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Questions and Answers
What types of nerve fibers does the first system apply to?
What types of nerve fibers does the first system apply to?
Which lettered nomenclature is used in the first system?
Which lettered nomenclature is used in the first system?
Which statement about the first system is correct?
Which statement about the first system is correct?
What is the main function of the nerve fibers described in the first system?
What is the main function of the nerve fibers described in the first system?
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In the context of the first system, what do Afferent and Efferent refer to?
In the context of the first system, what do Afferent and Efferent refer to?
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What is the primary function of the sensory pathways?
What is the primary function of the sensory pathways?
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Which part of the central nervous system perceives sensory information?
Which part of the central nervous system perceives sensory information?
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Which of the following is NOT a modality of sensation processed by the sensory cortex?
Which of the following is NOT a modality of sensation processed by the sensory cortex?
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What type of energy do sensory pathways transmit to the sensory cortex?
What type of energy do sensory pathways transmit to the sensory cortex?
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Sensory information includes which of the following sensations?
Sensory information includes which of the following sensations?
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What is the primary role of sensory receptors in the sensory system?
What is the primary role of sensory receptors in the sensory system?
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Which part of the brain is primarily associated with vegetative functions?
Which part of the brain is primarily associated with vegetative functions?
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In the functional organization of the sensory system, what happens to the sensory information after it is received by sensory receptors?
In the functional organization of the sensory system, what happens to the sensory information after it is received by sensory receptors?
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Which of the following best describes the role of the internal structures of the primitive brain?
Which of the following best describes the role of the internal structures of the primitive brain?
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What does the term 'transduce' refer to in the context of sensory receptors?
What does the term 'transduce' refer to in the context of sensory receptors?
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What primary function does the neocortex serve in the brain?
What primary function does the neocortex serve in the brain?
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Which system is primarily associated with behavior and emotions?
Which system is primarily associated with behavior and emotions?
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Which part of the brain would you associate with basic survival functions such as heartbeat and breathing?
Which part of the brain would you associate with basic survival functions such as heartbeat and breathing?
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In terms of brain structure, which area is responsible for the integration of sensory information and higher-order processing?
In terms of brain structure, which area is responsible for the integration of sensory information and higher-order processing?
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Which of the following pairs of functions and their corresponding brain structures is correct?
Which of the following pairs of functions and their corresponding brain structures is correct?
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What is the primary function of the myelin sheath?
What is the primary function of the myelin sheath?
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What is the composition of the myelin sheath?
What is the composition of the myelin sheath?
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How does the myelin sheath affect nerve impulse conduction?
How does the myelin sheath affect nerve impulse conduction?
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What type of neurons are primarily associated with myelin sheaths?
What type of neurons are primarily associated with myelin sheaths?
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Which statement about the myelin sheath is true?
Which statement about the myelin sheath is true?
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What is the primary function of the input region of a neuron?
What is the primary function of the input region of a neuron?
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Which part of the neuron is responsible for the integration of signals to initiate action potentials?
Which part of the neuron is responsible for the integration of signals to initiate action potentials?
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What type of cells are glial cells, and how do they compare to neurons?
What type of cells are glial cells, and how do they compare to neurons?
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Which of the following accurately describes the chemical release zone of a neuron?
Which of the following accurately describes the chemical release zone of a neuron?
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What is the role of astrocytes within the central nervous system?
What is the role of astrocytes within the central nervous system?
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Study Notes
Introduction to Neurophysiology
- The nervous system is the highest body control system, sharing this role with the endocrine system
- The functional unit is the neuron, responsible for integration and transmission
- The nervous system has two primary divisions:
- Central Nervous System (CNS): Includes the brain and spinal cord
- Peripheral Nervous System (PNS): Includes sensory receptors, sensory nerves, and ganglia outside the CNS
- The CNS and PNS extensively communicate with each other.
Objectives
- Students will be able to identify the nervous system as the highest control system
- Students will be able to identify the functional divisions of the nervous system
- Students will be able to name and describe the parts of a neuron and their functions
- Students will be able to list and describe different nerve fiber types in mammals
- Students will be able to define reflex action and describe the components of a reflex arc
- Students will be able to outline the functional organization of the sensory and motor system
- Students will be able to identify the higher functions of the brain
Anatomical Division of the Nervous System
- The CNS consists of the brain and spinal cord
- The PNS consists of spinal nerves and cranial nerves
- There are 12 pairs of cranial nerves
- There are 31 pairs of spinal nerves
Functional Division of the Nervous System
- The nervous system has two major functional divisions:
- Somatic nervous system: Communicates with sensory organs and voluntary muscles
- Autonomic nervous system: Communicates with internal organs and glands and further divides into: Sympathetic and Parasympathetic division
- Sympathetic division (arousing)
- Parasympathetic division (calming)
- Sensory (afferent) nervous system (sensory input)
- Motor (efferent) nervous system (motor output)
Sensory System
- Sensory receptors detect sensory information in the periphery
- Sensory receptors include visual, auditory, chemoreceptors, and somatosensory (touch) receptors
- Sensory nerve pathways transmit sensory information to sensory areas of the CNS (e.g. cerebral cortex)
- The sensory cortex perceives the transmitted sensory information as different sensations (touch, pressure, electromagnetic waves, warmth, cold, pain, etc.)
Motor System
- The motor or efferent division carries information out of the nervous system to the periphery
- The motor response involves the contraction of skeletal muscles, smooth muscles, or cardiac muscles, or secretion by endocrine and exocrine glands
Basic Tasks
- Sensory receptors monitor internal and external environments
- The CNS analyzes sensory information and integrates it often with stored information
- The PNS signals effector organs such as muscles or glands when necessary
Integration of Sensory Information
- The CNS decodes incoming sensory impulses
- Sensory information from several sources may be integrated
- The CNS may integrate information with information stored in memory
Signaling Effectors to Respond
- The CNS sends nerve impulses to effector organs (muscles, glands, etc.).
- This allows the body to appropriately respond
- Sometimes the process of signal transmission and decoding by effector organs happens only via simple spinal reflexes
Neurons
- Nerve cells (neurons) are the structural units of the nervous system
- Neurons have a cell body, dendrites, axon, axon hillock, myelin sheath, nodes of Ranvier, and terminal branches/bulbs
- Neurons are specialized for impulse transmission
- There are four functional domains of a neuron: input region, trigger zone, propagation region, and chemical release zone.
Types of Neurons
- Neurons are classified based on structural differences into bipolar, pseudo-unipolar, and multipolar types
- Neurons also have several ways to functionally classify them.
Types of Nerve Fibers
- Nerve fibers are classified by conduction velocity (dependent on fiber size and presence/absence of myelin) into two classification systems: A, B, C fibers and I, II, III, IV fibers.
- Large myelinated fibers have fast conduction velocities
- Small unmyelinated fibers have slow conduction velocities.
Reflex Action
- Reflexes are involuntary responses to stimuli
- Reflexes are an essential component of homeostasis
- Reflex actions occur via a pathway called the reflex arc
- The reflex arc involves a receptor, afferent nerve, central nervous system, efferent nerve, and effector
General Functions of the Nervous System
- The nervous system has three basic functions: sensory, integrative, and motor functions
- Sensory function involves reception of stimuli and sending of information to the brain and spinal cord via the PNS
- Integrative function analyses sensory information to create a response
- Motor function sends instructions via the PNS to effector organs
Sensory & Motor Systems
- Sensory and motor systems work in conjunction to allow actions
- Sensory systems include many receptors on the skin, inside the body, and in the muscles
- Some prominent sensory systems involved are somatic, eye, ear
Functional Integration of CNS
- Brain functions high intellectual functions (Neocortex), behavior and emotions (Limbic system), and vegetative functions (Paleocortex)
- Primitive brain
Functional Organization of the Sensory System
- Sensory receptors receive sensory information and convert them to electrical signals
- Sensory pathways transmit the information to sensory areas of the CNS
- The sensory cortex then perceives these signals as different sensations
Functional Organization of the Motor System
- Voluntary movements are initiated by the cerebral cortex and carried through descending motor tracts
- Muscle tone is involuntary activity of skeletal muscles and is maintained through stretch reflexes
- Coordination of movement stems from the cerebellum and basal ganglia
Higher Functions of the Brain
- Higher functions include language, speech, perception, memory, learning, consciousness, sleep, arousal, high intellectual functions, and behavior.
Schwann Cells
- Schwann cells form the myelin sheath in the PNS
- Schwann cells aid in the regeneration of axons
Glial Cells (Neuroglia)
- Glial cells (neuroglia) are much more common than neurons
- Astrocytes form the blood-brain barrier and maintain the chemical environment for nerve impulse generation
- Oligodendrocytes form the myelin sheath in the CNS, increasing speed of nerve impulse conduction
- Microglial cells act as phagocytes in the CNS
What is a Nerve?
- A nerve is a bundle of axons outside the CNS
- There are varying types of nerves: mixed nerves, sensory nerves
Cranial and Spinal Nerves
- There are 12 pairs of cranial nerves, most connecting with the brain stem
- 31 pairs of spinal nerves branch out from the spinal cord to the different parts of the body
References
- Lippincott's Illustrated Reviews: Physiology, 2013
- Linda S. Costanzo, Physiology (6th Ed), 2018
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Description
Explore the fundamentals of neurophysiology, focusing on the nervous system's role as the highest body control system. This quiz covers essential topics like the divisions of the nervous system, the function of neurons, and the components of reflex actions. Test your understanding and reinforce your knowledge on critical aspects of this fascinating subject.
