Nervous System Part 1 Flashcards
what is the resting potential that is found on the cell membranes of nerve and muscle cells?
an electrical charge that must be present at all times to allow action potentials to be present in the muscle and nerve cells.
why is the RP called a transmembrane potential?
it is the difference in charge found across the cell membrane. the RP is a slight negative charge on the inside of the cell membrane compared to a slight positive charge found on the outside of the cell membrane.
what is the voltage of the RP in millivolts?
-70 millivolts
what is the main cause of the resting potential?
the constant leaking of potassium through the nongated potassium channels creates most of the voltage for the RP.
why are action potentials so important to the body? what three main body functions do AP’S control?
AP’S are the electrical currents that control brain activity, help control organ activities, and cause muscle contraction.
why is the action potential called a reversal of the resting potential?
in the AP the positive charges are on the inside of the cell membrane. in RP the positive charges are on the outside of the cell membrane.
what is another way to describe the action potential?
it is a strong depolarization because it is a positive electrical charge. the value of AP is +20 Mv.
in what two other ways is the AP different from the RP?
the RP is present when the muscle cells are resting. the AP causes action.
what are the three phases of the AP and what causes each phase?
first phase: depolarization. caused when gated sodium channels open causing sodium to enter. causes the voltage to change from -70 to +20.
second phase: repolarization. caused when gated potassium channels open causing K to exit.
third phase: hyperpolarization. caused by too much K leaving the cell. the gated K channels remain open. this causes the voltage to drop slightly below -70.
why do sodium and potassium move in opposite directions when their gated channels are opened? how is their movement connected to their contractions inside versus outside the cells?
NA moves into cells when its gated channels are opened because there is a large concentration of NA outside of cells. K moves outside of the cells through its channels because there is a large concentration of K inside the cells. NA/K pumps move three NA out of the cells while moving two K into the cells.
when an excitatory neurotransmitter is released form a nerve cell at a synapse does it automatically cause an action potential?
no.
what does an excitatory neurotransmitter is released form a nerve cell at a synapse cause?
it causes a depolarization to occur. a depolarization is when the RP becomes more positive. it is a small positive charge.
what specific ion channel is opened by an excitatory neurotransmitter?
an excitatory NT causes a depolarization by opening gated sodium channels letting sodium in. this means an excitatory NT’s receptor is actually a gated NA channel.
how can an action potential be caused by an excitatory neurotransmitter?
two depolarizations must occur together and add together to produce an action potential, when added. the two depolarizations bust reach -55 mV in order to created the AP. -55 is the threshold.
(use picture on page 4)
in the left graph image, the two arrows (with E) represent two seperate releases of excitatory neurotransmitter. the three picture images on the right show A, B, and C of that graph. what is happening?
temporal summation of depolarizations or two depolarizations overlapping in time to create an action potential.
what is the purpose of an inhibitory neurotransmitter?
it tries to stop an AP from occurring in a musclce or nerve. it cancels out AP.
what does an inhibitory neurotransmitter do when it is released at a synapse?
it causes a hyperpolarization to occur. a hyper polarization is when the resting potential becomes more negative. it can cancel out a depolarization if it is present.
what specific ion channel is opened by an inhibitory neurotransmitter?
an inhibitory NT opens gated K channels. this lets K exit the cell, creating a hyperpolarization.
what is an inhibitory NT that is used in skeletal muscle?
dopamine
how does Parkinsons disease show the importance of inhibitory NTs in our bodies?
whith parkinsons disease, the brain produces less and less dopamine over time. this means that dopamine no longer cancels out APs in skeletal muscle. the result is that the body has uncontrolled muscle contractions.
what is an inhibitory NT used solely within the CNS? how is it useful medicinally?
GABA. it stops APs from being made in the brain. anticonvulsants for epilepsy stop seizures because they increase GABA release. seizures are caused by random APs that fire off in the brain.
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is an example of a NT like this that is used in both the sympathetic and parasymphathetic nervous systems? page 5nicotinic rec
ACH, acetylcholine
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is the general name for this NTs receptors? page 5
cholinergic receptors
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. at what location is this NT used in both the sympathetic and the parasympathetic nervous systems? page 5
in the ganglia
many NTs have both excitatory or inhibitory effects, depending on the recepor type they bind to in an organ. what is the specific name for this NTs receptors in this location? page 5
nicotinic receptors
in what other location are nicotinic receptors found?
in skeletal muscle. they are part of the somatic nervous system, the nerves that cause skeletal muscle contraction.
when ACH is released onto organs is it released from sympathetic or parasympathetic nerves?
parasympathetic nerves release ACH onto organs,
what is the specific name for ACH receptors in organs?
cholinergic receptors foundin all organs are called muscarinic receptors.
give an example of how ACH causes excitatory effects in some organs while causing inhibitory effects in others?
ACH causes excitatory effects in digestive organs because it increases digestive activities, such as increasing the stomach’s production of gastric juice. however ACH causes inhibitory effects in the heart because it slows down the heart rate.
In a synapse formed between two neurons what part of the second neuron do the terminal knobs of the first neuron synapse with?
The dendrites.
What important happens at the synapse between the synaptic knob and the dendrite?
Depolarizations or hyperpolarizations are produced depending on the type of neurotransmitter is released onto the dendrites.
Two types of neurotically cells wrap around the neuron cell axons to form myelin sheaths. Which of these neuron liar cells does this within the CNS?
Oligodendrocytes.
