BIOL 121 Lecture Notes - Lecture 1: Fluid Compartments, Extracellular Fluid, Ph
Document Summary
The study of the normal functioning of a living organism and its component parts. The body is in constant interaction with the external environment, some organ systems are continuous with the external environment: respiratory system, digestive system, urinary system, reproductive system. Homeostasis: the ability of the body to maintain a relatively constant internal environment. Feedback loops can be positive or negative but only negative feedback loops are homeostatic. Negative feedback loops: measure the existing value of some factor, compare it to a selected set point value and employ the difference of these two values to initiate a series of physiological changes that return. Fluid outside the cell (interstitial fluid and plasma) Functions of the cell membrane: physical isolation, regulation of exchange within the environment, communication between the cell and its environment. Phosphate head --> hydrophilic (points outwards, likes water), polar. Fatty acid tail --> hydrophobic (points inward, doesn"t like water), non- polar, makes a hydrophobic core.
