Life Sciences

Life Science is the study of living organisms (plants, animals and human beings).  Biology is the centerpiece of the Life Sciences.

Biology is the study of living organisms.  It is concerned with the characteristics, classification and behaviors of organisms and how species were formed.  Microbiology was created with the discovery of micro-organisms by use of the optical microscope (17th century).  Key biological developments include genetics, Darwin’s theory of evolution through natural selection and the germ theory of disease.  Biology can be divided into four groups: 1) molecular (chemistry of life), 2) cellular (study of the cell), 3) physiology (internal structure of organisms), 4) ecology (interactions of organisms).  Genetics Timeline.

Medicine is the science and art of maintaining and restoring health by the prevention and treatment of illness in human beings.  The word medicine is derived from the Latin ars medicina, meaning the art of healing.

The clinical examination involves study of:
 • Vital signs (height, weight, body temperature, blood pressure, pulse, respiration rate, hemoglobin oxygen saturation)
 • General appearance of the patient and specific indicators of disease
 • Skin
 • Head, eye, ear, nose, and throat (HEENT)
 • Cardiovascular (heart and blood vessels)
 • Respiratory (large airways and lungs)
 • Abdomen and rectum
 • Genitalia (and pregnancy)
 • Musculoskeletal (including spine and extremities)
 • Neurological (consciousness, awareness, brain, vision, cranial nerves, spinal cord, peripheral nerves)
 • Psychiatric (orientation, mental state, evidence of abnormal perception or thought).

Physiology is the science of the function of living systems.  It investigates how organisms, organ systems, organs, cells, and bio-molecules carry out the chemical or physical functions that exist in a living system. Human physiology is the science of the mechanical, physical, and biochemical functions of humans in good health, their organs, and the cells of which they are composed. The principal level of focus of physiology is at the level of organs and systems within systems.  Much of the foundation of knowledge in human physiology was provided by animal experimentation. Physiology is closely related to anatomy where anatomy is the study of form and physiology is the study of function. Due to the frequent connection between form and function, physiology and anatomy are intrinsically linked and are studied in tandem as part of a medical curriculum.

Significant Life Science Theories

Biology: Germ Theory of Disease
Proposes that microorganisms are the cause of many diseases.  Highly controversial when first proposed, germ theory was validated in the late 19th century and is now a cornerstone of modern medicine and microbiology.  French bacteriologist Louis Pasteur is considered the father of microbiology. 

Biology: Theory of Evolution
All living things are related to one another through common ancestry from earlier forms that differed from the present forms.  Exactly how evolution occurs is still a matter of debate.  Biologists agree that all living things arose through a long history of changes shaped by physical and chemical process that are still taking place.  According to the theory, variability among individuals in a population of sexually reproducing organisms is produced by mutation and genetic recombination.  The resulting genetic variability is subject to natural selection in the environment.

Biology: Cell Theory
Cell theory of life states: 1) all living material is made up of cells, 2) all cells are derived from previously existing cells; most cells arise by cell division, but in sexual organisms they may be formed by the fusion of sperm and egg, 3) a cell is the most elementary unit of life, 4) every cell is bounded by a plasma membrane, an extremely thin skin separating it from the environment and from other cells, 5) all cells have strong biochemical similarities and 6) most cells are about  0.001 cm (0.0004 in) in length; the smallest cells of mycoplasma are 0.3 micrometers in size, whereas some giant algae cells reach several centimeters long.