Nerve Cells and Nerve Impulses Flashcards
The nervous system is composed of two types of cells: ______ and _____.
neurons and glia
Which part of an animal cell is a network of tubes that modifies & transports proteins?
a) Nucleus
b) Ribosomes
c) Endoplasmic reticulum
d) Plasma membrane
e) Mitochondrion
c) Endoplasmic reticulum
A network of thin tubes that transports newly
synthesized proteins to other locations. Ribosomes may be attached.
What is the nucleus?
a) structure that contains DNA; genetic material
b) synthesizes new proteins
c) network of tubes that modifies & transports proteins
d) separates the inside of the cell from the outside
e) performs metabolic activities (makes energy)
a) structure that contains DNA; genetic material
The structure that contains the chromosomes
What does a neuron do?
Receive information and transmit it to other cells.
What is the mitochondrion?
a) structure that contains DNA; genetic material
b) synthesizes new proteins
c) network of tubes that modifies & transports proteins
d) separates the inside of the cell from the outside
e) performs metabolic activities (makes energy)
e) performs metabolic activities (makes energy)
Mitochondrion: The structure that provides the cell with energy. It requires
fuel and oxygen to function
Approximately how many neurons are in the human brain?
100 billion neurons
The human brain contains approximately 100 billion neurons (though that
estimate varies from person to person).
Which part of an animal cell synthesizes new proteins?
a) Nucleus
b) Ribosomes
c) Endoplasmic reticulum
d) Plasma membrane
e) Mitochondrion
b) Ribosomes
Site of protein synthesis in the cell
What are the four major components of larger neurons?
dendrites, cell body, axon, and presynaptic terminal.
Larger neurons contain four major components: dendrites, cell body, axon, and presynaptic terminal.
The tiniest neurons may lack axons and well-defined
dendrites
Branching fibers that extend from the cell body and get narrower at their end are: a) Dendrites b) Dendritic spines c) Cell body (soma) d) Axon e) Myelin sheath: f) Nodes of Ranvier g) Presynaptic terminal
a) Dendrites
Dendrites: Branching fibers that extend from the cell body and get
narrower at their end. The dendrite’s surface is lined with specialized
synaptic receptors, at which the dendrite receives information from
other neurons.
List five types of glia.
Astrocytes Microglia Oligodendrocytes Schwann cells Radial glia
What kind of neuron Conducts impulses to muscles and glands from the spinal cord? a) Purkinje cell b) Motor neuron c) Sensory neuron d) Pyramidal cell
b) Motor neuron
Swelling at the tip of the axon is the:
a) Dendrites
b) Dendritic spines
c) Cell body (soma)
d) Axon
e) Myelin sheath:
f) Nodes of Ranvier
g) Presynaptic terminal
g) Presynaptic terminal
Presynaptic terminal (end bulb): Swelling at the tip of the axon. The
part of the neuron that releases chemicals that cross the junction between
one neuron and the next.
Define nodes of Ranvier.
Interruptions along the myelin sheath
Glia are _______ and ________ than neurons:
a) larger and less numerous
b) smaller and less numerous
c) larger and more numerous
d) smaller and more numerous
d) smaller and more numerous
Glia are smaller and more numerous than neurons.
Which neuron is sensitive to certain kinds of stimulation (e.g., light, touch, etc.)? a) Purkinje cell b) Motor neuron c) Sensory neuron d) Pyramidal cell
c) Sensory neuron
A long, thin fiber, which is the information-sending part of the neuron, sending an electrical impulse toward other neurons, glands, or muscles is the: a) Dendrites b) Dendritic spines c) Cell body (soma) d) Axon e) Myelin sheath: f) Nodes of Ranvier g) Presynaptic terminal
d) Axon
Axon: A long, thin fiber (usually longer than dendrites), which is the
information-sending part of the neuron, sending an electrical impulse
toward other neurons, glands, or muscles.
What brings information into a structure?
a) Afferent axons
b) Efferent axons
c) Interneurons
a) Afferent axons
Which type of glia absorbs chemicals released by axons and later returns those chemicals back to the axon, remove waste products, cause blood vessels to dilate and recycles glutamate?
Astrocytes: A type of glia that absorbs chemicals released by axons and later
returns those chemicals back to the axon to help synchronize the activity of
neurons. Astrocytes remove waste products as well, particularly those created
after neurons die. Astrocytes also cause blood vessels to dilate to bring in more nutrients at times of increased brain activity. They act as a recycling system for glutamate released by neurons (absorbing excess glutamate then converting it
to glutamine and passing it back into the neurons).
What is the cell body (soma) of a neuron?
Cell body (soma): Contains the nucleus, ribosomes, mitochondria, and other structures found in most cells
Neurons entirely located within a single structure of the nervous system are said to be:
a) Afferent
b) Efferent
c) Interneurons
c) Interneurons
Why do we need a Blood-Brain Barrier? (5 reasons)
- The blood-brain barrier is needed because the brain lacks the type of immune
system present in the rest of the body. - Because neurons cannot be replicated and replaced, the barrier is in place to
minimize the risk of irreparable brain damage. - A wall is formed that keeps out most viruses, bacteria, and harmful chemicals.
- When viruses do enter, like the rabies virus, it can infect the brain and lead to
death. - A virus that enters your nervous system probably stays with you for life (e.g.,
chicken pox and shingles)
What is the refractory period?
The refractory period is a period immediately after an action potential occurs
when the neuron will resist the production of another action potential.
Which two glia build the myelin sheaths around certain neurons, and where is each located?
a) Astrocytes
b) Microglia
c) Oligodendrocytes
d) Schwann cells
e) Radial glia
CNS Oligodendrocytes: A type of glia that builds the myelin sheaths around certain
neurons in the brain and spinal cord.
PNS Schwann cells: A type of glia that builds the myelin sheaths around certain
neurons in the periphery of the body.
What do efferent axons do?
Sends information away from a structure
What does the blood brain barrier do?
It keeps out most viruses, bacteria, and harmful chemicals.
The only molecules that can cross the blood brain barrier are molecules for which there is a specific transport mechanism, or molecules which are electrically neutral and thus lipid soluble.
What is the cell membrane made of?
Lipid bilayer of cell membrane is made of phospholipid molecules
What is the typical resting
membrane potential of a neuron?
-70 millivolts (mV)
This may vary from one neuron to
another.
During the resting potential, chloride channels (or gates) are:
a) open
b) closed
c) mostly closed
d) mostly open
a) open
During the resting potential, chloride channels (or gates) remain open along the
membrane, which allows ions to pass through
What cells guide the migration of neurons and the growth of axons and dendrites during embryonic development?
a) Astrocytes
b) Microglia
c) Oligodendrocytes
d) Tubule filaments
e) Radial glia
e) Radial glia
Radial glia: Guides the migration of neurons and the growth of axons and
dendrites during embryonic development.
During the resting potential, potassium channels (or gates) are:
a) open
b) closed
c) mostly closed
d) mostly open
c) mostly closed
Potassium channels are mostly closed, causing potassium to cross the membrane slowly
What cells builds the myelin sheaths around certain neurons in the brain and spinal cord?
Oligodendrocytes (CNS)
What blocks most molecules from passing through the Blood Brain Barrier?
Endothelial cells form walls of the capillaries. These cells are tightly joined in
the brain, blocking most molecules from passing. In the rest of the body, the
endothelial cells are separated by large gaps.
Which glia cells remove waste material as well as viruses, fungi, and other microorganisms?
a) Astrocytes
b) Microglia
c) Oligodendrocytes
d) Tubule filaments
e) Radial glia
b) Microglia
Microglia: Very small cells that remove waste material as well as viruses,
fungi, and other microorganisms.
During the resting potential, sodium channels (or gates) are:
a) open
b) closed
c) mostly closed
d) mostly open
b) closed
Sodium gates remain
closed, restricting the passage of sodium ions
What can cross passively (without using energy) through the blood-brain barrier?
a) necessary chemicals (e.g. glucose)
b) Small uncharged molecules
c) Small charged molecules (i.e. ions)
d) Most medicines and drugs
b) Small uncharged molecules
Small uncharged molecules (e.g., oxygen and carbon dioxide) and molecules
that can dissolve in the fats of the capillary wall can cross passively (without
using energy) through the blood-brain barrier.
The neuron membrane is selectively permeable. State which of the following can cross, and how.
a. water
b. glucose
c. sodium
d. carbon dioxide
a. water can pass freely (though is slowed by polar regions)
b. glucose is actively transported across (uses GLUT receptors, which are insulin-dependent in some cell types)
c. sodium passively passes through sodium gates (which are closed at resting potential) and via active transport through the Sodium-potassium pump which transports three sodium ions outside of the cell while also drawing two potassium ions
d. carbon dioxide can pass freely (passive diffusion across membrane re concentration gradient)
At rest, describe the forces at work on sodium ions regarding the:
a) electrical gradient
b) concentration gradient
The electrical gradient: opposite electrical charges attract, so sodium (which is positively charged) is attracted to the negative charge inside the cell.
The concentration gradient (difference in distribution of ions between the inside and the outside of the membrane): Sodium is more concentrated outside the membrane than inside and is thus more likely to enter the cell than to leave it.
Given that both the electrical and concentration gradients tend to move
sodium into the cell, sodium would be expected to quickly enter the cell.
However, when the membrane is at rest, sodium channels are closed.
What is hyperpolarization?
Hyperpolarization (increased polarization): Occurs when the negative charge inside the axon increases (e.g., -70 mV becomes -80 mV)
Potassium ions are:
a) Positively charged
b) Negatively charged
a) Positively charged
When the negative charge inside the axon decreases (e.g., -70 mV becomes -55 mV), it is called: a) Action potential b) Hyperpolarization c) Depolarization d) Threshold of excitation
c) Depolarization
Depolarization (reduce polarization towards zero): Occurs when the negative
charge inside the axon decreases (e.g., -70 mV becomes -55 mV).
What can crosses through the blood-brain barrier via an active transport system (a protein-mediated process that uses energy)?
a) necessary chemicals (e.g. glucose)
b) Small uncharged molecules
c) Small charged molecules (i.e. ions)
d) Most medicines and drugs
a) necessary chemicals (e.g. glucose)
An active transport system (a protein-mediated process that uses energy)
exists to pump necessary chemicals, such as glucose, through the blood-brain
barrier
