List the fxn and location of the Nodes of Ranvier:
fxn: unmyelinated spaces between cells
location: PNS and CNS
Distinguish between neurons and glial cells:
Neurons
Excitablility
conductivity
serections (neurotransmitters)
longevity
no mitosis
high metabolic rate
Glial Cells
binds/supports neurons
miotic
insulate
transfer nutrients/wastes
Describe what multiple sclerosis is and how it effects the nervous system:
Multiple sclerosis: "hard condition", oligodendrocytes are replace by scar tissue
Nervous system: nerve conduction is disrupted, autoimmune disorder triggered by a virus
Symptoms: speech defects, blindness, numbness
what is an electrical potential? (include the word polarized in your answer)
there is a seperation of charge across the membrane, in which one side is more electronegative, and one side more electropositive making the membrane polaized.
List two ways in which electrial potential can be increased:
force increases with decreasing distance of charge seperation
force increases with the quantity of the charge
List the factors that influence and maintain resting membrane potential:
Ion difference between ICF and ECF
membrane permability to ions
depolarization
repolarization
The flow of sodium into a cell or potassium out of a cell is an example of :
current
Which ion is responsible for depolarization? repolarization? hyperpolarization?
depolarization: Na+
repolarization: K+
hyperpolarization: K+, Cl-
Which ion has a stronger influence on the membrane's charge? why?
K+ has the strongest influence, the membrane is most permible to it.
Compare and contrast local (graded potentials) and action potentials:
Local (graded) pontential
vary magnititude depending on what the stimulus is
can be summated
decrease with distance at thershold singal triggers
can be reversible (refractory peroid)
can be excitatory ( depolarizing) or inhibitory (hyperpolarizing)
Action Potentialsdoes not decrease with distance
can not summate
irreversible
At what point does a local potential become and action potential?
at threshold
True/False: All local potentials are all or nothing and have uniform strength
False: all action potentials are all or nothing adn have uniform strength.
What division of the nervous system carries signals from the CNS to effectors such as muscles and glands?
Which of the following cell types is an important component of the blood-brain barrier and functions to nourish and regulate the composition of the extracellular fluid surrounding neurons?
At resting membrane potential, the Na+ concentration is higher inside the cell than outside the cell.
True
False
False
At resting membrane potential, the K+ concentration is higher inside the cell than outside the cell.
True
False
True
Which of the following is FALSE regarding local potentials?
The strength of a local potential decreases as it spreads from the point of stimulation.
Local potentials are reversible if the stimulation stops before threshold is reached.
Local potentials can be either excitatory (depolarizing) or inhibitory (hyperpolarizing).
Local potentials, like action potentials, are "all-or-none": they either do not occur at all or exhibit the same peak voltage regardless of stimulus
strength.
Local potentials, like action potentials, are "all-or-none": they either do not occur at all or exhibit the same peak voltage regardless of stimulus strength.
List the events that occur before and during an action potential:
local potentials depolarize the membrane
threshold voltage is reached
volted-gated Na+ chanels open
voltage of the cell is positive
repolarization
membrane is hyperpolarized
resting membrane potential is restored
Depolarization is caused by the movement of ____ ions _____ the cell.
Na+ ; out of
K+ ; into
Na+ ; into
Ca++ ; into
K+ ; out of
Ca++ ; out of
Na+; into
Repolarization is caused by the movement of ____ions ______the cell.
Na+ ; into
Na+ ; out of
K+ ; out of
Ca++ ; out of
Ca++ ; into
K+ ; into
K+: out of
Hyperpolarization is caused by the movement of ____ions _____the cell.
K+ ; into
Ca++ ; into
Ca++ ; out of
Na+ ; into
K+ ; out of
Na+ ; out of
K+; out of
Signal conduction in a nerve fiber is fastest in neurons that are:
small and myelinated
large and unmyelinated
small and unmyelinated
large and myelinated
small and myelinated
The _______ is the phase of an action potential in which no stimulus, no matter how strong, will trigger a new action potential.
inhibitory period
hyperpolarization
absolute refractory period
excitatory period
relative refractory period
absolute refractory period
how do anesthetics work to control pain?
volted gated channels remain closed, RMP remains at -70mV, so the sensory signal isnt being transmitted
Distinguish between absolute and relative refractory peiords?
absolute
the inbetween threshold
no stimulus can trigger an action potential
relative
hyperpolarization, below RMP
will need a stronger stimulus to trigger an action potential
Describe the factors that affect the rate of impulse conduction along an axon:
the diameter of the nerve (bigger is better)
the presence or absence of myelin
Distinguish between continuous and salatory conduction:
unmyelinated continuous (slow) conduction
Na+ leakage
anion attraction
non decremental, signal stays strong over a distance
regenerating AP along axon (new Na+ source)
aids in digestion regulation
myelinated saltatory (fast ) conduction
AP is generated only at the node (myeling b/w nodes)
insulation: ions cant go in/out thru myelin, only when nerve is exposed can generate AP
signal is decremental( limited # of Na+ ions)
aids in motor fxn/sharp sensory
Expalin what is ment by presynaptic and postsynaptic neuron:
presynaptic neruon: the neruon that the signal arrives at, and releases the neruotransmitter
postsynaptic neruon: the neuron that responds to the neruotransmitter
1. local potential builds in nerver fiber with dendrites
2. soma - on the other side of the soma is AP
3. presynaptic neuron
4. synaptic junction - neurotransmitter is released
5. the next nerve responds to neurotransmitter
6. repeats all the way to the brain
* postsynaptic neuron is presynaptic neuron for the next neuron
Describe the structure and fxn of chemical synapses:
structure: snyaptic knob, synaptic vessicles (contain neurotransmitters), synaptic cleft (space between receptors and postsynaptic neuron)
fxn: the way in which neruons communicate by neurotransmitters
Describe the mechanisms used to clear neurotransmitters from synapses and why this is necessary:
Mechanisms
Diffusion into the ECF
Reuptake, amino acid (-) reabsorbtion
Degradation in synaptic cleft (breakdown enzymes)
Why: postsynaptic neuro could continue firing indefinitely, causing a breakdown in physiological coordination
Summarize the different classes of neurotransmitters:
Excitatory
ACh
Aspartic acid
gluatmic acid
epinephrine
norepiephrine
dopamine
inhibitory
amino acids
glycine
GABA
Situational
serotonin
histimine
what are the three main types of neurotransmitters?
which one is ACh?
Excitatory, inhibitory, and situational
ACh is excitatory
Explain the difference between excitatory and inhibitatory postsnyaptic potentials and the mechanism by which each is generated:
Excitatory
EPSP (excitatory postsynaptic potential)
a change in voltage potential towards the threshold
Depolarization ( doesnt shoot up, only a slight amount of Na+ flowing in)
Potential is a little higher than normal (-70 mV vs. -60mV)
Neuron is most likely to fire
Inhibitatory
IPSP ( inhibitatory postsynaptic potential)
change in voltage potential goes away from threshold
Hyperpolarization( starts off more negative than RMP)
Neuron is less likely to fire ( will need a stronger signal)
Explain the concept of summation and distinguish between temporal and spatial summation:
summation: the process of adding up postsynaptic potentials and responding to their net effect, occurs in the trigger zone
temporal summation: a single synapse genereates EPSP so quickly that each is generated before the previous one fadeds, allows EPSP to add up over time to a threshold voltage that triggers AP
spatial summation: occurs when EPSP from several synapses add up to threshold at the axon hillock, several synapses acting together admit enought Na+ to reach threshold
Put the following events in order:
K. chemical, light, or heat stimulus occurs
k. NTs open channels at the dendrite
b. Local potential occurs in soma
d. membrane depolarzied to reach threshold at axon hillock
f. action potential occurs
c. voltage-gated calcium channels open
h. NT released
a. neurotransmitters (NT) travel across synaptic cleft
j. NTs open channels in postsynaptic neuron
g. EPSP's summate
e. threshold reached in postsynaptic neuron
what is the term used to describe a neuron's ability to process, recall and store information and make decisions?
intergration
which of the following is in the correct order for the firing of an action potential?
B.
which of the following is false regarding excitatory post snyaptic potenial (EPSP)?
B.
action potentials are conducted most rapidly down axons that are:
D.
on a myelinated axon, the spaces between the myelin are called:
C.
The myelination of nerves within the CNS is a role of the:
D.
which of the following best describes the relative refractory peroid of an action potenital?