[13:29, 2/4/2025] Nathalia: In studying biological organisms, including humans, you will encounter four key concepts: (1) structure and function relationships, (2) movement of chemicals along gradients, (3) cellto-cell communication, and (4) feedback loops. Throughout this chapter, we will highlight these key concepts. Then as you progress through the textbook, look for these key concepts. They will be discussed within every organ. system. Anatomy is the scientific discipline that investigates the body's structures-for example, the shape and size of bones. The word anatomy means to dissect or cut apart and separate the parts of the body for study. In addition, anatomy examines the relationship between the structure of a body part and its function. For example, the structure of a hammer informs us of its primary use: to deliver a hard blow to a small area of an object. Similarly, the fact that bone cells are surrounded by a hard, mineralized substance enables the bones to provide strength and support. This is the first of the four key concepts of anatomy and physiology: structure and function relationships. Understanding the relationship between structure and function makes it easier to understand and appreciate anatomy. Anatomy can be studied at different levels. Developmental anatony studies the structural changes that occur between conception and adulthood. Embryology (em-bree-OL-oh-jee), a subspecialty of developmental anatomy, considers changes from conception to the end of the eighth week of development. [13:29, 2/4/2025] Nathalia: Some structures, such as cells, are so small that they must be studied using a microscope. Cytology (sigh-TOL-oh-jee; cyto, cell) cxamines the structural features of cells, and histology (his TOL-oh-jee; hist, tissue) examines tissues, which are composed of cells and the materials surrounding them Gross anatomy, the study of structures that can be examined without the aid of a microscope, can be approached either systemically or regionally. A system is a group of structures that have one or more common functions, such as the cardiovascular, nervous, respiratory, skeletal, or muscular systems. In systemic anatomy, the body is studied system by system. In regional anatomy, the body is studied area by area. Within each region, such as the head, abdomen, or arm, all systems are studied simultaneously. The regional approach is taken in many graduate programs at medical and dental schools. The systemic approach is used in this and most other introductory textbooks. Surface anatomy involves looking at the exterior of the body to visualize structures deeper inside the body. For example, the sternum (breastbone) and bulges from the ribs can be seen and palpated (felt) on the front of the chest. Fealth professionals use these structures as anatomical landmarks to identify regions of the heart and points on the chest where certain heart sounds can best be heard Anatomical imaging uses radiographs (x-rays), ultrasound, magnetic resonance imaging (MRI), and other technologies to create pictures of internal structures ( table 1.1). Anatomical imaging has revolutionized medical science. Anatomical imaging allows medical personnel to look inside the body with amazing accuracy and without the trauma and risk of exploratory surgery. The risk of anatomical imaging is minimized by using the lowest possible number of doses providing the necessary information. No known risks exist from ultrasound or electromagnetic fields at the levels used for diagnosis. Both surface anatomy and anatomical imaging provide important information for diagnosing disease [13:31, 2/4/2025] Nathalia: However, no two humans are structurally identical. Anatomical anomalies are physical characteristics that differ from the normal pattern. Anatomical anomalies can vary in severity from relatively harmless to life-threatening. For example, each kidney is normally supplied by one blood vessel, but in some individuals a kidney is supplied by two blood vessels. Either way, the kidney receives adequate blood. On the other hand, in the condition called "blue baby" syndrome, certain blood vessels arising ftrom an infant's heart are not attached in their correct locations; blood is not effectively pumped to the lungs, and so the tissues do not receive adequate oxygen. Physiology iS the scientific investigation of the processes or functions of living things. There are tWo major goals when studying human m E physiology: (I) examining the body s responses to stimuli and (2) examining the body's maintenance of stable internal conditions within a narrow range of values in a constantly changing environment. Like anatomy, physiology can be considered at many levels. Cell physiology examines the processes occuring in cells such as energy production from food, and systemic pliysiology considers the functions of organ systems. Types of systemic physiology are cardiovascular physiology, which focuses on the heart and blood vessels, and neuroplysiology which focuses on the function of the nervous system. Physiology often examines systems rather than regions because a particular function can involve portions of a system in more than one region. The second key concept of anatomy and physiology is integral to studying physiology as you will learn: Chemicals move along gradients We will examine that more in 9 chapter 3. Page 12 Studies of the human body must encompass both anatomy and physiology because structures, functions, and processes are interwoven Pathology (pa-THOL-oh-jee) is the medical science dealing with all aspects of disease, with an emphasis on the cause and development of abnormal conditions, as well as the structural and functional changes resulting from disease. Exercise plysiology focuses on the changes in function and structure caused by exercise