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82 Cards in this Set
- Front
- Back
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Main Function of the Nervous System
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the master controlling and communicatiing system of the body
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Function of the Nervous System
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a.) Sensory Input
b.) Integration c.) Motor Output |
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Sensory Input
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monitoring stimuli occurring inside and outside the body (our sensese, what we receive)
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Integration
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interpretation of sensory input
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Motor Ouput
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response to stimuli by activating effector organs
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Parts of the CNS
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Brain and the spinal cord
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Function of the CNS
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integration and command center
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Function of the Peripheral Nervous System
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carries messages to and from the spinal cord and brain
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Parts of the PNS
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Paired spinal and cranial nerves
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Divisions of the PNS
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Sensory afferent
Motor efferent |
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Sensory Afferent Fibers
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carry impulses from skin, skeletal muscles and joints to the brain
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Visceral Efferent Fibers
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transmit impulses from visceral organs to the brain
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Motor Efferent Division
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transmits impulses from the CNS to effector organs
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Function of the Somatic Nervous System
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conscious control of skeletal muscles
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Function of Autonomic Nervous System
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regulates smooth muscle, cardiac muscle, and glands
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Divisions of the Autonomic Nervous System
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a.) Sympathetic
b.) Parasympathetic |
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Neurons
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excitable cells that transmit electrical signals
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Supporting Cells (Neuroglia)
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cells that surround and wrap neurons
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What do neuroglia provide for neurons?
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supportive scaffolding
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What do neuroglia promote?
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health and growth
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What is the most abundant type of neuroglia?
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astrocytes
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Function of an Astrocyte
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Support and brace neurons, anchor neurons to their nutrient supplies, guide migration of young neurons, control the chemical environment
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Function of Microglia
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phagocytes that monitor the health of neurons
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Characteristics of Microglia
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small, ovoid cells with spiny processes
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Function of Ependymal Cells
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they range in shape from squamous to columnar
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What do ependymal cells line?
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They line the central cavities of the brain and spinal column
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What are oligodendrocytes?
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branched cells that wrap CNS nerve fibers
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What are Schwann Cells?
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they surround fibers of the PNS
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What are Satellite Cells?
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they surround neuron cell bodies with ganglia
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What a neuron made up of?
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an cell body, an axon and dendrites
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What is the function of a neuron's plasma membrane?
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electrical signaling, cell to cell signaling during development
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What does the nerve cell body contain?
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a nucleus and a nucleolus
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What is the nerve cell body major function?
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it is the major biosynthetic center, and it is the focal point for the outgrowth of neuronal processes
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What doesn't it have?
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centrioles
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What well-developed feature does it have?
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Nissl bodies (rough ER)
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What are the processes called in the CNS?
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tracts
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What are the processes called in PNS?
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nerves
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What are the two types of processes?
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axons and dendrites
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Physical Characteristics of Dendrites
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short, tapering, branchlike
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What is the fucntion of dendrites of motor neurons?
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they are receptive, or input, regions of the neuron
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What are axons?
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they are slender processes of uniform diameter arising from the hillock
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What are long axons called?
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nerve fibers
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Axon Collaterals
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rare branches if present
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Axon terminal
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branched terminals of an axon
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What is the function of an axon?
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to generate and transmit action potentials, to secrete neurotransmitters from the axonal terminals
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Movement along axons happen in two ways what are they?
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Anterograde and Retrograde
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Anterograde
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toward the axonal terminal
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Retrograde
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away from axonal terminal
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Physical Characteristics of Myelin Sheath
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whitish, fatty (protein-lipoid)m segmented sheath around most long axons
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Functions of the Myelin Sheath
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1. Protect the neuron
2. Electrically insulate fibers from one another 3. Increase the speed of nerve impulse transmission |
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What is the myelin sheath made of in the PNS?
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Schwann Cells
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What is a neurilemma?
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remaining nucleus and cytoplasm of a Schwann Cell
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What is a Schwann Cell?
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1. Envelopes an axon in a trough
2. Encloses the axon with its plasma membrane 3. Has concentric layers of membrane that make up the myelin sheath |
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Nodes of Ranvier
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gaps in myelin sheath between adjacent Schwann cells
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What is another name for Nodes of Ranvier?
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Neurofibril Nodes
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What are the sites of the Nodes of Ranvier?
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they are the sites where axon collaterals can emerge
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What do Schwann Cells surround?
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Nerve fibers, but coiling doesn't take place
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In the CNS, how are myelin sheaths formed?
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oligodendrocytes
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What do they no have in the CNS that they do have in the PNS?
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neurilemma
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White Matter
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dense collections of myelinated fibers
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Gray Matter
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mostly soma and unmyelinated fibers (cell bodies, less myelin)
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Neuronal Structural Classification
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1. Multipolar
2. Bipolar 3. Unipolar |
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Multipolar Neurons
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three or more processes
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Bipolar Neurons
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two processes (axon and dendrites)
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Unipolar Neurons
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single, short process
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Functional Classification of Neurons
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1. Sensory (afferent) neurons
2. Motor (efferent) neurons 3. Interneurons (association neurons) |
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What is another name for sensory?
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afferent
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What is another name for motor?
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efferent
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What do sensory afferent neurons do?
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transmit impulses toward the CNS
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What do the motor efferent neurons do?
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they carry impulses away from the CNS
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What is another name for interneurons?
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association neurons
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What do interneurons do?
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they shuttle signals through CNS pathways
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Neurons are highly what?
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irritable and reactive
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Action Potentials are also called what?
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Nerve impulses
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What are action potentials?
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they are electrical impulses carried alonf the length of axons, always the same regardless of stimulus
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What is the underlying functional feature of the nervous system?
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action potential
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Voltage
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measure of potential energy generated by separated charge
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Potential Difference
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voltage measured between two points
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Current
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the flow of electrical charge between two points
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Resistance
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hindrance to charge flow
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Insulator
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substance with high electrical resistance
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Conductor
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substance with low electrical resistance
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