Topic 8 Flashcards
Central nervous system (CNS)
consists of the brain and spinal cord
Peripheral nervous system (PNS)
Consists of cranial nerves and spinal nerves that contain both sensory and motor fibers
Connects CNS to muscles, glands & all sensory receptors
Somatic (voluntary) nervous system (SNS)
Sensory neurons from cutaneous and special sensory receptors to the CNS
Motor neurons to skeletal muscle tissue
Autonomic (involuntary) nervous systems (ANS)
Sensory neurons from visceral organs to CNS
Motor neurons to smooth & cardiac muscle and glands
sympathetic division
speeds up heart rate
parasympathetic division
Slows down heart rate
Enteric nervous system (ENS)
Involuntary sensory & motor neurons control GI tract
Neurons function independently of ANS & CNS
Sensory function
sense changes in the internal and external environment
Integrative function
analyze the sensory information, store some aspects, and make decisions regarding appropriate behaviors
Motor function
Respond to stimuli by initiating action
Neurons
Functional unit of the nervous system
Dendrites
small neuronal cell processes (carry impulse toward the cell body of a neuron)
Cell Body
contains a single nucleus and other organelles (produce neurotransmitters)
Axon
a long, single neuronal cell process (carry impulse away from the cell body of a neuron)
Multipolar neuron
Multiple connections
Bipolar neuron
2 connections
Unipolar neuron
1 connection
Sensory or afferent neurons
Nerve impulse (action potential) conducted to the CNS Most are Unipolar
Motor or efferent neurons
Nerve impulse (action potential) conducted away from the CNS to effectors Multipolar
Interneurons or association neurons
Between sensory and motor neurons (in the CNS)
Most are multipolar
Neuroglia
“glue” that holds nervous tissue together
●Actively participate in the activities of nervous tissue
●do not generate or propagate action potentials
●4 types of neuroglial cells are found in the CNS, 2 types in the PNS
The 4 types of neurogila of the CNS
Astrocytes
Oligodendrocytes
Microglia
Ependymal cells
Astrocytes
Star-shaped, the largest and most numerous of the neuroglia
Maintains the blood-brain-barrier
Protect neurons by wrapping around blood capillaries
Play a role in learning and memory – guides the formation of neural synapses
Oligodendrocytes
Smaller than astrocytes and with fewer processes
forms and maintains myelin which insulates nerve cells in the CNS
Analogous to Schwann cells of the PNS
Microglia
Small cells that remove cellular debris
Ependymal cells
Cuboidal to columnar cells – possess microvilli and cilia
Line the ventricles of the brain and central canal of the spinal cord
play a role in cerebrospinal fluid (CSF) homeostasis, brain metabolism, and the clearance of waste from the brain
The 2 types of neurogila of the PNS
Schwann cells
Satellite cells
Schwann cells
Cells encircling PNS axons
Each cell produces part of the myelin sheath surrounding an axon in the PNS
Participate in axon regeneration
Satellite cells
Flat cells, provide structural support and regulate exchange of materials
Myelination
Process of ensheathing axons with myelin
Ganglion
A group (mass) of neuronal cell bodies lying outside the CNS
Nucleus
A cluster of unmyelinated neuronal cell bodies in the CNS
Nerve
A bundle of axons located in the PNS
Tract
A bundle of axons located in the CNS
Gray matter
Areas in the CNS and ganglia containing neuronal cell bodies, dendrites, unmyelinated axons, axon terminals, and neuroglia
White matter
Areas in the CNS that primarily contain myelinated axons
Action Potential AKA Nerve Impulse
Electrical signal that propagates along the membrane of a neuron or muscle fibre
Factors that affect speed of propagation
Amount of myelination
Axon diameter
Temperature
