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what do sensory cells tranduce?
physical and chemical stimuli into neuronal signals
what does sensory transduction begin with?
begins with a receptor protein that can detect a specific stimulus
what does the receptor protein do in sensory transduction?
it opens or closes ion channels in the membrane, which changes the resting potential.
what is our main way of sensing the world?
our main is through vision, but others can be
- 1. thermo-sensitive
- 2. electrical detection
- 3. magnetic fields of earth for direction
what is an Ionotropic receptor? and examples
- 1. Ion channels directly affect ion channels
- 2.Pressure sensitive
- 3.Temperature sensitve
what is a Metabotropic receptor? and examples
1.affect ion channels through G proteins and second messengers
what happens with an Ionotropic recpeptor?(Example)
Voltage-gated Ca2+, electric charge opens the channel
what happens with a Metabotropic receptor?(example)
- 1. Activated by ligand gated channel
- 2. Protein binds
- 3. Then, ions such as K+ are allowed to go in
- 1. G protein activates effector molecules
- 2.Alllows voltage gated Na+ or K+ channel to open and let ions in
- 1.Light activates the protein instead of molecule
- 2.Iniates a signaling cascade that controls an ion channel
the 5 senses
- 1. Touch
- 2. Smell
- 3. taste
- 4. Vision
- 5. Hearing
Sensory receptor proteins can be....
graded membrane potentials that travel a short distance
Receptor potentials can generate action potentials in two ways:
- 1. Can generate action potentials in the receptor cell
- 2. Can trigger release of neurotransmitter so that a downstream neuron generates an action potential
stimulating a sensory cell produces what?
a receptor potential
- 1. End plate Potential
- -created by acetylcholine causing depolarization of the muscle cell membrane.
- 1. Excitatory Postsynaptic potential
- - Depolarization in the membrane of a postsynaptic neuron caused by the binding of an excitatory neurotransmitter from a presynaptic cell to a postsynaptic receptor
- -makes it more likely for a postsynaptic neurone to generate an action potential
- 1.Inhibitory Postsynaptic Potential
- - local change in the degree of hyperpolarization of the postsynaptic membrane of a neuron in response to the arrival of an inhibitory impulse
- - makes a postsynaptic neuron less likely to generate an action potential.
- 1.Stretching opens membrane
- 2.Sodium flows in
- 3.Causes depolarization
- 4.Causes a receptor potential at the cell's dendrites
- 5.Spreads throughout the body
- 6.Spreads to the base of cell's axxon hillock
- 7.Voltage gated Na+ start to open because of enough depolarization
- 8.Creates action potentials that travel down the axon to the CNS
The rate at which potentials are fired by axon depends on....
- 1.The magnitude of the receptor potential
- 2.How much muscle is stretched
Sensation depends on...
1.What part of the CNS recieves sensory messages
Intensity of sensation is coded as...
the frequency of action potentials
Neuronal activity in the auditory cortex is perceived as...
If you stimulate the visual cortex, even...
blind subjects report seeing light
Sensory systems include...
- 1.sensory cells
- 2.associated structures
- 3.neural networks:process information
1.Diminishing response to repeated stimulation
what does adaptation allow animals to do?
1.Ignore background conditions but remain sensitive to changing or new stimuli
Example:Some sensory cells don't adapt
1.Mechanoreceptors for balance and pain
Olfactory and gas
Olfactory adapts to gas, don't realize it's there anymore can be very bad
1.Receptor proteins that bind to various molecules
what are chemoreceptor ligands responsible for?
- 3.Monitor internal environment such as CO2 levels in bloodstream
Olfaction is what sense
sense of smell
sense of smell depends on...
where are olfactory sensors embedded?
- 1.In epithelial tissue, at top of nasal cavity
- 2.In vertebrates
1.A molecule that activates an olfactory receptor protein
where do odorants bind to receptor proteins?
on the olfactory cilia of olfactory neurons
- 1.G-protein activates an enzyme
- 2.Increase of 2nd messenger (cAMP) in the cytoplasm
- 3.cAMP binds to cation channels in the sensory cell's plama membrane
- 4.Influx of Na+ and Ca2+
- 5.Creates a depolarization
- 6. starts the action potential
- 7.Calcium will bind to chloride ions
- 8.Negative (Cl-) ions will flow out and we get an action potential
a little depolarization is a ......and alot is....
receptor potential and a lot is an action potential
In the olfactory bulb, where do axxons from neurons with the same receptors converge?
- 2.Some people report tasting red
- 3.Wiring in the cortex is messes up