The Nervous System Wired for Action Flashcards
Nervous system
The system of neurons, nerves, tracts, and associated tissues that, together with the endocrine system, coordinates activities of the organism in response to signals received from the internal and external environments.
Peripheral nervous system (PNS)
The portion of the nervous system that lies outside the brain and spinal cord—that is, all parts outside the central nervous system.
Somatic nervous system (SNS)
The part of the nervous system comprising the sensory and motor neurons that innervate the sense organs and the skeletal muscles.
Autonomic nervous system (ANS)
The portion of the nervous system innervating smooth muscle and glands, including the circulatory, digestive, respiratory, and reproductive organs. It is divided into the sympathetic nervous system and parasympathetic nervous system.
What are the branches of autonomic nervous system?
- parasympathetic branch
- sympathetic branch
Sympathetic branch
The branch of the ANS that arouses the body.
Parasympathetic branch
The branch of the ANS that quiets the body.
Nerve
A bundle of axons outside the central nervous system (CNS), enclosed in a sheath of connective tissue to form a cordlike structure. Nerves connect the CNS with the tissues and organs of the body. They may be motor, sensory, or mixed (containing
axons of both motor and sensory neurons).
Neurilemma
The neurilemma, or sheath of Schwann, is the delicate outermost layer of the nerve cell fiber in the peripheral nervous system, which aids in the regeneration of damaged nerve tissues.
Central nervous system
(CNS)
The entire complex of neurons, axons, and supporting tissue that constitute the brain and spinal cord. The CNS is primarily involved in mental activities and in coordinating and integrating incoming sensory messages and outgoing motor messages.
Cranial nerve
Any of the 12 pairs of nerves that arise directly from the brain and are distributed mainly to structures in the head and neck.
Spinal nerve
Any of the 31 pairs of nerves that originate in the gray matter of the spinal cord and emerge through openings between the vertebrae of the spine to extend into the body’s dermatomes (skin areas) and skeletal muscles. Major nerves that carry sensory and motor messages in and out of the spinal cord.
Reflex arc
A neural circuit that is involved in a reflex. In its simplest form, it consists of an afferent, or sensory, neuron that conducts nerve impulses from a receptor to the spinal cord, where it connects directly or via an interneuron to an efferent motor neuron that carries the impulses to an effector, that is, a muscle or gland.
Sensory neuron
A neuron that receives information from the environment, via specialized receptor cells, and transmits this information—in the form of nerve impulses—through synapses with other neurons to the central nervous system.
Effector cells
Cells capable of producing a response.
Interneuron
Any neuron that is neither sensory nor motor but connects other neurons within the central nervous system. Also called connector neuron.
Is the spinal cord’s only function to connect the brain to the peripheral nervous system?
The spinal cord can do
some simple “computing”
of its own
Motor neuron
A neuron whose axon connects directly to muscle fibers. Because motor neurons are the fnal stage of output from the nervous system and are the only means of stimulating muscle fibers, they are known as the final common path.
White matter
Parts of the nervous system composed of nerve fibers that are enclosed in a myelin sheath, which gives a white coloration to otherwise grayish neural structures. The sheaths cover only the fibers, so regions containing mainly cell bodies are gray.
Spinal cord
The part of the central nervous system that extends from the lower end of the medulla oblongata, at the base of the brain, through a canal in the center of the spine as far as the lumbar region.
Neurogenesis
The production of new neurons during early nervous system development and throughout the lifespan.
