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Questions and Answers
What is the primary function of the basal nuclei in the cerebrum?
What is the primary function of the basal nuclei in the cerebrum?
Which lobe of the brain is primarily responsible for visual processing?
Which lobe of the brain is primarily responsible for visual processing?
Which layer of the meninges is the innermost and transparent layer that adheres to the brain?
Which layer of the meninges is the innermost and transparent layer that adheres to the brain?
What connects the right and left hemispheres of the cerebrum?
What connects the right and left hemispheres of the cerebrum?
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What is the function of the cerebellum in relation to the cerebral cortex?
What is the function of the cerebellum in relation to the cerebral cortex?
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What type of cells form myelin in peripheral nerves?
What type of cells form myelin in peripheral nerves?
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Which of the following accurately describes the difference between white matter and grey matter?
Which of the following accurately describes the difference between white matter and grey matter?
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What is the outermost protective covering of the central nervous system?
What is the outermost protective covering of the central nervous system?
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What is the function of nodes of Ranvier in myelinated nerve fibers?
What is the function of nodes of Ranvier in myelinated nerve fibers?
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How are the meninges characterized in relation to the central nervous system?
How are the meninges characterized in relation to the central nervous system?
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What is one of the main functions of glial cells in the nervous system?
What is one of the main functions of glial cells in the nervous system?
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Which type of neuroglia is primarily responsible for insulating neurons?
Which type of neuroglia is primarily responsible for insulating neurons?
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In which system would you find Schwann cells?
In which system would you find Schwann cells?
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What distinguishes oligodendrocytes from Schwann cells?
What distinguishes oligodendrocytes from Schwann cells?
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What is the term for a collection of neuron cell bodies in the peripheral nervous system?
What is the term for a collection of neuron cell bodies in the peripheral nervous system?
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Which of the following statements is correct regarding a tract and a nerve?
Which of the following statements is correct regarding a tract and a nerve?
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Which type of glial cell is known for its role in recognizing and removing pathogens?
Which type of glial cell is known for its role in recognizing and removing pathogens?
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What connective structures hold together peripheral nerve fibers?
What connective structures hold together peripheral nerve fibers?
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What defines a unipolar neuron in the nervous system?
What defines a unipolar neuron in the nervous system?
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In which type of neuron are the dendrites typically limited and the axons usually short?
In which type of neuron are the dendrites typically limited and the axons usually short?
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What is the primary function of sensory neurons?
What is the primary function of sensory neurons?
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Which neuron type is responsible for transmitting impulses from the CNS to effectors?
Which neuron type is responsible for transmitting impulses from the CNS to effectors?
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Which statement describes multipolar neurons?
Which statement describes multipolar neurons?
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How are interneurons primarily characterized?
How are interneurons primarily characterized?
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Which type of neuron is most commonly associated with the skin, joints, and internal organs?
Which type of neuron is most commonly associated with the skin, joints, and internal organs?
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Which of the following describes a characteristic of bipolar neurons?
Which of the following describes a characteristic of bipolar neurons?
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Study Notes
Nervous System Organization: Part II
- The nervous system is organized into the central nervous system (CNS) and peripheral nervous system (PNS)
- Part I covered organization of the nervous system, classification of sensory receptors, somatic nervous system, autonomic nervous system, and cell types in the nervous system.
Neuronal Classification
- Neurons are categorized structurally into three types: unipolar, bipolar, and multipolar.
- Unipolar neurons: Possess a single process that branches close to the cell body into a trunk to supply dendrites for incoming signals and an axon for outgoing signals. Typically sensory neurons with receptors located in skin, joints, muscles, and internal organs. Dendritic and axon lengths vary.
- Bipolar neurons: Two processes emerge from the cell body; one forms a dendrite, the other forms an axon. Typically sensory neurons involved in visual and auditory systems. Axons are short.
- Multipolar neurons: Multiple branched extensions (dendrites) originate from the neuron cell body. Axons are typically long and allow for integration of information from other neurons. These are the majority of neurons in the body.
Functional Types of Neurons
- Sensory neurons: Long axons; transmit nerve impulses from sensory receptors to the central nervous system.
- Motor neurons: Long axons; transmit nerve impulses from the CNS to effectors (muscles and glands).
- Interneurons: Usually smaller, with many interconnections. Relay messages between other neurons.
Neuroglia
- Neuroglia are non-neuronal cells that support and protect neurons. Provide support, form myelin, and maintain homeostasis (e.g. proper levels of ions like Calcium and Potassium).
- Four main functions:
- Surround neurons and hold them in place
- Supply nutrients and oxygen to neurons
- Insulate one neuron from another
- Destroy pathogens and remove dead neurons.
Types of Neuroglia
- Astrocytes: Star-shaped glial cells throughout CNS tissue (brain and spinal cord). Maintain appropriate levels of ions and nutrients for neurons, help with migration of neurons during development, and aids in blood brain barrier formation.
- Microglial cells: Small glial cells responding to injury or disease in the CNS. Protect neurons from disease by clearing away debris and dead cells. Some texts describe microglia having a "mainly scavenging" function.
- Ependymal cells: Form lining of ventricles in brain and central canal of spinal cord. These cells produce and circulate cerebrospinal fluid.
- Oligodendrocytes: Found in CNS. Form supporting network around CNS neurons. Produces myelin sheath around several adjacent axons.
- Schwann cells: Found in PNS. Forms myelin sheath around a portion of a single axon. Aids in regeneration of PNS axons.
Nuclei vs. Ganglia
- Nuclei: Collections of neuron cell bodies in the CNS.
- Ganglia: Collections of neuron cell bodies in the PNS.
Tracts vs. Nerves
- Tracts: Collections of nerve fibers (axons) in the CNS.
- Nerves: Collections of nerve fibers (axons) in the PNS.
Myelinated vs. Unmyelinated Nerves
- Myelinated fibers conduct nerve impulses more rapidly than unmyelinated fibers.
- Myelin is formed by oligodendrocytes in the CNS, and Schwann cells in the PNS.
- Nodes of Ranvier are gaps between myelinated sections of the nerve fibers where depolarization occurs. This accelerates impulse propagation.
Brain Regions
- Cerebrum: Largest part of the brain; divided into right and left hemispheres. Involved in processing sensory and motor information and higher cognitive functions such as reasoning and planning.
- Cerebellum: Second largest part of the brain, responsible for coordinating movement, balance, and posture. Contains more neurons than other parts of the nervous system.
- Brainstem: Connects the cerebrum and cerebellum to the spinal cord. Composed of midbrain, pons, and medulla oblongata. Responsible for regulating many essential functions and reflexes.
- Diencephalon: Includes the thalamus (involved in relaying sensory information), hypothalamus (controls many autonomic functions like temperature and appetite) and pineal gland (produces melatonin).
Protective Coverings of CNS
- Outermost covering is bone (cranial bones and vertebrae).
- Innermost covering is the meninges (dura mater, arachnoid mater and pia mater). Dura mater is the tough outer layer, arachnoid mater resembles a web and lines the dura, and the innermost pia mater adheres to the spinal cord.
Brain Lobes
- Frontal lobe: Reasoning, planning, speech, movement, emotions, problem-solving
- Parietal lobe: Movement, orientation, recognition, perception
- Occipital lobe: Visual processing
- Temporal lobe: Auditory stimuli, memory, speech perception
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Description
This quiz focuses on the organization of the nervous system, specifically the central and peripheral nervous systems. It also explores the structural classification of neurons, including unipolar, bipolar, and multipolar types, as well as their associated functions. Test your understanding of these key concepts in neuroanatomy!
