Lecture 14: Sensory Physiology Flashcards
What two things do sensory information provide us with
1) Information from environment
2) Information about ourselves
What are the 3 senses
1) Conscious
2) Unconscious
3) Receptors
Define the two senses in Consciousness
1) Special senses = the 5 main senses
2) Somatic senses: Touch temp, pain, itch all within the somatosensory cortex of the parietal lobe
What are the two unconscious senses
1) Somatic (muscle tension
2) Visceral senses (involving organs)
Proprioception can be what two senses
Conscious or unconscious
In neuroscience a receptor can refer to what
a) A protein that binds a ligand
b) A structure that detects sensory information
What are the 5 general properties of sensory systems
1) Receptors are most sensitive to certain forms of energy and stimuli
2) Sensory transduction converts stimuli to graded potentials
3) Sensory neurons have receptive fields
4) The CNS integrates sensory information
5) Coding and processing distinguish stimulus properties
What is modality
Refers to what is perceived after a stimulus (form of stimuli)
What are the 4 main modality detected by sensory receptors
1) Heat
2) Light
3) Mechanical energy
4) Chemical stimuli/ligands
What are the 3 general structural forms of sensory receptors and describe each
1) Simple : free nerve endings
2) Complex = Nerve endings ensheathed in non-neuronal accessory cells
3) Special: nerve ending creates a synapse with a specialized transducer cell
Transduction process involves changes in what
membrane potentials of sensory neurons
Receptor threshold refers to what
the minimum amount/intensity of a stimulus required for activation of a specific receptor
What is the cause of large secondary receptive fields
convergence
the more convergence there is for a secondary sensory neuron, the _____ the receptive field will become
Larger
What will be perceived if 2 stimuli fall within the same receptive field
only 1 will be percieved
Acuity means
the degree of sensitivity
Describe the relationship between the amount of space in the somatosensory cortex and the sensitive of the body part
More area for one body part = more sensitive
Perceptual threshold is
the level of stimulus required in order to be consciously aware
Coding and processing is a ___ level of processing that occurs where
Higher; CNS
Define modality
the form of a stimulus
Why does Phantom Limb Syndrome occur
Experience pain in a missing limb due to previously associated cortical neurons inappropriately activating in response to activities of neighbouring areas or secondary neurons in spinal cords
What is the difference between tonic and phasic receptors?
Tonic = slow=adapting
Phasic = fast-adapting
Coding refers to what
the propertites of the action potentials generated in sensory neurons
What are the types and functions of the skin mechanoreceptors
1) Free Never Endings = detects pain and itch
2) Meissner Corpuscles = light touch
3) Merkel Discs = steady pressure, texture
4) Ruffini Endings = Stretch, Tension
5) Pacinian corpuscles = deep pressure/vibrations
Temperature receptors are ___ channels found on what
ion channels found on free nerve endings
When do nociceptors activate in response to temperature?
Above 45 degrees C
What is the reason we feel pain or heat after an injury
the release of arachidonic Acid
Are there more cold receptors or warm receptors
cold
Transient Receptor Potential (TRP) channels are
cation channels used to initiate action potentials for thermoreceptors
Where are nociceptors found
Free nerve endings
What type of axons deliver fast, sharp pain and what type delivers slow, intense pain and whats a difference between them?
fast = a-beta and a-delta
slow = c-fibers
Fast have myelinated slow doesnt
Pain killers are often known as what kind of drugs
Analgesic
Itch is perceived when
activation of a certain type of C-Fibre in the skin
Capsaicin activates what
Warm receptors
Chemoreceptors respond to what
chemical ligands that bind to the receptor smell and taste
Ipsilateral refers to what
the same side
Define Labeled line Coding
The association of a receptor with a specific sensation
What are the four main kinds of modality
1) Touch
2) Proprioception
3) Temp
4) Nociception
When do warm receptors kick in
37-45 Degrees S
What type of ion channels do warm receptors primarily involve
TRPV1
Define Proprioception
Awareness of body or limb location and orientation within space
