Introduction to the Human Body PDF

Introduction to the Human Body 1 http://evolve.elsevier.com/Herlihy Objectives 1.  efine the...

Introduction to the Human Body 1 http://evolve.elsevier.com/Herlihy Objectives 1.  efine the terms anatomy and physiology. D 6. L ist common terms used for relative positions of the body. 2. List the levels of organization of the human body. 7. Describe the three major planes of the body. 3. Describe the 12 major organ systems. 8. List anatomical terms for quadrants and regions of the 4. Define homeostasis. body. 5. Describe the anatomical position. 9. Describe the major cavities of the body. Key Terms abdominopelvic cavity (p. 9) mediastinum (p. 9) spinal (vertebral) cavity (p. 9) anatomical position (p. 7) organs (p. 2) thoracic cavity (p. 9) anatomy (p. 1) pericardial cavity (p. 9) transverse plane (p. 7) cranial cavity (p. 9) physiology (p. 1) ventral cavity (p. 8) dorsal cavity (p. 8) pleural cavities (p. 9) viscera (p. 8) frontal plane (p. 7) quadrants (p. 10)    homeostasis (p. 6) sagittal plane (p. 7) The human body is a wonderful creation. Millions of mi- ANATOMY AND PHYSIOLOGY: WHAT croscopic parts work together in a coordinated fashion to THEY ARE keep you going for approximately 75 years. Most of us are curious about our bodies—how they work, why they do WHAT’S IT MEAN? not work, what makes us tick, and what makes us sick. As you learn more about the body, you will sometimes have Anatomy (ah-NAT-o-mee) is the branch of science that the same questions as the cartoon character below: “What studies the structure of the body. For example, anato- is this? Why do I need it? How does it work? Why don’t my describes what the heart looks like, how big it is, I have one?” As you study anatomy and physiology, you what it is made of, how it is organized, and where it is will learn the answers to these questions. located. The word anatomy comes from the Greek word meaning to dissect. The science of anatomy arose from observations made by scientists centuries ago as they dissected bodies that were usually stolen from the lo- cal graveyard. Physiology (fiz-ee-OL-o-jee) is the branch of sci- ence that describes how the body functions. For ex- ample, physiology describes how the heart pumps blood and why the pumping of blood is essential for life. Pathophysiology (path-o-fiz-ee-OL-o-jee) is the branch of science that describes the consequences of the improper functioning of the body (i.e., how a body part functions when a person has a disease). Pathophysiology describes what happens during a heart attack and when the heart functions poorly or not at all. 1 2 CHAPTER 1 Introduction to the Human Body ability to grasp an object (Fig. 1.1). The heart pumps blood, and the long, strong, flexible tail of the mon- key allows it to hang from the tree. Structure and function are related. Re-Think 1. What is the difference between anatomy and physiology? 2. Using any household item, explain what is meant by   “structure and function are related.” Do You Know... Why This Grave Is Being Robbed, and Why the Grave Robber Is in Big, Big Trouble? Dissection of the human body during medieval times was not allowed. Thus the only way that early anatomists were able to obtain human bodies for dissection was to rob graves. Medieval scientists hired people to rob graves. Punishment for robbing graves was swift and severe. This lad will be in big, big trouble if he is caught, and it looks as if he will be. Surprisingly, grave robbing was common early in this century and in this country. Many a medical student who enrolled in the most prestigious medical schools had to “get” his own cadaver (dead body). Fig. 1.1 Structure and Function are Closely Related. Go Figure (Refer to Fig 1.1) 1. T/F __ The purpose of this figure is to show that anatomy      (structure) is related to function (physiology). WHY DO I NEED TO KNOW THIS? THE BODY’S LEVELS OF ORGANIZATION Why study anatomy and physiology as part of your professional curriculum? Unless you gain a good The body is organized from the very simple to the understanding of normal anatomy and physiology, complex, from the microscopic atom to the complex you cannot understand the diseases and disorders human organism. Note the progression from simple experienced by your patients, nor can you under- to complex in Fig. 1.2. Tiny atoms form molecules. stand the basis for the various forms of treatment, These, in turn, form larger molecules. The larger such as drug therapy and surgical procedures. You molecules are eventually organized into cells, the ba- want to give your patients the best possible care, so sic unit of life. Specialized groups of cells form tis- you must have a sound understanding of the hu- sues. Tissues are then arranged into organs, such as man body. the heart, stomach, and kidney. Groups of organs, in Anatomy and physiology are closely related. turn, create organ systems. Each organ system has a Structure and function go together. When you exam- function, such as digestion, excretion, or reproduc- ine the anatomy of a body part, ask yourself how tion. All the organ systems together form the human its structure relates to its function. For example, the organism. From simple to complex, the body is built structure of the hand is related to its function: its from the tiny atom to the human being.  Introduction to the Human Body CHAPTER 1 3 Atoms Molecules Cells Tissue Organ system Organism Organ Fig. 1.2 Levels of Organization, from Atoms to Human Organism. Go Figure (Refer to Fig 1.2) maintenance of body posture. Cardiac muscles are 1. T/F __ The stomach and intestines are organs that are found in the heart and enable the heart to pump   part of the digestive organ system. blood throughout the body. Smooth muscles are found in various organs and tubes; contraction and relaxation of this muscle type helps move body flu- id. Vascular smooth muscle, for instance, helps to MAJOR ORGAN SYSTEMS move blood through the blood vessels. Twelve major organ systems make up the human body. The nervous system is made up of the brain, spinal Each performs specific functions that enable the hu- cord, nerves, and sense organs. Sensory nerves re- man body to operate as a coordinated whole. Refer to ceive information from the environment and bring Fig. 1.3 and identify the location and distribution of the it to the spinal cord and brain, where it is interpret- organs of each system. ed. Decisions made by the brain and spinal cord are The integumentary (in-teg-yoo-MEN-tar-ee) system transmitted along motor nerves to various body consists of the skin and related structures, such as structures to elicit a response such as leg movement. hair and nails. The integumentary system forms a And, of course, our brain thinks, emotes, remem- covering for the body, helps to regulate body tem- bers, reflects, integrates, creates, and performs all perature, and contains some of the structures neces- those higher-level functions that characterize the sary for sensation. human brain. The skeletal system forms the basic framework of The endocrine (EN-doh-krin) system contains nu- the body. It consists primarily of bones, joints, and merous glands that secrete hormones and chemi- cartilage. The skeleton protects and supports body cal substances that regulate body activities such organs and enables us to move around. Because the as growth, reproduction, metabolism, and water bones contain bone marrow they also produce most balance. of the blood cells. The circulatory (SER-kyoo-lah-tor-ee) system con- The muscular system has three types of muscles. sists of the blood, heart, and blood vessels. This sys- Skeletal muscles attach to the bones and are re- tem pumps (heart) and transports (blood vessels) sponsible for movement of the skeleton and the blood throughout the body. Blood carries nutrients 4 CHAPTER 1 Introduction to the Human Body Integumentary system Skeletal system Muscular system Nervous system Circulatory system Endocrine system Fig. 1.3 Major Organ Systems of the Body.  Introduction to the Human Body CHAPTER 1 5 Lymphatic system Digestive system Respiratory system Urinary system Reproductive system Fig. 1.3, cont’d 6 CHAPTER 1 Introduction to the Human Body Go Figure (Refer to Fig 1.3) 1. The heart and blood vessels are organs that form the _______________ system. (nervous, lymphatic, endocrine, circulatory) 2. The kidneys, brain, and lungs are ________________. (organ systems, parts of the circulatory system, organs,   nerve cells) and oxygen to all the body’s cells and also carries the waste away from the cells to the organs of excretion. The lymphatic (lim-FAT-ik) system is made up of the lymph nodes, lymphatic vessels, lymph, and other lymphatic organs. Lymph and lymphatic structures play an important role in fluid balance and in the defense of the body against pathogens and other foreign material. The immune system is an elaborate defense sys- tem that protects the body not only from patho- gens, but also from allergens, such as pollens, bee venom, and some of our own cells that have gone awry (cancer cells). The immune system is widely distributed throughout the body (it is not shown in Fig. 1.3). The respiratory system contains the lungs and other structures that conduct air to and from the lungs. Oxygen-rich air moves into the lungs; the oxygen is picked up by the blood and distributed throughout Fig. 1.4 Anatomical Position. the body. Carbon dioxide–rich air moves out of the lungs, thereby ridding the body of waste. The respi- Go Figure (Refer to Fig 1.4) ratory system also plays a key role in the regulation 1. Which of the following is true of the anatomical position? of acid-base balance. ______________ (head is bowed, the person is sitting, The digestive system is composed of organs de- palms of the hand are facing forward, forearms are signed to ingest food and break it down into sub-   flexed) stances that can be absorbed by the body. Food that is not absorbed is eliminated as waste. called homeostatic mechanisms. Homeostatic imbalance The urinary system contains the kidneys and other results in disease or dysfunction. structures that help excrete waste products from the body through the urine. More importantly, the uri- Sum It Up! nary system helps control the water, electrolyte, and acid-base balance in the body. Anatomy and physiology describe the structure and function of the body. The body is constructed from simple to complex The reproductive system is made up of organs and (atoms to molecules to cells to tissues to organs to organ structures that enable humans to reproduce. systems to the human organism). The 12 major organ sys- tems are shown in Fig. 1.3. Homeostatic mechanisms en- HOMEOSTASIS: STAYING THE SAME able the body to “stay the same” despite changing internal and external environments.    Homeostasis (ho-me-o-STAY-sis) literally means stay- ing (stasis) the same (homeo). The term refers to the body’s ability to maintain a stable internal environ- ment in response to a changing environment. For ex- ANATOMICAL TERMS: TALKING ABOUT ample, in a healthy person, body temperature stays THE BODY at approximately 98.6°F (37°C), even when room tem- Special terms describe the location, position, and re- perature increases to 100°F or decreases to 60°F. The gions of body parts. Because these terms are used fre- amount of water in your cells stays the same wheth- quently, you should become familiar with them now. er you drink 2, 3, or 4 L of water per day. Your blood People in the medical field are often accused of speak- sugar remains within normal limits whether you have ing their own language. Indeed, we do! We always use just eaten a turkey dinner or have fasted for 6 hours. these terms as if the body were standing in its anatomi- Mechanisms that help to maintain homeostasis are cal position.  Introduction to the Human Body CHAPTER 1 7 ANATOMICAL POSITION the center. For example, the heart is located central- ly, whereas the blood vessels are located peripher- In its anatomical position, the body is standing erect, ally (away from the center and extending toward with the face forward, the arms at the sides, and the the limbs). The brain and spinal cord are called the toes and palms of the hands directed forward (Fig. 1.4). central nervous system, and the nerves are called the peripheral nervous system. RELATIVE POSITIONS Specific terms describe the position of one body part Re-Think in relation to another body part. These are direction- 1. Use the terms proximal and distal to describe the al terms. They are like the more familiar directions relationship of the wrist to the elbow. of north, south, east, and west; however, describing 2. Use the terms proximal and distal to describe the Canada as being located north of the United States relationship of the fingers to the wrist. 3. Use the terms medial and lateral to describe the parts of would be correct, whereas describing the head as   the thigh. Do the same with the eye. “north of the chest” would sound strange. Therefore, in locating body parts, we use other terminology. The terms come in pairs. Note that the two terms in each pair are generally opposites. Remember, the references PLANES OF THE BODY are valid only for the body in its anatomical position. When we refer to the left side of the body, the top half Superior and inferior. Superior means that a part is of the body, or the front of the body, we are referring above another part or is closer to the head. For exam- to the planes of the body. Each plane divides the body ple, the head is superior to the chest. Inferior means with an imaginary line in one direction. Fig. 1.5 shows that a part is located below another part or is closer to the following three important planes: the feet. For example, the chest is inferior to the head. Sagittal plane (see Fig. 1.5A). The sagittal plane di- Anterior and posterior. Anterior means toward the vides the body lengthwise into right and left por- front surface (the belly surface). Posterior means to- tions. If the cut is made exactly down the midline ward the back surface. For example, the heart is an- of the body, the right and left halves of the body are terior to the spinal cord, but the heart is posterior to equal. This division is a midsagittal section. the breastbone. Another word for anterior is ventral, Frontal plane (see Fig. 1.5B). The frontal plane di- and another word for posterior is dorsal. Consider vides the body into anterior (ventral) and posterior the dorsal fin of a fish. It is the dorsal part of the (dorsal) portions. This plane creates the front part of shark that can be seen moving effortlessly and very the body and the back part of the body. The frontal quickly toward your surfboard! plane is also called the coronal plane. Coronal means Medial and lateral. Imagine a line drawn through the “crown,” so the imaginary line for the coronal plane middle of your body, dividing it into right and left is made across the part of the head where a crown halves. This is the midline. Medial means toward the would sit and then downward through the body. midline of the body. For example, the nose is medial Transverse plane (see Fig. 1.5C). The transverse to the ears. Lateral means away from the midline plane divides the body horizontally, creating an up- of the body. For example, the ears are lateral to the per (superior) and a lower (inferior) body. When the nose. In the anatomical position, the hand is closer body or an organ is cut horizontally or transversely, to the lateral thigh than to the medial thigh. it is called a cross section. Proximal and distal. Proximal means that the structure is nearer to the point of attachment, often the trunk of the body. Because the elbow is closer to the point of REGIONAL TERMS attachment than is the wrist, the elbow is described Specific terms describe the different regions or areas of as proximal to the wrist. The wrist is proximal to the the body. Fig. 1.6 illustrates the terms used to identify the fingers, meaning that the wrist is closer to the trunk regions on the anterior and posterior surfaces of the body. than are the fingers. Distal means that a part is farther On the anterior surface, identify the following away from the point of attachment than another part. regions: For example, the wrist is distal to the elbow, and the Abdominal: anterior trunk just below the ribs fingers are distal to the wrist. Antecubital: area in front of the elbow Superficial and deep. Superficial means that a part is Axillary: armpit located on or near the surface of the body. The skin Brachial: arm is superficial to the muscles. Deep means that the Buccal: cheek area; cavity between the gum and cheek body part is away from the surface of the body. The Cephalic: head bones, for example, are deep to the skin. Cervical: neck region Central and peripheral. Central means that the part Cranial: nearer to the head is located in the center. Peripheral means away from Digital: fingers, toes 8 CHAPTER 1 Introduction to the Human Body A B C Fig. 1.5 Planes of the Body. (A) Sagittal. (B) Frontal (coronal). (C) Transverse. Go Figure (Refer to Fig 1.5) Sum It Up! 1. Which plane provides a right and left? Specific terms describe the relative positions of one body _________________ (coronal, sagittal, frontal, transverse) part to the other. The terms are valid when used in ref- 2. Which plane is also referred to as coronal? erence to the body in its anatomical position. The terms ____________________ (frontal, transverse, sagittal, are paired as opposites and include superior and inferior,   midsagittal) anterior (ventral) and posterior (dorsal), medial and lateral, proximal and distal, superficial and deep, and central and peripheral. The body can be cut into three planes: sagit- Femoral: thigh area tal (right and left), frontal or coronal (front and back), and Flank: fleshy area along each side between the lower transverse (top and bottom) planes. Common terms are ribs and the top of the hip bones used to identify specific areas of the anterior and posterior Inguinal: area where the thigh meets the trunk of the surface areas.    body; often called the groin Oral: mouth Orbital: area around the eye Patellar: front of the knee over the kneecap Re-Think Pedal: foot 1. A sagittal plane yields right and left halves of the Plantar: sole of the foot body. Compare this with frontal and transverse Pubic: genital area planes. Sternal: middle of the chest (over the breastbone area) 2. Of the following terms, which can be seen only on the Umbilical: navel posterior view of the body: umbilical, antecubital, gluteal, On the posterior surface, identify the following regions:   lumbar, sternal, patellar, and popliteal? Caudal: near to the lower region of the spinal column (near the tailbone) Deltoid: rounded area of the shoulder closest to the arm CAVITIES OF THE BODY Gluteal: buttocks Lumbar: area of the back between the ribs and the hips The organs, called viscera (VISS-er-ah), are located Occipital: back of the head within the cavities of the body. Cavities are large inter- Popliteal: behind, or back of, the knee area nal spaces. The body contains two major cavities: the Scapular: shoulder blade area dorsal cavity and the ventral cavity (Fig. 1.7).  Introduction to the Human Body CHAPTER 1 9 Cranial Cephalic Orbital Occipital Buccal Oral Cervical Deltoid Sternal Scapular Abdominal Axillary Brachial Lumbar Antecubital Flank Caudal Inguinal Umbilical Digital Gluteal Pubic Femoral Patellar Popliteal Pedal Plantar A B Fig. 1.6 Regional Terms. (A) Anterior view. (B) Posterior view. VENTRAL CAVITY Go Figure (Refer to Fig 1.6) The larger ventral cavity is located toward the front 1. Provide the other terms that describe the following: of the body and has two divisions, the thoracic (thoh- buttocks, armpit, groin, belly button, mouth. (axillary, inguinal, oral, gluteal, umbilical) RASS-ik) cavity and the abdominopelvic (ab-DOM-i- 2. This area is seen only on the posterior view. no-PEL-vik) cavity.   _______________ (umbilical, sternal, lumbar, patellar) THORACIC CAVITY The thoracic cavity is located above the diaphragm and is surrounded by the rib cage. The thoracic cav- DORSAL CAVITY ity is divided into two compartments by the mediasti- The dorsal cavity is located toward the back of the num (MEE-dee-ass-TI-num), a space that contains the body and has two divisions, the cranial cavity and the heart, thymus gland, and parts of the esophagus, tra- spinal (vertebral) cavity. chea, and large blood vessels attached to the heart. The The cranial cavity is located within the skull and con- pericardial (pair-i-KAR-dee-al) cavity (not shown) is lo- tains the brain. The spinal, or vertebral, cavity extends cated within the mediastinum and contains the heart. downward from the cranial cavity and is surrounded by The right and left lungs are located on either side of the bony vertebrae; it contains the spinal cord. The cranial mediastinum in the pleural cavities. The lungs occupy and spinal cavities form one continuous space. most of the space within the thoracic cavity. 10 CHAPTER 1 Introduction to the Human Body Mediastinum Pleural cavities Cranial cavity Spinal cavity Dorsal Thoracic cavity cavity Diaphragm Abdominal Ventral cavity cavity Abdomino- pelvic cavity Pelvic cavity Fig. 1.7 Major Body Cavities. Go Figure (Refer to Fig 1.7) from the level of the hips and includes the remainder of the intestines, the rectum, the urinary bladder, and 1. Which of the following is located within the ventral, the internal parts of the reproductive system. thoracic, and pleural cavities? _______________? (heart, stomach, lungs, brain) Because the abdominopelvic cavity is so large, it is sub- 2. Which cavity houses only the brain? ______________ divided into smaller areas for study. Quadrants and re- (cranial, dorsal, thoracic, mediastinum) gions divide the abdominopelvic cavity. Note the organs 3. Which structure separates the thoracic cavity from located in each quadrant or region, as shown in Fig. 1.8. the abdominopelvic cavity? _________________?   (mediastinum, diaphragm, spine, umbilicus) Division into Quadrants The abdominopelvic cavity can be divided into four quadrants (see Fig. 1.8A). The quadrants are named for ABDOMINOPELVIC CAVITY their positions: right upper quadrant (RUQ), left upper The abdominopelvic cavity is located below the dia- quadrant (LUQ), right lower quadrant (RLQ), and left phragm. The upper portion of this cavity is the ab- lower quadrant (LLQ). dominal cavity. It contains the stomach, most of the Quadrant terms are used frequently in the clinical intestines, and the liver, gallbladder, pancreas, spleen, setting. For example, a patient in the emergency room and kidneys. The lower portion of the abdominopelvic who has acute pain in the RLQ may be diagnosed with cavity is called the pelvic cavity. It extends downward appendicitis. Note that the RLQ appears to be on your  Introduction to the Human Body CHAPTER 1 11 Right Left hypo- Epigastric hypo- chondriac region chondriac Right upper Left upper region region quadrant quadrant Right Left Umbilical lumbar lumbar region region region Right lower Left lower quadrant quadrant Right Hypo- Left iliac gastric iliac region region region A B Fig. 1.8 The Abdominopelvic Cavity. (A) Four quadrants. (B) Nine regions. Go Figure (Refer to Fig 1.8) just below the umbilical region. Hypogastric literally means below (hypo) the stomach (gastric). 1. Which of the regions is included in the Six regions are located on either side of the central RUQ? _____________ (left lumbar, right hypochondriac, hypogastric, umbilical) regions. They include the hypochondriac, lumbar, and 2. Which of the following is immediately inferior to the iliac regions. The right and left hypochondriac regions epigastric region? ______________________? (left iliac, are located on either side of the epigastric region and   RUQ, umbilical, LUQ) overlie the lower ribs. The word hypochondriac literally means below (hypo) the cartilage (chondro) and refers to the composition of the ribs (cartilage). The right and left left. This is similar to looking in a mirror. Keep this in lumbar regions are located on either side of the umbili- mind when you are studying the diagrams in the text. cal region and are inferior to the hypochondriac regions. Here’s an easy way to remember this: Lower your right The right and left iliac regions, also called the right and arm. It will be lateral to the RUQ and RLQ. left inguinal regions, are located on either side of the hy- pogastric region. Knowledge of these regions helps you Division into Regions understand terms such as epigastric pain and umbilical A second system divides the abdominopelvic cavity hernia. Remember that quadrants and regions refer only into nine separate regions that resemble the squares to the abdominopelvic cavity and not to the thoracic for tic-tac-toe (see Fig. 1.8B). The three central regions cavity. (from top to bottom) are the epigastric, umbilical, and hypogastric regions. The epigastric region is located Other Cavities below the breastbone. Epigastric literally means upon Four smaller cavities are located in the head. They (epi) the stomach (gastric). The umbilical region is the include the oral cavity, nasal cavities, orbital cavities, centermost region and surrounds the umbilicus, or and middle ear cavities. (These cavities are described navel (belly button). The hypogastric region is located in later chapters.) 12 CHAPTER 1 Introduction to the Human Body Re-Think Sum It Up! 1. What muscle structure separates the thoracic cavity from The organs or viscera are located within body cavities. The the abdominopelvic cavity? two major cavities are the dorsal cavity, located toward the 2. Of the following terms, determine which pertain to the back of the body, and the larger ventral cavity, located in the ventral cavity: thoracic cavity, brain, vertebral cavity, front of the body. The dorsal cavity is subdivided into the abdominopelvic cavity, pleural cavity, dorsal cavity, cranial cavity and the spinal cavity. The ventral cavity is di-   mediastinum, stomach, heart, and spinal cord. vided by the diaphragm into the thoracic cavity (including the mediastinum, pericardial cavity, and pleural cavities) and the abdominopelvic cavity. The abdominopelvic cavity is divided into quadrants and regions.       Medical Terminology and Disorders   Introduction to Medical Terminology The medical profession has its own language, called medical terminology. In general, there are four main types or kinds of word parts. By learning these and how they can be put together, you can often “translate” many long and challenging medical words by breaking them up into their word parts. A word root is the core of the word and provides the basic meaning or “subject” of the word. The other word parts, such as suffixes and prefixes, modify the word root so that it takes on a new meaning. For example, in the word hepatitis, the word root is hepat-, meaning liver. A suffix is a word part attached to the end of the word root; it modifies the word root. If we add -itis, which is a suffix that means inflammation, to the word root for liver, hepat-, we get hepatitis, which means inflammation of the liver. A prefix is a word part attached to the beginning of the word root; it modifies the word root. For example, the word nutrition refers to a normal and healthy food intake. By adding the prefix mal- (French for bad), as in malnutrition, the word root has been modified to mean poor or bad nutrition. Combining vowels are word parts used to ease the pronunciation, as in angioplasty (angi/o/plasty). Angi- means blood vessel, and -plasty means repair of. The -o- joining the word parts eases the pronunciation; it does not modify the meaning of the word. When you see angi/o-, you are seeing the word root and its combining vowel. In the Medical Terminology and Disorders tables you will see many terms with which you are probably familiar, but what you may not be familiar with is what their individual word parts are and how they are put together to make up many of the words you use every day. For instance, consider -ectomy, which means excision or removal of. Think of all the terms that have -ectomy at the end—such as lobectomy, vasectomy, hysterectomy, appendectomy, tonsillectomy—and you will see how valuable knowing what this one word part is. MEDICAL TERM WORD PARTS WORD PART DESCRIPTION MEANING OR DERIVATION anatomy ana- up or apart Anatomy is the branch of science that describes -tomy incision; to cut the structure of a body, especially as revealed by dissection. For example, the heart has four chambers. antecubital ante- before; in front of Antecubital space is the area of the arm anterior to -cubital From the word meaning “elbow” the elbow. A sample of blood is commonly drawn from a vein in the antecubital space. biology bio- life Biology is the study of life and living organisms. -logy study of diagnosis dia- apart Diagnosis is the process of identifying the nature and -gnos/o- knowing cause of a disease or injury through an analysis of data, such as the patient’s symptoms and laboratory -osis condition or increase studies. pathologist path/o- pertaining to disease A pathologist examines tissue for evidence of disease. -logist one who specializes in homeostasis home/o- sameness Homeostasis refers to the relative constancy of the -stasis stand still internal environment of the body despite many challenges to upset the balance. transverse trans- across A transverse plane cuts across the body; an upper -verse From the word meaning “to turn” and lower body is created.  Introduction to the Human Body CHAPTER 1 13    Medical Terminology and Disorders   Introduction to Medical Terminology—cont’d MEDICAL TERM WORD PARTS WORD PART DESCRIPTION MEANING OR DERIVATION midepigastric mid- middle Related to the middle of the epigastric region of the -epi- above or upon abdomen. A person may complain of midepigastric discomfort. -gastr/o- stomach -ic pertaining to prognosis pro- before Refers to a likely course or outcome of a disease. For -gnos/o- knowing example, the prognosis of a person who seeks early treatment of a basal cell carcinoma (skin cancer) is -osis condition or increase excellent; the prognosis of a person with metastatic cancer is less favorable. quadrant quadr/i- four The abdominopelvic cavity is divided into four equal -ant performing/promoting. areas called quadrants. Get Ready for Exams! Summary Outline 1. Ventral cavity a. Thoracic cavity: superior to the diaphragm; Anatomy is the study of structure; physiology is the study of contains the pleural cavities (lungs), mediasti- function. Structure (anatomy) and function (physiology) are num, and pericardial cavity related. b. Abdominopelvic cavity: located inferior to the I. The Body’s Levels of Organization diaphragm A. From simple to complex: atoms to molecules to c. Abdominal cavity: upper part that contains the cells to tissues to organs to organ systems to human stomach, most of the intestines, and the liver, organism spleen, and kidneys B. Major organ systems (12) d. Pelvic cavity: lower part that contains the repro- 1. Integumentary system ductive organs, urinary bladder, and lower part 2. Skeletal system of the intestines 3. Muscular system e. For reference: the abdominopelvic cavity is 4. Nervous system divided into four quadrants and nine regions. 5. Endocrine system 6. Heart and circulatory system 7. Lymphatic system Review Your Knowledge 8. Immune system Matching: Directions of the Body 9. Respiratory system Directions: Match the following words with their descrip- 10. Digestive system tions. Some words may be used more than once or not at all. 11. Urinary system 12. Reproductive system a. posterior 1. ___ T  oward the midline of the body; C. Homeostasis: the body’s ability to maintain a stable b. distal opposite of lateral internal environment in response to various internal c. medial 2. ___ S  tructure that is nearer to the trunk and external challenges. d. anterior than another part; opposite of distal e. proximal 3. ___ P  art of the radius (forearm bone) II. Anatomical Terms: Talking About the Body f. superior that is closer to the wrist than to the A. Anatomical position: the body standing erect, arms g. deep elbow by the side, with palms and toes facing forward 4. ___ T  he lungs are located above the B. Relative positions: superior-inferior, anterior-posterior, diaphragm; their position relative to medial-lateral, proximal-distal, superficial-deep, the diaphragm is described as being central-peripheral above C. Planes (three): sagittal, frontal (coronal), and trans- 5. ___ T  oward the front (the belly surface); verse planes another word is ventral D. Regional terms: listed in Fig. 1.6 E. Cavities of the body 1. Dorsal cavity a. Cranial cavity: contains the brain b. Spinal (vertebral) cavity: contains the spinal cord 14 CHAPTER 1 Introduction to the Human Body Matching: Regional Terms 6. T he frontal plane Directions: Match the following words with their descriptions. a. splits the body into right- and left-half sections. a. inguinal 1. ___ Armpit b. is also the coronal plane. b. oral 2. ___ Kneecap area c. splits the body into a top and a bottom section. c. lumbar 3. ___ Breastbone area d. creates a transverse cross section. d. axillary 4. ___ Front part of the elbow area 7. Which of the following terms best describes when a e. buccal 5. ___ Fleshy area along the side person sweats in order to decrease body temperature? f. patellar between the ribs and hip bone a. Pathophysiology g. flank 6. ___ Pertaining to the mouth b. Evisceration h. antecubital 7. ___ Lower back area extending from c. Homeostasis i. sternal the chest to the hips d. Midsagittal j. scapular 8. ___ Pertains to the space between 8. Which of the following is true of these terms: sternal, the cheek and gum umbilical, patellar, and antecubital? 9. ___ Groin region a. All are superior to the inguinal area. 10. ___ S houlder blade area b. All lie within the ventral cavity. c. All can be viewed on the anterior body. Multiple Choice d. All lie within the dorsal cavity. 1. This part of the humerus (arm bone) is closer to the 9. These structures are located within the pleural cavities, elbow than to the axillary region. the thoracic cavity, and the ventral cavity. a. Anterior a. Heart and great vessels b. Superior b. Lungs c. Distal c. Brain and spinal cord d. Proximal d. Intestines 2. Describe the relationship of the mediastinum to the 10. These structures are located within the pericardial cav- diaphragm. ity, the mediastinum, and the thoracic cavity. a. Distal a. Heart and great vessels b. Deep b. Liver and stomach c. Anterior c. Lungs d. Superior d. Intestines 3. The umbilical region is located 11. The common element of the words pathology, patho- a. inferior to the inguinal region. gen, and pathophysiology is that they all refer to b. superior to the RUQ. a. persons who dissect bodies. c. inferior to the diaphragm. b. homeostatic mechanisms. d. within the midepigastric region. c. disease. 4. The sternal area is d. drugs that are used to treat diseases. a. the groin. b. referred to as the breastbone area. c. located within the RLQ. d. observed only on the posterior view of the body. 5. Which of the following is not descriptive of the mediastinum? a. Thoracic cavity b. Dorsal cavity c. Ventral cavity d. Superior to the diaphragm 3 Cells http://evolve.elsevier.com/Herlihy Objectives 1. L abel a diagram of the main parts of a typical cell, and do D escribe the active and passive movements of the following: substances across a cell membrane. Explain the role of the nucleus. Define tonicity and compare isotonic, hypotonic, and Describe the functions of the main organelles of the hypertonic solutions. cell. 3. Describe the phases of the cell cycle, including mitosis. Identify the components of the cell membrane. 4. Explain what is meant by cell differentiation. 2. Do the following regarding transport mechanisms: 5. Explain the processes and consequences of uncontrolled and disorganized cell growth and apoptosis. Key Terms active transport (p. 36) equilibrium (p. 37) osmosis (p. 38) apoptosis (p. 45) exocytosis (p. 41) passive transport (p. 36) cell (p. 30) facilitated diffusion (p. 38) permeable (p. 31) cell cycle (p. 42) filtration (p. 40) phagocytosis (p. 41) cell membrane (p. 31) Golgi apparatus (p. 34) pinocytosis (p. 41) cytoplasm (p. 33) lysosomes (p. 34) ribosomes (p. 34) differentiate (p. 44) mitochondria (p. 33) stem cells (p. 44) diffusion (p. 36) mitosis (p. 42) tonicity (p. 39) endocytosis (p. 41) nucleus (p. 32)    endoplasmic reticulum (ER) (p. 34) organelles (p. 33) What do this monk and a cell have in common? While The cell is the structural and functional unit of all looking at a piece of cork under a microscope in the living matter. Cells vary considerably in size, shape, 1600s, Robert Hooke saw cube like structures that re- and function. A red blood cell (RBC), for example, is sembled the rooms, or cells, occupied by monks in a tiny, whereas a single nerve cell may measure 4 feet monastery. Hooke thus called his structures “cells.” in length (Fig. 3.1). The shapes and structures of the The study of cellular structure and function is called cells are also very different. The RBC is shaped like cytology. a Frisbee and is able to bend. The shape allows it to squeeze through tiny blood vessels and deliver oxygen and other nutrients throughout the body. Some nerve cells are very long, and many resemble bushes or trees. Their shapes enable them to conduct electrical signals quickly over long distances. Cell structure and func- tion are closely related. Go Figure (Refer to Fig. 3.1) Microscope 1. T/F __ All cells must be small enough to fit through blood   vessels. TYPICAL CELL Cells Despite the differences, cells have many similari- ties. Fig. 3.2 is a typical cell with its many cellular 30  Cells CHAPTER 3 31 Blood vessel Go Figure (Refer to Fig. 3.2) 1. T/F __ All purple-colored structures are in the cytoplasm. 2. T/F __ Mitochondria, endoplasmic reticulum, and   ribosomes are within the nucleus. CELL MEMBRANE Red blood cells The cell is encased by a cell membrane, also called the plasma membrane. The cell membrane separates intracellu- lar (inside the cell) material from extracellular (outside the cell) material. In addition to physically holding the cell to- gether, the cell membrane performs other important func- tions. One of its chief functions is the selection of substanc- es allowed to enter or leave the cell. Because the membrane chooses the substances allowed to cross it, the membrane is said to be selectively permeable, or semipermeable. What makes up a cell membrane? The cell mem- brane is composed primarily of phospholipids and Nerve cell protein, as well as a small amount of carbohydrates (Fig. 3.3). The phospholipids are arranged in two lay- ers. The protein molecules in the membrane perform several important functions; they provide structural support for the membrane, act as binding sites for hormones, and poke holes, or pores, through the lipid membrane. These pores form channels through which water and dissolved substances flow. Go Figure (Refer to Fig. 3.3) 1. Which structure is described as a lipid bilayer? ____________ (ribosome, cilia, centriole, cell membrane) 2. Proteins that penetrate the cell membrane form __________________ through which water and small   solute can flow. (ATP, pores, cilia, ribosomes) Substances move across the semipermeable mem- brane in two ways. They can dissolve in the lipid por- tion of the membrane, as do oxygen and carbon dioxide (lipid-soluble substances). Substances can also cross the membrane by flowing through the pores. Water and electrically charged substances such as sodium and chloride cannot penetrate the lipid membrane and must use the pores. These are called water-soluble substances. The size of the pores also helps select which substances cross the membrane. Substances larger than the pores cannot cross the membrane, whereas smaller substances such as sodium and chloride flow through easily. The solubility characteristics of the membrane also play an important role in pharmacology. Drugs are classified as lipid (fat) soluble or water soluble. Drug solubility de- termines its distribution throughout the body. Fig. 3.1 Cells Come in All Shapes and Sizes. Re-Think 1. What is meant by a semipermeable membrane? components. Each specialized cell, such as a nerve cell, 2. How does a fat-soluble substance cross the cell possesses some or all of the properties of the typical membrane? How does a water-soluble substance cross cell. Table 3.1 lists and summarizes the functions of the   the cell membrane? cellular components. 32 CHAPTER 3 Cells Microtubule Centrioles Cell membrane Free ribosome Mitochondrion Nucleus Cytoplasm Nuclear membrane Lysosome Nucleolus Rough endoplasmic reticulum Golgi (covered with apparatus fixed ribosomes) Smooth endoplasmic reticulum Cilia Fig. 3.2 A Typical Cell. The nucleus is filled with a fluid substance called INSIDE THE CELL nucleoplasm. Within the nucleoplasm are two other The inside of the cell is divided into two compart- structures: the nucleolus and chromatin. The nucleo- ments: the nucleus and the cytoplasm. The inside of lus, or little nucleus, synthesizes ribosomes that move the cell resembles the inside of a raw egg; the “yellow through nuclear pores into the cytoplasm, where they yolk” is the nucleus, and the “white” is the cytoplasm. play a role in protein synthesis. Chromatin is composed mainly of strands of DNA NUCLEUS (deoxyribonucleic acid), the carriers of the genetic code. The nucleus is the control center of the cell (see Fig. In nondividing cells, chromatin appears as a tangled 3.2). In particular, the nucleus contains the genetic array of fine filaments. In dividing cells, however, chro- information and controls all protein synthesis. Most matin strands coil tightly, forming DNA-containing adult cells have one nucleus; only mature RBCs structures called chromosomes. The genetic code and have no nucleus. Surrounding the nucleus is a dou- protein synthesis are described more fully in Chapter 4. ble-layered nuclear membrane. The nuclear mem- brane contains large pores that allow the free move- Re-Think ment of certain substances between the nucleus and Why is the nucleus called the control center of the cell?    cytoplasm.  Cells CHAPTER 3 33 Table 3.1   Cell Structure and Function CELL STRUCTURE DESCRIPTION AND FUNCTION Cell Membrane Contains the cellular contents; selects what enters and leaves the cell Cilia Hairlike projections that move substances across surface of cell membrane Flagellum Single long hair for swimming movement of the sperm Microvilli Accordion-like folds in the membrane; increase transport of water and dissolved solute Nucleus Control center of the cell; stores genetic information Chromatin Threadlike structures in the nondividing cell that contain DNA; chromatin threads form chromosomes in a dividing cell Nucleolus Synthesizes RNA and ribosomes Nucleoplasm Gel in the nucleus Nuclear membrane Separates the nucleoplasm from the cytoplasm Cytoplasm Gel located inside the cell but outside the nucleus Cytosol Medium composed of water and dissolved solute; organelles suspended in the cytosol Organelles Tiny organs suspended in the cytosol Mitochondria Site of adenosine triphosphate production; “power plants” of the cell Endoplasmic reticulum (ER) Membranes that form channels for the flow of cellular substances such as proteins Rough ER Contains ribosomes where protein is synthesized Smooth ER Site of lipid and steroid synthesis; synthesis of glycogen in liver and skeletal muscle Golgi apparatus Finishes and packages protein for export Ribosomes Site of protein synthesis Free Ribosomes that float within the cytosol; make protein used within the cell Fixed Ribosomes fixed to the ER, making it appear rough; concerned with the synthesis of protein that is exported Lysosomes Intracellular house cleaning, phagocytosis, removal of damaged organelles Cytoskeleton Microfilaments and microtubules that provide for intracellular shape, support, and movement Centrioles Paired, short, rod-shaped microtubules that form spindles and help separate the chromosomes during mitosis Inclusion bodies Temporary insoluble material such as glycogen granules and pigments such as melanin CYTOPLASM example, is very active and therefore has many mito- Cytoplasmic Gel chondria per cell. Bone cells are less active metaboli- The cytoplasm, or the “gel in the cell,” is found inside cally and have fewer mitochondria. the cell but outside the nucleus (like the white of a raw The mitochondrial membrane has two layers (Fig. egg). The cytoplasm contains the cytosol and organ- 3.4); the outer layer is smooth, whereas the inner layer elles. The cytosol is the intracellular fluid and is com- has many folds, referred to as cristae. The enzymes asso- posed primarily of water, electrolytes, proteins, and ciated with adenosine triphosphate (ATP) production nutrients. The cytosol also contains inclusion bodies, are located along the cristae. Because the mitochondria insoluble materials such as glycogen granules, and produce most of the energy (ATP) in the body, they pigments such as melanin. The organelles, or “little or- are referred to as the “power plants” of the cell. (See gans,” are dispersed throughout the cytoplasm; each Chapter 2 for an explanation of ATP and Chapter 4 for organelle has a specific role. Locate the organelles in a description of ATP production.) Fig. 3.2 and Table 3.1. Go Figure (Refer to Fig. 3.4) CYTOPLASMIC ORGANELLES 1. The power plant represents the Mitochondria ________________________. (nucleus, endoplasmic The mitochondria are tiny, slipper-shaped organelles. reticulum, ribosomes, mitochondria) The number of mitochondria per cell varies, depend- 2. The enzymes necessary for ATP production are most ing on the metabolic activity of the cell (how hard the associated with or represented by the __________. cell works). The more metabolically active the cell, (electrical plug, outer mitochondrial membrane, cristae, the greater the number of mitochondria. The liver, for   fuel barrel) 34 CHAPTER 3 Cells Carbohydrate Extracellular space chain Glycoprotein Phospholipid: Phosphate Lipid chains Cytoskeleton Protein Intracellular space (that forms (cytoplasm) pores) Fig. 3.3 Structure of the Cell Membrane: Phospholipid Bilayer and Protein. Ribosomes Golgi Apparatus Ribosomes are cytoplasmic organelles involved in The Golgi apparatus is a series of flattened membra- protein synthesis. Some ribosomes are attached to the nous sacs (Fig. 3.5). Proteins synthesized along the endoplasmic reticulum and are called fixed ribosomes. RER are transported to the Golgi apparatus through Fixed ribosomes are largely concerned with the syn- channels formed by the ER. The Golgi apparatus puts thesis of exportable protein—that is, protein secreted the finishing touches on the protein. For example, a by the cell for use elsewhere in the body. Other ribo- glucose molecule may be attached to a protein within somes, called free ribosomes, float freely within the cyto- the Golgi apparatus. A segment of the Golgi membrane plasm and generally synthesize proteins that are used then wraps itself around the protein and pinches itself within the cell. off to form a secretory vesicle. In this way, the Golgi apparatus packages the protein. Note that many of the Endoplasmic Reticulum organelles, particularly the ribosomes, ER, and Golgi The endoplasmic reticulum (ER) is a network of mem- apparatus, are involved in protein synthesis. (Protein branes within the cytoplasm (see Fig. 3.2). These long, synthesis is described in Chapter 4.) folded membranes form channels through which sub- stances, especially newly synthesized protein, move. Go Figure (Refer to Fig. 3.5) The two types of ER include the type containing ribo- 1. T/F __ The Golgi apparatus packages protein in a somes along its surface; it is called rough endoplasmic membrane that eventually fuses with the cell membrane. reticulum (RER) because of its rough, sandpaper-like 2. T/F __ Protein is synthesized in the Golgi apparatus and appearance. The RER is primarily concerned with   transported to the ribosomes for storage. protein synthesis. Protein synthesized along the RER is transported through the channels and delivered to the Golgi apparatus for further processing. The ER Lysosomes that does not contain ribosomes on its surface appears Lysosomes are membranous sacs containing powerful smooth; it is called smooth endoplasmic reticulum (SER). enzymes. Lysosomal enzymes break down intracellu- SER is primarily involved in the synthesis of lipids, ste- lar waste and debris, including damaged organelles, roids, glycerides, and glycogen in skeletal muscle and and thus help “clean house.” Lysosomal enzymes liver cells. perform several other functions. They kill ingested  Cells CHAPTER 3 35 Outer membrane Enzymes Cristae Inner membrane Mitochondrion Fig. 3.4 Mitochondria Are the “Power Plants” of the Cells. ATP, Adenosine triphosphate. Nucleus Rough endoplasmic reticulum Golgi apparatus Inside the cell Protein Secretory vesicle Outside the cell Cell membrane Fig. 3.5 The Golgi Apparatus: Packages the Protein for Export. bacteria. Lysosomes also break down the contractile Cytoskeleton proteins of inactive muscles, as occurs in retired ath- The cytoskeleton is composed of threadlike structures letes and chronically bedridden persons. called microfilaments and microtubules. The cytoskeleton 36 CHAPTER 3 Cells helps maintain the shape of the cell and assists the cell is an example of a flagellum; the tail enables the sperm in various forms of cellular movement. Cellular move- to swim. ment is particularly evident in muscle cells, which con- tain large numbers of microfilaments. Microtubules Sum It Up! are the primary component of the cytoskeleton. In The cell is the structural and functional unit of all living mat- addition to making the cell strong and rigid, the mi- ter. Although cells differ considerably, they also share many crotubules anchor the position of the organelles within similarities. The “typical cell” illustrates these similarities. The the cytoplasm. Microtubules also play a key role in cell cell is surrounded by a cell membrane. The inside of the cell division; they form the spindle apparatus that helps is divided into the nucleus, the control center, and the cyto- distribute the chromosomes to opposite ends of the plasm, which contains the cytosol and many little organs, dividing cell. (Cell division is explained in Chapter 4.) or organelles, each of which has a special task to perform. Table 3.1 lists the organelles and their functions.    Centrioles Centrioles are paired, rod-shaped, and short micro- MOVEMENT ACROSS THE CELL tubular structures that form the spindle apparatus in MEMBRANE a dividing cell. Cells that have no centrioles are inca- pable of cell division; these include neurons, mature Cells are bathed in an extracellular fluid that is rich in RBCs, skeletal muscle cells, and cardiac muscle cells. nutrients such as oxygen, glucose, and amino acids. These nutrients are needed in the cell and must there- Re-Think fore be able to cross the cell membrane. The cell’s waste, which accumulates within the cell, must also be able to 1. What is the primary function of the mitochondria? cross the cell membrane for eventual elimination. 2. What is the difference between fixed and free ribosomes? A number of mechanisms assist in the movement of 3. What is the difference between the rough and smooth water and dissolved substances across the cell mem-   ER? brane. The transport mechanisms can be divided into two groups: passive transport and active trans- port mechanisms. Table 3.2 summarizes both types of ON THE CELL MEMBRANE transport. The passive transport mechanisms require no ad- MICROVILLI ditional input of energy in the form of ATP. Passive For cells that are particularly involved with the move- transport is something like the downward movement ment of large amounts of water and its dissolved sol- of a ball (Fig. 3.6A). The ball is at the top of the hill. utes, the membrane forms accordion-like folds called Once released, the ball rolls downhill. The ball does microvilli (sing., microvillus). The folding of the cell not need to be pushed; it moves passively, without any membrane increases surface area, thereby increasing input of energy. Passive transport mechanisms cause the amount of fluid absorbed. For example, some of water and dissolved substances to move without ad- the cells in the digestive tract have millions of foldings, ditional energy, like a ball rolling downhill. called microvilli, to absorb water and the end products Active transport mechanisms require an input of of digested food. energy in the form of ATP. Active transport is like the upward movement of a ball (see Fig. 3.6B). For the ball CILIA to move uphill, it must be pushed, therefore requiring Cilia are short, hairlike projections on the outer sur- an input of energy. face of the cell membrane. Cilia use wavelike motions to move substances across the surface of the cell. For Go Figure (Refer to Fig. 3.6) example, cilia are abundant on the cells that line the 1. T/F __ The stationary figure represents “no ATP input” or respiratory passages. The cilia help move mucus and   passive transport. trapped dust and dirt toward the throat, away from the lungs. Once in the throat, the mucus can be re- moved by coughing or swallowing. The cilia therefore PASSIVE TRANSPORT MECHANISMS help clear the respiratory passages. Cigarette smoking damages the cilia and thus deprives the smoker of this The passive mechanisms that move substances across benefit. the membrane include diffusion, facilitated diffusion, osmosis, and filtration. FLAGELLA Flagella (meaning “whiplike”) are similar to cilia in DIFFUSION that both are hairlike projections of the cell membrane. Diffusion is the most common transport mechanism. Flagella, however, are thicker, longer, and fewer in Diffusion is the movement of a substance from an area of number; they help move the cell. The tail of the sperm higher concentration to an area of lower concentration.  Cells CHAPTER 3 37 Table 3.2   Transport Mechanisms MECHANISM DESCRIPTION AND FUNCTION Passive Diffusion Movement of a substance from an area of high concentration to an area of low concentration Facilitated diffusion Helper molecule within the membrane assists movement of substances from area of high concentration to area of low concentration Osmosis Diffusion of water (solvent) from an area with more water to an area with less water; the water compartments are separated by a semipermeable membrane Filtration The pushing of water and dissolved substances from an area of high pressure to an area of low pressure; the water and dissolved substances are pushed Active Active transport pump Moves a substance uphill (from an area of low concentration to an area of high concentration); requires an input of energy (adenosine triphosphate) Endocytosis Taking in or ingestion of substances by the cell membrane Phagocytosis Engulfing of solid particles by the cell membrane (cellular eating) Pinocytosis Engulfing of liquid droplets (cellular drinking) Exocytsois Secretion of cellular products (e.g., protein, debris) out of the cell Passive (downhill) Active (uphill) A B Fig. 3.6 Transport Mechanisms. (A) Passive transport mechanism. The ball rolls downhill on its own. (B) Active transport mechanism. The ball must be pushed uphill using adenosine triphosphate (ATP). For example, a tablet of red dye is placed in a glass causes oxygen to move across the membrane of an al- of water (Fig. 3.7A). The tablet dissolves, and the dye veolus of the lung into the blood (see Fig. 3.7C). Oxygen moves from an area where it is most concentrated (glass diffuses from the alveolus because the concentration of 1) to an area where it is less concentrated (glasses 2 and oxygen is higher within the alveolus than within the 3). Diffusion continues until the dye is evenly distribut- blood. Conversely, carbon dioxide, a waste product ed throughout the glass. The point at which no further that accumulates within the blood, diffuses in the op- net diffusion occurs (glass 3) is called equilibrium. posite direction (carbon dioxide moves from the blood The scent of our pet skunk, Perfume, also illustrates into the alveolus). The lungs then exhale it, thereby diffusion (see Fig. 3.7B). Perfume’s scent does not eliminating waste from the body. Thus the process of take long to permeate the area! Diffusion is involved diffusion moves oxygen into the blood and carbon di- in many physiological events. For example, diffusion oxide out of the blood. 38 CHAPTER 3 Cells 1 2 3 A B Alveoli Lungs Alveoli Blood Blood vessels C Oxygen Carbon dioxide Fig. 3.7 Diffusion. (A) Diffusion of a red dye. (B) Diffusion of Perfume’s “perfume.” (C) Diffusion of oxygen and carbon dioxide across the alveolar cell membrane in the lung. Go Figure (Refer to Fig. 3.7) Go Figure (Refer to Fig. 3.8) 1. Which of the following best describes the events 1. Which of the following best describes facilitated in panels A, B, and C? __________ (malodorous, diffusion? _____________ (active transport, uphill ATP-requiring, occurs only in living systems, passive pumping, passive transport, ATP-requiring) transport) 2. Which word best describes “helped”? ________________ 2. Oxygen moves from the alveoli in the lungs into the   (osmosis, facilitated, pump, ATP-requiring) blood by _____________. (active transport, ATP-driven   transport, diffusion, being pumped) OSMOSIS Osmosis is a special case of diffusion. Osmosis is the dif- fusion of water through a selectively permeable mem- FACILITATED DIFFUSION brane. A selectively permeable—or semipermeable— Facilitated diffusion is a form of diffusion that is re- membrane allows the passage of some substances while sponsible for the transport of many substances (facili- restricting the passage of others. During osmosis, the tate means “to help”). As in diffusion, substances move water diffuses from an area with more water to one with from a higher concentration toward a lower concen- less. The dissolved substances, however, do not move. tration (Fig. 3.8). In facilitated diffusion, however, the Two different solutions in the glass illustrate os- substance is helped across the membrane by a mol- mosis. The glass is divided into two compartments ecule within the membrane. The helper molecule in- (A and B) by a semipermeable membrane (Fig. 3.9). creases the rate of diffusion. The transport of glucose Compartment A contains a dilute glucose solution, by facilitated diffusion is illustrated in Fig. 3.8 by a boy whereas compartment B contains a more concentrated carrying the glucose. Note that he is moving downhill, glucose solution. The membrane is permeable only to indicating that facilitated diffusion is a passive trans- water. The glucose cannot cross the membrane and is port process. therefore confined to its compartment.  Cells CHAPTER 3 39 Selectively permeable Cell membrane membrane Solute Side A: Side B: Side A Side B Dilute Concentrated Membrane solution solution Fig. 3.9 Osmosis. The effect of osmotically active particles on the movement of water. Glucose being “helped” downhill Do You Know... Why a Blood Clot May Continue to “Grow,” Even When the Bleeding Stops? The components of the blood clot are osmotically active par- ticles. Water therefore diffuses into the blood clot, causing it to enlarge. If the expanding blood clot is located within the brain, it presses on the brain tissue, causing a variety of life- threatening neurological deficits.    Fig. 3.8 Facilitated Diffusion. Go Figure (Refer to Fig. 3.9) TONICITY 1. T/F __ Solute is diffusing from side B to A. Tonicity is the ability of the concentration of a solution to 2. T/F __ Water is diffusing from side A to B.    affect the volume and pressure within a cell. Note what happens when a cell is placed in solutions of different con- During osmosis, the water moves from compart- centrations (Fig. 3.10). The following three terms are used ment A to compartment B (from the area where there to illustrate tonicity: isotonic, hypotonic, and hypertonic. is more water to the area with less). T