nerves and action potentials Flashcards
dendrite
collection site of the neuron; input; signal moves towards the soma
soma
integration; center of the neuron, houses the nucleus
axon
conduction; signal moves away from the soma
axon terminal
transmission
axon hillock
location where the axon meets the soma; where action potentials are generated
glial cells
neuron support cells, provide metabolic and structural support
Schwann cells
glial cells that provide a myelinated sheath to speed up signal transmission; found in the peripheral nervous system
oligidendrocytes
glial cells that provide a myelinated sheath to speed up signal transmission; found in the central nervous system
astrocytes
glial cells that line capillaries and serve as metabolic intermediates
neuronal circuit
signal>sensory neurons>interneurons or motor neurons>effector
sensory neurons
step in the neuronal circuit that decide on action potentials; afferent fibers
interneurons
step in the neuronal circuit that links in the central nervous system; send signals out
motor neurons
step in the neuronal circuit that signals muscle movement; efferent fibers
afferent fibers
signals coming in
efferent fibers
signals going out
polarized cell
has electrical potential; resting state
depolarized cell
moving from negative to less negative due to some potential
repolarized cell
returning to resting polarized state after a potential
hyperpolarization
period of becoming too negative to overcompensate for an action potential
graded potential
graded response, initial disturbance dies with distance or time, can be summed, no threshold, no refractory period, duration and intensity varies, can be de or hyper polarizing, initiated by stimulus, or spontaneously
Action potential
all or nothing response, can be regeneratively propagated, cant be summed, requires a threshold to be met, refractory period, duration is constant, only depolarizing, only initiated by membrane depolarization
passive electrical resting potential
capacitance and resistance occurring across the cell membrane
active electrical resting potential
voltage gated channels allow rapid depolarization
capacitance
the ability to hold a charge and resist change
local response
a kind of action potential that barely reaches the threshold creating a weak signal that dies out before reaching the central nervous system
rising phase of an action potential
sodium channels open allowing an influx of sodium to enter the cell which surpasses the threshold and leads to a rapid depolarization of the cell
termination phase of an action potential
top of the peak; sodium channels close to stop depolarization
repolarization phase of an action potential
potassium channels open reestablishing the equilibrium in the cell
hyperpolarization phase of an action potential
refractory period in which the cell becomes more polar than its resting phase; another action potential is not possible at this time
resting phase of an action potential
sodium potassium pumps return to normal and cell maintenance occurs
voltage gated channels
protein channels open to a specific type of ion
what determines the speed at which action potentials travel
capacitance and resistance both can be reduced by increasing fiber diameter meaning larger fibers transmit faster action potentials
myelin sheath
layer of glial cells around a neuron that speed up transmission by reducing the amount of depolarization that must occur; insulates the neuron
node of ranvier
the gap between the glial cells in the myelin sheath where regenerative depolarization occurs; allows for saltatory conductance
synapse
coupling between 2 neurons or between a neuron and its effector
electrical synapse
less common type of synapse; nerve cells are connected via gap junctions allowing ions to pass between nerves
chemical synapse
most common type of synapse; nerves communicate via a transmitter substance that is ionotropic or metabotropic
ionotropic chemical synapse
presynaptic action potential depolarizes the membrane, voltage gated channels are activated, calcium diffuses into the cell signaling NT filled vesicles to migrate into the membrane, exocytosis of NT into the synaptic cleft, the transmitter binds directly to the receptor to activate a response; fast
metabotropic chemical synapse
presynaptic action potential depolarizes the membrane, voltage gated channels are activated, calcium diffuses into the cell signaling NT filled vesicles to migrate into the membrane, exocytosis of NT into the synaptic cleft, binds to a receptor that initiates a second messenger; slow
PSP post synaptic potential
graded potentials resulting from NT; integrated at the axon hillock which is where the soma meets the axon
EPSP excitatory post synaptic potential
induces changes in Vm to increase the probability of initiating an action potential; positive
IPSP inhibitory post synaptic potential
induces changes in Vm to decrease the probability of initiating an action potential; negative
spatial summation
adding signals from multiple sources; occurs in conjunction with temporal summation
temporal summation
adding more to a single signal over time; occur in conjunction with spatial summation
sensory reception
gathering processing and responding to information
exteroceptors
receive information from outside the body and communicate it to the central nervous system; 5 senses
interoceptors
receive information from inside the body and communicate it to the central nervous system
mechanoreceptors
detect deformation; mechanical distortion of the plasma membrane leads to the opening of ion channels; touch
thermoreceptors
sense temperature both internally and externally
nociceptors
sense tissue damage and pain
electromagnetic receptors
detect light
chemoreceptors
sense chemical concentrations; involved in taste and smell
process of sensory perception
detection>amplification>transduction>transmission; relying on selectivity and sensitivity
sensory transduction
process by which stimulus energy is changed into the energy of a nerve impulse resulting in charged ionic conductance; activation of a receptor by a stimulus reaching a receptor cell; a graded potential
amplification
a cascade of protein interactions modifies an intracellular second messenger causing ion channels to either open or close
sensory adaptation
changes in perceived intensity of sensation even when the physical intensity has not changed
tonic receptor
action potentials slow with continued stimulation
phasic receptor
action potentials stop with continued stimulation
range fractionation
sensitivities of different neurons vary which increases the range of detection
photoreceptors
a form of electromagnetic receptor that transduces energy in photons into action potentials to be integrated in the central nervous system
compound eye
image forming eyes with multiple lenses; either apposition or superposition transmission; ex: insect eyes
apposition eye
a form of compound eye where each lens goes to its own receptor structured in an omatidium
superposition eye
each individual lens all come together to one rhabdom
omatidium
structures in an apposition eye including the corneal lens and crystalline lens attach to the rhabdom which captures several light forming images
vertebrate eye
a single lens with minimal refraction, signal is received by sensory receptors at the back of the eye where the image is flipped and the size is modified
pigment epithelium of the eye
region of the eye behind the retina where images are recieved
horizontal cells of the eye
connect rods and cones and integrate their separate signals
bipolar cells of the eye
link horizontal cells to the amacrine cells
amacrine cells of the eye
aid in metabolic control of image reception and transmission
ganglion cells of the eye
location where action potential is generated and sent to the optic nerve which connects to the central nervous system
rods and cones
image reception cells found in various numbers in the retina appearing in different concentrations in each part of the eye
macula
location in the eye with the highest concentration of rods and cones
convergence
both eyes converge on a single visual axis so they’re both looking at the same object; only possible with binocular vision
accomodation
an object must be brought into focus on the retina; some animals move the lens or retina; some change the shape of the lens
vision in water
light detection decreases as depth increases, light is differentially absorbed with blue being the last color to be absorbed; the refractory index of water is close to that of the retina so this is fixed by a thick spherical lens or moving the lenses
rhodopsin
a visual pigment that allows vertebrates to see light; made up of retinal and opsin; light activated, changes shape when absorbing a photon it flips between cis and trans
retinal
part of rhodopsin; a form of vitamin A that absorbs light
opsin
part of rhodopsin; a lipo protein not capable of absorbing light
dark current
in the dark, sodium channels open, maintaining 30mV resting potential and releasing glutamate, closed when light is detected
ciliary muscles of the eye
control the shape of the lens, when relaxed, the lens is flat and focused on the distance, when contracted the lens becomes spherical and can focus up close
pacinian corpuscles
type of mechanoreceptor; layers of connective tissue sending signals at the onset and offset of a stimulus
stretch receptors
a type of mechanoreceptor that sends faster signals as muscles stretch and slower signals as muscles contract
insect bristles
work similarly to mechanoreceptors; sense direction of a stimulus based on which ways bristles bend, bending opens potassium channels
hair cells
similar to mechanoreceptors; cilia on the surface and fluid filled canals give direct water contact to sense direction; lack axons, synaptic transmission
lateral line system
capulas sense vibrations, cilia attached to hair cells are embedded in the capula
statocysts
organs of equilibrium in crustaceans and bivalves; statolith presses on hair cells based on orientation; crustaceans also utilize a horizontal and vertical canal
vertebrate inner ear
organ of equilibrium and audition; tympanic membrane connects the incus, malleus, and stapes which aid in sound modification; semicircular canals filled with endolymph are lined with hair cells embedded in a gelatinous layer; vibrations are converted to nerve impulses in the cochlea
external ear
collects and funnels sound to transmit vibrations to the fluid filled inner ear
middle ear
tympanic membrane receives sound signals which are magnified by the malleus incus and stapes before being sent to the oval window
invertebrate sensilla
chemoreceptors containing dendrites to detect certain chemicals; each sensilla only detects one chemical
taste buds
chemoreceptors in terrestrial vertebrates; group taste receptors internally; basal cells detect taste and are regularly replaced; no axon; sour and salt are ionotropic receptors; sweet bitter and umami are metabotropic receptors
smell receptors
chemoreceptors for gathering information from a distant chemical environment, perceived by dendrites within a mucus layer to a primary afferent axon with a secondary messenger
vertebrate olfaction
olfactory bulb and vermonasal organ in the hard pallet allow organisms to scent the air through their mouth
Eimer’s organ
specific to the nose of the star nosed mole, allows them to rapidly determine whether or not something is edible
