multicellularity, nervous system, sensory system Flashcards
(130 cards)
1
Q
reoccuring themes of physiology
A
1) homeostasis
2) form and function
3) overcoming the limits of diffusion
2
Q
simple multicellularity
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- adhesion molecules that cause adjacent cells to stick together (colonies)
-no major specialization of communication between cells - every cell in contact with external environment
3
Q
complex multicellularity
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- specialized cell functions
- communication between cells
- take in info from environment -> signal -> craft response
4
Q
pros of multicellularity
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- longer life span
- greater efficiency of specialized cells
- sexual reproduction leads to more genetic diversity
- bigger better fit for survival
5
Q
multicellularity cons
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- increased energetic costs
- have to do more than just diffusion for survival
- takes longer to reach reproductive maturity
- possibility for infections
6
Q
surface area: volume ratio
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the smaller the animal = larger the SA: V ratio
* smaller organism -> faster molecular diffusion rate
7
Q
4 types of tissues
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connective, epithelial, muscular, nervous
8
Q
connective tissues
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fat, bone, cartilage
9
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epithelial tissues
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connectivity/ diffusion tissues
ex. gut epithelial tissues in GI tract
10
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muscular tissue
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skeletal, smooth (ex. digestive muscles), cardiac
11
Q
nervous tissues
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specialized cells that conduct signaling
12
Q
organ
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a collection of tissues that structurally form a functional unit specialized to perform a particular function
13
Q
mechanisms of substance transport
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diffusion and bulk transport
14
Q
pathway for systems based in homeostasis
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- communication of info to all different specialized cells
- translate signals into actions
- distribution of nutrients, energy and oxygen to muscles
- removal of waste
- defense immune system
15
Q
homeostasis neg feedback ex
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feel cold -> signal to hypothalamus -> muscles shiver -> stop signals once at right temp
16
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nervous system
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network of neurons that receive, process and transmit information
17
Q
group of neurons
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nerve
18
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ganglia
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collection of nerves
19
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cephalization
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concentrating sensory organs and sensory neurons at front/anterior of the body; helps sense the environment
20
Q
convergent evolution
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evolved independently several times
ex. cephalization
21
Q
nervous system 3 step mechanism; input and output
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1) sense (sensory input)
2) integrate/ process
3) coordinate response (motor output)
22
Q
central nervous system
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brain and spinal cord; sending and receiving messages to various parts of the body.
23
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peripheral nervous system
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part of your nervous system that lies outside your brain and spinal cord; sends info from different areas of your body back to your brain and carries out commands from your brain to various parts of your body
24
Q
3 types of neurons
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1) sensory neurons
2) interneurons
3) motor neurons
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sensory neurons
carries sensed impulses from the receptor to the CNS
*structure: cell body can be along axon
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interneurons
enables communication between sensory or motor neurons and the central nervous system; in CNS
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motor neurons
carries a signal from the central nervous system (CNS) to an effector cell, which then carries out the desired response
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pre synaptic neuron
sends signal
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post synaptic neuron
receives signal
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signal transduction steps
1) stimuli received by dendrites + cell body
2) signal goes to axon hillock to determine if signal is strong enough to fire action potential
3) signal through axon terminal -> release neurotransmitter
4) neurotransmitter bonds to post synaptic cell membrane -> new signal
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axon hillock
the region of a neuron that controls the initiation of an electrical impulse based on the inputs from other neurons or the environment; is signal big enough to fire action potential?
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relative charges of inside and outside of cell
inside: neg
outside: pos
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is there more potassium inside or outside of the cell
inside
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is there more sodium inside or outside of the cell
outside
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are there more sodium or potassium channels
potassium
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sodium potassium pump
moves Na+ out of the cell and K+ into the cell against the concentration gradient (active transport)
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K+ equilibrium potential
-90 mV
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Na+ equilibrium potential
+60 mV
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resting membrane potential
the electrical potential difference across the plasma membrane when the cell is in a non-excited state.; -70 mV
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what dictates the resting membrane potential of a neuron
equilibrium potential
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what is used to maintain resting membrane potenial
sodium potassium pump
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action potential
the change in electrical potential associated with the passage of an impulse along the membrane of a muscle cell or nerve cell
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action potential steps
1) threshold
2) depolarization
3) repolarization
4) refractory
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action potential; threshold
positive ions come into cell increasing its voltage (more pos)
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action potential; depolarization
large amounts of Na+ come into the cell; large increase in + V
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action potential; repolarization
large amounts of K rush out of the cell through open pore decreasing cell voltage
*once potential gets to around +40
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action potential; refractory
membrane potential drops below the resting membrane potential; have to build potential back up
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how are the K+ and Na+ pores opened and closed
inactivation gates
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Saltatory propagation
electrical impulses along axons is highly accelerated by the myelin sheath and produces saltating or “jumping” action potentials
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node of ranvier
a gap in the myelin sheath of a nerve that allow the generation of a fast electrical impulse along the axon.
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synapse
end of axon terminal where chemical signals released
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presynaptic membrane
end of neuron that is sending the signal; has Ca2+ channel that is opened by depolarization, Ca2+ released moves vesicles to exocytosis with membrane
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where are neurotransmitters released
synaptic cleft
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how are signals recived
postsynaptic membrane has ligand/ signal receptors that take neurotransmitters from synaptic cleft
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glial cells functions
- wrap axon in myelin sheath
-maintain the blood brain barrier
-structure/ stabilize neurons
-maintain homeostasis of interstitial fluid
-maintain ion conc
-release lactate for energy
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how do signals flow down axons
bounce/jump from node (protein region)-> to node (no myelin sheath)
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Astrocytes
type of glial cell (70% of CNS); functions
-maintain the blood brain barrier
-structure/ stabilize neurons
-maintain homeostasis of interstitial fluid
-maintain ion conc
-release lactate for energy
-clear neurotransmitters from synapse
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how many kinds of neurotransmitters do most neurons release
only 1
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how many kinds of neurotransmitters do most neurons accept at dendrites
many!
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how many other neurons does 1 neuron synapse with
hundreds
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ESPS
Excitatory postsynaptic potential;
2 types : non summation and temporal summation
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non summation esps
increase in potential (excitatory) BUT not enough to set off action potential (not up to threshold)
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temporal summation esps
potential sums up to threshold potential -> sets off action potenial
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ISPS
Inhibitory postsynaptic potential; membrane potential goes below resting potential.
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central nervous system
brain and spinal cord
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peripheral nervous system
part of your ns that is not brain and spinal cord; somatic and autonomic
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somatic nervous system
subcategory of PNS; controls voluntary, consciously controlled movement
ex. sensing the environment (sensory neurons) and controlled movement (motor neurons)
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autonomic nervous system
subcategory of PNS; controls involuntary, unconsciously controlled movement
2 subcategories; sympathetic and parasympathetic
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sympathetic nervous system
division of PNS autonomic NS; fight or flight response (increased heart rate, dilated pupils, inhibits intestinal system to focus on survival)
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parasympathetic nervous system
division of PNS autonomic NS: rest and digest response (slows heart, stimulates intestinal systems/ digestion, constricts pupils)
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thermo-sensitive sensory cells
constantly monitor temp and fire action potentials
- too cold -> signal muscles to shiver
- to hot -> signal for heat loss through sweat
*homeostasis
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muscle contraction mechanism
- controlled by muscle neurons
- acetylcholine binds to muscle membrane receptors -> depolarization of muscle cell -> contraction
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motor end plate
The specialized postsynaptic region of a muscle cell
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afferent nerve
bring sensory information to CNS
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efferent nerve
transfer info from CNS
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sensory receptors
special proteins in sensory cells embedded in sensory organs that detect changes in our environment
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sensory transduction
signal from environment taken in and processed (3 main types of receptors)
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chemoreceptors
molecule in environment is specific to certain receptor; indirectly opens ion channel to depolarize cell
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photoreceptors
signal into cell, ion channels close, cell is hyperpolarized
* how our eyes perceive light
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mechanoreceptors
how we perceive tactile information; pressure deforms cuticle, physical change in the ion channel, channels open and cell is depolarized
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what do mechanoreceptors detect
detect touch, pressure, vibration and tension
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mechanoreceptor reactivity
*highly sensitive; low threshold of activation
*highly myelinated -> fast signal
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action potential firing rate
depends on the strength of the signal
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action potential firing rate; continuous stimuli
same high firing rate but less frequent as stimuli prolonges
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lateral inhibition
enhances edge and boarder detection of signal by reducing extiment of adjacent interneurons
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olfactory sensory neurons
neurons in nose that sense odors that bind to receptors on chemosensitive hairs
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chemosensitive hairs
pick up signals from olfactory sensory neurons -> signal transduction pathway -> amplification
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what do interneurons do for smell pathway
integrate info from olfactory receptor before sending info to brain
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sense of smell and nose size
bigger nose -> more chemosensitive hairs (greater SA) -> better sense of smell
ex. chihuahua vs bloodhound
*evolution and genetics
90
how are sweet, savory and bitter flavors received
g protein coupled receptors
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how are salty flavors received
Na+ depolarizes cell -> opens Ca2+ channel
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how are sour flavors received
H+ ion channels depolarizes cell AND inhibits K+ channels
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oral referral
causes you to perceive whats going on in the nose as if it is inside the mouth
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what flavors detected by nose
menthol (mint), carbonation, spice/hot
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stereocilia
hair-like protrusions on the surface of sensory cells that serve as mechanoreceptors; motion and gravity
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statocyst
a small organ of balance and orientation in some aquatic animals that contain statolith; help perceive current direction
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statolith
particle in statocysts that stimulates sensory receptors in response to gravity, so enabling balance and orientation
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mechanoreceptor hair cell
Hair cells in the inner ear that detect sound and head movement.
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support cell
mediators of hair cell development, function, death
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vestibular system
functions to detect the position and movement of our head in space; moves faster than eyes
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semicircular canal
fluid movements through semicircular canals cause disruption to sensory cells -> open ion channels -> signal transduction
* in inner ear
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outer ear
collects sound waves and channels them into the ear canal;
auditory canal (pinna -> auditory canal -> eardrum)
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middle ear
connects the sound waves from the external environment and transfers them to the inner ear for auditory transduction.
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inner ear
transform the vibrations into electrical impulses that then travel along the eighth cranial nerve (auditory nerve) to the brain
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malleus, incus, and stapes
3 bones in middle ear
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Vestibulocochlear Nerve; 2 branches
- vestibular branch: balance and spatial sensation
-cochlear branch: special sensation of hearing
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Cochlea
receiving and analyzing the sounds which are interpreted by hair cells or stereocilia.
108
entrance to cochlea
oval window and round window
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eardrum
vibrates when sound hits it at same frequency of sound wave -> initiates hearing
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3 step mechanism for hearing
1) sound wave directed into auditory canal by pinna
2)sound hits eardrum at same frequency as sound wave -> passed on
3) sound -> mechanical force -> fluid waves (inside cochlea)
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hair cell activation in inner ear
disturbed by fluid wave -> open ion channels -> k+ flows into the cell -> depolarization and signal transduction
*once pathway is activated fluid wave goes opposite direction to depolarize cell
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basilar membrane
membrane in cochlea that supports hair cells, serves as the base layer of the organ of Corti, and propagates sound vibrations that allow the brain to interpret sound
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tectorial membrane
membrane above the hair cells; stimulates movement of hair cells
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organ of Corti
transduction of auditory signals; mechanoreceptor hairs anchored at organ of corti
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retinal
compound bound to the protein opsin; when light hits cis-retinal -> trans-retinal -> activation of protien
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opsin
photoreceptor protein; signaling state regulated by activation of retinal -> G protein pathway cascade
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fovea
part of retina that sharpens visions; (most cones in fovea)
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retina
layer of photoreceptors and glial cells that capture the light that enters your eye and helps translate it into images
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lens
focuses light for the retina
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cornea
transparent shield
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ciliary muscle
muscle in eye that allows you to focus; changes the shape of the lens when your eyes focus on a near object
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iris
colored part of eye; adjusts the size of the pupil to control the amount of light that enters the eye.
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optic nerve
nerves at back of eyes that relay visual info the the brain
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rod and cone functions
rods: cells that allow us to see things in dim lighting
cones: help see color (red, blue, green or combo of both; dependent on nm of wavelength)
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phototransduction cascade
G protein coupled pathway activated by opsin conformational change (retinal) -> cGMP PDE -> Na+ channels close -> HYPERPOLARIZATION
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PDE function
closes Na+ channels to hyperpolarize the cell; at rest cGMP keeps channels open
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bipolar cell
retinal interneurons; photoreceptor cells (rods and cones) -> ganglion cells
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ganglion cell
neurons that connect the retinal input to the visual processing centres within the central nervous system.
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horizontal cell
sharpen image; lateral inhabiton
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amacrine cell
adjust motion and brightness; lateral inhibition
