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Questions and Answers
What primary role does the central nervous system (CNS) serve?
What primary role does the central nervous system (CNS) serve?
How many pairs of spinal nerves are present in the human body?
How many pairs of spinal nerves are present in the human body?
Which of the following divisions is responsible for involuntary control of internal organs?
Which of the following divisions is responsible for involuntary control of internal organs?
What is the primary function of the spinal cord?
What is the primary function of the spinal cord?
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What is the function of the somatic nervous system?
What is the function of the somatic nervous system?
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What role does the axon of a neuron play in the transmission of impulses?
What role does the axon of a neuron play in the transmission of impulses?
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Which of the following best describes the function of glial cells in the human CNS?
Which of the following best describes the function of glial cells in the human CNS?
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How many axons does each neuron typically have?
How many axons does each neuron typically have?
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Which part of the neuron is responsible for bringing impulses toward the soma?
Which part of the neuron is responsible for bringing impulses toward the soma?
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What is one factor that influences certain biological functions?
What is one factor that influences certain biological functions?
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What percentage of human genes are involved in the formation of the human CNS?
What percentage of human genes are involved in the formation of the human CNS?
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In which of the following ways can characteristics be categorized?
In which of the following ways can characteristics be categorized?
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Which of the following accurately describes a criterion used for classification?
Which of the following accurately describes a criterion used for classification?
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What is another factor, aside from the length of axons, that impacts classification?
What is another factor, aside from the length of axons, that impacts classification?
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Which criterion is NOT used for classification in the mentioned context?
Which criterion is NOT used for classification in the mentioned context?
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Which type of neuron carries impulses from the central nervous system (CNS) to peripheral effectors?
Which type of neuron carries impulses from the central nervous system (CNS) to peripheral effectors?
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What is the primary feature of the axoplasm in the axis cylinder of a neuron?
What is the primary feature of the axoplasm in the axis cylinder of a neuron?
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What is the purpose of the myelin sheath surrounding a nerve fiber?
What is the purpose of the myelin sheath surrounding a nerve fiber?
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Which cells are responsible for producing myelin in the central nervous system (CNS)?
Which cells are responsible for producing myelin in the central nervous system (CNS)?
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What characterizes non-myelinated nerve fibers?
What characterizes non-myelinated nerve fibers?
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What is the primary role of nerve growth factors (NGF) in the nervous system?
What is the primary role of nerve growth factors (NGF) in the nervous system?
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Which type of neurons do nerve growth factors primarily influence?
Which type of neurons do nerve growth factors primarily influence?
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What is a characteristic of neuroglia in the nervous system?
What is a characteristic of neuroglia in the nervous system?
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How do Schwann cells contribute to the nervous system?
How do Schwann cells contribute to the nervous system?
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What distinguishes neuroglia from neurons?
What distinguishes neuroglia from neurons?
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Study Notes
Nervous System Anatomy
- The nervous system is divided into two primary parts: the central nervous system (CNS) and the peripheral nervous system (PNS).
- The CNS consists of the brain and spinal cord, responsible for processing information and decision-making.
- The PNS comprises cranial nerves and spinal nerves, transmitting electrical signals throughout the body.
Nervous System Physiology
- The PNS is further divided into the somatic nervous system and the autonomic nervous system.
- The somatic nervous system controls voluntary movements of skeletal muscles.
- The autonomic nervous system controls involuntary functions of internal organs, including the sympathetic and parasympathetic nervous systems.
Spinal Cord
- The spinal cord has 31 segments, each giving rise to a pair of spinal nerves.
- There are 31 pairs of spinal nerves: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal.
- The spinal cord serves as a communication pathway between the brain and body tissues.
Functions of the Nervous System
- The CNS receives information from the body through afferent (sensory) signals via peripheral nerves.
- The CNS stores information in memory.
- The CNS integrates and processes incoming information.
- The CNS sends signals to tissues throughout the body through efferent (motor) signals via peripheral nerves.
Central Nervous System Composition
- The human CNS contains over 100 billion neurons and 50-100 times that number of glial cells.
- About 40% of human genes are involved in the formation of the CNS.
Neuron Structure
- Neurons are the fundamental units of the nervous system responsible for transmitting information.
- Each neuron consists of a cell body (soma), an axon, and dendrites.
- All neurons have a single axon, but dendrites can be absent, single, or multiple.
- The axon carries impulses away from the soma (centrifugally).
- Dendrites carry impulses toward the soma (centripetally).
Neuron Classification
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Number of poles:
- Multipolar: Neuron with multiple extensions from the soma.
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Function:
- Motor (efferent) neurons: Carry impulses from the CNS to effector organs (muscles, glands, blood vessels).
- Sensory (afferent) neurons: Carry impulses from the periphery to the CNS.
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Length of axon:
- Long axon neurons
- Short axon neurons
Axis Cylinder
- Composed of the central core of cytoplasm (axoplasm) surrounded by a membrane (axolemma).
- The axolemma is a continuation of the cell membrane of the soma.
- Contains mitochondria, neurofibrils, axoplasm, and vesicles.
- Myelinated nerve fibers have an insulating myelin sheath surrounding the axis cylinder.
Myelin Sheath
- Composed of concentric layers of protein alternating with lipid.
- Produced by Schwann cells in the PNS and oligodendrogliocytes in the CNS.
- Myelin is compacted when extracellular membrane protein (Po) locks the extracellular portion of opposing membrane proteins.
- Gaps in the myelin sheath are called nodes of Ranvier.
- The segment between two nodes is called an internode.
Non-Myelinated Nerve Fibers
- Lack a myelin sheath.
- Nerve fibers are simply covered by Schwann cells, without wrapping.
- No internodes or nodes of Ranvier.
- The neurilemma and axis cylinder are close together.
- In the CNS, there is no neurilemma.
Functional Division of Neuron
- Divided into four zones:
- Receptor zone: Receives signals from other neurons or sensory receptors.
- Trigger zone: Generates the nerve impulse.
- Conduction zone: Transmits the nerve impulse along the axon.
- Secretory zone: Releases neurotransmitters at the synapse.
Nerve Growth Factors (NGF)
- Promote early growth and development in neurons.
- Primarily affect sympathetic and sensory neurons, especially those involved in pain.
Neuroglia
- Supporting cells of the nervous system (glia means glue).
- Not excitable and do not transmit nerve impulses.
- Outnumber neurons 10-50 times.
- Can multiply through mitosis.
- Schwann cells invest axons and are also glial cells.
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Description
This quiz explores the anatomy and physiology of the nervous system, covering both the central and peripheral systems. It includes details about the components of the CNS and PNS, as well as the functions of the somatic and autonomic nervous systems. Test your understanding of the spinal cord and its segments.
