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27 Cards in this Set

  • Front
  • Back
what is the function of Sense?
to detect and send info to the CNS regarding internal and external environment
what do Visceral afferents do?
they detect information about the internal environment
what types of information do visceral afferents detect?
blood pressure
internal temperature
CO2 concentration
does visceral afferent info reach consciousness?

why do we need them?
no; they are necessary for maintaining homeostasis
what are sensory afferents?
axons that detect info re: outside temp and position in space (somatic),or vision, hearing, taste, or smell (special sense).
what is a stimulus?
the energy that impinges upon and activates a sensory receptor
what are the 2 possible forms of sensory receptors?
1. The specialized end of an afferent neuron that directly passes a change in potential along the neuron.

2. a seperate cell that releases a chemical to generate a change in potential of the afferent neuron.
what is stimulus transduction?
the process where a stimulus (like light or tissue stretching) is transformed into electrical energy
what is an adequete stimulus?
the type of energy that normally stimulates a neuron, and does it best.
what is the difference between a Receptor Potential and Generator Potential?
Receptor Potentials occur when a SEPERATE cell from the neuron is stimulated and then causes ion channels to open.

Generator Potentials occur when a special membrane portion of the afferent neuron ITSELF recieves the stimulus and causes ion channels to open.
what is an example of a RECEPTOR potential?
a ROD or CONE in the eye.
a seperate cell is stimulated by light, and releases a chemical messenger to diffuse across a synapse to chemical-messenger-gated channels in the afferent neuron.
What are two examples of GENERATOR Potentials?
The stimulus acts right on the aff. neuron itself, and current - graded potential - flows from the initial membrane stimulated to where there are voltage-gated channels to activate.
How are Action Potentials generated by
-Receptor potentials
-Generator potentials
Receptor potentials cause a chemical to diffuse and activate/open chemical msngr-gated ion (Na+) channels.

Generator potentials cause charge to open voltage-gated Na+ channels.
What is "Adaptation"?
a decrease in action potential generation with the same strength of stimulus.
What type of receptors are slow or non-adaptive?

2 examples?
Tonic receptors.
Pain receptors - meant to tell us when we're in danger..

Muscle-joint receptors - give information re; where our limbs are in space - if we forget, we'd fall over.
what are rapidly-adapting receptors called?
How do Phasic receptors work?
example: putting on a watch.
You put on a watch and feel it initially, then immediately get used to the constant presence. - Stim remains Constant, but the receptor turns off.
When you remove the watch, you feel it - that is the OFF-RESPONSE.
what are Phasic receptors really concerned with?
stimulus INTENSITY -
PUT it on
TAKE it off
while it's on, you don't care.
what does a Pacinian corpuscle do?

what type of receptor is it?
detects changes in pressure and vibration, proportional to how intense it is.

the neuron is wrapped in layers of connective tissue. when something presses on it, Na channels open and a generator potential is generated. When the pressure removes, an off-stimulus fires. PHASIC
What is the "Receptive Field"?
the area within which the sensory neuron responds to sensory information
what is acuity?
one's ability to discriminate between senses. the smaller the receptive field, the more acute the sensation is.
what is Receptor Density?
the amount of neurons there are in a receptive field.
How do you get the greatest Acuity?
by having a very high density of receptors in a very small receptor field.
what does the CNS Code of Information include?
1. Stimulus intensity
2. Stimulus location
3. Stimulus Identity
how is a stimulus intensity increased or changed?
a. Frequency - the greater NUMBER of generator potentials induced by a stimulus, the greater number of Action potentials will result.

b. Receptor Fields - the greater number of them for the same neuron type, the more intense of a sensation will be felt.
How is it that the CNS code of info tell you the LOCATION of a stimulus?
Because everytime a neuron fires, it sends the SAME information from the SAME TYPE of stimulus
How does the CNS code convey what TYPE of stimulus is firing the neuron?
Because according to Muller's doctrine, a specific neuron will convey a specific type of info to the CNS