Nervous System Flashcards
Three Functions of the Nervous System
Receives sensory input (internal and external) - PNS -> CNS
Processes and integrates information
Generates motor output
Two Major Components
Central Nervous System
Peripheral Nervous System
Central Nervous system consists of…
Brain and spinal cord
Neurons
Cells that transmit nerve impulses
Neuroglia (Glial Cells)
Support and nourish neurons; more numerous than neurons in brain
Two types of Neuroglia
Schwann cells
Oligodendrocytes
Schwann Cells
Form myelin sheath (insulators) of neurons in peripheral nervous system, leaving gaps called nodes of Ranvier
Oligodendrocytes
Form myelin sheath in central nervous system - “white matter”
Nervous Tissue
Located in the nerves, and conducts nerve impulses
Myelin Sheath
A lipid covering on long axons that acts to increase the speed of nerve impulse conduction, insulation, and regeneration in the peripheral nervous system
Nodes of Ranvier
Gaps between myelination on the axons
Saltatory Conduction
Conduction of the nerve impulse from node to node (don’t have to open so many ion channels)
Multiple Sclerosis
Disease in which the myelin sheath is attacked by the immune system, causing malfunctioning of the nervous system and muscle weakness or paralysis
Three types of neurons
Sensory
Interneuron
Motor
Sensory Neuron
Transports nerve signals from sensory receptors to central nervous system
Receptor
Special structures that detect changes in the environment
Interneuron
Lie within central nervous system; composite input from sensory neurons and other interneurons, then communicate with motor neurons
Motor
Transport impulses from central nervous system to effector
Effector
Carry out responses to environmental changes
Dendrite
Many short extensions that carry impulses to a cell body
Cell body
Main cell where organelles and nuclei reside
Axon (nerve fiber)
Single, long extension that carries impulses away from the cell body (exception - sensory neuron)
Synapse
Small gap between the sending neuron (pre-synaptic membrane) and the receiving neuron (post-synaptic membrane)
How do signals get from sensory neurons to the brain and then to the right neurons to get muscles to move?
Sensor -> Afferent Pathway -> integration -> Efferent Pathway -> Motor
Nerve Impulses
Convey information in nervous system, i.e., action potential, via electrochemical signals
Resting Potential
Axon is NOT conducting a nerve impulse