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Reflex arc demonstrated. When a reflex arc in an animal consists of only one sensory neuron and one motor neuron, it is defined as monosynaptic, referring to the presence of a single chemical synapse. In the case of peripheral muscle reflexes (patellar reflex, achilles reflex), brief stimulation to the muscle spindle results in contraction of ...
Pharyngeal reflex — also known as the gag reflex. Photic sneeze reflex — a sneeze caused by sudden exposure to bright light. Plantar reflex — in infants up to 1 year of age, a curling of the toes when something rubs the ball of the foot. Pupillary accommodation reflex — a reduction of pupil size in response to an object coming close to ...
Grasp reflex. Newborn babies have a number of other reflexes which are not seen in adults, referred to as primitive reflexes. These automatic reactions to stimuli enable infants to respond to the environment before any learning has taken place. They include: Asymmetrical tonic neck reflex; Palmomental reflex; Moro reflex, also known as the ...
This can be part of a withdrawal reflex—initiated by the Aδ fibers in the reflex arc of activating withdrawal responses. [ 7 ] [ 8 ] These are the type III group. Aδ fibers carry cold, pressure, and acute pain signals; because they are thin (2–5 μm in diameter) and myelinated , they send impulses faster than unmyelinated C fibers , but ...
Like the knee jerk reflex, the Lazarus sign is an example of a reflex mediated by a reflex arc—a neural pathway which passes via the spinal column but not through the brain. As a consequence, the movement is possible in brain-dead patients whose organs have been kept functioning by life-support machines , precluding the use of complex ...
In contrast, the tendon reflex operates as a negative feedback mechanism to control muscle tension. Although the tendon reflex is less sensitive than the stretch reflex, it can override the stretch reflex when tension is great, for example, causing a person to drop a very heavy weight. Like the stretch reflex, the tendon reflex is ipsilateral.
The singular example of a monosynaptic reflex is the patellar reflex. The next simplest reflex arc is a three-element chain, beginning with sensory neurons, which activate interneurons inside of the spinal cord, which then activate motor neurons. Some reflex responses, such as withdrawing the hand after touching a hot surface, are protective ...
The short-latency reflex (SLR) is the fastest (~40-50 ms) and involves a mono-synaptic pathway. The medium-latency reflex (MLR) utilizes interneurons within the spinal cord and is typically ~80-90 ms. The long-latency reflex (LLR) is ~120-140 ms, suggesting that it is mediated by additional supraspinal input from the brain. [2]