The first part of this course on Veterinary Physiology (part A) is largely based on topics from the Ba1 program such as chemistry, physics and histology. In this context, functional aspects of cell communication are studied: function of membranes, intercellular transport, chemical communication, hormone receptor interactions, membrane potential, ion pumps and action potential. In addition, neural and hormonal regulation mechanisms are studied with special attention to the nervous system, the senses and the endocrine system. Finally, the function of several specific organ systems is studied: bone, muscle, blood. Parallel, general mechanisms are studied such as the use of organic nutrients, regulation of body temperature and the use of bio-energy and growth. Where possible, links with the clinics are included.