Table of Contents. Show more. Show less. About the Authors. Because normal cell function depends on the constancy of this fluid, it is not surprising that in multicellular animals, an immense number of regulatory mechanisms have evolved to maintain it.
Cannon coined the term homeostasis. The buffering properties of the body fluids and the renal and respiratory adjustments to the presence of excess acid or alkali are examples of homeostatic mechanisms. There are countless other examples, and a large part of physiology is concerned with regulatory mechanisms that act to maintain the constancy of the internal environment.
Many of these regulatory mechanisms operate on the principle of negative feedback; deviations from a given normal set point are detected by a sensor, and signals from the sensor trigger compensatory changes that continue until the setpoint are again reached. Basic knowledge of cell function and structure is essential to an understanding of homeostasis, the organ systems and the way they function in the body. A key tool for examining cellular constituents is the microscope. A light microscope can resolve structures as close as 0.
Although cell dimensions are quite variable, this resolution can provide a good look at the inner workings of the cell. The advent of common access to phase contrast, fluorescent, confocal, and many other microscopy techniques along with specialized probes for both static and dynamic cellular structures further expanded the examination of cell structure and function.
Read More: Physeo Psychiatry pdf free. The membrane that surrounds the cell is a remarkable structure. It is composed of lipids and proteins and is semi-permeable, allowing the passage of some substances and excluding others.
However, its permeability can also vary because it contains numerous regulated ion channels and other transport proteins that can change the number of substances that move through it.
It is generally known as the plasma membrane. The nucleus and other organelles of the cell are linked by similar membranous structures.
Although the chemical structures of membranes and their properties vary considerably from place to place, they have certain common characteristics. Kim E. You can download the PDF format of Ganong physiology by using the link given below. If the download link is not responding kindly inform us through the comments section. Download PDF Free. We highly encourage our visitors to purch ase orig inal books from the respected publishers.
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