Question

Alan stands on a sharp object at home causing sharp pain in his foot. His knee buckles/bends immediately after standing on the sharp object.
Using your knowledge of somatic and autonomic reflexes (M4L4) answer the following questions. Be sure to clearly label the different parts.
Part A. Provide one example of a somatic reflex and one example of an autonomic reflex. (1 mark)
Part B. Identify two reflex pathways that are activated as a result of Alan standing on the sharp object. For each pathway identify: the specific receptor, all neurons and synapses involved and the impact on the specific effector tissue.

Answer 1

1. Jerking of hand when accidentally touching a hot pan is an example of somatic reflex. Coughing is an autonomic refflex. Coughing initiates immediately when smoke hits the nostrils.

2. Withdrawal reflex and the crossed extensor reflex are activated as a result of Alan standing on the sharp object.

Sensors in the withdrawl reflex are nociceptors that can sense pain which simulate lower motor neurons in the spinal cord which then stimulate contraction of skeletal muscle to withdraw Alan's leg from sharp object. It ususally involves flexor muscles  such as the hamstrings and hip flexorsto contract and hence, also called as the flexor reflex.

Crossed extensor reflex invovles stimualting the pain fibers of Alan's foot whichs ends signals to spinal cord through the dorsal horn along with stimulating excitatory and inhibitory interneurons on the same side of the body. These lower motor neurons stimulates the extensor muscles on the opposite side of the Alan's body to keep ready to handle increased load while she shift her weight to that side.