Sensation Flashcards
Define:
1. Sensory unit
2. Receptive field
Single sensory axon and all its peripheral branches that vary in number
Spatial dustribution from which a stimulus produces a response in that unit. It differs from one area to another allover the body.
Mention classifications of sensations
Site, type, localization, ascending sensory pathway
Mention the mixed sensations
Vibration
Stereognosis
Mention the thalamic sensations
Slow pain
Crude tough
Wide degrees of thermal variation
Classify sensations according to ascending sensory pathway
Spinothalamic, thermal, crude touch, pain, itch & tickle, sexual sensations
Dorsal column, fine touch , stereognosis, vibration, proprioception, deep pressure
Define crude touch, tickle & itch
The ability of body to detect contact with objects
Local repeated mechanical stimulation of cutaneous receptors by light moving objects
Sensation of irritation caused by chemicals (histamine & kinins) that lead to scratch reflex
Higher nervous perception site for crude touch & itch & tickle
Thalamus
Higher nervous perception site for thermal senstaions
Thalamus & sensory cortex
Receptors for crude touch & itch & tickle & thermal sensations
All are FNE ex cold which is FNE & Krause end bulb & crude touch also hair end organ.
Adaptation for crude touch & thermal s.
Rapid
Moderate but hot is faster
How to examine for crude touch & thermal
Cotton wool test
Two test tube test
Mechanism of stimulation of thermal sensations
Changes in conc of metabolites in thermoreceptors that activate or inactivates ion channels
Excess change in temp activate transient receptor potential Which are also ion channels
Cold spots are more numerous tyan hot spots by
3-10 times
Thermoreceptors are more numberous in …than ….than.l.l
Lips, hand, trunk
