C2.2 Neural Signalling Flashcards
What is the function of the sodium-potassium pump?
Restores the resting membrane potential by exchanging three Na+ ions for two K+ ions
The sodium-potassium pump uses energy to maintain ion concentration gradients.
What ensures that action potentials can only go in one direction?
The refractory period, during which sodium channels are closed
This prevents backflow of action potentials.
What happens when an action potential reaches the synapse?
Voltage-gated calcium channels open, allowing calcium ions to flow into the cell
This triggers the release of neurotransmitters.
Define saltatory conduction.
A faster method of impulse transmission in myelinated fibers where the impulse jumps from node to node
This is facilitated by the myelin sheath.
What is the resting membrane potential of a neuron?
-70mV
It indicates the polarized state of the neuron when not conducting an impulse.
Fill in the blank: Action potentials are ______.
all or nothing
This means that once the threshold is reached, the action potential will occur with the same magnitude.
What is the role of excitatory postsynaptic potentials (EPSPs)?
They make an action potential more likely by causing depolarization
EPSPs result from the opening of ion channels allowing Na+ influx.
What are the two types of fibers involved in transmitting impulses related to pain?
Afferent nerve fibers and efferent fibers
Afferent fibers transmit impulses toward the brain, while efferent fibers transmit impulses from the brain.
True or False: Myelination decreases the speed of nerve impulses.
False
Myelination increases the speed of impulses by saltatory conduction.
What occurs during repolarization of a neuron?
K+ ions rush out of the cell, restoring the resting membrane potential
This happens after the peak potential is reached.
What is the function of neurotransmitters at synapses?
They transmit signals across the synapse to the postsynaptic neuron
This occurs via exocytosis into the synaptic cleft.
What is the peak potential during an action potential?
+40mV
This is the maximum membrane potential reached during depolarization.
Fill in the blank: The ______ period is when a neuron cannot send another impulse until it has reestablished the negative resting potential.
refractory
During this time, the neuron is hyperpolarized.
What are the types of receptors found in the skin for pain perception?
Thermoreceptors, Meissner’s corpuscles, nociceptors, Pacinian corpuscles, Ruffini endings, free nerve endings
Each receptor type is responsible for different sensory information.
What is the difference between presynaptic and postsynaptic neurons?
Presynaptic neuron carries impulse towards a synapse, while postsynaptic neuron carries impulse away from a synapse
Presynaptic neurons are the ‘sender’ and postsynaptic neurons are the ‘receiver’.
What is the role of calcium ions in synaptic transmission?
They cause synaptic vesicles to fuse with the membrane, releasing neurotransmitters
This process is essential for communication between neurons.
What are the disadvantages of neonicotinoid use?
Reduction in honeybee and bird populations
This is due to the loss of insects as a food source and has led to restrictions in some countries.
Fill in the blank: The inside of the postsynaptic cell becomes less negative during ______.
depolarization
This occurs due to the influx of Na+ ions.
What is the function of Schwann cells?
They form the myelin sheath around axons, providing insulation
This insulation is crucial for increasing the speed of nerve impulses.
What are companion cells?
Cells that wrap their cell membrane around the axon many times.
They form a thick insulating lipid layer called the myelin sheath.
Define presynaptic neuron.
Neuron that carries impulse towards a synapse, known as the ‘Sender’.
Define postsynaptic neuron.
Neuron that carries impulse away from a synapse, known as the ‘Receiver’.
What is a neuromuscular junction?
A specialized synapse between a motor neuron and a muscle fibre.
What neurotransmitter is released by motor neurons at the neuromuscular junction?
Acetylcholine.
What initiates muscle contraction at the neuromuscular junction?
Binding of acetylcholine to receptors on the plasma membrane of the muscle fibre, leading to depolarization.
What occurs during depolarization in the action potential?
A sudden large depolarization occurs after the excitation threshold is reached.
What follows depolarization in the action potential process?
Repolarization occurs rapidly, followed by brief hyperpolarization.
What is the refractory period?
The period immediately after the action potential where no depolarization can occur.
True or False: Neonicotinoid pesticides can be broken down by acetylcholinesterase.
False.
What results from neonicotinoid pesticides binding to acetylcholine receptors?
Permanent overstimulation of target cells, leading to fatal convulsions and paralysis.
What determines the strength of graded potentials?
Amount of neurotransmitter released and time the neurotransmitter is in the area.
What are the two types of postsynaptic potentials?
- EPSP (excitatory postsynaptic potentials)
- IPSP (inhibitory postsynaptic potentials)
What do inhibitory postsynaptic potentials (IPSPs) do?
They hyperpolarize the postsynaptic cell, making an action potential less likely.
What is temporal summation?
Two excitatory stimuli close in time cause EPSPs that add together.
What is spatial summation?
Two simultaneous stimuli at different locations cause EPSPs that add together.
What is modulation in pain perception?
Diminution, suppression, or amplification of pain influenced by thoughts and emotions.
Where is conscious awareness primarily associated?
The cerebral cortex of the brain.
What is the relationship between consciousness and neuronal activity?
Consciousness is an emergent property of neuronal activity.
What is the resting potential?
The voltage across the membrane when a neuron is not firing.
What drives the generation of resting potential in neurons?
Pumping of sodium and potassium ions by ATP-driven ion pumps.
What are the three types of neurons?
- Sensory neurons
- Motor neurons
- Relay neurons
What is the difference between myelinated and unmyelinated neurons?
Myelinated neurons have action potentials that ‘hop’ between nodes of Ranvier, increasing conduction speed.
What is the function of ionotropic receptors?
They mediate fast and brief synaptic activity by directly opening ion channels.
What are nociceptors?
Specialized nerve endings activated by strong mechanical and thermal stimuli.
What is pain transduction?
The conversion of various forms of energy affecting nociceptors into electrical energy, generating action potentials.
What happens if generator potentials do not sufficiently depolarize the cell membrane?
An action potential will not be generated, and no nerve impulse will be sent.
What is the role of acetylcholine in synapses?
It activates a postsynaptic cell by binding to a specific receptor.
What happens at an excitatory synapse?
It depolarizes the local membrane potential of the postsynaptic cell.
What happens at an inhibitory synapse?
It hyperpolarizes the local membrane potential of the postsynaptic cell.
What does cocaine do to neurotransmitter levels?
It blocks the dopamine transporter, elevating extracellular dopamine levels.
What is the mind-body problem?
The incompatibility between the physical properties of the brain and the subjective qualities of the mind.
What happens to the membrane potential during the action potential?
It rises or becomes less negative when sodium channels open.
What is the threshold potential for generating an action potential?
Approximately -50mV.
What is the process of converting energy affecting nociceptors into electrical energy?
It generates action potentials that lead to the production of nerve impulses.
What triggers an action potential in a neuron?
A stimulus causes the opening of some sodium channels, raising the membrane potential to threshold (-50mV).
What happens during the depolarization phase of an action potential?
Na+ voltage-gated channels open, flooding the cell with Na+, causing the membrane potential to become less negative.
What are the four main structural regions of a neuron?
- Network of dendrites
- Cell body
- Axon
- Axon terminal (synaptic) knobs
What is synaptic transmission?
The process where neurotransmitters bind to neuroreceptors in the post-synaptic membrane, causing channel openings.
What effect does the influx of sodium ions have on the post-synaptic cell membrane?
It causes depolarization, which may initiate an action potential if the threshold is reached.
What is the resting potential of a neuron?
-70mV difference between the inside and the outside of the neuron.
What is the role of the sodium-potassium pump?
It maintains high Na+ outside and high K+ inside the neuron through active transport.
True or False: Myelinated neurons conduct nerve impulses faster than unmyelinated neurons.
True
What is the significance of the refractory period in action potentials?
It is the time required for the neuron to return to resting potential after an action potential.
Fill in the blank: The opening of _______ channels during depolarization causes sodium ions to rush into the neuron.
Na+ voltage-gated
What is the role of calcium ions in synaptic transmission?
They increase the permeability of the presynaptic membrane, causing neurotransmitter release.
What occurs during the repolarization phase of an action potential?
Potassium ions exit the neuron, causing the membrane potential to fall back to a negative value.
What is the effect of inhibitory neurotransmitters like K+ and Cl– on postsynaptic neurons?
They cause hyperpolarization, reducing the ability to produce an action potential.
Define ‘emergent properties’ in relation to consciousness.
Emergence occurs when global properties arise from local interactions of individual parts.
What is the function of acetylcholinesterase (AChE) in synaptic transmission?
It breaks down acetylcholine in the synapse to prevent overstimulation.
What factors affect the speed of nerve impulse transmission?
- Amount of myelination
- Diameter of the axon
- Temperature
What are the four key stages of an action potential?
- Resting potential
- Depolarization
- Repolarization
- Refractory period
What is the role of neurotransmitters in synaptic transmission?
They chemically transmit messages between neurons.
What is the significance of the oscilloscopes in studying neurons?
They measure the membrane potential and display it as a graph.
Fill in the blank: Pain serves as our built-in _______ system.
alarm
What does the term ‘psychopharmacology’ refer to?
The study of chemicals that alter the functions of cells within the nervous system.
How do local currents propagate action potentials along the axon?
By the diffusion of Na+ ions in and out of the axon.
What is the phenomenal concept of mind?
It refers to the subjective quality of experience.
