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Questions and Answers
What condition must be met for another action potential to occur during the relative refractory period?
What is the approximate resting membrane potential for neurons?
What is the role of voltage-gated Na+ channels during the action potential?
What best describes the absolute refractory period?
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Which statement describes saltatory conduction?
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What primarily occurs in the frontal lobe of the cerebrum?
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Which structure is primarily involved in the coordination of movements and receives input from proprioceptors?
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What type of matter is primarily found in the cerebral cortex?
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Which part of the brain acts as a relay center for auditory information?
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What is the primary function of the medulla oblongata?
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Which lobe of the cerebrum is responsible for interpreting textures and shapes?
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What is the function of the basal nuclei?
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Which structure is considered part of the emotional brain?
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What is the role of the thalamus in the diencephalon?
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What does the cingulate gyrus contribute to?
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Which component of the brainstem is involved in respiratory control?
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What is the primary function of the occipital lobe?
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Which structure is responsible for initiating and terminating movements?
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What primary role does the hypothalamus serve among the brain's structures?
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What role do oligodendrocytes play in the central nervous system?
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What distinguishes a multipolar neuron from other types?
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What is the primary function of sensory or afferent neurons?
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Which supporting cell type regulates the external environment of neurons in the CNS?
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What is a key factor that can influence action potential propagation?
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Which of the following statements is true about resting membrane potential?
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What type of neurons are responsible for connecting sensory and motor pathways?
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What is the primary function of Schwann cells in the peripheral nervous system?
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Which structures are primarily responsible for the conduction of impulses away from the neuron cell body?
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Study Notes
Neurons
- Neurons are specialized nerve cells responsible for transmitting impulses.
- Cell body (soma) contains the nucleus and is the central part of the neuron.
- Neurons have two processes:
- Dendrites, which carry impulses toward the soma.
- Axons, which carry impulses away from the soma.
Types of Neurons
- Unipolar: One extension from the cell body.
- Bipolar: Two extensions from the cell body.
- Multipolar: Multiple dendrites and one axon.
Neuron Functions
- Sensory (afferent): Transmit impulses from receptors to the CNS.
- Motor (efferent): Relay impulses from the CNS to effectors (muscles or glands).
- Association (interneurons): Connect sensory and motor neurons.
Supporting Cells (CNS)
- Oligodendrocytes: Form myelin sheaths around CNS axons.
- Microglia: Migrate to phagocytose foreign materials.
- Astrocytes: Regulate the external environment of neurons in the CNS.
- Ependymal cells: Line brain ventricles and the spinal cord's central canal.
Supporting Cells (PNS)
- Schwann cells: Form myelin sheaths around peripheral axons.
- Satellite cells: Support neuron cell bodies within ganglia of the PNS.
Nervous System Structure
- CNS (Central Nervous System): Comprises the brain and spinal cord.
- PNS (Peripheral Nervous System): Includes somatic (motor sensory) and autonomic (involuntary) nervous systems.
Terminologies
- Nerve: Bundle of axons in the PNS containing sensory and motor fibers.
- Ganglion: Grouping of neuron cell bodies outside the CNS.
- Nucleus: Grouping of neuron cell bodies within the CNS.
- Tract: Grouping of axons that interconnect CNS regions.
Resting Membrane Potential
- A constant membrane potential in excitable and non-excitable cells when at rest.
- Neurons typically have a resting membrane potential of -70mV.
- The interior of the cell is negatively charged compared to the outside.
Action Potential
- Involves rapid changes in membrane potential (approximately 100mV).
- Generated by depolarization of excitable membranes due to voltage-gated Na+ channels.
- Involves phases of depolarization, repolarization, and hyperpolarization.
Propagation Factors
- Degree of myelination affects impulse transmission speed.
- Larger axon diameters enhance conduction velocities.
- Temperature influences action potential propagation.
Refractory Periods
- Absolute Refractory Period: No action potential can occur during this time regardless of stimulus.
- Relative Refractory Period: A stronger-than-normal stimulus can initiate a new action potential.
Central Nervous System Organization
- Cerebrum: The largest brain part (80% of brain mass) with lobes controlling various functions (voluntary movement, personality, speech).
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Cerebral Cortex:
- Contains sensory, motor, and association areas.
- Gray matter consists of cellular bodies, while white matter includes axon tracts.
Lobes of the Cerebrum
- Frontal Lobe: Involved in voluntary motor control, personality, and intellect.
- Parietal Lobe: Processes somatosensory information and language.
- Temporal Lobe: Handles auditory information and memory.
- Occipital Lobe: Focuses on visual processing and perception.
Limbic System
- Known as the "emotional brain," it plays a key role in emotions and memory.
- Key components include the cingulate gyrus, amygdala, hippocampus, and septal nuclei.
Diencephalon
- Central core of the brain housing sensory and motor processing nuclei.
- Includes thalamus (sensory relay), hypothalamus (homeostasis), and epithalamus (includes pineal gland).
Brainstem Regions
- Midbrain: Contains nuclei for visual and auditory reflexes.
- Pons: Relays signals between different brain regions and assists in regulating respiration.
- Medulla Oblongata: Controls autonomic functions like heart rate and respiration, and houses vital centers.
Cerebellum
- Located at the back of the brain, involved in coordination and balance through input from proprioceptors.
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Description
This quiz covers fundamental concepts of neurons and action potentials, focusing on their role in the central nervous system. It explores how neurons stimulate or inhibit muscle contractions and affect gland activities. Enhance your understanding of neurophysiology and its critical functions in the body.
