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Questions and Answers
The nervous system is composed of 10 distinct systems.
False
Neurotransmitters are essential for synapses to function properly.
True
Graded potentials can occur in the axons of nerve cells.
False
Muscle stretch receptors play a role in the overall function of the muscular system.
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Action potentials propagate in both directions along a nerve cell axon.
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There are no sensory cells involved in the nervous system's function.
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The role of neuroglia includes supporting the propagation of action potentials.
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The study of bio-electric potentials helps in understanding the function of systems within physiology.
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Sensory cells generate graded potentials that decrease with an increase in stimulus.
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Stretch receptors are responsible for detecting changes in muscle length.
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The speed of information transmission in axons can reach up to 1000 metres/second.
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Neurotransmitters travel long distances quickly between synapses.
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Sweet taste buds respond to sodium ions (Na+) in saliva.
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The cell body of a nerve cell functions solely as an integrator of incoming signals.
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Sensory systems typically lack a specialized sensory cell type that releases neurotransmitters.
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Information transfer at synapses is characterized by a slow and gradual process.
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Visual receptors detect photons of light for sensory processing.
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Graded potentials are mainly generated in the axons of nerve cells.
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The resting membrane potential (RMP) is +30 mV inside the cell relative to outside.
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Graded potentials occur when the membrane potential increases to -55 mV.
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At -55 mV, K+ channels open while Na+ channels remain closed.
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Voltage-gated Na+ channels play a critical role in the rapid changes in membrane potential.
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The opening of Na+ channels decreases the membrane potential from -70 mV to +30 mV.
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The brain can differentiate between stimuli even though the action potentials generated are identical in nature.
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Graded potentials in sensory cells are responsible for the rapid generation of action potentials in the axon.
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An action potential is generated if the threshold of -70 mV is reached.
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Neurotransmitters diffuse over long distances to reach post-synaptic cells.
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The influx of Na+ ions causes graded potentials in sensory cells.
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A high frequency of action potentials occurs when the threshold is consistently maintained above -55 mV.
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The absence of graded potentials leads to the generation of action potentials in sensory neurons.
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Neurotransmitter receptors on the cell body of nerve cells affect the generation of graded potentials at the axon hillock.
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Sensory cell activation occurs through the opening of potassium channels.
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The propagation of action potentials occurs in a direction determined by the neuroglia.
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Nerve impulses travel at a speed of 360,000 m in one hour.
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Copper wire transmits signals 3 x 10^6 times faster than nerve impulses.
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The resting membrane potential of a neuron is typically around -70 mV.
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Diffusion occurs at a speed of 0.000000008 Km/h.
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Nerve impulses propagate at the same speed as copper wire.
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The speed of a nerve impulse is 100 ms-1.
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Na+ ions are essential for the generation of nerve impulses.
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The spinal cord is located 1 meter from the toe.
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Diffusion is faster than the transmission of a nerve impulse.
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Nerve impulses are influenced by the charge difference across the neuron's membrane.
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Study Notes
Nervous System Overview
- The nervous system is responsible for decision making and controlling various body functions.
- It receives information from the external and internal environment.
- This information is then processed and used to control muscle function, cardiac function, gastrointestinal function, and other systems.
Nerve Impulse Transmission
- Nerve impulses are generated and propagated by changes in membrane potential.
- Sensory cells generate graded potentials, which are short-distance, quick, and diffusive.
- Synapses release neurotransmitters (NTs), which also travel short distances and quickly through diffusion.
- NTs bind to post-synaptic receptors, initiating further signaling.
- The cell body of nerve cells also acts as a sensory cell, gathering information from dendrites.
- Axons propagate action potentials (APs), which are longer-distance transmissions, much faster than graded potentials, reaching up to 100 meters per second.
Graded Potentials and Action Potentials
- Graded potentials are small changes in membrane potential, initiated by stimuli on sensory cells.
- The intensity of the stimulus impacts the amplitude of graded potential.
- When the graded potential at the axon hillock reaches a threshold of -55 mV, an action potential is triggered.
- Action potentials are all-or-none events, meaning once a threshold is reached, the AP occurs with consistent amplitude and duration.
Nerve Impulse Generation
- Ion channels play a crucial role in nerve impulse generation.
- Activation of voltage-gated Na+ channels on sensory cells causes rapid Na+ influx.
- This influx depolarizes the membrane, leading to the generation of graded potentials.
- When the depolarization surpasses a threshold, voltage-gated Na+ channels open, leading to a rapid influx of Na+ and AP generation.
Action Potential Propagation
- Action potentials travel down axons, the long extensions of nerve cells.
- The propagation is driven by a sequential opening and closing of voltage-gated Na+ and K+ channels.
- During the rising phase, Na+ channels open, influx of Na+ depolarizes the membrane.
- During repolarization, K+ channels open, potassium efflux repolarizes the membrane.
- The refractory period ensures that action potentials propagate in one direction, preventing backward movement.
Neuronal Circuits
- Neurons connect in intricate circuits, enabling the transmission of information throughout the nervous system.
- Sensory cells release NTs, which stimulate the post-synaptic neuron.
- This process can trigger the release of further NTs at the next synapse.
- The brain interprets different sensory inputs based on the specific regions of the brain where nerve endings terminate.
Role of Neuroglia
- Neuroglia are supporting cells that play several vital roles in the nervous system.
- They protect and insulate neurons.
- They provide nutrients and support for neurons.
- They contribute to nerve impulse transmission and neuronal circuit formation.
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Description
Explore the fundamental aspects of the nervous system, including its role in decision-making and body function control. Learn how nerve impulses are generated and transmitted, encompassing aspects such as graded potentials and neurotransmitter activity.
