Nervous System Flashcards
What are the functions of the nervous system?
-sensory input (receptor monitor stimuli inside and outside body)
-integration (process, interprets, assimilates experiences)
-motor output (response; muscle contraction, glandular secretion)
What is included in the CNS?
brain and spinal cord
What is included in the PNS?
nerves and ganglia
Sensory signals
picked up by sensory receptors
Motor signals
carried away from the CNS
What is included in somatic sensory?
vision, hearing, skin, proprioception
What is included in visceral sensory?
smell, taste, hunger, viscera
What is the action in somatic motor?
contraction of skeletal muscles
What is the action in visceral motor?
secretion of glands, contraction of smooth and cardiac muscles, part of the Automatic Nervous System
What are glial cells?
-found in the CNS and PNS
-smaller
-mitosis
-protect and nourish neurons
-provide organized and supporting framework
-more abundant than neurons
-not capable of impulse transmission
Astrocytes
-star-shaped
-most abundant
-connect neurons to blood vessels
-control flow of substances
-control chemical composition (bouncer)
Ependymal cells
-cuboidal epithelial cells
-found in ventricles and central canal of spinal cord
-have basal projections to contract, produce spinal fluid
Microglia
-small cells with projections
-not abundant
-don’t originate in nervous tissues
-modified white blood cells
-remove debris
Oligodendrocytes
large with globular bodies and slender projections
-form myelin sheath in axons for insultation, protection, nourishment
-one cell can wrap around multiple axons
Satellite cells
-flattened cells
-regulate nutrient and waste exchange
Neurolemmocytes
-Schwan cells
-surround axons for insulation and protection
What are the functional classifications of neurons?
-Sensory neurons: originate in sensory receptors, respond to stimuli, travel to CNS
-Motor neurons: originate in CNS, travel to effectors
-Interneurons: located btw motor and sensory neurons, found in CNS, make up 99.*% of neurons in the body
What are the structural classifications of neurons?
-Unipolar neurons: sensory neurons
-Bipolar neurons: rare, found in nose and inner ear
-Multipolar neurons: most common type, motor and interneurons, cell body mostly in CNS
Nuclei
clusters of neuron bodies in CNS
Ganglia
cluster of neuron bodies in PNS
Tract
clusters of axons in CNS
Fibers/nerves
clusters of axons in PNS
Gray matter
cell bodies of interneurons and motor neurons, nonmyelinated interneurons (where connections happen)
White matter
fiber tracts of myelinated and nonmyelinated axons (highway)
What is myelination? Why is it important?
-process by which part of an axon is wrapped with a myelin sheath
-speeds up signals and insulates neuron
Synapses
junctions where axons contact other neurons, muscle cells, or glands
Electrical Synapses
-membranes of pre and post synaptic neurons bound together
-bidirectional
-fast and secure flow of ions
-not common in brain
-found in smooth muscle and cardiac muscle
Chemical Synapses
-have signaling molecule, neurotransmitter
-unidirectional
-more common
-Ach is most common
What are factors that influence the rate of conduction?
Axon diameter: larger diameter = faster
Presence of myelin increase rate
Continuous conduction
Saltatory conduction is only in exposed regions
What are the differences between monosynaptic and polysynaptic reflexes?
Monosynaptic: direct communication between sensory and motor neurons
Polysynaptic: interneuron facilitates sensory-motor communication
