Overview of Human Anatomy and Physiology
Learning Objectives
At the completion of this chapter the student will be able to:
1.Define anatomy and physiology, and list the structural levels of organization in the human body.
2.Differentiate and understand the characteristics of living organisms.
3.Describe the role of homeostasis in the human body, and provide specific examples.
4.Identify the major organ systems of the body and describe their purpose.
5.Use proper anatomical terminology to describe the body and relative positions.
6.Discern and appreciate the types of movement of the body and their proper names.
Case Study Introduction
It’s a cold, rainy Monday night and you just have one of those bad feelings. You are a Paramedic, and this feeling comes all too often. Suddenly, you and your partner are called to the scene of an automobile accident that has just occurred on the major highway leading into town.
As you arrive on scene, you find the driver unconscious and still in the car. On primary assessment, you notice that she is still breathing, though with difficulty, on her own. You see blood around her nose and mouth, and you hear a gurgling sound as she breathes. You also notice that she is wearing her seatbelt, but the vehicle air bags did not deploy.
Another person who witnessed the accident tells you that she saw the driver try to steer away from a truck that had lost control in the rain. However, the driver of the car, in the midst of maneuvering, also lost control of her vehicle and ended up veering off the highway, spinning out of control, and hitting the guardrail directly head-on before coming to a stop.
As your partner sets up the medical equipment, you take a secondary assessment. The victim’s breathing is shallow and rapid, with multiple lacerations on her face. She has a thready radial pulse of 150 beats per minute, and her blood pressure in 90/50. Respirations are at 28 breaths a minute, diminished on the right side.
Your partner hands you a cervical collar and you place it on the victim, stabilizing her cervical spine. You crew arrives and together the team pulls the victim out of the vehicle and places her on a backboard, transporting her to the ambulance. Inside the ambulance, you begin a more detailed survey, monitoring her vitals and looking for more injuries. You notice a large contusion on her sternum and several lacerations superior to the antecubital fossa, and on the medial aspect of her right arm. She also has a deformity on the lateral aspect of the left thigh. While you start all life-saving protocols, including IV fluids and an ECG, your partner calls the nearest hospital with the report you have given him.
■ Introduction
When studying the human body as a whole, a basic and step-by-step progression is the most logical approach. The human body is a complex and dynamic system composed of many different structures and functions. Therefore, a necessary and thorough understanding of the human body’s anatomy and physiology is essential.
It is wise to always begin the study of any subject by first defining that subject. What is anatomy and physiology? Anatomy, by definition, is simply the study of a living organism’s structure or its form, while physiology is the study of its function. More simply, anatomy is the study of what an organism looks like, and physiology is the study of how that living organism operates. Remember this: throughout the course of Anatomy and Physiology, you are simply learning form and function.
Anatomy is further divided into gross anatomy and microscopic anatomy. Gross anatomy is studied through the dissection of anatomical structures visible to the naked eye. Microscopic anatomy, true to its namesake, is the study of very small anatomical structures that require the assistance of a microscope to be adequately seen. Moreover, it becomes sensible to classify the human body from its most simple to its most complex level of structural organization.
Figure 1-1 Organ systems.
Here we have one of the most basic, yet, extremely important aspects to the study of anatomy and physiology, (and hence a favorite test question for instructors and examiners worldwide); the order of the levels of structural organization of the human body, from the simplest to the most complex as follows:
The following is an overly simplified, yet accurate example of the above: Atoms of hydrogen and oxygen form and function together to produce a molecule of hydroxide. Molecules (for example, hydroxide and phosphate) form and function together to produce the phospholipid bilayer of a cell.
A group of cells known as stratified squamous cells form and function together to produce a tissue called epithelium.
The epithelial tissue forms and functions together to produce an organ called skin. The skin, hair, and nails form and function together to produce an organ system called the integumentary system. The integumentary system forms and functions together with ten other organ systems to produce an organism – the human being.
Next, to fully understand the human as an organism, we must first look at the big picture, an overview if you will, of the body’s form and function. One of the most fundamental concepts to keep in mind during your investigation of the human body it to remember that the body is a dynamic, living organism – that is the human body’s structure and functioning must be maintained at all times via self-sustaining processes.
■ Characteristics of Living Organisms
As previously noted, when studying the human body, it’s imperative to remember that it’s a living organism. The human body must be distinguished from non-living objects, not simply for mere classification purposes, but for a proper and systematic understanding of the dynamics regarding the actual anatomy and physiology involved in the human body.
Six characteristics said to be required of livings organisms are discussed below.
All living things are composed of one or more cells. All organisms start from a single cell, which will divide several times until differentiation is completed, where the cell’s form and function change – producing various kinds of cells to carry out diverse purposes within the organism.
Note: Viruses are a debatable omission; they are not composed of cells, but rather exist and function in a “host” cell. However, they are still classified as living organisms.
All living things are organized.1 The complexity of a living organism is assembled from microscopic, albeit structured levels, grouping common forms and functions together. Macroscopically, they become observable as the cells are structured to allow for the most physiological sense of the organism. Here, another essential premise in anatomy and physiology should be made: Form always follows function, meaning that organisms are structured conducive and according to how they work – not vice versa.
All living organisms require the use of energy.2 A chemical process by which nutrients are absorbed and converted into energy to be used at the cellular level is called metabolism.
