Reflexes Uncovered

Receptor

Once an individual steps on tack, an action follows until the effectors react, informing the person’s brain about the pain and then taking action. This process is referred to as reflex action. On stepping a tack, the receptor cells detect the change in the environment, stimuli and react to the change, restoring the homeostasis. When stimuli such as pain from the tack are subjected to the body, specialized cells react to them; these cells are known as receptors (Biga et al., 2020). These receptors are located in the skin; they make the muscles contract and the foot jerk upwards in response to the pain. The skin surface's reception of pain is first felt, then transmitted to the epidermis, then to the dermis, which houses the sensory receptors. The skin also has receptors that respond to touch. In this context, the primary sensory receptor-targeted is the nociceptors, whose main role is to respond to damage or threat of damage to body tissues, which are known to perceive pain.

Other aspects that need to be discussed include the potential action generation, which involves brief changes in the voltage across the membrane due to the flow of sodium ions into and out of the neuron. The role of this process is to ensure sodium balance and regulation of blood pressure. Closely related to potential action generation is the transmembrane potential and resting membrane potential. The transmembrane potential is the difference in electrical potential between the interior and the exterior of receptor cells, while the resting membrane of a neuron is about -70mV less than the outside. The purpose of these membranes in reception is to transmit signals between different parts of the cells. Depolarization begins when action potential begins at the axon hillock; during this process, the sodium ions rush back into the cell, getting more positive. When the threshold potential is reached, then action potential is induced. Additionally, the movement of potassium ions outside the neurons makes potential membranes negative, thus causing repolarization, and the membrane potential is more negative, which is referred to as hyperpolarization. These elements determine the effectiveness of neurons in transmitting the message from the receptors to the effectors.

Sensory Neuron

This is the channel where the stimuli flow from the receptor to the central nervous system. These comprise the nerve cells, neurons that carry the message from the stimulated receptors. All the message is carried to the central nervous system, brain, and spinal cord, and back. The sensory neuron is responsible for carrying the message to the central nervous system while the motor neuron takes the message to the effector, forming a reflex arc (Abulhasan & Grey, 2017). In the mast of the reflexive arcs, the sensor neuron connects with the motor neurons through association neurons in the central nervous system. This interneuron takes place in the spinal cord.

Integration Center

Integration is the correct connection between the sensory neuron, which carries the message from the receptor, and the motor neuron carrying the message to the effector; this occurs in the interneurons of the central nervous system, thus making the right connections. Response to stimuli occurs the same way as a reflex, with complex behaviors that involve the integration of the brain.  Integration in the central nervous system works similarly to the central switching office. The brain acts as the information processing unit, where interpretation of the message is made, and a decision is achieved to move.

 

 

Motor Neuron

Ass we had stated earlier, the motor neuron carries messages back from the central nervous system to the effector. There are two types of motor neurons, lower motor neurons traveling from the spinal cord to muscles and the upper motor neurons traveling, which joins the brain and the spinal cord. This junction formed is referred to as neuromuscular junction, which is highly specialized in linking the motor neuron nerve terminal and muscle fibers (Lepore et al., 2019).  Collection of these motor neurons forms the motor unit; these neuronal axons are covered by myelin sheath to form an insulation layer, to allow rapid conduction of electrical signals.

Effector

The message from the central nervous system reaches the effector and gets stimulated, and reacts through response. The effector is primarily specialized in movement; some of its components include prime mover, a muscle that caused the specified movement. Also, the synergists are any skeletal muscles that offer support to the prime mover in its movement. Antagonists are those muscles that reverse particular movement, and these muscles are attached to bones. Bones monitor the usage and adjust the strength and shiftiness of movements within the muscles. Also, during the movement of muscles, a lot of calcium is needed to displace the troponin and reveal the active sites. These are sites where myosin binds to for the power stroke.

Reflex

A reflex is an involuntary and nearly instantaneous movement, especially resulting from stimuli. When an individual steps on a tack accidentally, they automatically and swiftly jerk their leg away without thinking. The path taken by the nerve impulse in a reflex is denied as a reflex arc. Additionally, a withdrawal reflex is a spinal reflex whose aim is to protect the body from damaging stimuli; this is achieved through stimulation of sensory, association, and motor neurons (Feffer, 2018). An example of the withdrawal reflex is the crossed extensor reflex, which occurs when the flexors in the withdrawing limb contract and the extensors relax, which is reversed in the other limb. The example of stepping on a tack, the leg that is stepping pulls away, while the other leg takes the whole body's weight.

 

References

Abulhasan, J. F., & Grey, M. J. (2017). Anatomy and physiology of knee stability. Journal of Functional Morphology and kinesiology, 2(4), 34.

Biga, L. M., Dawson, S., Harwell, A., Hopkins, R., Kaufmann, J., LeMaster, M., ... & Runyeon, J. (2020). Anatomy & physiology.

Feffer, A. (2018). CHAPTER SEVEN. The Reflex-Arc. In The Chicago Pragmatists and American Progressivism (pp. 147-158). Cornell University Press.

Lepore, E., Casola, I., Dobrowolny, G., & Musarò, A. (2019). Neuromuscular junction as an entity of nerve-muscle communication. Cells, 8(8), 906.