1 Anatomy and Physiology Big Picture

Why Study Anatomy and Physiology?

You probably have a general understanding of how your body works, but to truly understand the intricate functions of the human body and dispel many misconceptions that you have learned about your body over the years, you must approach the study of the body in an organized way.

This course will help you understand those intricacies and attack misconceptions head-on. This course will expose you to the complex levels of organization taking place inside the body and provide you with the information you need to delve deeply into the specific aspects of the body systems. This will prepare you for the more complex topics you will encounter in your future courses.

Core Principles in Anatomy and Physiology

• Living organisms are causal mechanisms whose functions are to be understood by applications of the laws of physics and chemistry.
• The cell is the basic unit of life.
• Life requires information flow within and between cells and between the environment and the organism.
• Living organisms must obtain matter and energy from the external world. This matter and energy must be transformed and transferred in varied ways to build the organism and to perform work.
• Homeostasis maintains the internal environment in a more or less constant state compatible with life.
• Understanding the behavior of the organism requires understanding the relationship between structure and function (at each and every level of organization).
• Living organisms carry out functions at many different levels of organization simultaneously.
• All life exists within an ecosystem made up of the physiochemical and biological worlds.
• Evolution provides a scientific explanation for the history of life on Earth and the mechanisms by which changes to life have occurred.

Organizing Anatomy and Physiology Concepts

The goal of this course is for you to think and speak in the language of the domain while integrating the knowledge you gain about anatomy to support explanations of physiological phenomenon. The course focuses on a few themes derived from the core principles, that when taken together, provide a full view of what the human body is capable of and the exciting processes going on inside of it. These organizational themes are:

• Structure and function of the body, and the connection between the two.
• Homeostasis, the body’s natural tendency to maintain a stable internal environment.
• Levels of Organization, the major levels of organization in the human organism from the chemical and cellular levels to the tissues, organs and organ systems.
• Integration of Systems, concerning which systems are subsets of larger systems, and how they function together in harmony and conflict.

You can see how these themes directly relate to the core principles. As these themes are used to describe the inner workings of each of the body’s organ systems, an integrated collection of organs that function together, those systems can be categorized based on their contribution to the specific vital functions for human life. The vital functions provide the context for the whole body, and how each organ system plays a role in keeping us alive. So, the information provided for each of the organ systems is organized according to those functions that are essential to the survival of the human body. The vital functions for human life are:

• Exchange with the environment
• Transport within the body
• Structure, support, and movement
• Control and regulation

All multicellular organisms need these vital functions to operate properly in order to survive. In addition to understanding the Themes and Vital Functions that help us organize our knowledge about the structure and function of the different body organ systems, knowing and using proper terminology related to body planes and directional terms will also help you in your quest for Anatomy and Physiology mastery.

Themes in Anatomy and Physiology

Everyone has a body and, by adulthood, a general understanding of how it works. But to truly understand the intricate functions of the human body—and the problems that occur when something goes wrong—you must approach the study of the body in an organized way. This course will help you understand the functions of the human body. We will discuss the details of many complex functional systems, but will also look at how all of these systems work in harmony to keep you healthy. As you move through this course, you should keep four main themes in mind: structure and function, homeostasis, levels of organization, and integration of systems.

Structure and Function

The first theme is the connection between structure and function. You will be studying both anatomy, which focuses on the body’s structures, and physiology, which focuses on the body’s functions. In fact, it is virtually impossible to study one without the other, because function relies so completely upon structure. For example, the structure of the bones in the skeletal system provides the support necessary for the function of walking upright. The vocal cords would not be able to fulfill their function—the production of sound—if their structure were disrupted. The large surface area of the small intestine allows it to efficiently perform its primary function: absorbing nutrients from food. And the list goes on.

Homeostasis

The second theme will be homeostasis, or the body’s natural tendency to maintain a relatively stable internal environment. Most of the body’s functions are driven by homeostasis. Homeostasis occurs at all different levels. For example, body temperature is regulated around 98.6, a temperature that is optimal for cell function and organism function. To maintain this temperature, we sweat to cool down on a hot day and we shiver to increase temperature when we are cold. Other variables, like blood pressure, blood pH, blood calcium concentrations are similarly maintained within a narrow range that is optimal for human health. Many diseases occur because of disruptions in homeostasis.

Levels of Organization

The third theme will be the hierarchical organization of the parts of the body. You can think of the body’s parts as being organized into a hierarchy of levels. Your body, like all things in the physical world, is built from chemical building blocks. The smallest of these building blocks are atoms of elements, which combine to form bigger and more complicated structures called molecules. These molecules, such as water, proteins, carbohydrates (glucose), and lipids are used to build cells, the smallest unit of structure capable of carrying out all life processes. Groups of related cells that work together to perform specific functions make up tissues, and tissues that work together form organs. Organs do not work independently; they are organized into organ systems that complete more complex tasks.

The digestive system, for example, includes the mouth, stomach, intestines, and many other organs—all of which are integral to proper functioning of the system as a whole. The organ systems work together to support life in the entire organism—in this case, a human being.

Understanding this hierarchy is important because disruptions might occur at any level. For example, a depletion of calcium atoms from the body can lead to weak bones. Or a single mutation in a DNA molecule can lead to organ dysfunction, such as the disturbed lung function found in individuals with cystic fibrosis.

Integration of Systems

Finally, each section of the course will discuss the integration of all the body’s systems. In order to carry out its functions, every organ system relies on the healthy functioning of other systems. When these systems all work together, the organism thrives. A breakdown in one system can cause failures in other systems as well.