Term of the Day

Splanchnic Nerve: A preganglionic autonomic nerve of the abdominopelvic viscera. Preganglionic, sympathetic fibers that pass through the paravertebral (sympathetic chain) ganglia without synapsing form splanchnic nerves. Instead, they synapse in a prevertebral (visceral) ganglion such as the celiac ganglion, the superior mesenteric ganglion, or the inferior mesenteric ganglion (e.g. thoracic -- greater, lesser, least -- splanchnic nn, lumbar splanchnic nn, and sacral splanchnic nn). Pelvic splanchnic nerves are parasympathetic and formed by branches of the ventral rami of S2, S3, and S4. Their ganglia are at or near the target organ.

P.S. Have a very Happy New Year!

Term of the Day

Alkaline Reflux Gastritis: inflammation of the stomach caused by reflux of bile and pancreatic secretions (proteolytic enzymes and bicarbonate-rich fluid) that disrupt the mucosal barrier of the stomach. It is one of the risk factors associated with gastrectomy or pyloroplasty. Symptoms include nausea, bilious vomiting, and epigastric pain that worsens after eating and is not relieved by antacids.

Concept of the Week: Everybody Do the Chloride Shift!

The majority of carbon dioxide is transported in the blood as bicarbonate ion (60-70%). The chemical reaction that forms the bicarbonate takes place within the erythrocytes (red blood cells) and is catalyzed by the enzyme carbonic anhydrase. Carbon dioxide reacts with water in the cytosol to form carbonic acid, which then dissociates into a negatively charged bicarbonate ion and a positively charged hydrogen ion. The bicarbonate ions quickly diffuse out into the blood plasma. This, however, would result in a net loss of negative charge within the RBC if the process were not counterbalanced. The chloride shift balances the loss of bicarbonate as negatively charged chloride ions diffuse into the RBC from the plasma. Thus, the loss of negatively charged bicarbonate is offset by an equal acquisition of negatively charged chloride, allowing the RBC to maintain its normal membrane potential. What happens to the hydrogen ion? It binds to hemoglobin, which acts as a buffer to prevent intracellular pH from dropping too low. It drops just low enough to trigger the Bohr effect, which reduces the affinity of hemoglobin for oxygen and facilitates oxygen release to the tissues.

Term of the Day

Glomerular Filtration: The first step in the process of urine formation. Due to the relatively high hydrostatic pressure in the glomerular capillaries, a filtrate of blood plasma is forced out of the capillaries into Bowman's capsule. Electrolytes and small molecules enter the filtrate, but large molecules and cells do not (at least in the healthy kidney).

Welcome to the Anatomy and Physiology Student's Forum!

I'm Scott Boulding, and I have been a professional Anatomy & Physiology, Pathophysiology, and Biology teacher for some years now. The idea for this blog was born of my own students' struggles with and attempts to master the large volume of challenging material these courses represent. One of them aptly described the learning process as akin to "taking a sip of water out of a fire hose!" So, I decided to create an online forum in which they could share ideas, ask questions, provide useful links, exchange study tips, and so on. Soon realizing that such a resource could benefit other students from the high school through the grad school levels, I decided to make this blog available to the general public. If you are taking Anatomy and Physiology, Human Biology, Gross Anatomy, Human Physiology, or Pathophysiology, this blog is for you. If you are a teacher of any of these courses, you are also welcome to provide comments, feedback, and answers to student questions. Everyone with an interest in these subjects is welcome here!

In addition to the questions and comments threads, I will also be posting key terms and their definitions daily (think of it as your Anatomy and Physiology Word-a-Day calendar), as well as discussing and explaining a different A&P concept each week. Feel free to add to the discussion, expand upon the information, ask questions -- whatever will be useful to you as you try to learn the material! From time to time, I will also throw in some short quizzes to help you test your knowledge and understanding

If you feel like you need more intensive tutoring, you can also find me at www.globalscholar.com or at http://imlive.com/waitingroom1ms.asp?hostnick=DocentisMaximus. If you're in the Tampa Bay area and want some live, one-on-one tutoring, just drop me an email (sboulding@tampabay.rr.com), and I'll be happy to arrange a meeting that is convenient for both of us.

In the meantime, enjoy the blog; I hope you find it helpful. As with anything, you'll get out of it what you put into it -- trite, I know, but true, nevertheless. Good luck with your studies!

Scott Boulding