Question: as a graduate teaching assistant for your physiology class you...
As a graduate teaching assistant for your physiology class, you are required to provide an evaluation of the following examples of student work with fundamental endocrine concepts. No two answers can have the same grade assigned.
Assign one grade to each of the following, either an A, C, or F. Don't repeat grades.
1.) Hormones are chemical messengers that enter the blood. Whether or not transport proteins are required and intracellular signals are generated depends upon the distance separating the site of secretion and specific target cells. Examples of this are glucocorticoids, which bind to plasma transport proteins, enter the target cell, and interact with intracellular receptors.
2.) Blood transportation of chemical messengers is a critical criterion for endocrine classification. Whether the messenger is water-soluble or lipid-soluble determines both the necessity of a plasma transport protein and the location of the hormone receptor on/in the target cell. For example, the water-soluble hormone TRH does not require a plasma binding protein, interacts with extracellular receptors, and activates production of a second messenger.
3.) Organic molecules released into the bloodstream are distributed to cells throughout the body as a means of eliciting cellular responses across great distances. The well-established presence of thyroxine binding globulin (TBG), a plasma transport protein, suggests that T4 is hydrophilic, must interact with membrane-bound receptors, and directly targets genetic regulation.