INTRODUCTION TO THE BODY HUMAN ANATOMY & PHYSIOLOGY

Anatomy/Physiology ANATOMY - study of the structure of an organism and the relationships of its parts Anatomists learn about the human body by dissection PHYSIOLOGY – study of the function of living organisms and their parts Requires active experimentation Anatomical structures are designed for their specific functions FORM FITS FUNCTION! “Struc-Func”

History of Anatomical Studies Andreas Vesalius Obtained bodies of executed criminals for dissection Founder of modern human anatomy Published the first true anatomy textbook De humani corporis fabrica (On the Workings of the Human Body) Henry Gray Published Gray’s Anatomy Recent editions still used by medical students today

“Muscle Man” as seen in De Humani Corporis Fabrica by Andreas Vesalius

Hand-colored diagram of blood vessels in the neck as seen in Gray’s Anatomy (2 nd ed.) by Henry Gray

Structural Levels of Organization The body is a single structure, but it is made up of trillions of smaller structures working together to make a functioning organism Atoms combine to form molecules Molecules combine to form organelles Organelles combine to form cells (smallest “living” unit) Cells that work together combine to form tissues Tissues that work together to form organs Organs that work together form an organ system Organ Systems that work together form an organism

Structural Levels of Organization

Balance of Body Functions All living organisms have mechanisms that ensure survival of the body by keeping consistent internal conditions Homeostasis – regulation of the living environment – “biological balance” Every organism must have some sort of self-regulation to maintain homeostasis Known as FEEDBACK LOOPS

Negative Feedback Loop Negates or opposes a change in a condition By reversing the change, it returns to normal

Positive Feedback Loop Not as common Amplify or reinforce a change that is occurring Causes increase in rate of occurrence of events until something stops the process Examples: Uterine contractions in the birthing process; increasingly rapid sticking together of platelets to cuts

System – Group of organs that perform a more complex function than any organ alone Integument Skeletal Muscular Nervous Endocrine Circulatory Respiratory Digestive Lymphatic Urinary Listing of the 11 organ systems (the human body’s largest and most complex structural unit)