Chapter 1 Major Themes of Anatomy & Physiology Structure and Function Homeostasis

Anatomy - The Study of Form Anatomy involves: Simplest observation – examination of surface structures Deeper understanding requires cadaver dissection (which is cutting & separation of tissues to study their relationships) Comparative anatomy - the study of more than one species to analyze evolutionary trends – we obtain many insights into human anatomy by studying other species. Physical examination Palpation (feeling structures with the fingertips), auscultation (listening to natural sounds made by the body), percussion (tapping on the body and listening for echoes) Gross anatomy - what is visible with naked eye Histology - examination of cells with microscope

Physiology - The Study of Function Study of bodily functions by use of methods of experimental science Comparative physiology involves the study of different species Basis for the development of new drugs and medical procedures

What is Life? Properties that distinguish from nonliving things: organization & cellular composition biochemical composition (DNA, proteins, etc) metabolism is transformation of molecules into others responsiveness is ability to sense & react to stimuli homeostasis is to maintain stable internal environment development is change over time (growth or differentiation) reproduction is producing copies of themselves What is death? Clinical death is no brain waves for 24 hours

Structure - A Hierarchy of Complexity Subatomic particles compose atoms Atoms compose molecules Molecules compose organelles Organelles compose cells Cells compose tissues Tissues compose organs Organs compose organ systems Organ systems compose the organism

Homeostasis Hippocrates noted that body normally returns to a state of equilibrium by itself needs to detect the change & oppose it Walter Cannon (1871-1945) coined the term homeostasis indicating stable internal environment Internal environment described as dynamic equilibrium fluctuates within a range around a certain set point Forrest Definition (1996): A state of internal constancy But how do we maintain homeostasis?....

Negative Feedback and Stability Negative Feedback is the mechanism of Homeostasis Negative Feedback’s keeps a variable close to its set point Body senses a change & activates mechanisms to reverse it

Negative Feedback, Set Point Room temperature does not stay at set point of 68 degrees -- it only averages 68 degrees

Human Thermoregulation Temperature sensing nerve cells in base of brain control shivering, sweating & vasomotor activity vasodilation & vasoconstriction Evaporation of water & heat radiation occur

Structures Needed for Feedback Loop Receptor = structure that senses change (sensor) stretch receptors in heart & large blood vessels send information of an elevated BP to integrator Integrator = control center (integration center) cardiac center in brainstem that signals heart to slow Effector = structures that carry out commands of the control center (Effector Organ) heart slows and BP decreases

Positive Feedback Loops Self-amplifying cycle in which a physiological change leads to an even greater change in the same direction Normal way of producing changes during birth, blood clotting, protein digestion & generation of nerve signals

Fever If temperature rises above 108 degrees metabolic rate increases causing body to produce heat faster still Temperature increases & cycle repeats again Fatal at 113 degrees

Review of Major Themes Unifying principles behind all aspects of human anatomy and physiology cell theory: all structure & function result from the activity of cells homeostasis: maintaining stable conditions within the body hierarchy of structure: levels of complexity unity of form and function: physiology can not be separated from anatomy (Shape Dictates Function)