but some are attached to the endoplasmic reticulum (ER)
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6
Q

Endoplasmic Reticulum (ER)

A

-A network of thin tubes that transport newly synthesized proteins to other locations

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7
Q

Motor neuron

A

-A motor neuron has it’s soma (cell body) in the spinal cord, and receives excitation though its dendrites and conducts impulses along its axon to a muscle

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8
Q

Sensory neuron

A
  • Is specialized at one end to be highly sensitive to a particular type of stimulation, such as light, sound, or touch.
  • Tiny branches lead directly from the receptors into the axon, and the cell’s soma is located on a little stalk off the main trunk
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9
Q

Dendrites

A

-Are branching fibers that get narrower near their ends
-The dendrites surface is lined with specialized
synaptic receptors”, at which the dendrite receives information from other neurons.
-The greater the surface area of a dendrite, the more information it can receive
-Many dendrites contain DENDRITIC SPINES

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10
Q

Dendritic spines

A

-Short outgrowths on dendrites that increase the surface area available for synapses

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11
Q

Cell body (soma)

A
  • Contains the nucleus, ribosomes, and mitochondria
  • Most of a neuron’s metabolic work occurs here
  • The cell body is also covered with synapses on its surface, similar to the dendrites
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12
Q

Axon

A
  • Is a thin fiber of constant diameter
  • The axon conveys an impulse toward other neurons, an organ, or a muscle.
  • Axons can be more than a meter long
  • A neuron can have many dendrites, but only ONE axon, but the axon may have branches
  • The end of each branch has a swelling, called a PRESYNAPTIC TERMINAL
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13
Q

Myelin sheath

A

-Many vertebrate axons are covered with an insulating material called a myelin sheath, with interruptions (spaces) known as NODES OF RANVIER

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14
Q

Presynaptic terminal

A
  • A swelling at the end of axon branches

- At that point the axon releases chemicals that cross through the junction between that neuron and another cell

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15
Q

Afferent axon

A
  • Brings information INTO a structure

- Every sensory neuron is an afferent to the rest of the nervous system

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16
Q

Efferent axon

A
  • Carries information AWAY from a structure

- Every motor neuron is an efferent from the nervous system

17
Q

Interneuron (or intrinsic neuron)

A

-If a cell’s dendrites and axon are entirely contained within a single structure, the cell is an interneuron or intrinsic neuron

18
Q

Astrocytes

A
  • A star-shaped glia cell, which wraps around the synapses of functionally related axons
  • Astrocytes are important for generating rhythms , such as your rhythm of breathing
  • They alose dilate the blood vessels to bring more nutrients into brain areas that have heightened activity
19
Q

Microglia

A
  • Tiny cells that act as part of the immune system, removing viruses and fungi from the brain
  • They also contribute to learning by removing the weakest synapses
20
Q

Oligodendrocytes and Schwann cells

A
  • Oligodendrocytes in the brain and spinal cord and Schwann cells in the periphery of the body build the myelin sheaths that surround and insulate certain vertebrate axons
  • They also supply an axon with nutrients necessary for proper functioning
21
Q

Radial glia

A
  • Guide the migration of neurons and their axons and dendrites during embryonic development
  • When embryological development finishes, most radial glia differentiate into neurons, and a smaller number differentiate into astrocytes and oligodendrocytes
22
Q

Blood brain barrier

A
  • The mechanism that excludes most chemicals from the vertebrate brain
  • Endothelial cells form the walls of the capillaries. In the brain, they are joined so tightly that they block viruses, bacteria, and other harmful chemicals from passage
  • Oxygen and carbon dioxide are small, uncharged molecules that can pass through the cell walls freely
  • Molecules that dissolve in the fats of the membrane also cross easily (ex. vitamins A and D, drugs such as antidepressants and even heroin)
23
Q

Active transport

A

-A protein-mediated process that expends energy to pump chemicals from the blood into the brain

24
Q

Electrical gradient (AKA polarization)

A

-A difference in electrical charge between the inside and outside of the cell

25
Q

Resting potential

A
  • The electrical potential inside the membrane is slightly negative with respect to the outside, mainly because of negatively charged proteins inside the cell. This difference in voltage is called the resting potential
  • The resting potential prepares the neuron to respond rapidly
26
Q

Selective permeability

A
  • Some chemicals pass through the membrane more freely than others do
  • Oxygen, carbon dioxide, urea, and water cross freely through channels that are always open
27
Q

Sodium-potassium pump

A
  • A protein complex, repeatedly transports three sodium ions out of the cell while drawing two potassium ions into it
  • The sodium-potassium pump is an active transport that requires energy
28
Q

Concentration gradient

A

-The difference in distribution of ions across the membrane

29
Q

Action potentials

A

-Messages sent by axons

30
Q

All-or-none law

A

-The amplitude and velocity of an action potential are independent of the intensity of the stimulus that initiated it, provided that the stimulus reaches the threshold

31
Q

Propagation of the action potential

A
  • During an action potential, sodium ions (Na) enter a point on the axon
  • Temporarily, that spot is positively charged in comparison to neighbouring areas along the axon
  • The positive ions flow within the axon to neighbouring regions
  • The positive charges slightly depolarize the next area of the membrane, causing it to reach its threshold and open its voltage-gated sodium channels
  • Then the membrane regenerates the action potential at that point. In this manner the action potential travels along the axon
32
Q

Myelin

A

-An insulating material composed of fats and proteins

33
Q

Saltatory conduction

A
  • The jumping of action potentials from node to node

- A myelinated axon admits sodium only at its nodes

34
Q

Refractory period

A
  • Remember that at the peak of the action potential, the sodium gates snap shut
  • As a result, the cell is in a refractory period during which it resists the production of further action potentials
35
Q

Absolute refractory period

A
  • The first part of the refractory period

- During this part, the membrane cannot produce another action potential, regardless of the stimulation

36
Q

Relative refractory period

A
  • The second part of the refractory period

- During this part, a stronger-than-usual stimulus is necessary to initiate an action potential

37
Q

Local neurons

A
  • Many small neurons have no axon.
  • Neurons without an axon exchange information with only their closest neighbours, therefore we call them local neurons
  • Because they do not have an axon, they do not follow the all-or-none law
  • When a local neuron receives information from other neurons, it has a graded potential
38
Q

Graded potential

A

-A membrane potential that varies in magnitude in proportion to the intensity of the stimulus

Psych 270 (8 decks)

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