Lecture Exam Three: Fundamentals of the Nervous System Flashcards
Which area below describes the 3 functional areas of the nervous system in a logical order?
sensory input, integration, motor output
To extend your arm, your […] nervous system is activated.
somatic
Somatic motor is….
voluntary skeletal movements
Autonomic is…
involuntary to smooth muscles, glands, and cardiac muscles
Which of the following is NOT part of the peripheral nervous system?
spinal interneurons
**anything directly dealing with the brain and spinal cord
Your heat beat increases rapidly and forcefully. This response is a result of your […] nervous system.
autonomic
The two basic cell types in your nervous system are…
- neurons
2. glial
What are the four main neuroglia that support the CNS neurons?
- astrocytes
- microglial cells
- ependymal cells
- oligodendrocytes
Glial cell is the most abundant, versatile, and highly branched of glial cells?
astrocytes
Where can you find astrocytes?
cling to neurons, synaptic endings, and capillaries
Which type of glial cell are small, ovoid cell with thorny processes that touch and monitor neurons?
microglial cells
Microglial cells […] toward […] neurons.
migrate; injured
Microglial cells can transform to […].
phagocytize microorganisms
Which type of glial cell line the central cavities of the brain and spinal column?
ependymal cells
Which type of glial cell has processes that wrap CNS nerve fibers, forming insulating myelin sheaths?
oligodendrocytes
Electrical wire is to electrical insulating tape as peripheral neurons are to …
Schwann cells
Schwann cells form […] to surround neurons in the […].
myelin sheath; PNS
What are the three special characteristics of neurons?
- extreme longevity
- amitotic (few exceptions)
- highly metabolic rate: requires continuous supply of oxygen and glucose
Each neuron in our bodies has a life span of …
an average human life
Movement of substances towards the cell body of a neuron is termed […] movement. Away from the cell body is […].
retrograde; anterograde
How is herpes complex associated with the nervous system?
this virus and bacterial toxin damages neural tissue by using retrograde axonal transport
What other viruses, besides herpes simplex, take advantage of the retrograde axonal transport?
polio, rabies, and tetanus toxin
Myelin sheath is composed of […], whitish, […] substance.
myelin; protein-lipid
Function of myelin:
- protect and electrically insulate axon
2. increase speed of nerve impulse transmission
Myelinated fibers are […] sheaths that surround […] axons.
segmented; long-diameter
Non-myelinated fibers:
do not contain sheath and are therefore slow conductors
The portion of an axon that communicates with its target cell is […].
axon terminal
The basis for differentiation between gray and white matter in the CNS is the presence of […] in white matter.
myelinated fibers
[…] are the most common structural type of neuron in humans.
multipolar
Which structural type of neuron is rare?
bipolar
Bipolar: two processes, […].
one axon and one dendrite
Where can you find bipolar processes?
retina and olfactory mucosa
Unipolar: one […] process, […].
T-like process; two axons
Unipolar is also known as…
pseudonipolar
What are the two types of processes of unipolar?
- peripheral: associated with sensory receptor
2. proximal: enters CNS
When considering the relationship between a structural classification and a functional classification of neurons, it can be said that […].
essentially all bipolar neurons are sensory neurons
T/F: Neurons have a resting membrane potential?
true
**they can change rapidly
In electricity, like charges […].
repel each other
When opposite charges are separated the system…
has potential energy
[…] is the flow of electrical charge (…) between two points.
current
Current flow is dependent on what two factors?
- voltage
2. resistance
Voltage:
measure of potential energy generated by separated charge
Resistance:
hindrance to charge flow
Ohm’s Law:
I = V/R
I = current (amps) V = voltage (voltz) R = resistance (ohms)
The greater the potential difference in charge between two points, the […] the voltage.
greater
What is the voltage across a membrane called?
membrane potential
In a living neuron, the cell’s […] provides resistance (R) to current flow.
plasma membrane
What are the two main types of ion channels
- leakage (nongated) channels
2. gated channels
Leakage (nongated channels) are always…
open
Gated channels which is opened/closed by…
the shape alteration of the protein
List the types of gated channels:
- chemically gated
- voltage gated
- mechanically gated
A typical resting membrane potential for a nerve cell is […] mV.
-70 mV
The chief contributor to the negative charge of a resting neuron’s intracellular fluid is:
a high intracellular concentration of anionic proteins
ECF has a higher concentration of […], balance by […]. While the ICF has a higher concentration of […], balanced by […].
sodium ions; chloride ions; potassium ions; negatively charged proteins
The movement of potassium into an animal cell requires…
an energy source such as ATP
T/F: The Na/K pump has a role with the generation of a single action potential.
false
Suppose a cell has only potassium channels, at what membrane potential would the concentration and electrical gradients for potassium be in balance?
-90
**if Na was leaked it would change the potential to -70
**would be maintained
How does a nerve cell compensate for the leakage of sodium ions into the cell, and potassium ions out of the cell?
Na/K pumps
**maintain potential
Maintenance of the resting membrane potential is possible due to:
- ATP expenditure of the neuron
2. the actions of the Na/K pump
Depolarization of the neuron refers to:
reduction in membrane potential
Hyperpolarization:
the membrane potential increases, the inside becoming more negative
You would expect a neuron that depolarizes to -65 mV would:
return to resting membrane potential without generating an action potential
Which type of potential change decays with distance?
all types…
- graded potential
- synaptic potential
- generator potential
- receptor potential
Graded potentials (3):
- short-lived, localized changes
- triggered by stimulus that opens gated ion channels
- named according to location and function
Graded potentials– The stronger the stimulus…
the more voltage changes and the farther current flows
Graded potentials– Opening of gated ion channels results in …
depolarization or sometimes hyperpolarization
Graded potentials– Name the two types of potentials:
- receptor potential (generator potential)
2. postsynaptic potential
Principle way of neurons to send signals:
action potentials
Action potentials only occur in…
muscle cells and axons of neurons
Action potentials are also referred to as…
nerve impulse within nerves
What gates are open within action potential?
voltage-gated channels
Sodium ion concentration in the cytoplasm of a neuron […] when its voltage-gated sodium channels open.
increases
The point at which the all-or-none principle of action potential generation is reached is termed the […].
threshold
T/F: All depolarization events produce APs.
false
What is needed in order for an AP to be triggered?
depolarization must reach a threshold voltage
At the threshold, what happens at and to the membrane(4)?
- the membrane is depolarized by 15-20 mV
- sodium ion permeability increases
- sodium influx exceeds potassium efflux
- positive feedback cycle begins
Neurons generally repolarizes once the membrane potential reaches approx…
+30 mV
Why does repolarization occur?
voltage-gated potassium channel gates open
Repolarization: Na+ channels are […] and K+ channels […].
inactivating; open
Repolarization– What happens to the AP due to the closing of Na channels?
AP spike stops rising
Repolarization– What happens to the potassium ions?
exits cell down its electrochemical gradient
A neuron under the influence of a neurotransmitter that opens K+ channels will…
be less likely to fire an action potential
Hyperpolarization: Some […] remain open, and […] channels rest.
K+ channels; Na+
What occurs to the membrane during hyperpolarization?
inside of membrane becomes more negative than in resting state
**slight dip in resting voltage
If a sodium potassium pump is applied to a neuron, the next action potential that fires will appear…
the same as normal
Propagation allows AP to be transmitted from origin down ….
entire axon length toward terminals
Sodium influx through voltage gates in one membrane area cause what events to follow?
- local currents
- opening of sodium voltage gates in adjacent membrane areas
- depolarization of that area
- depolarization is next area
AP is […] so in nonmyelinated axons, each successive segment of membrane […], then […].
self-propagating; depolarizes; repolarizes
T/F AP occurs only in a forward direction.
true
In an organism, action potentials are propagated unidirectionally toward the axon ending because:
membranes become nonresponsive due to inactive sodium channels after action potential generation
In most sensory systems, an increase in stimulus intensity is signaled by:
- more transmitter release
- more action potentials
** not because of a larger action potential
During the relative refractory period (what occurs to the system):
- the threshold is substantially elevated
2. exceptionally strong stimuli could trigger action potentials
List the two types of refractory periods:
- absolute refractory period
2. relative refractory period
Why is it the during a refractory period, the neuron cannot trigger another AP?
voltage-gated Na channels are closed and neuron cannot respond to another stimulus
Absolute refractory period:
time from opening sodium channels until resetting of the channels
Relative refractory period (what is it):
follows absolute refractory period where
- most sodium channels have returned to their resting state
- some potassium channels are still open
The conduction of an action potential along an unmyelinated axon is faster in […].
large diameter fibers
What are the two factors of conduction velocity?
- axon diameter
2. degree of myelination
Degree of myelination holds two types of conductions:
- continuous conduction
2. saltatory conduction
[…] only occurs in nonmyelinated axons, a […] conduction.
continuous conduction; slow
[…] only occurs in myelinated axons and is about […] times faster.
saltatory; 30
The location at which a neuron interacts with its target cell (either another neuron or muscle cell, etc.) is called the […].
synapse
Neurotransmitters are important in functioning […] synapses.
chemical
During the events involved in information transfer across a chemical synapse, which of the following steps would be directly interrupted by exposing a neuron to a calcium channel blocker?
neurotransmitter exocytosis from the presynaptic neuron
Certain psychosomatic drugs exert their effects by keeping the concentration of neurotransmitters elevated within the synapse. These drugs could exert their effects by:
- inhibiting enzymes associated with the postsynaptic membrane that degrade the neurotransmitter
- inhibiting reuptake of the neurotransmitter by astrocytes or the presynaptic terminal
Generally speaking, opening chloride channels in the postsynaptic membrane will result in an […].
inhibitory postsynaptic potential (IPSP)
Identify the false statement (SKIP kinda).
Spatial summation occurs with action potentials
Which molecule could serve as a second messenger for a G-protein linked metabotropic receptor?
- cyclic AMP
- calcium ion
- cyclic GMP
- diacylglycerol
What occurs in the discharge zone of neuronal pool?
neurons are most likely to generate impulses
Spinal reflexes are an example of:
serial processing
Parallel processing example:
sensed smell may remind one of an odor and any associated experiences
What occurs in the facilitated zone of a neuronal pool?
- neurons on periphery of pool are farther away from incoming fiber
- usually not excited to threshold unless stimulated by another source
