Neuron Quiz Flashcards
steps for depolarization and repolarization of the neuron
an impulse is received. if it is -55mV or greater, action potential occurs by the sodium gates opening to let Na+ ions through the membrane and bringing the neuron to a voltage of +35mV. The sodium gates then close and the potassium gates open to release K+ outside of the membrane until a voltage of -90mV is reached. The gates then close and the sodium potassium pump starts running to bring the cell back to a resting potential of -70mV so it can transmit another impulse
what is the gap between the synaptic knob and the postsynaptic membrane called
synaptic cleft
what does myelin do
It protects myelinated neurons and speeds up the rate of nerve impulse transitions.
what is the resting potential voltage
-70mV`
What is a motor neuron?
Nerve cells in the central nervous system that transmit signals to the sensory systems, glands, and muscles to regulate voluntary and involuntary movements.
What does an Effector do?
Brings internal conditions back into a normal range
Effectors can be muscles or glands that enact the necessary changes.
What is stimulus threshold?
The minimum amount of stimulus needed to generate a nerve impulse by opening enough sodium channels, measured at -55mV.
what is the rate of exchange for the sodium potassium pump
pumps 3 Na+ out and 2 K+ in for every molecule of ATP
What is an axon and what does it do?
A long cylindrical extension of a neuron’s cell body that transmits impulses away from the cell body along its length to the next neuron.
what are the 4 steps that occur at the neural synapse
- the impulse travels down the axon into the synaptic terminal
- the synaptic vesicles move toward and fuse with the presynaptic membrane based on Ca+ entering the terminal
- the neurotransmitters are released into the synaptic cleft
- neurotransmitters bind to the receptor proteins and affect the postsynaptic neuron based on wether the transmitters were excitatory or inhibitory
maximum membrane voltage before repolarization begins to occur
+35mV
voltage at hyperpolarization
-90mV
What does the control centre do after receiving information from the sensor?
Activates an effector
This action is necessary to reverse the change detected.
What is a synaptic vesicle?
A small secretory vesicle found inside the synaptic terminal that stores and transports neurotransmitters.
What is the neurilemma?
The outermost cytoplasmic layer/cell membrane of a Schwann cell.
What are dendrites and what do they do?
Short, branching terminals on a nerve cell (neuron) that receive signals from other neurons or sensory receptors and relay the impulse to the cell body. They are numerous and highly branched.
What happens after the sensor detects a change in a negative feedback process?
Signals a control centre
This signaling is crucial for the next steps in restoring homeostasis.
what type of neurons are only found in the CNS and transmit impulses from sensory to motor neurons
interneurons
What are nodes of Ranvier?
Gaps in the myelin sheath insulating the axon of a myelinated nerve cell.
What is summation?
The process of combining electrical impulses at a neuromuscular junction to determine if an action potential is created.
What is a neuromuscular junction?
The synapse between a motor neuron and a muscle cell.
True or False: The effector’s role is to maintain or restore homeostasis.
True
Effectors are essential for returning the system to its normal state.
What is the all or none principle?
The principle that describes how a nerve impulse can’t exist in different strengths; it either occurs or does not occur based on the voltage provided by the stimulus.
what does the cell body of a neuron do
It processes input from the dendrites and relays it to the axon if the input is large enough.
what is another name for a nerve impulse
action potential
What is the role of the Control Centre?
Activates the effector based on information received from the sensor
The control centre processes information and coordinates the response.
What is the cell body of a neuron?
The main part of a neuron that contains the nucleus and other organelles and serves as the site of the cell’s metabolic reactions
is the neuron polarized or depolarized at rest
polarized
What is a neuron?
The structural and functional unit of the nervous system that consists of a nucleus, cell body, dendrites, axons, and a myelin sheath. Neurons are specialized to respond to physical and chemical stimuli to conduct electrochemical signals.
what produces myelin
neurilemma of shwann cell
what do the nodes of Ranvier do
They cause the membrane of the axon to be exposed, allowing action potentials to occur only at these nodes.
What is a sensory neuron?
A nerve cell that carries information about changes in external and internal environments to the central nervous system, sending signals from the outer part of the body back to the CNS.
What is myelin and what is it composed of?
The fatty insulating layer around the axon of a nerve cell that is composed of Schwann cells.
What is a Negative Feedback Loop?
The main homeostatic mechanism that works in the body to keep a variable
Negative feedback loops help maintain stability in physiological processes.
What is an interneuron?
The central nodes of neural circuits that enable communication between sensory or motor neurons and the central nervous system, located only in the brain or spinal cord.
What is a Stimulant/Stimulus?
Something that causes a change in the internal conditions
This term refers to any factor that can initiate a response in a biological system.
what does acetylcholine do to effectors
stimulate skeletal muscles and slow down the strength and rate of cardiac muscle contraction
what type of neuron transmits nerve impulses from a receptor to the CNS
sensory
What is a glial cell?
Support cells of the nervous system that nourish neurons, remove their waste, defend against infection, and provide a supporting framework for all nervous system tissue.
What is a Schwann cell?
A type of insulating glial cell that wraps around the axon of a neuron to create a myelin sheath.
What is a synaptic terminal?
A bulb at the end of the axon in which neurotransmitter molecules are stored and released.
is the neuron depolarized or polarized when transmitting an impulse
depolarized
What is a synapse?
The junction between two neurons or between a neuron and an effector (muscle or gland).
where do depolarization and repolarization steps occur
at the node of Ranvier on the axon
what ions exist outside of the axon and which ones exist inside the axon when the nerve cell is at rest
Na+ is on the outside, K+ and Cl- are on the inside
saltatory conduction
process by which action potentials are transmitted from one node of Ranvier to the next along a myelinated axon
What does a Sensor/Receptor do?
Detects a change in the internal environment
Sensors or receptors are crucial for monitoring internal conditions.
What is acetylcholine?
The primary neurotransmitter of both the somatic nervous system and the parasympathetic nervous system, which can either be excitatory or inhibitory depending on the receptor.
volatge at resting
-70mV
what happens to the neurotransmitters after they have done their job
they are broken down by enzymes and then swept up by glial cells that return the transmitters back to the presynaptic neuron
What is acetylcholinesterase?
An enzyme that breaks down acetylcholine into acetic acid and choline through hydrolysis.
Summarize how a negative feedback process operates.
A sensor detects a change, signals a control centre, which activates an effector to restore balance
This process is vital for maintaining internal stability.
stimulus threshold voltage
-55mV
What is resting potential?
The potential difference across the membrane in a resting neuron when it is polarized and able to generate a nerve impulse, measured at -70mV.
what happens if the neurotransmitter is inhibitory
the wont bind to the sodium gates and the gates will remained closed causing the nerve impulse to end
what happens if the neurotransmitter is excitatory
it will bind to the sodium gates and open them so that the nerve impulse continues
Fill in the blank: In a negative feedback process, a _______ detects a change that disrupts a balanced state.
[Sensor/Receptor]
This component is essential for initiating the feedback mechanism.
What is the refractory period?
The brief time (a few milliseconds) between the triggering of an impulse along an axon and the axon’s readiness for the next impulse, during which the neuron is hyperpolarized and returning to its resting potential.
What is action potential?
The change in charge that occurs when the gates of the K+ channels close and the gates of the Na+ channels open after a wave of depolarization is triggered in an axon.
what type of neuron transmits impulses from the CNS to the effectors
motor
What is a neurotransmitter?
Chemical messengers secreted by neurons that carry a neural signal from one neuron to another or from a neuron to an effector such as a gland or muscle fiber.
