Professor Saltzman introduces the basic concepts of renal physiology. Professor Saltzman first introduces the function and anatomy of the kidney. Special attention is given to the cell types and structural aspect of the nephron, the functional unit of the kidney. Filtration, secretion of toxic waste, and reabsorption of water, ions, and nutrients through the glomerulus and various segments of the nephrons is discussed in detail.

The midterm exam covers Lectures 1 through 15.

Professor Saltzman talks about electrical conductivity in the heart: that is, the generation and propagation of electrical potential in heart cells. He describes the role of ion channels and pumps in transporting sodium, potassium, and calcium ions to create action potential. This propagation of signal from the sinoatrial node through different tissues, which can be replaced by a pacemaker, eventually stimulates contraction of muscle fibers throughout the heart.

Professor Saltzman describes the blood flow through the systemic and pulmonary circulatory system. More specifically, he describes, with the help of diagrams, the events that lead to blood flow in the body as a function of contraction/relaxation by specific chambers of the heart, and the effect of four valves which help direct flow. Important terms and concepts such as systole/diastole pressures, cardiac output (CO) as a function of heart rate (HR) and ejection volume (EV), and the action potential propagation that stimulates heart muscle contraction are discussed.

Professor Saltzman discusses the biophysics of the circulatory system. He begins by describing the anatomy of different types of blood vessels, and states the relationship between pressure difference (ΔP) as the driving force for fluid flow (Q) in a tube (i.e., blood vessel) with some resistance R (ΔP = RQ). R can be calculated using if dimensions of the tube (L, r) and fluid viscosity (μ) are known: R = 8μL/πr4.

Professor Saltzman reviews the pharmacokinetic first-order rate equation that can be used to model changes in drug concentration in the blood, as well as its derivation from the law of conservation of mass. The importance of maintaining a drug concentration that is sufficient for therapeutic purpose, but below a toxic level, is emphasized. Since this is directly affected by drug administration method, ways to localize and sustain therapeutic concentrations of drug, such as incorporating in slow-releasing, biocompatible polymers are introduced.

Professor Saltzman starts the lecture with an introduction to pharmacokinetics and pharmacodynamics. Professor Saltzman talks about the concept of dose-response. He introduces different routes of drug administration and how they affect drug distribution and bioavailability (i.e., intravenous, oral, and sublingual routes). First-pass drug metabolism by the liver is also identified as an important source of drug degradation.

Professor Saltzman continues his presentation on the topic of vaccine. First, Professor Saltzman describes the host immune response to pathogen recognition, in terms of immunoglobulin release, T-cell activation, and memory cell production. The production, distribution, and challenges involved in making of the Salk polio vaccine and the modern, oral polio vaccine are discussed. Professor Saltzman then talks about the range of bioengineering approaches that can be used to produce vaccine: attenuated, subunit, and DNA-based.

Professor Saltzman talks about the importance of vaccines, and particularly the role of bioengineering in vaccine development. He first addresses the question of "what is a vaccine" and the role of the immune system. He then describes the biological basis, symptoms, and history of smallpox as a devastating disease worldwide, and how--starting with the work of Edward Jenner--an effective vaccine was systematically developed from cow lesions. Next, methods to deliver vaccine to a wide population are introduced.

Professor Saltzman continues his discussion of cell communication in the body, extending the description to the nervous and immune system. Professor Saltzman describes the mode of signal transmission in neurons: action potential in the axon, and neurotransmitter release at the synaptic cleft. He also introduces elements of the innate and adaptive immune system. The adaptive immune system is presented as a host/foreign antigen recognition system involving immune cells (T, B, and macrophages), antibodies, and the major histocompatibility complex 1 and 2.