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Questions and Answers
What does the neural plate become?
What does the neural plate become?
What are the three sources of the peripheral nervous system?
What are the three sources of the peripheral nervous system?
The neural tube is completely formed in the 3rd week of embryonic development.
The neural tube is completely formed in the 3rd week of embryonic development.
False
Which of the following structures does NOT directly arise from the neural crest?
Which of the following structures does NOT directly arise from the neural crest?
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What are the three primary brain vesicles that develop during the fourth week of embryonic development?
What are the three primary brain vesicles that develop during the fourth week of embryonic development?
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The telencephalon gives rise to the cerebral hemispheres and the olfactory bulbs.
The telencephalon gives rise to the cerebral hemispheres and the olfactory bulbs.
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Which of the following is NOT a consequence of the disproportionate growth between the spinal cord and vertebral column?
Which of the following is NOT a consequence of the disproportionate growth between the spinal cord and vertebral column?
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Meningomyelocele is a more severe form of spina bifida than meningocele.
Meningomyelocele is a more severe form of spina bifida than meningocele.
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What is the term for the abnormal increase in cerebrospinal fluid within the skull?
What is the term for the abnormal increase in cerebrospinal fluid within the skull?
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Anencephaly is a condition where the rostral end of the neural tube fails to close completely.
Anencephaly is a condition where the rostral end of the neural tube fails to close completely.
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What are the two primary functional units of the nervous system?
What are the two primary functional units of the nervous system?
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Synapses are the junction points for communication between neurons.
Synapses are the junction points for communication between neurons.
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Which type of synapse transmits signals in one direction?
Which type of synapse transmits signals in one direction?
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The strength of a neurotransmitter is determined solely by the nature of the chemical substance itself.
The strength of a neurotransmitter is determined solely by the nature of the chemical substance itself.
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Which type of ion channel is opened by excitatory neurotransmitters?
Which type of ion channel is opened by excitatory neurotransmitters?
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What term describes the summation of postsynaptic potentials from multiple presynaptic terminals that occur simultaneously?
What term describes the summation of postsynaptic potentials from multiple presynaptic terminals that occur simultaneously?
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Temporal summation occurs when a single presynaptic terminal releases neurotransmitters repeatedly at a rapid rate.
Temporal summation occurs when a single presynaptic terminal releases neurotransmitters repeatedly at a rapid rate.
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Fatigue of synaptic transmission can be attributed to exhaustion of the neurotransmitter stores.
Fatigue of synaptic transmission can be attributed to exhaustion of the neurotransmitter stores.
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Hypoxia can cause a temporary loss of neuronal excitability.
Hypoxia can cause a temporary loss of neuronal excitability.
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Strychnine, an inhibitory neurotransmitter, can cause muscle spasms by blocking the action of glycine.
Strychnine, an inhibitory neurotransmitter, can cause muscle spasms by blocking the action of glycine.
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General anesthetics achieve their effect by decreasing the threshold for neuronal excitation.
General anesthetics achieve their effect by decreasing the threshold for neuronal excitation.
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Hypocalcemia can decrease the release of neurotransmitters.
Hypocalcemia can decrease the release of neurotransmitters.
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Which of the following is NOT a factor that contributes to the negative resting membrane potential of a neuron?
Which of the following is NOT a factor that contributes to the negative resting membrane potential of a neuron?
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The action potential propagates in both directions along the axon.
The action potential propagates in both directions along the axon.
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Myelination increases the speed of action potential conduction.
Myelination increases the speed of action potential conduction.
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What are the two main refractory periods associated with action potentials?
What are the two main refractory periods associated with action potentials?
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Local anesthetics, such as procaine and tetracaine, primarily target sodium channels.
Local anesthetics, such as procaine and tetracaine, primarily target sodium channels.
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Calcium ions are crucial for the initiation of action potentials in skeletal muscle fibers.
Calcium ions are crucial for the initiation of action potentials in skeletal muscle fibers.
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Which of the following is NOT a characteristic of spontaneous rhythmicity?
Which of the following is NOT a characteristic of spontaneous rhythmicity?
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The refractory period of the cardiac pacemaker cells is longer than that of skeletal muscle fibers.
The refractory period of the cardiac pacemaker cells is longer than that of skeletal muscle fibers.
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The all-or-nothing principle states that a nerve fiber will only partially depolarize if the stimulus is below the threshold.
The all-or-nothing principle states that a nerve fiber will only partially depolarize if the stimulus is below the threshold.
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Study Notes
Nervous System Overview
- The nervous system is responsible for controlling bodily functions and communication.
- It has two main parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
- The CNS includes the brain and spinal cord. The PNS includes nerves that connect the CNS to the rest of the body.
Development of the Nervous System
- The CNS begins to form during the third week of embryonic development.
- The neural plate forms, then develops into the neural tube.
- The neural tube gives rise to the brain and spinal cord.
- The peripheral nervous system (PNS) develops from neural crest cells, neural tube, and mesoderm.
Development of the Neural Tube
- Neural plate folds inward to form neural groove, then neural folds.
- Neural folds fuse to form neural tube.
- Anterior and posterior neuropores close at different times.
- Closure of these openings creates a continuous neural tube.
- The neural tube differentiates into brain vesicles which develop into the brain structures.
Development of Brain Vesicles
- Three primary vesicles, prosencephalon, mesencephalon, and rhombencephalon, develop.
- The primary vesicles further subdivide to form the five secondary brain vesicles, telencephalon, diencephalon, mesencephalon, metencephalon, and myelencephalon.
- These vesicles give rise to structures like the cerebral hemispheres, thalamus, hypothalamus, midbrain, pons, and cerebellum.
Spinal Cord Development
- The caudal end of the neural tube develops into the spinal cord.
- Caudal part develops into the spinal cord, with its associated spinal nerves diverging throughout the vertebral column.
- The spinal cord extends down the vertebral column initially, but it does not grow as quickly as the vertebral column, and as a result the spinal cord is shifted upwards to higher levels.
Other Important Structures
- Neural crest cells: give rise to various structures outside the CNS, including certain ganglia (clusters of nerve cells), Schwann cells (supporting cells for PNS nerves), and melanocytes (pigment cells).
- Placodes: localized thickenings of the surface ectoderm that give rise to some sensory organs and nerves.
- Olfactory and otic placodes are examples of placodes.
Neural Tube Wall Layers
- The neural tube wall has three layers: neuroepithelial (innermost), mantle, and marginal (outermost layers).
- These layers give rise to later neuronal and glial (support) cell populations.
- The alar and basal plates form the dorsal and ventral horns of the spinal cord respectively.
Spinal Cord Positional Changes
- The spinal cord grows slower than the vertebral column.
- As a result, the lower end of the spinal cord is located higher than the vertebral column's lower spine by adulthood.
- This creates the cauda equina (horse's tail) where nerve roots descend in the spinal canal.
Congenital Anomalies
- Spina bifida: a defect where the vertebral arches fail to fuse properly. Types include occulta, meningocele, and myelomeningocele.
- Hydrocephalus: excessive cerebrospinal fluid in the brain.
- Anencephaly: a defect where a substantial part of the brain fails to develop normally.
Sensory Part of the Nervous System
- Receptors are initiated by sensory experience detecting stimuli (temperature, pressure, light).
- The information of sensory events from receptors transmits to spinal cord (multiple locations), cerebellum and specific regions of the brain through peripheral nerves.
- This information is interpreted in the brain, causing a response if needed.
Motor Part of the Nervous System
- The nervous system controls: skeletal muscle contraction, smooth muscle contraction, and gland secretion.
- Skeletal muscles can be controlled from various levels of the CNS, including the spinal cord, brainstem, basal ganglia, cerebellum, and motor cortex.
- The autonomic nervous system is responsible for involuntary functions like heart rate and digestion.
Synaptic Transmission
- Synapses are junctions between neurons.
- Chemical synapses: rely on neurotransmitters (chemical messengers) to transmit signals across the synaptic cleft between neurons.
- Electrical synapses: transmit signals through direct ionic current, connecting adjacent cells directly.
- Synaptic activity is influenced by multiple factors like presence or absence of various ions, and the amount of neurotransmitters.
- Postsynaptic potentials can be either excitatory (depolarizing) or inhibitory (hyperpolarizing).
Nervous System Integration
- Information processing is crucial for initiating appropriate responses: meaning that the nervous system must interpret and process information to ensure appropriate responses.
- Some information is considered irrelevant by the brain and is often ignored or relegated to a subconscious level.
- Three major levels of CNS function: spinal cord, lower brain, higher cortical level.
Action Potential Generation and Transmission
- Action potential: a rapid change in membrane potential, essential for transmitting impulses along nerve fibers and between neurons.
- The action potential is initiated at the axon hillock, and then travels across the fiber's myelinated or unmyelinated portions.
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Description
This quiz covers the structure and development of the nervous system, including the central and peripheral nervous systems. It delves into the embryonic development of the CNS and PNS, detailing the processes involved in the formation of the neural tube and its differentiation. Test your knowledge of these fundamental concepts in neuroscience.
