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Questions and Answers
What type of neuron has a single, short process that usually functions as a dendrite?
What type of neuron has a single, short process that usually functions as a dendrite?
Which type of neuron carries impulses away from the central nervous system?
Which type of neuron carries impulses away from the central nervous system?
Which component of the synapse releases neurotransmitters to transmit impulses?
Which component of the synapse releases neurotransmitters to transmit impulses?
What is the primary function of myelin in the nervous system?
What is the primary function of myelin in the nervous system?
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Which type of neuroglia is responsible for forming the blood-brain barrier?
Which type of neuroglia is responsible for forming the blood-brain barrier?
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What type of neuroglia disposes of debris and dead brain cells in the central nervous system?
What type of neuroglia disposes of debris and dead brain cells in the central nervous system?
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Which cells produce myelin in the peripheral nervous system?
Which cells produce myelin in the peripheral nervous system?
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What are the gaps in the myelin sheath known as?
What are the gaps in the myelin sheath known as?
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What are the two main types of cells that make up nervous tissue?
What are the two main types of cells that make up nervous tissue?
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What is the primary function of dendrites in a neuron?
What is the primary function of dendrites in a neuron?
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Which part of the neuron contains the nucleus and is the main metabolic center?
Which part of the neuron contains the nucleus and is the main metabolic center?
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What characteristic is absent in the axon hillock?
What characteristic is absent in the axon hillock?
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Which type of neuron process is primarily responsible for action potential generation?
Which type of neuron process is primarily responsible for action potential generation?
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Which term describes the movement along axons toward the axon terminals?
Which term describes the movement along axons toward the axon terminals?
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What is the function of myelinated axons in the CNS and PNS?
What is the function of myelinated axons in the CNS and PNS?
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How are axon terminals described in a neuron?
How are axon terminals described in a neuron?
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Study Notes
Nervous Tissue Properties
- Nervous tissue is irritable and conductive
- Responds to stimuli by generating and transmitting nerve impulses
- Found throughout the body as an integrated network
- Composed of two cell types: neurons (nerve cells) and glial cells (neuroglia)
Nervous System Divisions
- Nervous system is divided into the central nervous system (CNS) and peripheral nervous system (PNS)
The Neuron
- Excitable, independent functional unit with complex morphology
- Specializes in transmitting nerve impulses
- Consists of three major parts: cell body, dendrites, and axon
Cell Body (Soma or Perikaryon)
- Contains the nucleus and nucleolus
- Responsible for metabolism and protein synthesis
- Outgrowth point for neuronal processes
- Lacks centrioles (amitotic nature)
- Prominent basophilic Nissl bodies (rough ER)
- Contains an axon hillock
Neuron Cytoskeleton
- Formed by microtubules and neurofilaments
Neuron Processes
- Arm-like extensions from the soma
- Collectively referred to as nerve fibers
- Two types: dendrites and axons
- Myelinated axons are called tracts in the CNS and nerves in the PNS
Dendrites
- Short, tapering processes
- Branch extensively to form a dendritic tree
- Function as the receptive or input regions of the neuron
- Lack Golgi complexes
Axons
- Slender processes with uniform diameter arising from the axon hillock
- Axon hillock lacks RER, ribosomes, and Nissl substance
- Usually unbranched
- Contains axon terminals (terminal boutons)
- Axolemma is the plasma membrane
- Axoplasm is the cytoplasm
Axon Function
- Generate and transmit action potentials
- Secrete neurotransmitters from the axonal terminals
- Movement along axons occurs in two directions: anterograde (toward the axon terminal) and retrograde (toward the cell body)
Neuron Classification: Structure
- Multipolar: Three or more processes
- Bipolar: Two processes (axon and dendrite)
- Unipolar (pseudounipolar): Single, short process (usually dendrite)
- Anaxonic: Lack axons
Neuron Classification: Function
- Sensory (afferent): Transmit impulses toward the CNS
- Motor (efferent): Carry impulses toward the body surface
- Interneurons (association neurons): Any neurons between a sensory and motor neuron
Synapse
- Specialized region of contact between two neurons
- Transmits nerve impulses using neurotransmitters
- Three types: axodendritic, axosomatic, and axoaxonic
- Consists of three parts: presynaptic part, synaptic cleft, and postsynaptic part
Myelin
- White, fatty material covering axons
- Protects and insulates axons
- Increases the transmission rate of nerve impulses
- Produced by Schwann cells in the PNS and oligodendrocytes in the CNS
- Gaps in the myelin sheath are called Nodes of Ranvier
Neuroglia
- Supporting cells in the CNS
- Literally means “nerve glue”
- Support, insulate, and protect neurons
- Only their nuclei are visible in H & E staining
- Capable of multiplying in mature nervous tissue
- Cannot generate or transmit impulses
Types of Neuroglia in CNS
- Astrocytes: Star-shaped cells with expanded ends that attach to blood capillaries. Two types: protoplasmic (in gray matter) and fibrous (in white matter). Control the chemical environment of the brain (forming the blood-brain barrier).
- Microglia: Spiderlike phagocytes (white blood cells) that dispose of debris (dead cells and bacteria).
- Ependymal cells: Line the cavities of the brain and spinal cord, circulate cerebrospinal fluid by beating their cilia. Arranged in a single layer, ciliated cuboidal or columnar shaped.
- Oligodendrocytes: Small, round cells with few cytoplasmic processes. Produce myelin sheaths in CNS.
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Description
Explore the fascinating properties of nervous tissue, including its irritable and conductive characteristics. Learn about the central and peripheral nervous system divisions, the structure and function of neurons, and the importance of neuron processes. This quiz provides a comprehensive overview of key concepts in neurobiology.
