1. Physiology of the sensory system

5. Sensory

6. Types of Sensory Receptors
Mechanoreceptors
detect deformation
Thermoreceptors
detect change in temperature
Nociceptors
detect damage (pain receptors)
Electromagnetic
detect light
Chemoreceptors
taste, smell

7. Classification of Somatic Sensations
mechanoreceptive - stimulated by mechanical displacement.
tactile
touch
pressure
vibration
tickle and itch
position or proprioceptive
static position
rate of change

8. Classification of Somatic Sensations
thermoreceptive.
detect heat and cold.
nociceptive.
detect pain and are activated by any factor that damages tissue.

9. Receptor Potential the membrane potential of the receptor.
excitation of the receptor results from a change in this potential.
when the receptor potential rises above the threshold, action potentials appear and the receptor is active.
the greater the intensity of the stimulus, the greater the receptor potential, and the greater the rate of action potential generation.

10. Relationship between receptor potential and action potentials
Figure 46-2

11. Types of sensation types of sensations General sensation
Somatic
visceral
Special senses
Smell, taste, vision etc

12. Types of sensation types of sensations General sensation
Somatic
visceral
Special senses
Smell, taste, vision etc
exteroceptor
proprioceptor

13. Types of sensation types of sensations General sensation
Somatic
visceral
Special senses
Smell, taste, vision etc
exteroceptor
Proprioceptor : muscle length and tension, joint position and their motion

14. Sensations receptors

15. Sensations modalities
FAST
SLOW
Prorioception
Fine touch & pressure
Vibration
Temperature
Crud touch (itch & rub)
Pain

16. Sensations modalities
FAST
SLOW
Prorioception
Fine touch & pressure
Vibration
Temperature
Crud touch (itch & rub)
Pain
Posterior Column-Medial lemniscus
Pathway
(PCML)

17. PCML Pathway

18. Sensations modalities
Important (critical)
Non critical
Prorioception
Fine touch & pressure
Vibration
Temperature
Crud touch (itch & rub)
Pain
Antero-lateral system (ALS)
Other name: Spinothalamic pathway

19. ALS Pathway

20. Conduction speed
Number of synapses
Myelination
Nerve axon size

24. Relationship Between Receptive Fields and Cortical Representation
Text Fig. 17-3
Text Fig
Smaller the receptive fields, greater the density of receptors. This relationship allows for greater discrimination in sensory inputs.
Inverse relationship in the cortex. Smaller the receptive fields larger the cortical area Larger the receptive fields smaller the cortical area

25. Visceral sensory & referred pain

26. Visceral sensory & referred pain

27. Visceral sensory & referred pain

28. Visceral sensory & referred pain

29. Referred pain
right
Left
liver

30. Sensory in the face
(Trigeminal system)

31. (Trigeminal system)
Carry all the sensation modalities from the face to the brain

32. (Trigeminal system)
Carry all the sensation modalities from the face to the brain