chapter 10 Flashcards
what are sensory neurons
Sensory neurons have an end to receive sensory stimuli and produce the nerve impulse and the other delivers impulse to synapse in the CNS. The cell body is located in the middle
Sensory receptors are specialized cells that generate graded potentials called _____ ______ in response to a stimulus.
receptor potentials
- Stimulus_: energy or chemical activating a sensory receptor
- Modalities (types of senses) arise from different receptors, each sensory neuron is specific to a sensation
- In other words, it’s all action potentials but pathways, synapses and the brain work to aid in interpretation
Mechanoreceptors
mechanical deformation
thermoreceptors
heat and cold
photoreceptors
light
chemoreceptors
chemical composition
nociceptors
pain
stimulus strength
increasing the frequency of AP
adaptation
a decrease in receptors sensitivity
phasic receptos
respond quickly but just as quickly adapt to stimulus
tonic receptor
maintain response to stimulus
area stimulated is called the
receptor field; changes the firing rate of a neuron
characteristics of a receptor field
- size of receptor field depends on the density of receptors
- the more receptors, the smaller the receptive filed (fingertips), the larger the area of the somatosensory cortex
- a small receptive field=greater tactile acuity: sharpness of the sensation
- large receptive fields mean fewer receptors (Back)
Lateral inhibition
-enhances the contrast between the center and periphery of a stimulated region, thereby increasing the brain’s ability to localize a sensory input.
- Receptors in the central area are stimulated more than neighboring receptors
- Receptors that are most strongly stimulated inhibit those around them.
another phrase for lateral inhibition
sharpening of sensation
the sharpening of sensation or lateral inhibition-reduces input from neighboring sensory neurons
true; you can pinpoint the sensation more accurately?
Mechanoreceptors in skin
- Respond to touch and pressure
- Some have large receptive fields
- ->ex. Palm of your hand
- Others have small well-defined receptive fields
- ->ex. fingertips
Thermoreceptors !
- Respond to thermal cues, Some chemicals can open channels as well
- More receptors for cold (located close to surface) than warm
Nociceptors!
Respond to intense mechanical deformation, extreme temps and chemicals
-pain
transient receptor potential channels
Painful heat or painful cold stimulates a whole different set of channels to open in the membrane called: transient receptor potential channels
Referred pain
- Occurs due to both visceral and somatic afferent neurons converging on the same neurons in the spinal cord.
- Brain refers to somatic source
- Common areas of pain felt even though pain is in an internal organ
How is pain different from other sensory information?
-After initial AP: changes can occur that may increase of decrease sensitivity to pain
-Pain can last after original stimulus is gone
-Pain can be altered by past experiences,
Emotions and simultaneous activations of
Other senses
EX: phantom limb
-Pain reduction depends mainly on endogenous
Opioids
