Neural signalling Flashcards
What are neurons?
Neurons are specialized cells in the nervous system that carry electrical impulses, facilitating communication between different parts of the body.
What structures make up the cell body of a neuron?
The cell body of a neuron consists of cytoplasm and a nucleus, which contain the cell’s genetic material and organelles necessary for cellular function.
What are dendrites?
Dendrites are multiple, shorter fibers that extend from the neuron’s cell body and receive signals from other neurons, transmitting information toward the cell body.
What is an axon?
An axon is a long, single fiber that extends from the neuron’s cell body, transmitting electrical impulses away from the cell body to other neurons or target tissues.
How do electrical impulses travel along neuron fibers?
Electrical impulses, or action potentials, are conducted along the axon and dendrites through changes in membrane potential, allowing rapid communication between neurons.
What is the role of myelin in neuronal signaling?
Myelin is a fatty substance that insulates axons, increasing the speed of electrical impulse conduction through a process called saltatory conduction.
How do neurons communicate with each other?
Neurons communicate through synapses, where neurotransmitters are released from one neuron and bind to receptors on another neuron, transmitting signals across the synaptic gap.
What is the significance of neuronal structure in function?
The specialized structure of neurons, with distinct regions (cell body, dendrites, axon), allows for efficient processing and transmission of information throughout the nervous system.
How do variations in axon length affect neuronal function?
Variations in axon length can influence the speed and distance over which signals are transmitted; longer axons can connect distant parts of the nervous system more effectively.
Why is understanding neuron structure and function important in biology?
Understanding neuron structure and function is crucial for comprehending how the nervous system operates, informing research on neurological disorders and potential treatments.
What is the resting potential of a neuron?
The resting potential is the electrical charge difference across the plasma membrane of a neuron when it is not actively transmitting an impulse, typically around -70 mV.
How is the resting potential generated?
The resting potential is generated by the active transport of sodium (Na⁺) and potassium (K⁺) ions across the plasma membrane, creating concentration gradients.
What role does the sodium-potassium pump play in maintaining resting potential?
The sodium-potassium pump actively transports three sodium ions out of the cell and two potassium ions into the cell, using energy from ATP to establish and maintain concentration gradients.
What are the concentration gradients established by the sodium-potassium pump?
The sodium-potassium pump creates a higher concentration of sodium outside the cell and a higher concentration of potassium inside the cell, contributing to membrane polarization.
Why is the resting potential negative?
The resting potential is negative due to a higher permeability of the membrane to potassium ions, which diffuse out of the cell, leaving behind negatively charged proteins and other anions.
What is membrane polarization?
Membrane polarization refers to the difference in electrical charge across the plasma membrane, resulting in a polarized state that is essential for generating action potentials.
How do changes in ion concentrations affect neuronal signaling?
Changes in ion concentrations can alter membrane potential; for example, an influx of sodium ions during depolarization can trigger an action potential, while efflux of potassium ions during repolarization restores resting potential.
What happens if the sodium-potassium pump fails?
If the sodium-potassium pump fails, ion gradients would dissipate, leading to loss of resting potential, impaired neuronal signaling, and potentially cell dysfunction or death.
How does ATP contribute to maintaining resting potential?
ATP provides the energy required for the sodium-potassium pump to actively transport ions against their concentration gradients, ensuring proper ion balance and membrane potential.
Why is understanding resting potential important in neuroscience?
Understanding resting potential is crucial for comprehending how neurons transmit signals, enabling insights into normal brain function and disorders related to neuronal signaling dysfunctions.
What is a nerve impulse?
A nerve impulse is an electrical signal that travels along the axon of a neuron, allowing communication between neurons and other cells.
How is a nerve impulse generated?
A nerve impulse is generated when a neuron reaches a threshold potential, leading to the rapid depolarization and repolarization of the neuron’s membrane, known as an action potential.
What is an action potential?
An action potential is a rapid change in membrane potential that occurs when positively charged ions, primarily sodium (Na⁺), rush into the neuron, followed by potassium (K⁺) exiting the cell.
How do sodium and potassium ions contribute to the action potential?
The influx of sodium ions during depolarization causes the membrane potential to become more positive, while the efflux of potassium ions during repolarization restores the resting potential.
What is the significance of the all-or-nothing principle in action potentials?
The all-or-nothing principle states that once a threshold is reached, an action potential will occur fully; it does not vary in strength, ensuring consistent signal transmission.
How does an action potential propagate along an axon?
An action potential propagates along an axon through a wave of depolarization and repolarization, with each segment of the axon undergoing this change in response to the previous segment’s action potential.
What role does myelin play in nerve impulse conduction?
Myelin insulates axons and allows for saltatory conduction, where action potentials jump between nodes of Ranvier, significantly increasing conduction speed.
What are nodes of Ranvier?
Nodes of Ranvier are gaps in the myelin sheath along an axon where ion channels are concentrated, facilitating rapid depolarization and repolarization during action potentials.
Why is the movement of positively charged ions significant in nerve signaling?
The movement of positively charged ions (Na⁺ and K⁺) creates changes in membrane potential that are essential for generating and propagating electrical signals in neurons.
Why is understanding nerve impulses important in neuroscience?
Understanding nerve impulses is crucial for comprehending how information is transmitted throughout the nervous system, informing research on neurological disorders and therapies targeting neuronal function.
What factors influence the speed of nerve impulse transmission?
The speed of nerve impulse transmission is influenced by axon diameter, myelination, and the presence of ion channels.
How do giant axons of squid compare to smaller non-myelinated nerve fibers in terms of speed?
Giant axons of squid can transmit impulses at speeds up to 100 meters per second, while smaller non-myelinated nerve fibers transmit impulses much slower, typically around 1 meter per second.
What is the role of myelination in nerve impulse speed?
Myelination increases the speed of nerve impulse transmission by allowing action potentials to jump between nodes of Ranvier, a process known as saltatory conduction.
How do myelinated fibers compare to non-myelinated fibers in terms of conduction speed?
Myelinated fibers conduct impulses significantly faster than non-myelinated fibers; for example, myelinated fibers can transmit signals at speeds ranging from 5 to 120 meters per second.
What is a negative correlation in the context of conduction speed and animal size?
A negative correlation indicates that as animal size increases, the conduction speed of nerve impulses tends to decrease, likely due to longer distances that signals must travel.
What is a positive correlation in relation to axon diameter and conduction speed?
A positive correlation means that as axon diameter increases, the conduction speed of nerve impulses also increases, as larger diameters reduce resistance to ion flow.
What mathematical tool can be used to determine the strength of correlations?
Correlation coefficients can be applied to quantify the strength and direction of relationships between variables, such as conduction speed and axon diameter.
What does the coefficient of determination (R²) indicate?
The coefficient of determination indicates the proportion of variance in the dependent variable (e.g., conduction speed) that can be explained by variation in the independent variable (e.g., axon diameter).
Why is understanding variations in nerve impulse speed important?
Understanding variations in nerve impulse speed is crucial for comprehending how different types of neurons function and communicate, impacting overall nervous system efficiency.
How do these principles apply to neurological research and medicine?
These principles help inform research on neurological disorders and guide therapeutic approaches by understanding how changes in axon properties affect nerve signaling and communication.
What are synapses?
Synapses are junctions between neurons or between neurons and effector cells that facilitate communication through the transmission of signals.
What type of synapse is primarily discussed in this context?
The focus is on chemical synapses, which use neurotransmitters to transmit signals across the synaptic gap.
How do chemical synapses function?
In chemical synapses, an action potential in the presynaptic neuron triggers the release of neurotransmitters into the synaptic cleft, which then bind to receptors on the postsynaptic neuron.
What is the role of neurotransmitters in synaptic transmission?
Neurotransmitters act as signaling molecules that cross the synaptic cleft and bind to receptors on the postsynaptic membrane, initiating a response in the target cell.
What happens when neurotransmitters bind to postsynaptic receptors?
Binding of neurotransmitters can lead to changes in membrane potential, either depolarizing or hyperpolarizing the postsynaptic cell, depending on the type of neurotransmitter and receptor involved.
Why is signal transmission at synapses unidirectional?
Signal transmission at synapses is unidirectional because neurotransmitters are released from the presynaptic neuron and act on receptors in the postsynaptic neuron, ensuring that signals travel in one direction.
What are some examples of neurotransmitters involved in synaptic transmission?
Common neurotransmitters include acetylcholine, dopamine, serotonin, and norepinephrine, each playing distinct roles in neuronal communication.
How do synapses contribute to neural plasticity?
Synapses can strengthen or weaken over time based on activity levels, contributing to neural plasticity, which is essential for learning and memory.
What is the significance of synapses in the nervous system?
Synapses are crucial for transmitting signals between neurons and coordinating responses within the nervous system, enabling complex behaviors and functions.
Why is understanding synapses important in neuroscience?
Understanding synapses provides insights into how information is processed in the brain and informs research on neurological disorders, drug development, and therapeutic interventions targeting synaptic function.
What triggers the release of neurotransmitters from the presynaptic membrane?
The release of neurotransmitters is triggered by the depolarization of the presynaptic membrane, which occurs when an action potential travels down the neuron.
How does depolarization affect calcium ion levels in the presynaptic neuron?
Depolarization causes voltage-gated calcium channels in the presynaptic membrane to open, allowing calcium ions (Ca²⁺) to flow into the neuron.
What is the role of calcium ions in neurotransmitter release?
Calcium ions act as a signaling molecule that initiates the fusion of neurotransmitter-containing vesicles with the presynaptic membrane, leading to their release into the synaptic cleft.
What happens to neurotransmitters after they are released into the synaptic cleft?
Once released, neurotransmitters diffuse across the synaptic cleft and bind to specific receptors on the postsynaptic membrane, transmitting the signal to the next neuron or effector cell.
Why is calcium considered a crucial signaling chemical inside neurons?
Calcium serves as a key intracellular messenger that regulates various cellular processes, including neurotransmitter release, muscle contraction, and gene expression.
What occurs during synaptic transmission after neurotransmitter binding?
Binding of neurotransmitters to postsynaptic receptors can lead to changes in membrane potential, resulting in either excitation or inhibition of the postsynaptic neuron.
How does the influx of calcium ions contribute to vesicle fusion?
The increase in intracellular calcium concentration triggers proteins that facilitate vesicle fusion with the presynaptic membrane, allowing neurotransmitter release.
What happens if calcium channels do not open during depolarization?
If calcium channels do not open, neurotransmitter release will be impaired, preventing effective communication between neurons and potentially disrupting neural signaling.
Why is understanding neurotransmitter release important in neuroscience?
Understanding neurotransmitter release mechanisms is essential for comprehending how signals are transmitted in the nervous system and for developing treatments for neurological disorders.
What are some examples of neurotransmitters released at chemical synapses?
Common examples include acetylcholine, dopamine, serotonin, and norepinephrine, each playing distinct roles in neuronal communication and modulation of physiological processes.
What is an excitatory postsynaptic potential (EPSP)?
An excitatory postsynaptic potential (EPSP) is a temporary depolarization of the postsynaptic membrane potential, making it more likely for the neuron to fire an action potential.
How do neurotransmitters facilitate the generation of EPSPs?
Neurotransmitters are released from the presynaptic neuron and diffuse across the synaptic cleft to bind to receptors on the postsynaptic membrane, initiating an EPSP.
What is the role of acetylcholine in synaptic transmission?
Acetylcholine is a neurotransmitter that binds to receptors on the postsynaptic membrane, leading to depolarization and the generation of EPSPs in various types of synapses, including neuromuscular junctions.
Describe the process of neurotransmitter diffusion across the synaptic cleft.
After being released from vesicles in the presynaptic neuron, neurotransmitters diffuse across the synaptic cleft, a narrow gap between neurons, to reach and bind to receptors on the postsynaptic neuron.
