Functions of Nerve Tissue
• Allows an organism to sense stimuli in both the internal and external environment.
• The stimuli are analyzed and integrated to provide appropriate, coordinated responses in various organs.
• The afferent or sensory neurons conduct nerve impulses from the sense organs and receptors to the central nervous system.
• Internuncial or connector neurons supply the connection between the afferent and efferent neurons as well as different parts of the central nervous system.
• Efferent or somatic motor neurons transmit the impulse from the central nervous system to a muscle (the effector organ) which then react to the initial stimulus.
• Autonomic motor or efferent neurons transmit impulses to the involuntary muscles and glands.
• It is the functional unit of the nervous system.
• It gathers and processes information from receptors in contact with the external environment and generates appropriate response signals.
• Networks of neurons help combine multiple sensory signals responsible for complex behaviors like abstract thinking, learning, memory, language, planning, etc.
• When damaged, they do not regenerate.
Structural Components of a Neuron
Cell Body (soma)
• contains the nucleus and most of the organelles responsible for maintaining the neuron's metabolic functions.
• Stretches from the cell body to a distance ranging from several millimeters up to one meter
• Transmit nerve signals away from the nerve cell body towards other nerves, muscle, or glands
• Neurons only have one axon
• Many, but not all, axons are sheathed in multiple layers of a lipid-rich material called myelin [functions as a kind of electrical "insulation" greatly facilitating nerve impulse transmission]
• Axons of the PNS can regenerate provided that the nerve cell body is not damaged
• Numerous short projections from the...