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

TLS Online TPP Program

#Id: 5625

#Unit 7. System Physiology – Animal

The receptor (Pacinian corpuscle) converts mechanical energy into an electrical response, the magnitude is proportional to the intensity of the stimulus. Thus, the responses are described as graded potentials rather than all-or-none