Nervous system
a network of interconnected nerve cells
Neurons
basic functional units of the nervous system
Homeostasis
the ability of
... [Show More] animals, organs, and cells to actively regulate and maintain a stable internal state
What are the three types of nerve cells?
sensory neurons, interneurons, motor neurons
Sensory neurons
send and receive information about an animal's environment or it internal physiological state
Interneurons
process the information received by sensory neurons and transmit it to different regions of the body and the corresponding motor neurons
Motor neurons
produce suitable responses
Ganglia
groups of nerve cell bodies that process sensory information from a nearby region, and then signal motor neurons
Nerve cords and nerves
bundles of the long fiberlike extensions from multiple nerve cells
Cephalization
concentration of sense organs and nerve cells at the front of an animal's body
Glial cells
cells in the nervous system that support, nourish, and protect neurons
Membrane potential
the charge difference between the inside and the outside of a neuron
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Resting potential
-70 mV
Depolarization
the increase in membrane potential
Threshold potential
-50 mV
Refractory period
the period during which the inner membrane voltage falls below and then returns to the resting potential
Myelin Sheath
insulating membrane surrounding the axon in some neurons
Nodes of Ranvier
Gaps in the myelin sheath to which voltage-gated sodium channels are confined.
Saltatory propagation
the movement of an action potential along a myelinated axon, "jumping" from node to node
Temporal summation
Summation by a postsynaptic cell of input (EPSPs or IPSPs) from a single source over time.
Spatial summation
The sum of multiple synapses firing at different locations at one time to create a net effect.
Afferent neurons
Nerve cells that carry impulses towards the central nervous system
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Efferent neurons
Nerve cells that conduct impulses away from the central nervous system
Somatic nervous system
voluntary
Autonomic nervous system
involuntary
Sympathetic nervous system
the division of the autonomic nervous system that arouses the body, mobilizing its energy in stressful situations
Parasympathetic nervous system
the division of the autonomic nervous system that calms the body, conserving its energy
Reciprocal inhibition
The simultaneous contraction of one muscle and the relaxation of its antagonist to allow movement to take place
Chemoreceptors
respond to molecules that bind to specific protein receptors
Mechanoreceptors
respond to touch, pressure, vibration, stretch, and itch
Photoreceptors
respond to light
Lateral inhibition
enhances the strength of a sensory signal locally but diminishes it peripherally
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Hair cells
receptor cells for hearing
Stereocillia
these make up the individual 'hairs' of the hair cell
Statocyst
The organ of balance in most invertebrates
Statolith
a dense particle that moves freely within a statocyst, enabling it to sense gravity
Vestibular system
three semicircular canals that provide the sense of balance, located in the inner ear and connected to the brain by a nerve
Semicircular canals
three canals within the inner ear that contain specialized receptor cells that generate nerve impulses with body movement
Sweet, bitter, and savory
G-protein coupled
Salty
Na+ depolarize the cell, opening the voltage-gated Ca+ channels [Show Less]