Question

Sharp pain is carried by the smallest of the myelinated sensory fibers, the ____ __________ fibers, while burning pain is carried more slowly by small nonmyelinated ____ fibers. Both types of fibers release the neurotransmitters glutamate and substance P, which activate second-order sensory neurons.

Answer 1

Sharp pain is transmitted by A-delta fibers and burning pain by C fibers, with both releasing neurotransmitters glutamate and substance P to activate second-order neurons for pain perception.

Step-by-step explanation:

Sharp pain is conveyed by the smallest of the myelinated sensory fibers, termed A-delta fibers, while burning pain is transmitted more slowly by small nonmyelinated C fibers.

Both types of sensory fibers release the neurotransmitters glutamate and substance P, which are crucial in activating second-order sensory neurons essential for pain perception.

This process begins at free nerve endings with nociceptors responding to potentially harmful stimuli, such as mechanical, chemical, or thermal triggers that can cause tissue damage.

An example of how these receptors work is the response to capsaicin, found in hot peppers, which activates nociceptors and can be used in products like Icy Hot™ as a topical analgesic.

Answer 2

Sharp pain is carried by the smallest of the myelinated sensory fibers, the Aδ (A-delta) fibers, while burning pain is carried more slowly by small nonmyelinated C fibers. Both types of fibers release the neurotransmitters glutamate and substance P, which activate second-order sensory neurons.

Step-by-step explanation:

The transmission of pain signals involves specialized nerve fibers known as Aδ (A-delta) fibers and C fibers. Aδ fibers, characterized by their small size and myelination, are responsible for transmitting sharp, fast pain signals. These fibers quickly convey information about acute or sudden pain sensations, allowing the body to react swiftly to potential threats. On the other hand, C fibers, which are small and unmyelinated, transmit slower, burning pain signals. These fibers convey more prolonged or persistent pain experiences, often associated with inflammatory or tissue-damaging conditions.

Both types of pain fibers release neurotransmitters, such as glutamate and substance P, at the synapses with second-order sensory neurons. Glutamate is an excitatory neurotransmitter that enhances the transmission of pain signals, while substance P contributes to the sensation of pain by promoting inflammation and sensitizing pain receptors. The activation of second-order sensory neurons in the spinal cord and brainstem is a crucial step in the relay of pain signals to higher brain centers, where the perception and interpretation of pain occur.

Understanding the distinct characteristics of Aδ and C fibers, along with the role of neurotransmitters, provides insights into the complex mechanisms of pain perception. This knowledge is essential for developing effective pain management strategies and interventions targeted at specific types of pain and their underlying physiological processes.