central nervous system: afferent
acuity
(n.) sharpness (particularly of the mind or senses)
ependymal cells
-barriers beyween compartments - source of neural stem cells
adequate stimulus
form of energy to which a receptor is most responsive
Schwann cells
form the myelin sheath around axons of PNS neurons and participate in axon regeneration
axon
functions as the output portion of the neuron by generating action potentials and then propagating them toward another neuron, muscle fiber, or cell
lateral inhibition
increases contrast between activated receptive fields and inactive neighbors
-which sensory neurons are activated -where neurons terminate in brain
modality is indicated by...
motor neurons
most ___ ____ have numeerous dendrites and one main axon extending from their cell bodies
microglia
remove cellular debris formed during normal development of the nervous system and phagocytize microbes and damaged nervous tissue
Thermoreceptors
respond to changes in temperature
Oligodendrocytes
responsible for forming and maintaining the myelin sheath around axons of neurons in the CNS
interneurons
responsible for integration- they process incoming sensory information from sensory neurons and then elicit a motor response by activating the appropriate motor neurons
photoreceptors
responsive to visible wavelengths of light
detection
to the stimulus
detects, encodes, and transmits
3 processes of afferent divison
modality, location, intensity, duration
4 properties of stimulus
astrocytes, oligodendrocytes, microglia, and ependymal cells
4 types of neuroglia in CNS
tonic receptors
adapt slowly or not at all
CNS myelin
____ ___ is one of the factors inhibiting regeneration of neurons
action potential
a receptor of sufficent magnitude can produce
dendrites
a stimulus in the brain causes a graded potential to form in the _____ and cell body of an upper motor neuron
action potentials
action potentials awlays depolarize followed by repolarizing and return to resting potential
CNS
afferent neurons coney action potentials into the
tight junctions
astrocyte processes surrounding brain capillaries secrete chemicals that maintain the tightness of these ___ ____
neuroglia
astrocytes are the most nuemorus __
K+
astrocytes regulate the concentration of ions such as ___
cell body
because of its ability to direct protein synthesis and other activities, the _____ ___ functions as control center of neuron
false
binding of some neurotransmitters to their receptors always results in the opening of ion channels in postsynaptic membranes
tract
bundle of axons in CNS
nerve
bundle of axons in PNS
compound sensations
by combining combinations of sensory modalities, our brain can produce nonspecific sensations such as wetness
receptor potential
change in sensory receptor membrane potential
intensity
coded by frequency of action potentials
perception
conscious awareness of sensation
PNS
consists of all nervous tissue outside the CNS
motor tracts
consists of axons that carry action potentials away from the brain
sensory tracts
consists of axons that conduct action potentials towards the brain
motor areas
control execution of voluntary movements
medulla
controls involuntary actions such as breathing
brain stem
controls many life sustaining processes, such as respiration, blood pressure, and digestion
efferent neurons
convey action potentials away from the CNS to effectors in the periphery
Afferent division of PNS
conveys input into the CNS from sensory receptors in the body
somatic nervous system
conveys output from the CNS to skeletal muscles only
ANS
conveys outputs from the CNS to smooth muscle, cardiac muscle and glands
association areas
deal with the more complex integrative functions such as memory, emotions, reasoning, will, judgement, personality traits, and intelligence
osmoreceptors
detect changes in concentration of solutes in body fluids and resultant changes in osmotic activity
motor areas
direct skeletal muscle movement
proportional
duration of a series of action potentials is _____ to stimulus duration
sensory receptors
either the peripheral endings of sensory neurons or separate cells located close to sensory neurons
true
glia do not generate or propagate action potnetials
true
graded may be hyperpolarizing or depolarizing
astrocytes
help maintain the appropraite chemical environment for the generation of action potentials
false
in CNS there is repair of an axon after injury
chemoreceptors
include receptors for smell and taste and receptors that detect O2 and CO2 concentration in blood and chemical content of digestive tract
visceral afferent
incoming pathway from organs
ion channels
initiate membrane potential change
neurotransmitter
nerve action potnetial travels along the axon of interneuron, which results in ______ release at the next synapse with another internueron
glia
nourish and protect neurons and maintain homeostasis in the intersitial fluid that bathes them
brain stem
oldest region of brain
cerebral cortex
once internuerons in the ____ ____ are activated, perception occurs and you are able to feel the smooth surface of the pen touch your fingers
motor function
once sensory information is integrated, the CNS may elicit an appropriate response
non-specific cation
once the stimulus happens the opening of what channels occurs
nocieptors
pain receptors that are sensitive to tissue damage or distortion of tissue
CNS
processed sensory information, generates thoughts,emotions and memories, stimulates muscles to contract and glands to secrete
ependymal cells
produce and assist in the circulation of cerebrospinal fluid
phasic receptors
rapidly adapt to a constant stimulus and turn off
dendrites
recieve signals from stimuli in the environment and function as main input portion of neuron
hypothalamus
recieves sensory input from receptors for vision, taste, and smell
transmits
send action potential into CNS
sensory afferent
sensation arsiging from body surface and proprioception
mechanoreceptors
sensitive to mechanical energy
one
sensory neurons have how many process(S) that extend from their cell bodies
encodes
sensory transduction: mechanical stimulus----> electrical (AP)
dendrties
short, highly branched processes that extend from the cell body
secrete
stimulation of the effectors causes muscles to contract and glands to
permeability
stimulus leads to change in membrane ____
sensory receptor
structure that monitors changes in the external or internal environment
nerve action potential
the graded potnetial triggers the axon of the sensory neuron to form a ____ ___ ___
interneuron
the neurotransmitter stimulate the ____ to form a graded potential in its dendrites and cell body
cerebral cortex
what manipulates a picture so that we think it is moving