Trusted by 2+ million users, 1000+ happy students everyday
ANATOMY AND PHYSIOLOGY DEFINED OBJECTIVE •Define anatomy and physiology, and name several subspecialties of these sciences. Two branches of science—anatomy and physiology—provide the foundation for understanding the body's parts and functions.Anatomy(a NAT ō mē;‐‐ ‐ana= up;‐tomy‐= process of cutting) is the science of bodystructuresand the relationships among them. It was first studied bydissection(dis SEK shun;‐‐dis=‐ apart;section‐= act of cutting), the careful cutting apart of body structures to study their relationships. Today, a variety of imaging techniques (see Table 1.3) also contribute to the advancement of anatomical knowledge. Whereas anatomy deals with structures of the body,physiology(fiz′ ē OL ō jē;‐ ‐‐ ‐physio= nature;‐logy‐= study of) is the science of bodyfunctions—how the body parts work. Table 1.1 describes several subspecialties of anatomy and physiology. Table1.1Selected Subspecialties of Anatomy and Physiology SUBSPECIALTIES OF ANATOMYSTUDY OF Embryology (em' brē OL ō jē;‐‐‐ ‐embry= embryo;‐‐ logy= study of) The first eight weeks of development after fertilization of a human egg. Developmental biologyThe complete development of an individual from fertilization to death. Cell biologyCellular structure and functions. Histology (hiss' TOL ō jē;‐‐ ‐hist= tissue)‐ Microscopic structure of tissues. Gross anatomyStructures that can be examined without a microscope. Systemic anatomyStructure of specific systems of the body such as the nervous or respiratory systems. Regional anatomySpecific regions of the body such as the head or chest. Surface anatomySurface markings of the body to understand internal anatomy through visualization and palpation (gentle touch). Radiographic anatomy (rā' dē ō GRAF ik;‐‐ ‐‐radio= ray;‐‐ graphic= to write) Body structures that can be visualized with x rays.‐ Pathological anatomy (path' ō LOJ i kal;‐ ‐‐ ‐path= disease)‐ Structural changes (gross to microscopic) associated with disease.
3.Tissue level.Tissuesare groups of cells and the materials surrounding them that work together to perform a particular function, similar to the way words are put together to formsentences. There are just four basic types of tissues in your body: epithelial tissue, connective tissue, muscular tissue, and nervous tissue. Epithelial tissuecovers body surfaces, lines hollow organs and cavities, and forms glands.Connective tissueconnects, supports, and protects body organs while distributing blood vessels to other tissues.Muscular tissuecontracts to make body parts move and generates heat.Nervous tissuecarries information from one part of the body to another through nerve impulses. Chapter4describes the tissue level of organization in greater detail. Shown in Figure1.1is smooth muscle tissue, which consists of tightly packed smooth muscle cells. 4.Organ level.At the organ level different types of tissues are joined together. Similar to the relationship between sentences andparagraphs,organsare structures that are composed of two or more different types of tissues; they have specific functions and usually have recognizable shapes. Examples of organs are the stomach, skin, bones, heart, liver, lungs, and brain. Figure1.1shows how several tissues make up the stomach. The stomach's outer covering is a layer of epithelial tissue and connective tissue that reduces friction when the stomach moves and rubs against other organs. Underneath are three layers of a type of muscular tissue calledsmooth muscle tissue,which contracts to churn and mix food and then push it into the next digestive organ, the small intestine. The innermost lining is anepithelial tissue layerthat produces fluid and chemicals responsible for digestion in the stomach. 5.System level.Asystem(orchapterin our language analogy) consists of related organs (paragraphs) with a common function. An example of the system level, also called theorgan system level,‐is the digestive system, which breaks down and absorbs food. Its organs include the mouth, salivary glands, pharynx (throat), esophagus (food tube), stomach, small intestine, large intestine, liver, gallbladder, and pancreas. Sometimes an organ is part of more than one system. The pancreas, for example, is part of both the digestive system and the hormone producing endocrine system.‐ 6.Organismal level.Anorganism(OR ga nizm), any living individual, can be compared to a‐‐bookin our analogy. All the parts of the human body functioning together constitute the total organism. Figure1.1Levels of structural organization in the human body. The levels of structural organization are chemical, cellular, tissue, organ, system, and organismal.Kevin Somerville; Rubberball Productions/Getty Images Which level of structural organization is composed of two or more different types of tissues that work together to perform a specific function? In the chapters that follow, you will study the anatomy and physiology of the body systems. Table1.2lists the components and introduces the functions of these systems. You will also discover that all body systems influence one another. As you study each of the body systems in more detail, you will discover how they work together to maintain health, provide protection from disease, and allow for reproduction of the human species. Table1.2The Eleven Systems of the Human Body INTEGUMENTARY SYSTEM (Chapter5)SKELETAL SYSTEM (Chapters6–9)
DNA Illustrations Examples Anatomy Overview: The Integumentary System Anatomy Overview: The Skeletal System Anatomy Overview: The Muscular System Anatomy Overview: The Nervous System Anatomy Overview: The Endocrine System Anatomy Overview: The Cardiovascular System Anatomy Overview: The Lymphatic and Immune Systems Anatomy Overview: The Respiratory System Anatomy Overview: The Digestive System Anatomy Overview: The Urinary System Anatomy Overview: The Reproductive System CLINICAL CONNECTIONNoninvasive Diagnostic Techniques Health care professionals and students of anatomy and physiology commonly use several noninvasive‐ diagnostic techniques to assess certain aspects of body structure and function. Anoninvasive diagnostic techniqueis one that does not involve insertion of an instrument or device through the skin or a body opening. Ininspection,the examiner observes the body for any changes that deviate from normal. For example, a physician may examine the mouth cavity for evidence of disease. Following inspection, one or more additional techniques may be employed. Inpalpation(pal PĀ shun;‐‐palp= gently touching)‐ the examiner feels body surfaces with the hands. An example is palpating the abdomen to detect enlarged or tender internal organs or abnormal masses. Inauscultation(aws kul TĀ shun;‐‐‐auscult= listening)‐ the examiner listens to body sounds to evaluate the functioning of certain organs, often using a stethoscope to amplify the sounds. An example is auscultation of the lungs during breathing to check for crackling sounds associated with abnormal fluid accumulation. Inpercussion(pur KUSH un;‐‐percus=‐ beat through) the examiner taps on the body surface with the fingertips and listens to the resulting echo. For example, percussion may reveal the abnormal presence of fluid in the lungs or air in the intestines. It may also provide information about the size, consistency, and position of an underlying structure. An understanding of anatomy is important for the effective application of most of these diagnostic techniques. 1.3CHARACTERISTICS OF THE LIVING HUMAN ORGANISM OBJECTIVES
Basic Life Processes Certain processes distinguish organisms, or living things, from nonliving things. Following are the six most important life processes of the human body: 1.Metabolism(me TAB ō lizm) is the sum of all the chemical processes that occur in the body. One‐‐ ‐ phase of metabolism iscatabolism(ka TAB ō lizm;‐‐ ‐catabol= throwing down;‐ism‐= a condition), the breakdown of complex chemical substances into simpler components. The other phase of metabolism isanabolism(a NAB ō lizm;‐‐ ‐anabol= a raising up), the building up of complex chemical‐ substances from smaller, simpler components. For example, digestive processes catabolize (split) proteins in food into amino acids. These amino acids are then used to anabolize (build) new proteins that make up body structures such as muscles and bones. 2.Responsivenessis the body's ability to detect and respond to changes. For example, an increase in body temperature during a fever represents a change in the internal environment (within the body), and turning your head toward the sound of squealing brakes is a response to a change in the external environment (outside the body) to prepare the body for a potential threat. Different cells in the body respond to environmental changes in characteristic ways. Nerve cells respond by generating electrical signals known as nerve impulses (action potentials). Muscle cells respond by contracting, which generates force to move body parts. 3.Movementincludes motion of the whole body, individual organs, single cells, and even tiny structures inside cells. For example, the coordinated action of leg muscles moves your whole body from one place to another when you walk or run. After you eat a meal that contains fats, your gallbladder contracts and releases bile into the gastrointestinal tract to help digest them. When a body tissue is damaged or infected, certain white blood cells move from the bloodstream into the affected tissue to help clean up and repair the area. Inside the cell, various parts, such as secretory vesicles (see Figure3.20), move from one position to another to carry out their functions. 4.Growthis an increase in body size that results from an increase in the size of existing cells, an increase in the number of cells, or both. In addition, a tissue sometimes increases in size because the amount of material between cells increases. In a growing bone, for example, mineral deposits accumulate between bone cells, causing the bone to grow in length and width. 5.Differentiation(dif′ er en shē Ā shun) is the development of a cell from an unspecialized to a‐‐‐‐‐ specialized state. Such precursor cells, which can divide and give rise to cells that undergo differentiation, are known asstem cells.As you will see later in the text, each type of cell in the body has a specialized structure and function that differs from that of its precursor (ancestor) cells. For example, red blood cells and several types of white blood cells all arise from the same unspecialized precursor cells in red bone marrow. Also through differentiation, a single fertilized human egg (ovum) develops into an embryo, and then into a fetus, an infant, a child, and finally an adult. 6.Reproduction(rē prō DUK shun) refers either to (1) the formation of new cells for tissue growth,‐‐‐ repair, or replacement, or (2) the production of a new individual. In humans, the former process occurs continuously throughout life, which continues from one generation to the next through the latter process, the fertilization of an ovum by a sperm cell.
When any one of the life processes ceases to occur properly, the result is death of cells and tissues, which may lead to death of the organism. Clinically, loss of the heartbeat, absence of spontaneous breathing, and loss of brain functions indicate death in the human body. CLINICAL CONNECTIONAutopsy Anautopsy(AW top sē = seeing with one's own eyes) or‐‐necropsyis a postmortem (after death) examination of the body and dissection of its internal organs to confirm or determine the cause of death. An autopsy can uncover the existence of diseases not detected during life, determine the extent of injuries, and explain how those injuries may have contributed to a person's death. It also may provide more information about a disease, assist in the accumulation of statistical data, and educate health care students. Moreover, an‐ autopsy can reveal conditions that may affect offspring or siblings (such as congenital heart defects). Sometimes an autopsy is legally required, such as during a criminal investigation. It may also be useful in resolving disputes between beneficiaries and insurance companies about the cause of death. 1.4HOMEOSTASIS OBJECTIVES •Define homeostasis. •Describe the components of a feedback system. •Contrast the operation of negative and positive feedback systems. •Explain how homeostatic imbalances are related to disorders. Homeostasis(hō′ mē ō STĀ sis;‐‐ ‐‐homeo= sameness;‐stasis‐= standing still) is the condition of equilibrium (balance) in the body's internal environment due to the constant interaction of the body's many regulatory processes. Homeostasis is a dynamic condition. In response to changing conditions, the body's equilibrium can shift among points in a narrow range that is compatible with maintaining life. For example, the level of glucose in blood normally stays between 70 and 110 milligrams of glucose per 100 milliliters of blood.*Each structure, from the cellular level to the system level, contributes in some way to keeping the internal environment of the body within normal limits. Homeostasis and Body Fluids An important aspect of homeostasis is maintaining the volume and composition ofbody fluids,dilute, watery solutions containing dissolved chemicals that are found inside cells as well as surrounding them. The fluid within cells isintracellular fluid(intra= inside), abbreviated‐ICF.The fluid outside body cells isextracellular fluid(extra= outside), abbreviated‐ECF.The ECF that fills the narrow spaces between cells of tissues is known asinterstitial fluid(in′ ter STISH al;‐‐‐inter= between). As you progress with‐ your studies, you will learn that the ECF differs depending on where it occurs in the body: ECF within blood vessels is termedblood plasma,within lymphatic vessels it is calledlymph, in and around the brain
and spinal cord it is known ascerebrospinal fluid,in joints it is referred to assynovial fluid,and the ECF of the eyes is calledaqueous humorandvitreous body. The proper functioning of body cells depends on precise regulation of the composition of the interstitial fluid surrounding them. Because of this, interstitial fluid is often called the body'sinternal environment. The composition of interstitial fluid changes as substances move back and forth between it and blood plasma. Such exchange of materials occurs across the thin walls of the smallest blood vessels in the body, theblood capillaries. This movement in both directions across capillary walls provides needed materials, such as glucose, oxygen, ions, and so on, to tissue cells. It also removes wastes, such as carbon dioxide, from interstitial fluid. Control of Homeostasis Homeostasis in the human body is continually being disturbed. Some disruptions come from the external environment in the form of physical insults such as the intense heat of a hot summer day or a lack of enough oxygen for that two mile run. Other disruptions originate in the internal environment, such as a‐ blood glucose level that falls too low when you skip breakfast. Homeostatic imbalances may also occur due to psychological stresses in our social environment—the demands of work and school, for example. In most cases the disruption of homeostasis is mild and temporary, and the responses of body cells quickly restore balance in the internal environment. However, in some cases the disruption of homeostasis may be intense and prolonged, as in poisoning, overexposure to temperature extremes, severe infection, or major surgery. Fortunately, the body has many regulating systems that can usually bring the internal environment back into balance. Most often, the nervous system and the endocrine system, working together or independently, provide the needed corrective measures. The nervous system regulates homeostasis by sending electrical signals known asnerve impulses (action potentials)to organs that can counteract changes from the balanced state. The endocrine system includes many glands that secrete messenger molecules calledhormonesinto the blood. Nerve impulses typically cause rapid changes, but hormones usually work more slowly. Both means of regulation, however, work toward the same end, usually through negative feedback systems. Examples Animation: Communication, Regulation and Homeostasis Feedback Systems The body can regulate its internal environment through many feedback systems. Afeedback systemorfeedback loopis a cycle of events in which the status of a body condition is monitored, evaluated, changed, remonitored, reevaluated, and so on. Each monitored variable, such as body temperature, blood pressure, or blood glucose level, is termed acontrolled condition. Any disruption that changes a controlled condition is called astimulus. A feedback system includes three basic components: a receptor, a control center, and an effector (Figure1.2).
1.Areceptoris a body structure that monitors changes in a controlled condition and sends input to a control center. This pathway is called anafferent pathway(AF er ent;‐‐af= toward;‐‐ferrent= carried), since the information flowstowardthe control center. Typically, theinputis in the form of nerve impulses or chemical signals. For example, certain nerve endings in the skin sense temperature and can detect changes, such as a dramatic drop in temperature. 2.Acontrol centerin the body, for example, the brain, sets the range of values within which a controlled condition should be maintained (set point), evaluates the input it receives from receptors, and generates output commands when they are needed.Outputfrom the control center typically occurs as nerve impulses, or hormones or other chemical signals. This pathway is called anefferent pathway(EF er ent;‐‐ef= away from), since the information flows‐away fromthe control center. In our skin temperature example, the brain acts as the control center, receiving nerve impulses from the skin receptors and generating nerve impulses as output. 3.Aneffector(e FEK tor) is a body structure that receives output from the control center and‐‐ produces aresponseor effect that changes the controlled condition. Nearly every organ or tissue in the body can behave as an effector. When your body temperature drops sharply, your brain (control center) sends nerve impulses (output) to your skeletal muscles (effectors). The result is shivering, which generates heat and raises your body temperature.
Found this document preview useful?
You are reading a preview Upload your documents to download or Become a Desklib member to get accesss