Final answer:
Lividity is the term that describes the gravitational pooling of blood in the lower portions of a body after death, which is distinct from rigor mortis, algor mortis, and primary flaccidity. Secondary to an injury, blood clotting is a positive feedback mechanism that involves the clotting substances that initiate the process to prevent excessive blood loss. In contrast, lowering of blood glucose after a meal is an example of negative feedback where the effect of the initial stimulus is reversed.
Step-by-step explanation:
The term that refers to gravity causing blood to drain to the lowest portion of the body after death is lividity. This is part of the process that occurs after someone has died, where blood settles in the lower parts of the body, causing a purpling color in those areas. It's important to note that this is different from rigor mortis, which is the stiffening of the muscles after death, algor mortis, which refers to the cooling of the body, and primary flaccidity, which is the initial relaxation of muscles following death.
Blood clotting is an example of a positive feedback mechanism in the body. It occurs when substances are released in the injured blood vessel wall that begins the process of clotting. As each step of clotting occurs, it stimulates the release of more clotting substances to accelerate the process of sealing off the injured area. This adaptive cascade of events is crucial for preventing excessive blood loss after an injury.
The example given in the question, blood clotting after an injury, represents a positive feedback loop because it is a process where the end product enhances the initial stimulus. An example of negative feedback is the lowering of blood glucose after a meal, where the body acts to reverse the effect of the increased blood glucose.