TLS Online TPP Program

#Id: 5619

#Unit 7. System Physiology – Animal

Touch and pressure are sensed by four types of mechanoreceptors:

Meissner’s corpuscles

Merkel cells

Ruffini corpuscles

Pacinian corpuscles

TLS Online TPP Program

#Id: 5620

#Unit 7. System Physiology – Animal

The sensory nerves from mechanoreceptors are large myelinated Aα and Aβ fibers whose conduction velocities range from ∼70–120 & ∼40–75 m/s, respectively.

TLS Online TPP Program

#Id: 5621

#Unit 7. System Physiology – Animal

Impulses from nociceptors are transmitted via two

fiber types:

Thinly myelinated Aδ fibers (2–5 μm in diameter) that conduct at rates of ∼12–35 m/s 

Unmyelinated C fibers (0.4–1.2 μm in diameter) that conduct at low rates of ∼0.5–2 m/s

TLS Online TPP Program

#Id: 5622

#Unit 7. System Physiology – Animal

Activation of Aδ fibers, which release glutamate, is responsible for first pain (also called fast pain or epicritic pain)

TLS Online TPP Program

#Id: 5623

#Unit 7. System Physiology – Animal

When a small amount of pressure is applied to the Pacinian corpuscle, a nonpropagated depolarizing potential resembling an excitatory postsynaptic potential (EPSP) is recorded. This is called the generator potential or receptor potential

TLS Online TPP Program

#Id: 5624

#Unit 7. System Physiology – Animal