human physiology part 1

1. John Paul L. Oliveros, MD, DPPS Human PhysiologyBiology 012

2. Mechanism and causality • Physiology: is the study of how things work • Human physiology: individual molecular processes  processes that depend on many separate organs of the body • Mechanist view: “all phenomenon, no matter how complex, can be described in terms of physical and chemical laws” • Vitalism: “ a vital force, beyond physics and chemistry, is required to explain life” • Causality: to reduce a phenomenon to causally linked sequence of scientific events in order to explain it

3. Cell theory • Cells: • Simplest structural units in which a multicellular organism can be dividedand still retain funtions and characteristics of life • Cell differentiation: the process of transforming an unspecialized cell into a specialized cell • Cells with similar specialization migrate to adhere with other cells to form multicellular structures

4. Cells • 200 different kinds of cells in the body • Functional Classification • Muscle cells: • Generate mechanical forces that produces force and movement • Nerve cells: • Initiate and conduct electrical signals • Epithelial cells: • Selective secretions of ions and organic molecules • Located on the surfaces • Cover the body or organs • Line the walls of tubular or hollow structures • Connective Tissue cells • Connecting, anchoring, and supporting the structures of the body • Loose CT, fat cells, blood cells, bone cells

5. Tissues • Aggregate of a single type of cell • 4 classes • Muscle tissue • Nerve Tissue • Epithelial Tissue • Connective Tissue • Extracellular fluid • Extracellular matrix • Protein and mineral mixture specific for each tissue • Collagen fibers • Elastin fibers • Protein-carbohydratemixture • Functions: • Scafold for cellular attachments • Transmits information between cells ( chemical messengers)

6. Organs and Organ systems • Organs: • Composed of the 4 kinds of tissues arranged in various proportions and patterns • Functional Units: • Smaller similar subunits of an organ • Performs function of an organ • Organ systems: • A collection of organs that perform an overall function • 10 organ systems

8. Internal Environment • Cells in our body are not in direct contact with the external environment • The overall effect of the activities of the organ systems is to create within the body an environment in which all cells can survive and function • Internal environment: • Fluid environment surrounding each cell • AKA extracellular fluid

9. Internal Environment

10. Homeostasis • Homeostasis: • The relative constancy of the internal environment • Changes may occur but are small and kept within narrow ranges • Homeostatic control system: • a collection of body components that functions to keep a physical or chemical property of the internal environment relatively constant • 3 components : • Detection of the changes in the magnitude of the property • Relaying of information to appropriate sites • Commanding particular cells to change their funtion to restore property to its original value

11. Body-Fluid Compartments • Total Body Water (TBW): 60% of body weight • Intracellular Fluid: 2/3 of TBW • Extracellular fluid:1/3 of TBW • Interstitial fluid • 80% of ECF • Fluid in between and surrounding cells • Plasma: • 20% of ECF • Blood= plasma + suspended cells (blood cells)

12. Body-Fluid Compartments • Compartmentalization: • Important principle in physiology • Achieved by barriers between compartments • Barriers regulate passage of substances between compartments • Cell membranes: between cells and interstial fluid • Blood vessels: between plasma and interstitial fluid

13. Body Fluid Compartments