Stimulus-Induced Response Essay

Humans, as well as other organism, have internal processes that work together for homeostasis, which is an organism’s tendency to maintain equilibrium by controlling the internal environment. This is possible because the body can use receptors, the control center. And effectors to detect and respond to changes. This process begins when an external stimulus changes some variable that the body is monitoring. The change is detected by a receptor, or sensor, which sends the information gleaned to the control center via an afferent pathway. The control center, or the integrator, is able to analyze the input from the sensors and detect any variation from the set point. The set point that is being used for reference is simply a value that the body

When the external environment, or stimuli, around the body is cold, it is detected by receptors in the skin and spinal cord. Those receptors send the information that the body is cold to the control center located in the anterior hypothalamus/preoptic area (AH/POA). The AH/POA compares the sensory information with the hypothalamic set point and signals effectors accordingly. Using efferent pathways, a colder temperature than the set point will utilize a variety of effectors. For instance, vasoconstriction will occur, which is the constriction of cutaneous blood vessels so that blood flow will lessen and heat loss from the surface of the skin will decrease. This occurs because of an increased amount of norepinephrine being released. Additionally, the stimulations of the motor areas of the brain stem and spinal cord cause the skeletal muscles to shiver and generate warmth in the muscles. There are also chemical signals that stimulate cellular respiration and heat production. Lastly, increased thyroid activity increases thyroid hormones that thereby increase the metabolism of brown fat. Results from all of these efforts are sent back to the control center as negative feedback to determine whether additional measures are