Review of agonist and antagonist messenger and receptor binding. We discussed antigens as chemical substances which are recognized as "foreign", targeted by antibodies, bind to specific receptors, may originate within or outside the cell and elicit an antigen-antibody reaction. Antibodies were described as chemicals produced which are specific to a specific antigen, produced by specific cells and neutralize a pathogen or antigen. Based on the above, the antigen antibody reaction was outlined, and the allergic responses listed.

The question of what occurs after an endogenous messenger chemical
is bonded to a receptor according to specificity and affinity was presented. We determined that a response is brought about by target cells. A partial list of possible responses was outlined on the board. Using lego type blocks, the specificity of fit between messenger and receptor was demonstrated. How Exogenous chemicals perform was demonstrated using the block to show that the structure of the exogenous chemical (drug) was geometrically like the endogenous produced chemical. The concept of an agonist and an antagonist response was demonstrated and discussed. The thyroid hormone, introduced as an exongenous drug, was used as an example of an agonist response.

A series of questions was used to clarify the concept of cell receptors. How does the chemical messenger recognize the target cell? Where on the cell are these receptors found? What specifically must occur between the messenger and the receptor? Once chemical binding occurs, what is produced by the cell? What is meant by specificity of messenger-receptor binding? Using molecular models to show the geometric shape of messengers , and lego blocks, the definition of specificity was demonstrated. Affinity was demonstrated using the "fit" of lego blocks into each other, a greater affinity shown by a better fit. An example of typical responses was listed.

We discussed the need for cellular communication, accomplished through endogenous messengers which are chemical, produced by cells, and delivered into to the extracellular fluid and the importance and definition of the target cell producing a specific effect. Histamine was used as an example of a chemical messenger produced in response to a pathogen. Steps from the need for white blood cells to attack the pathogen, to histamine causing an increase in capillary permeability allowing a greater concentration of wbc's to pass through the capillary walls and attack the pathogen was outlined. Other effects of histamine were listed and anaphylactic shock discussed, along with emergency treatment. The chemistry of histamine was looked at as a preview to understanding the use of antihistamine.

We had a quick review of the cell membrane structures discussed last week. The definitions and explanation of the term pathogen was followed with examples of differences between pathogenic organism an non pathogenic organisms, and the clarifying of bacteria, virus and fungal pathogens. A discussion of the evolution of pathogenic organism to allow them to fit into receptor sites was followed up using the HIV virus as an example.
The concept of homeostasis, its definition and importance in maintaining living organisms, humans in particular, was followed by examples including blood pressure, heart rate, blood sugar levels, and sweating. The control of homeostatic responses is initiated by endogenous chemical entities, hormones and neurotransmitters which can be mimicked by exogenous chemical compounds to achieve a response.

Using the diagram of the cell membrane, the chemistry of phospholipids, amino acids, proteins and diglycerides was presented. The chemical structure of amino acids was presented and then shown how they form proteins. The structure of phospholipids was presented and shown how it fits into the structure of the cell membrane, and the function it performs. Antigens and receptor sites was explained in terms of "physical fit" and how the binding stimulates the reaction in the cell to that specific chemical.

The definition cells being units of structure and function was discussed. A diagram of the bilayer cell membrane was handed out and the major sections listed and explained. The history of the discovery of insulin and its eventual use in treating Diabetes was used as an example of hormones being produced within cells, and the importance of the cell membrane in transportation inside the cell.

The lesson started with a discussion about the chemical level of organization in living organisms.The division into inorganic and organic compounds was outlined, with examples of each. The organic compounds are carbohydrates, nucleic acids, lipids, and proteins. These were shown to constitute hormones, enzymes, neurotransmitters, and brain chemicals. Acetylcholine, norepinephrin, serotonin, dopamine and GABA. A discussion around the importance of these neuro chemicals, specific types of hormones, and digestive enzymes was presented. The chemical structure of these will be discussed individually, and compared to some exogenous drugs.

Discussion regarding the area(s) of study was presented and evaluated. A review of previous work covered in AP chemistry and also in biology involved a review of notes and papers as well as questions. A course which involved chemistry, physiology, and pharmacology was agreed upon. We spoke about endogenous substances and their affect on the human systems, and related the discovery and eventual overuse of penicillin, leading to the development of "super bugs"