What are Group II afferents?
What are Group II afferents?
Group II afferent fibers that innervate muscle spindles discharge in response to muscle stretch and Ia fibers and are subjected to similar gamma and descending effects. Group II fibers can make both monosynaptic and oligosynaptic connections with homonymous and synergist hind-limb alpha motoneurons.
What are primary afferents?
Primary afferents are sensory neurons (axons or nerve fibers) in the peripheral nervous system that transduce information about mechanical, thermal, and chemical states of the body and transmit it to sites in the central nervous system.
What are the two types of nerve fibers?
There are two types of axons in the nervous system: myelinated and unmyelinated axons.
Why is there a subdivision within the type II fibers?
In the body, Type II sensory fibers belong to pseudounipolar neurons. These changes are in part induced by PGE2 which is produced by COX1, and type II fibers with free nerve endings are likely to be the subdivision of fibers that carry out this function.
What do group Ia afferents detect?
Group Ia afferents (also called primary afferents) wrap around the central portion of all 3 types of intrafusal fibers; these specialized endings are called annulospiral endings. Because they innervate all 3 types of intrafusal fibers, Group Ia afferents provide information about both length and velocity.
Where are Type 2 muscle Fibres found?
muscles of the arms
Such fibres are found in large numbers in the muscles of the arms.
What are afferents?
Afferent neurons are sensory nerves These are sensory neurons carrying nerve impulses from sensory stimuli toward the central nervous system and brain. Afferent neurons carry signals to the brain and spinal cord as sensory data.
Where do primary afferents terminate?
Substance P-containing afferents (which include both A and C fibres) end mainly in lamina I and the outer part of lamina II, although some penetrate deeper into the dorsal horn. Some C fibres contain somatostatin and these terminate in the outer part of lamina II (Alvarez & Priestley, 1990; Sakamoto et al. 1999).
What is type a nerve fiber?
Warmth receptors. Type Aα fibers include the type Ia and type Ib sensory fibers of the alternative classification system, and are the fibers from muscle spindle endings and the Golgi tendon, respectively. Type Aβ fibres, and type Aγ, are the type II afferent fibers from stretch receptors.
How are nerve fibers classified?
Individual peripheral nerve fibers are classified based on the diameter, signal conduction velocity, and myelination state of the axons, as well as by the type of information transmitted and the organs they innervate.
What are type 2X muscle fibers?
Type IIX (also known as Type IIB) fibers produce the most force, but are incredibly inefficient based on their high myosin ATPase activity, low oxidative capacity, and heavy reliance on anaerobic metabolism (1,2).
How are afferents and efferents different in the brain?
That is, each brain region has its own unique set of afferent and efferent projections. In the context of a given brain region, afferents are arriving fibers while efferents are exiting fibers.
What is the difference between afferent and efferent nerve fibers?
[edit on Wikidata] Afferent nerve fibers refer to axonal projections that arrive at a particular brain region, as opposed to efferent projections that exit the region.
How are Type Ia and Type II sensory fibers different?
The type Ia fiber has “anulospiral” endings around the middle parts of the intrafusal fibers compared to type II fibers that have “flower spray” endings which may be spray shaped or anular, spreading in narrow bands on both sides of the chain or bag fiber.
What kind of nociceptors are mechanically sensitive afferents?
Aδ nociceptors can be further divided into two types (it appears to exist proximately 50% of each type) Type I Aδ are mechanically sensitive afferents (MSA) that respond with a slowly adapting discharge to strong punctuate pressure.