C2.2 Neural Signaling Flashcards
The resting membrane potential of a neuron is ____ millivolts
-70
Identify which ion plays a key role in generating an action potential.
Sodium (Na+)
An R^2 value closer to 1 represents..
a strong, positive correlation
An R^2 value closer to -1 represents..
a strong, negative correlation
During the resting potential, the inside of the neuron is negatively charged due to a higher concentration of
_________ ions inside the cell.
potassium
A larger axon diameter leads to ____ conduction speed.
faster
The junction between two neurons is called a ____.
synapse
Identify the name for a junction between a neuron and a muscle fibre.
neuromuscular junction
Excitatory neurotransmitters cause the postsynaptic membrane to become more ____ by allowing the entry of _____ ions.
positive, sodium
Acetylcholine released from the presynaptic membrane travels to the postsynaptic membrane through the process of _____.
diffusion
C. ____ potential arrives at presynaptic membrane.
B. Ca2+ diffuses into the ____ knob.
A. Voltage-gated Ca2+ channels ____.
D. Vesicles containing _____ move towards the presynaptic membrane.
F. Vesicles fuse with the ______ membrane.
E. Neurotransmitter is released in the synaptic ____.
action, presynaptic, open, acetylcholine, presynaptic, cleft
During depolarisation
______
ions flood inside the neuron.
sodium
An action potential is generated from the axon hillock only if the impulse crosses the threshold potential.
t
The conduction of an impulse through a myelinated neuron is called ____ conduction.
saltatory
Exogenous substances ________.
originate outside the body.
Cocaine affects the brain since it blocks the reuptake of ____.
dopamine
Inhibitory postsynaptic potentials increase membrane permeability of
______ ions into the cell.
chloride
What would cause action potential to be generated in the postsynaptic neuron?
In the presynaptic neuron, depolarisation at the axon hillock exceeds the threshold for excitation.
Summation takes into consideration both the ___ and _____ impulses.
excitatory, inhibitory
Identify the receptors for fine, discriminative touch and vibration in human skin.
Meissner corpuscles
________ is a shift in membrane potential toward a more positive state, whereas ______ is the return of the membrane potential to its resting state after depolarisation.
depolarisation, repolarisation
The rapid conduction of an action potential in myelinated nerve fibres is known as _______ .
Saltatory conduction
_____ is the process by which an action potential travels along a nerve fibre or axon.
Nerve impulse propagation
What do dendrites, axon and cell body do in a neuron?
dendrites: receive sensory information from environment
axon: long extension that carries electricals signal to the axon terminal
cell body(soma): contain nucleus/other organelles
Define membrane potential.
voltage created by the imbalance in charges(ions) between the inside and outside of the cell membrane
Define resting potential.
active transport by the sodium potassium pump allows neuron to establish membrane potential of -70 millivolts
Outline three mechanisms that together create the resting potential in a neuron.
inside neuron: relatively negative
(-70 millivolts)
- sodium ions outside of cell
- action performed by sodium potassium pump
State the voltage of the resting potential.
-70 (millivolts) mV
Outline the six steps of sodium-potassium pump action.
1.) gets 3 sodium from inside the cell
2.) ATP gives phosphate group
3.) pump changes shape & release sodium into extracellular space
4.) 2 potassium bind to pump
5.) Phosphate leaves
6.) pump returns to former shape & potassium enters cell
Define nerve impulse.
a signal transmitted along a nerve fiber. It consists of a wave of electrical depolarization that reverses the potential difference across the nerve cell membranes.
-happen in one direction
Define action potential.
a rapid sequence of changes in the voltage across a membrane.
Explain the difference in nerve impulse speed for myelinated and unmyelinated fibers.
- ONLY myelinated CAN do saltatory conduction
- impulse can jump from node to node instead of going in/out including myelin sheath
State the correlation between conduction speed of nerve impulses and animal size.
larger animals: slower reflex
- neurons need to travel farther
Saltatory conduction allows the impulse to travel much _____ than in an unmyelinated axon of the same diameter.
faster; (50 times)
Define synapse, synaptic gap and effector.
space between 2 neurons where the communicate, the space in between the axon of one neuron and the dendrites of another and is where the electrical signal is translated to a chemical signal, nerve cells that respond to a stimulus according to the instructions sent from the nervous system (mainly muscles)
List examples of effector cells.
Neutrophils, eosinophils, and basophils
A signal can only pass in _______ across a typical synapse and the role of neurotransmitters is _________.
one direction, chemical messenger that carry out info. at the synapse
______ functions as a chemical signal triggering _____ of neurotransmitter from a presynaptic cell.
Calcium, exocytosis
Acetylcholine is one of the most _____ neurotransmitters in both invertebrates and _____ and is used as the neurotransmitter in many synapses including between neurons and ___ fibers.
common, vertebrates, muscle
In a postsynaptic cell, neurotransmitters are released into the synaptic gap through the process of ______.
exocytosis, diffusion
In a cell each neurotransmitter has a specific _____ it can bind to. This ligand gated channel often causes the opening of ____ in the postsynaptic membrane.
receptor, ion channel
Gated ion channels: _______
allow positive ions to come in which cause depolarization - more likely to fire action potential
The minimum millivolts to fire an action potential is _____.
threshold potential
Outline the digestion of acetylcholine by acetylcholinesterase.
acetylcholinesterase breaks it into acetate and choline
An action potential is only initiated if the ______ potential is reached.
threshold (-50 mV)
Define depolarization.
positive voltage from sodium ions in the cell
Outline the mechanism of depolarization during an action potential using voltage gated sodium channels.
-threshold potential exceeds -50
Define repolarization.
The efflux(move out) of potassium (K+) ions results in the falling phase of an action potential.
Outline the mechanism of repolarization during an action potential using voltage gated potassium channels.
potassium leaves the cell, repolarizing the cell and making it negative
depolarization and repolarization are both examples of ______.
facilitated diffusion
A wave of depolarization and repolarization cause ______ to open along the length of an axon
ion channels
Describe the movement of sodium ions in a local current.
The influx of sodium ions generates the action potential, which then triggers neighboring regions to depolarize and propagate the signal down the axon.
Local currents cause each _____ part of the axon to reach the threshold potential.
successive
Explain how the movement of sodium ions propagates an action potential along an axon.
The influx of sodium ions generates the action potential, which then triggers neighboring regions to depolarize and propagate the signal down the axon.
Outline the cause and consequence of the refractory period after depolarization.
action potential absolutely cannot fire again due to all of the voltage-gated sodium channels being inactivated
-cell has positive charge
Outline the use of oscilloscopes:
Measures membrane potential using electrodes
Annotate an oscilloscope trace to show the resting potential, action potential, threshold potential, and refractory period
{view graph}
In myelinated neurons, the Na+ and K+ ion channels are clustered down the axon at ________.
nodes of Ranvier
Outline the effects of neonicotinoids on synaptic transmission.
-bind to acetylcholine receptors
-depolarization in cell doesn’t occur; action potential doesn’t fire
- irreversible change affects insects by causing death
Outline the effects of cocaine on synaptic transmission.
synaptic transmission promoter-
-blocks the reuptake of dopamine into brain
-too many dopamine messages into postsynaptic neuron
-feelings of happiness/euphoria
-forget other important messages the brain is sending “don’t jump off the cliff”
exogenous substances ______.
originate from outside of the body
Sensory neurons respond to pain by sending signals to the ________________. If enough excitatory neurotransmitters are released _________________
central nervous system
State the term that describes the accumulative effect of multiple releases of neurotransmitters to trigger an action potential.
summation
Excess acetylcholine in the synaptic space is broken down into choline and acetate by acetylcholinesterase. What happens to the choline?
The choline is reabsorbed back into the presynaptic neuron.
