Multiple Alleles Codominance and Incomplete Dominance

Some genes exist in more than two allelic forms that is, there are multiple alleles within the collective genetic makeup, or gene pool, of the population as a whole. For example, there are over 100 alleles responsible for cystic fibrosis, and there are 3 alleles for ABO blood types. Two of the ABO blood type alleles are dominant and symbolized with a capital I (for immunoglobulin) and a superscript IA and IB. There is one recessive allele, symbolized with a lowercase i. Which two alleles one...

The Hypothetico Deductive Method

Most physiological knowledge was obtained by the hypothetico-deductive method. An investigator begins by asking a question and formulating a hypothesis an educated speculation or possible answer to the question. A good hypothesis must be (1) consistent with what is already known and (2) capable of being tested and possibly falsified by evidence. Falsifiability means that if we claim something is scientifically true, we must be able to specify what evidence it would take to prove it wrong. If...

Gross Anatomy

The spinal cord (fig. 13.1) is a cylinder of nervous tissue that begins at the foramen magnum and passes through the vertebral canal as far as the inferior margin of the first lumbar vertebra (L1). In adults, it averages about 1.8 cm thick and 45 cm long. Early in fetal development, the spinal cord extends for the full length of the vertebral column. However, the vertebral column grows faster than the spinal cord, so the cord extends only to L3 by the time of birth and to L1 in an adult. Thus,...

The Integumentary System

Structure of the Skin and Subcutaneous Tissue 192 Types and Distribution of Hair 201 Structure of the Hair and Follicle 202 Connective Issues 212 Chapter Review 213 and Pseudoscience of Hair Analysis 202 Clinical Application UVA, UVB, and Sunscreens 210 Clinical Application Skin Grafts and Artificial Skin 211 To understand this chapter, it is important that you understand or brush up on the following concepts Stratified squamous epithelium (p. 161) Collagenous fibers (p. 167) Areolar and dense...

Neural Integration

When you have completed this section, you should be able to explain how a neuron decides whether or not to produce action potentials explain how the nervous system translates complex information into a simple code explain how neurons work together in groups to process information and produce effective output and describe how memory works at a cellular and molecular level. Synaptic delay slows the transmission of nerve signals the more synapses there are in a neural pathway, the longer it takes...

Conduction Speed of Nerve Fibers

The speed at which a nerve signal travels along a nerve fiber depends on two factors the diameter of the nerve fiber and the presence or absence of myelin. Signal conduction occurs along the surface of a fiber, not deep within its axoplasm. Larger fibers have more surface area and conduct signals more rapidly than smaller fibers. Myelin further speeds signal conduction for reasons discussed later. Nerve signals travel about 0.5 to 2.0 m sec in small unmyelinated fibers (2-4 m in diameter) and 3...

Behavior of Skeletal Muscle Fibers

When you have completed this section, you should be able to explain how a nerve fiber stimulates a skeletal muscle fiber explain how stimulation of a muscle fiber activates its contractile mechanism explain the mechanism of muscle contraction explain how a muscle fiber relaxes and explain why the force of a muscle contraction depends on its length prior to stimulation. Saladin Anatomy & I 11. Muscular Tissue I Text I The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function,...

An Inhibitory GABAergic Synapse

A GABA-ergic synapse employs y-aminobutyric acid (GABA) as its neurotransmitter. Amino acid neurotrans-mitters work by the same mechanism as ACh binding to ion gates and causing immediate changes in membrane potential. The release of GABA and binding to its receptor are similar to the preceding case. The GABA receptor, however, is a chloride channel. It responds by opening Saladin Anatomy & 12. Nervous Tissue Text The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function,...

Physiology of Osseous Tissue

When you have completed this section, you should be able to explain how minerals are deposited in bone tissue and removed from it discuss the role of the bones in regulating blood calcium and phosphate levels Saladin Anatomy & 7. Bone Tissue Text The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition describe how vitamin D is synthesized and how it affects the bones and list other hormones that affect bone physiology and state their effects. Even after a...

True or False

The feature that most distinguishes a lipid from a carbohydrate is that a lipid has c. a lower ratio of carbon to oxygen. d. a lower ratio of oxygen to hydrogen. 11. When an atom gives up an electron and acquires a positive charge, it is called a an_. 12. Dietary antioxidants are important because they neutralize_. 13. Any substance that increases the rate of a reaction without being consumed 14. All the synthesis reactions in the body form a division of metabolism called_. 15. A chemical...

Review of Key Concepts

Concepts of Cellular Structure (p. 94) 1. Cytology is the study of cellular structure and function. 2. All human structure and function is the result of cellular activity. 3. Cell shapes are described as squamous, polygonal, stellate, cuboidal, columnar, spheroid, ovoid, discoid, fusiform, and fibrous. 4. Most human cells are 10 to 15 m in diameter. Cell size is limited in part by the ratio of surface area to volume. 5. A cell is enclosed in a plasma membrane and contains usually one nucleus....

The Chemical Elements

A chemical element is the simplest form of matter to have unique chemical properties. Water, for example, has unique properties, but it can be broken down into two elements, hydrogen and oxygen, that have unique chemical properties of their own. If we carry this process any further, however, we find that hydrogen and oxygen are made of protons, neutrons, and electrons and none of these are unique. A proton of gold is identical to a proton of oxygen. Hydrogen and oxygen are the simplest...

Endocrine and Exocrine Glands

Glands are broadly classified as endocrine or exocrine. They originate as invaginations of a surface epithelium. In exocrine29 (EC-so-crin) glands, they usually maintain their contact with the surface by way of a duct, an epithelial tube that conveys their secretion to the surface. The secretion may be released to the body surface, as in the case of sweat, mammary, and tear glands, but more often it is released into the cavity (lumen) of another organ such as the mouth or intestine. Endocrine30...

Think About It

While raising blood calcium levels, PTH lowers blood phosphate levels by promoting urinary excretion of phosphate. Explain why this is important for achieving the purpose of PTH. Saladin Anatomy & 7. Bone Tissue Text The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition Prevention of hydroxyapatite formation Figure 7.16 Negative Feedback Loops in Calcium Homeostasis. (a) The correction of hypercalcemia by calcitonin. (b) The correction of hypocalcemia by...

Excitation

Excitation is the process in which action potentials in the nerve fiber lead to action potentials in the muscle fiber. The steps in excitation are shown in figure 11.8. 1. A nerve signal arrives at the synaptic knob and stimulates voltage-gated calcium channels to open. Calcium ions enter the synaptic knob. 2. Calcium ions stimulate exocytosis of the synaptic vesicles, which release acetylcholine (ACh) into the synaptic cleft. One action potential causes exocytosis of about 60 synaptic...

Excitation Contraction Coupling

Excitation-contraction coupling refers to the events that link the action potentials on the sarcolemma to activation of the myofilaments, thereby preparing them to contract. The steps in the coupling process are shown in figure 11.9. 6. A wave of action potentials spreads from the end plate in all directions, like ripples on a pond. When this wave of excitation reaches the T tubules, it continues down them into the sarcoplasm. 7. Action potentials open voltage-regulated ion gates in the T...

Learning Strategy

In the remainder of this chapter, we consider about 160 muscles. Many of the relatively superficial ones are shown in figure 10.4. The following suggestions may help you develop a rational strategy for learning the muscular system Examine models, cadavers, dissected animals, or a photographic atlas as you read about these muscles. Visual images are often easier to remember than words, and direct observation of a muscle may stick in your memory better than descriptive text or two-dimensional...

Fatigue and Endurance

Muscle fatigue is the progressive weakness and loss of contractility that results from prolonged use of the muscles. For example, if you hold this book at arm's length for a minute, you will feel your muscles growing weaker and Saladin Anatomy & I 11. Muscular Tissue I Text I The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition eventually you will be unable to hold it up. Repeatedly squeezing a rubber ball, pushing a video game button, or trying to take...

Types of Fibrous Connective Tissue

Fibrous connective tissue is divided into two broad categories according to the relative abundance of fiber loose and dense connective tissue. In loose connective tissue, much of the space is occupied by ground substance, which is dissolved out of the tissue during histological fixation and leaves empty space in prepared tissue sections. The loose connective tissues we will discuss are areolar, reticular, and adipose tissue. In dense connective tissue, fiber occupies more space than the cells...

Other Factors Affecting Bone

At least 20 more hormones, growth factors, and vitamins affect osseous tissue in complex ways that are still not well understood (table 7.2). Bone growth is especially rapid in puberty and adolescence, when surges of growth hormone, estrogen, and testosterone promote ossification. These hormones stimulate rapid multiplication of osteogenic cells, matrix deposition by osteoblasts, and multiplication and hypertrophy of the chondrocytes in the metaphyses. Adolescent girls grow faster than boys and...

Structure of a Chemical Synapse

Neuronal Synpatic Vesicle Release

The synaptic knob (fig. 12.17) was described in chapter 11. It contains synaptic vesicles, many of which are docked at release sites on the plasma membrane, ready to release their neurotransmitter on demand. A reserve pool of synaptic vesicles is located a little farther away from the membrane, clustered near the release sites and tethered to the cytoskeleton by protein microfilaments. The postsynaptic neuron does not show such conspicuous specializations. At this end, the neuron has no...

Chaperones and Protein Structure

Trna Attaches Mrna

The amino acid sequence of a protein (primary structure) is only the beginning the end of translation is not the end of protein synthesis. The protein now coils or folds into its secondary and tertiary structures and, in some cases, associates with other polypeptide chains (quaternary structure) or conjugates with a nonprotein moiety, such as a vitamin or carbohydrate. It is essential that these processes not begin prematurely as the amino acid sequence is being assembled, since the correct...

Centrioles

A centriole (SEN-tree-ole) is a short cylindrical assembly of microtubules, arranged in nine groups of three micro-tubules each (fig. 3.30). Two centrioles lie perpendicular to each other within a small clear area of cytoplasm called the centrosome41 (see fig. 3.5). They play a role in cell division described in chapter 4. Each basal body of a flagellum or cilium is a single centriole oriented perpendicular to the plasma membrane. Basal bodies originate in a centriolar organizing center and...

The Birth of Modern Medicine

Humani Corp

Medical science advanced very little during the Middle Ages. Even though some of the most famous medical schools of Europe were founded during this era, the professors taught medicine primarily as a dogmatic commentary on Galen and Aristotle, not as a field of original research. Medieval medical illustrations were crude representations of the body that served more to decorate a page than to depict the body realistically (fig. 1.2). Some were astrological charts that showed which sign of the...

Desmosomes

If a tight junction is like a zipper, a desmosome27 (DEZ-mo-some) is more like the snap on a pair of jeans, a patch that holds cells together and enables a tissue to resist mechanical stress, but does not totally encircle a cell. Desmosomes are common in the epidermis, cardiac muscle, and cervix of the uterus. The neighboring cells are separated by a small gap, which is spanned by a fine mesh of glycoprotein filaments. These filaments terminate in a thickened protein plaque at the surface of...

The Importance of Precision

A final word of advice for your study of anatomy and physiology Be precise in your use of terms. It may seem trivial if you misspell trapezius as trapezium, but in doing so, you would be changing the name of a back muscle to the name of a wrist bone. Similarly, changing occipitalis to occipital or zygomaticus to zygomatic changes other muscle names to bone names. A little error such as misspelling ileum as ilium changes the name of the final portion of the small intestine to the name of the hip...

Gap Communicating Junctions

A gap junction is formed by a ringlike connexon, which consists of six transmembrane proteins surrounding a water-filled channel. Ions, glucose, amino acids, and other small solutes can pass directly from the cytoplasm of one cell into the next through these channels. In the embryo, nutrients pass from cell to cell through gap junctions until the circulatory system forms and takes over the role of nutrient distribution. Gap junctions are found in the intercalated discs of cardiac muscle and...

The Hypodermis

Beneath the skin is a layer called the hypodermis,8 subcutaneous tissue, or superficial fascia9 (FASH-ee-uh). The boundary between the dermis and hypodermis is indistinct, but the hypodermis generally has more areolar and adipose tissue. When adipose tissue dominates, the hypodermis is called the subcutaneous fat (panniculus10 adi-posus). The hypodermis binds the skin to the underlying tissues, pads the body, serves as an energy reservoir, and provides thermal insulation. Infants and elderly...

The Scope of Anatomy and Physiology

Anatomy is the study of structure, and physiology is the study of function. These approaches are complementary and never entirely separable. When we study a structure, we want to know, What does it do Physiology lends meaning to anatomy and, conversely, anatomy is what makes physiology possible. This unity of form and function is an important point to bear in mind as you study the body. Many examples of it will be apparent throughout the book some of them pointed out for you, and others you...

Testing Your Comprehension

A woman in labor is often told to push. In doing so, is she consciously contracting her uterus to expel the baby Justify your answer based on the muscular composition of the uterus. 2. A major tenet of the cell theory is that all bodily structure and function is based on cells. The structural properties of bone, cartilage, and tendons, however, are due more to their extracellular material than to their cells. Is this an exception to the cell theory Why or why not 3. When cartilage is...

Second Messengers

Second Messenger System

Second messengers are of such importance that they require a closer look. You will find this information essential for your later understanding of hormone and neuro-transmitter action. Let's consider how the hormone epinephrine stimulates a cell. Epinephrine, the first messenger, cannot pass through plasma membranes, so it binds to a surface receptor. The receptor is linked on the intracellular side to a peripheral protein called a G protein (fig. 3.9). G proteins are named for the ATP-like...

Chromosomes and Heredity

When you have completed this section, you should be able to describe the paired arrangement of chromosomes in the human karyotype define allele and discuss how alleles affect the traits of an individual and discuss the interaction of heredity and environment in producing individual traits. Heredity is the transmission of genetic characteristics from parent to offspring. Several traits and diseases discussed in the forthcoming chapters are hereditary baldness, blood types, color blindness, and...

Wwwmhhecomsaladin3

Cross Section Spinal Cord Stretch

The Online Learning Center provides a wealth of information fully organized and integrated by chapter. You will find practice quizzes, interactive activities, labeling exercises, flashcards, and much more that will complement your learning and understanding of anatomy and physiology. Saladin Anatomy & Physiology The Unity of Form and Function, Third 13. The Spinal Cord, Spinal Nerves, and Somatic Reflexes The Spinal Cord, Spinal Nerves, and Somatic Reflexes Cross section through two...

Stratum Basale

The stratum basale (bah-SAY-lee) consists of a single layer of cuboidal to low columnar cells resting on the basement membrane of the epithelium. There are three types of cells in this layer 1. Keratinocytes (keh-RAT-ih-no-sites) are the majority of cells. They are named for their role in synthesizing the keratin of the skin. Keratinocytes of the stratum basale undergo mitosis and produce new epidermal cells to replace the dead ones that exfoliate (flake off) from the surface. 2. Melanocytes...

Instructors Presentation CDROM

This multimedia collection of visual resources allows instructors to utilize artwork from the text in multiple formats to create customized classroom presentations, visually based tests and quizzes, dynamic course website content, or attractive printed support materials. The digital assets on this cross-platform CD-ROM are grouped by chapter within the following easy-to-use folders. Art Library Full-color digital files of all illustrations in the book, plus the same art saved in unlabeled and...

Microvilli

Microvilli9 (MY-cro-VIL-eye singular, microvillus) are extensions of the plasma membrane that serve primarily to increase a cell's surface area (figs. 3.10 and 3.11a-b). They are best developed in cells specialized for absorption, such as the epithelial cells of the intestines and kidney tubules. They give such cells 15 to 40 times as much absorptive surface area as they would have if their apical surfaces were flat. On many cells, microvilli are little more than tiny bumps on the plasma...

Suggestions Still Welcome

Many features of this book, and many refinements in the writing, illustrations, and factual content, came about because of suggestions and questions from instructors and their students. In addition, many things that were tried experimentally in the first edition have been retained in the later editions because of positive feedback from users. But perfection in textbook writing seems to be an asymptote, ever approached but never fully reached. I invite my colleagues and students everywhere to...

Timing of Cell Division

One of the most important questions in biology is what signals cells when to divide and when to stop. The activation and inhibition of cell division are subjects of intense research for obvious reasons such as management of cancer and tissue repair. Cells divide when (1) they grow large enough to have enough cytoplasm to distribute to their two daughter cells (2) they have replicated their DNA, so they can give each daughter cell a duplicate set of genes (3) they receive an adequate supply of...

Online Learning Center

The Anatomy & Physiology Online Learning Center (OLC) at www.mhhe.com saladin3 offers access to a vast array of premium online content to fortify the learning and teaching experience. Essential Study Partner A collection of interactive study modules that contains hundreds of animations, learning activities, and quizzes designed to help students grasp complex concepts. Live News Feeds The OLC offers course specific real-time news articles to help you stay current with the latest topics in...

The Stem Cell Controversy

One of the most controversial scientific issues at the dawn of the twenty-first century has been stem cell research. At least 18 countries have recently debated or enacted laws to regulate stem cell research, with politicians, scientists, bioethicists, and religious leaders joining in the debate, and legions of lay citizens contributing their opinions to newspaper editorial pages. What are stem cells and why is this subject so controversial Stem cells are immature cells with the ability to...

Functions of Hair

In comparison to other mammals, the relative hairlessness of humans is so unusual that it raises the question, Why do we have any hair at all What purpose does it serve There are different answers for the different types of hair furthermore, some of the answers would make little sense if we limited our frame of reference to industrialized societies, where barbers and hairdressers are engaged to alter the natural state of the hair. It is more useful to take a comparative approach to this...

Electrical Potentials and Currents

Neuronal communication, like muscle excitation, is based on electrophysiology cellular mechanisms for producing electrical potentials and currents. An electrical potential is a difference in the concentration of charged particles between one point and another. It is a form of potential energy that, under the right circumstances, can produce a current. An electrical current is a flow of charged particles from the one point to the other. A new flashlight battery, for example, typically has a...

Oxygen Debt

You have probably noticed that you breathe heavily not only during a strenuous exercise but also for several minutes afterwards. This is because your body accrues an oxygen debt that must be repaid. Oxygen debt is the difference between the resting rate of oxygen consumption and the elevated rate following an exercise it is also known as excess postexercise oxygen consumption (EPOC). The total amount of extra oxygen consumed after a strenuous exercise is typically about 11 L. It is used for the...

Overview

Connective tissue typically consists mostly of fibers and ground substance, with widely separated cells. It is the most abundant, widely distributed, and histologically variable of the primary tissues. As the name implies, it often serves to connect organs to each other for example, the way a tendon connects muscle to bone or serves in other ways to support, bind, and protect organs. This category includes fibrous tissue, fat, cartilage, bone, and blood. The functions of connective tissue...

The Beginnings of Medicine

As early as 3,000 years ago, physicians in Mesopotamia and Egypt treated patients with herbal drugs, salts, physical therapy, and faith healing. The father of medicine, however, is usually considered to be the Greek physician Chapter 1 Major Themes of Anatomy and Physiology 3 Hippocrates (c. 460-c. 375 b.c.e.). He and his followers established a code of ethics for physicians, the Hippo-cratic Oath, that is still recited in modern form by many graduating medical students. Hippocrates urged...

Sebaceous Glands

Sebaceous32 (see-BAY-shus) glands produce an oily secretion called sebum (SEE-bum). They are flask-shaped, with short ducts that usually open into a hair follicle (fig. 6.11c), although some of them open directly onto the skin surface. These are holocrine glands with little visible lumen. Their secretion consists of broken-down cells that are replaced by mitosis at the base of the gland. Sebum keeps the skin and hair from becoming dry, brittle, and cracked. The sheen of well-brushed hair is due...

Alzheimer and Parkinson Diseases

Subthalamic Nucleus Anatomy

Alzheimer and Parkinson diseases are degenerative disorders of the brain associated with neurotransmitter deficiencies. Alzheimer29disease (AD) may begin before the age of 50 with symptoms so slight and ambiguous that early diagnosis is difficult. One of its first symptoms is memory loss, especially for recent events. A person with AD may ask the same questions repeatedly, show a reduced attention span, and become disoriented and lost in previously familiar places. Family members often feel...

Major Themes of Anatomy and Physiology

The Scope of Anatomy and Physiology 2 Anatomy The Study of Form 2 Physiology The Study of Function 3 The Beginnings of Medicine 3 The Birth of Modern Medicine 3 The Hypothetico-Deductive Method 7 Facts, Laws, and Theories 8 Evolution, Selection, and Adaptation 9 The Hierarchy of Complexity 12 Homeostasis and Negative Feedback 17 Positive Feedback and Rapid Change 18 The History of Anatomical Terminology 19 Singular and Plural Forms 21 The Importance of Precision 21 Review of Major Themes 21...

Electrolyte Concentrations

Differences Solution And Suspension

Electrolytes are important for their chemical, physical (osmotic), and electrical effects on the body. Their electri- 9Amedeo Avogadro (1776-1856), Italian chemist Will particles pass through a selectively Saladin Anatomy & I 2. The Chemistry of Life I Text I I The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition (b) 0.1 M glucose 0.1 M sucrose Figure 2.11 Comparison of Percentage and Molar Concentrations. (a) Solutions with the same percentage...

Focus Group Attendees

Akkaraju College of Dupage Les Albin Austin Community College Pegge Alciatore University of Louisiana-Lafayette Barbie W. Baker Florida Community College-Jacksonville Robert Bauman, Jr. Amarillo College Mary Bracken Trinity Valley Community College Kenneth Carpenter Southwest Tennessee Community College Matthew J. Craig Amarillo College Manuel E. Daniels, Jr. Tallahassee Community College Kathryn Gronlund Edison Community College Rebecca L. Hennig Odessa College Jacqueline A. Homan...

Mitochondria Evolution and Clinical Significance

It is virtually certain that mitochondria evolved from bacteria that invaded another primitive cell, survived in its cytoplasm, and became permanent residents. Certain modern bacteria called ricketsii live in the cytoplasm of other cells, showing that this mode of life is feasible. The two unit membranes around the mitochondrion suggest that the original bacterium provided the inner membrane and the host cell's phagosome provided the outer membrane when the bacterium was phagocytized. Several...

Testing Your Recall

Which of the following is not an essential part of anatomical position 2. A ring-shaped section of the small intestine would be a_section. 3. The tarsal region is popliteal region. Saladin Anatomy & Physiology The Unity of Form and Function, Third Edition 9. In which area do you think pain from 10. Which organ system regulates blood Atlas A General Orientation to Human Anatomy 53 13. The right and left pleural cavities are separated by a thick wall called the 7. Which of the following...

The Karyotype

A karyotype (fig. 4.15) is a chart of the chromosomes isolated from a cell at metaphase, arranged in order by size and structure. It reveals that most human cells, with the exception of germ cells (described shortly), contain 23 pairs of similar-looking chromosomes (except for X and Y chromosomes). The two chromosomes in each pair are called homologous9 (ho-MOLL-uh-gus) chromosomes. One is inherited from the mother and one from the father. Two chromosomes, designated X and Y, are called sex...

Long Term Memory

Long-term memory (LTM) lasts up to a lifetime and is less limited than STM in the amount of information it can store. LTM allows you to memorize the lines of a play, the words of a favorite song, or textbook information for an exam. On a still longer timescale, it enables you to remember your name, the route to your home, and your childhood experiences. There are two forms of long-term memory declarative and procedural. Declarative memory is the retention of events and facts that you can put...

General Anatomy

The study of dry bones and models in the laboratory can easily give the impression that the knee, elbow, or hip is a point at which one bone rubs against another. In life, however, the bones do not touch each other rather, fluid and soft tissues separate them and hold them in proper alignment (fig. 9.6). The bones of a synovial joint are separated by a joint (articular) cavity containing the synovial fluid. Synovial fluid is rich in albumin and hyaluronic acid, which give it a viscous, slippery...

Skin Grafts and Artificial Skin

Third-degree burns leave no dermal tissue to regenerate what was lost, and therefore they generally require skin grafts. The ideal graft is an autograft tissue taken from another location on the same person's body because it is not rejected by the immune system. An autograft is performed by taking epidermis and part of the dermis from an Chapter 6 The Integumentary System 211 undamaged area such as the thigh or buttock and grafting it to a burned area. This method is called a split-skin graft...

Acknowledgments

A textbook and supplements package on this scale is the product of a well coordinated effort by many dedicated people. I am deeply indebted to the team at McGraw-Hill Higher Education who have shown continued faith in this book and invested so generously in it. For their unfailing encouragement and material support, I thank Vice President and Editor-in-Chief Michael Lange and Publisher Marty Lange. My appreciation likewise goes out to Michelle Watnick for her years of energetic promotion of the...

RNA Structure and Function

DNA directs the synthesis of proteins by means of its smaller cousins, the ribonucleic acids (RNAs). There are three types of RNA messenger RNA (mRNA), ribosomal RNA (rRNA), and transfer RNA (tRNA). Their individual roles are described shortly. For now we consider what they have in common and how they differ from DNA (table 4.1). The most significant difference is that RNA is much smaller, ranging from about 70 to 90 bases in tRNA to slightly over 10,000 bases in the largest mRNA. DNA, by...

The Plasma Membrane

Phospholipid Cell

The electron microscope reveals that the cell and many of the organelles within it are bordered by a unit membrane, which appears as a pair of dark parallel lines with a total thickness of about 7.5 nm (fig. 3.6a). The plasma membrane is the unit membrane at the cell surface. It defines the boundaries of the cell, governs its interactions with other cells, and controls the passage of materials into and out of the cell. The side that faces the cytoplasm is the intracellular face of the membrane,...

Glial Cells and Brain Tumors

Unmyalinated Axons Brain

A tumor consists of a mass of rapidly dividing cells. Mature neurons, however, have little capacity for mitosis and seldom form tumors. Some brain tumors arise from the meninges (protective membranes of the CNS) or arise by metastasis from tumors elsewhere, such as malignant melanoma and colon cancer. Most adult brain tumors, however, are composed of glial cells, which are mitotically active throughout life. Such tumors are called gliomas21 Gliomas usually grow rapidly and are highly malignant....

True And False Physiology

Determine which five of the following statements are false, and briefly explain why. 1. If a cell were poisoned so it could not make ATP, osmosis through its membrane would cease. 2. Material can move either into a cell or out by means of active transport. 3. A cell's second messengers serve mainly to transport solutes through the membrane. 4. The Golgi complex makes lysosomes but not peroxisomes. 5. Some membrane channels are peripheral proteins. 6. The plasma membrane consists primarily of...

Answers in Appendix B

Determine which five of the following statements are false, and briefly explain why. 1. A single sagittal section of the body can pass through one lung but not through both. 2. It would be possible to see both eyes in one frontal section of the head. 3. The knee is both superior and proximal to the tarsal region. 4. The diaphragm is ventral to the lungs. 5. The esophagus is in the dorsal body cavity. 6. The liver is in the lateral abdominal region. 7. The heart is in the mediastinum. 8. Both...

Reviewers

No words could adequately convey my indebtedness and gratitude to the hundreds of A& P instructors and experts who have reviewed this book in all its editions, and who have provided such a wealth of scientific information, corrections, suggestions for effective presentation, and encouragement. For making the book beautiful, I am indebted to the team described earlier. For making it right, I am thankful to the colleagues listed on the following pages. Saladin Anatomy & I Front Matter I...

DNA Replication

Double Helix Watson Norton Third Edition

The law of complementary base pairing shows that we can predict the base sequence of one DNA strand if we know the sequence of the other. More importantly, it enables a Saladin Anatomy & Physiology The Unity of Form and Function, Third Edition 140 Part One Organization of the Body 140 Part One Organization of the Body Figure 4.10 Protein Packaging and Secretion. Some proteins are synthesized by ribosomes on the rough ER and carried in transport vesicles to the nearest cisterna of the Golgi...

Goodand Bad Cholesterol

Functional Groups Cholesterol

There is only one kind of cholesterol, and it does far more good than harm. When the popular press refers to good and bad cholesterol, it is actually referring to droplets in the blood called lipoproteins, which are a complex of cholesterol, fat, phospholipids, and protein. So-called bad cholesterol refers to low-density lipoprotein (LDL), which has a high ratio of lipid to protein and contributes to cardiovascular disease. So-called good cholesterol refers to high-density lipoprotein (HDL),...

Bones of the Skeletal System

It is often stated that there are 206 bones in the skeleton, but this is only a typical adult count. At birth there are about 270, and even more bones form during childhood. With age, however, the number decreases as separate bones fuse. For example, each half of the adult pelvis is a single bone called the os coxae (oss COC-see), which results from the fusion of three childhood bones the ilium, ischium, and pubis. The fusion of several bones, completed by late adolescence or the early 20s,...

Issues of Terminology

In 1999, the Terminologia Anatomica (TA) replaced the Nomina Anatomica as the international standard for anatomical terminology. I have updated the terminology in this edition accordingly, except in cases where TA terminology is, as yet, so unfamiliar that it may be more a hindrance than a help for an introductory anatomy course. For example, I use the unofficial femur rather than the official os femoris or femoral bone. The TA no longer recognizes eponyms, and I have avoided using them when...

Molecules and Chemical Bonds

Molecules are chemical particles composed of two or more atoms united by a covalent chemical bond (the sharing of electrons). The atoms may be identical, as in nitrogen (N2), or different, as in glucose (C6H12O6). Molecules composed of two or more different elements are called compounds. Oxygen (O2) and carbon dioxide (CO2) are both molecules because both consist of at least two atoms, but only CO2 is a compound, because it has atoms of two different elements. Molecules can be represented by...

Neurotransmitters and Related Messengers

Neurotransmitters

More than 100 confirmed or suspected neurotransmitters have been identified since Loewi discovered acetylcholine. Neurotransmitters fall into three major categories according to chemical composition (fig. 12.18). Some of the best-known ones are listed in table 12.3. Parts of the brain referred to in this table will become familiar to you as you study chapter 14, and you may wish to refer back to this table then to enhance your understanding of brain function. 1. Acetylcholine is in a class by...

Behavior of Whole Muscles

When you have completed this section, you should be able to describe the stages of a muscle twitch describe treppe and explain how it relates to muscle warm-up explain how muscle twitches add up to produce stronger muscle contractions distinguish between isometric and isotonic contraction and distinguish between concentric and eccentric contractions. Now you know how an individual muscle cell shortens. Our next objective is to move up to the organ grade of construction and consider how this...

Crossed-extensor Diagram

Branch to brachial plexus Phrenic nerve Segmental branch Hypoglossal nerve (XII) Lesser occipital nerve Great auricular nerve Transverse cervical nerve Segmental branch Hypoglossal nerve (XII) Lesser occipital nerve Great auricular nerve Transverse cervical nerve Branch to brachial plexus Phrenic nerve Saladin Anatomy & I 13. The Spinal Cord, Spinal I Text I The McGraw-Hill Physiology The Unity of Nerves, and Somatic Companies, 2003 Form and Function, Third Reflexes Edition 498 Part Three...

Uva Uvb and Sunscreens

Some people distinguish between two forms of ultraviolet radiation and argue, fallaciously, that one is less harmful than the other. UVA has wavelengths ranging from 320 to 400 nm and UVB has wavelengths from 290 to 320 nm. Visible light starts at about 400 nm, the deepest violet we can see. UVA and UVB are sometimes called tanning rays and burning rays, respectively. Tanning salons often advertise that the UVA rays they use are safe, but public health authorities know better. UVA can burn as...

Lipids

A lipid is a hydrophobic organic molecule, usually composed only of carbon, hydrogen, and oxygen, with a high ratio of hydrogen to oxygen. A fat called tristearin tri-STEE-uh-rin , for example, has the molecular formula C57H110O6 more than 18 hydrogens for every oxygen. Lipids are less oxidized than carbohydrates, and thus have more calories per gram. Beyond these criteria, it is difficult to generalize about lipids they are much more variable in structure than the other macromolecules we are...

Social Functions

Skin How Does Regulate Heat

The integumentary system plays an important role in the social relations of all vertebrate animals by enabling them to identify members of their own species and distinguish the sexes. Some mammals recognize each other by the color and distribution of hair. Animals may also accept or reject one another's company and choose mates based on the appearance of the integument, which may indicate an animal's state of health. Thus, it is not surprising that animals allocate a lot of time to grooming....

Transdermal Absorption

The ability of the skin to absorb chemicals makes it possible to administer several medicines as ointments or lotions, or by means of adhesive patches that release the medicine steadily through a membrane. For example, inflammation can be treated with a hydrocortisone ointment, nitroglycerine patches are used to relieve heart pain, nicotine patches are used to help overcome tobacco addiction, and other medicated patches are used to control high blood pressure and motion sickness. Unfortunately,...

Unmyelinated Nerve Fibers

Many nerve fibers in the CNS and PNS are unmyelinated. In the PNS, however, even the unmyelinated fibers are enveloped in Schwann cells. In this case, one Schwann cell harbors from 1 to 12 small nerve fibers in grooves in its surface. The Schwann cell's plasma membrane does not spiral repeatedly around the fiber as it does in a myelin sheath, but folds once around each fiber and somewhat overlaps itself along the edges fig. 12.7b . This wrapping is the neurilemma. A basal lamina surrounds the...

Reaction Rates

The basis for chemical reactions is molecular motion and collisions. All molecules are in constant motion, and reactions occur when mutually reactive molecules collide with sufficient force and the right orientation. The rate of a reaction depends on the nature of the reactants and on the frequency and force of these collisions. Some factors that affect reaction rates are Concentration. Reaction rates increase when the reactants are more concentrated. This is because the molecules are more...

Skin Markings

Hemangiomas18 he-MAN-jee-OH-mas , or birthmarks, are patches of discolored skin caused by benign tumors of the dermal blood capillaries. Capillary hemangiomas strawberry birthmarks are bright red to deep purple and are slightly swollen they usually disappear in childhood. Cavernous hemangiomas port wine stains are flat, are duller in color, and last for life. Freckles and moles are tan to black aggregations of melanocytes. Freckles are flat melanized patches that vary with heredity and exposure...

Nervous and Muscular Tissue Excitable Tissues

When you have completed this section, you should be able to explain what distinguishes excitable tissues from other tissues name the cell types that compose nervous tissue identify the major parts of a nerve cell visually recognize nervous tissue from specimens or photographs name the three kinds of muscular tissue and describe the differences between them and visually identify any type of muscular tissue from specimens or photographs. Excitability is a characteristic of all living cells, but...

The Language of Medicine

When you have completed this section, you should be able to explain why modern anatomical terminology is so heavily based on Greek and Latin recognize eponyms when you see them describe the efforts to achieve an internationally uniform anatomical terminology break medical terms down into their basic word elements state some reasons why the literal meaning of a word may not lend insight into its definition relate singular noun forms to their plural forms and discuss why precise spelling is...

Can We Replace Brain Cells

Until recently, neurons nerve cells of the brain were thought to be irreplaceable when they died, we thought, they were gone forever. We believed, indeed, that there was good reason for this. Motor skills and memories are encoded in intricate neural circuits, and the growth of new neurons might disrupt those circuits. Now we are not so sure. A chemical called BrDU bromodeoxyuridine can be used to trace the birth of new cells, because it becomes incorporated into their DNA. BrDU is too toxic to...

The Cell Surface

When you have completed this section, you should be able to describe the structure of a plasma membrane explain the functions of the lipid, protein, and carbohydrate components of the plasma membrane describe a second-messenger system and discuss its importance in human physiology describe the composition and functions of the glycocalyx that coats cell surfaces and describe the structure and functions of microvilli, cilia, and flagella. Throughout this book, you will find that many of the most...

Synovial Joints

When you have completed this section, you should be able to describe the anatomy of a synovial joint and its associated structures describe the six types of synovial joints list and demonstrate the types of movements that occur at diarthroses discuss the factors that affect the range of motion of a joint give an anatomical example of a first-, second-, and third-class lever and explain why each is classified as it is and relate the concept of mechanical advantage to the power and speed of joint...

Cell Shapes and Sizes

Cell Shapes And Sizes Human Physiology

There are about 200 types of cells in the human body, and they vary greatly in shape fig. 3.1 . Squamous3 SQUAY- 3squam scale ous characterized by XAVV Aj'JL lt gt 1 I - A'TTT-IH T-V Saladin Anatomy amp Physiology The Unity of Form and Function, Third Edition Chapter 3 Cellular Form and Function 95 mus cells are thin, flat, and often have angular contours when viewed from above. Such cells line the esophagus and cover the skin. Polygonal4 cells have irregularly angular shapes with four, five,...

What Are The Two Most Urgent Priorities In Treating A Burn Victim

A third-degree burn may be surrounded by painful areas of first- and second-degree burns, but the region of the third-degree burn is painless. Explain the reason for this lack of pain. Saladin Anatomy amp 6. The Integumentary Text The McGraw-Hill Physiology The Unity of System Companies, 2003 The two most urgent considerations in treating a burn patient are fluid replacement and infection control. A patient can lose several liters of water, electrolytes, and protein each day from the burned...

The Glycocalyx

Saladin Animal Cell

External to the plasma membrane, all animal cells have a fuzzy coat called the glycocalyx8 GLY-co-CAY-licks fig. 3.10 , which consists of the carbohydrate moieties sglyco sugar calyx cup, vessel sglyco sugar calyx cup, vessel Figure 3.10 Microvilli and the Glycocalyx. This is the apical surface of an absorptive cell of the small intestine. Figure 3.10 Microvilli and the Glycocalyx. This is the apical surface of an absorptive cell of the small intestine. Saladin Anatomy amp I 3. Cellular Form...

Hair and Nails

When you have completed this section, you should be able to distinguish between three types of hair describe the histology of a hair and its follicle describe the cycle of hair growth discuss some theories of the purposes served by various kinds of hair and describe the structure and function of nails. Saladin Anatomy amp Physiology The Unity of Form and Function, Third Edition Chapter 6 The Integumentary System 201 Hair, nails, and cutaneous glands are the accessory organs, or appendages, of...

Physiological Variation

Earlier we considered the clinical importance of variations in human anatomy, but physiology is even more variable. Physiological variables differ with sex, age, weight, diet, degree of physical activity, and environment, among other things. Failure to consider such variation leads to medical mistakes such as overmedication of the elderly or medicating women on the basis of research that was done on men. If an introductory textbook states a typical human heart rate, blood pressure, red blood...

Ceruminous Glands

Ceruminous seh-ROO-mih-nus glands are found only in the external ear canal, where their secretion combines 32seb fat, tallow aceous possessing Chapter 6 The Integumentary System 207 with sebum and dead epidermal cells to form earwax, or cerumen.33 They are simple, coiled, tubular glands with ducts leading to the skin surface. Cerumen keeps the eardrum pliable, waterproofs the auditory canal, and has a bactericidal effect.

Mammary Glands

The mammary glands and breasts mammae are often mistakenly regarded as one and the same. Breasts, however, are present in both sexes, and even in females they rarely contain more than small traces of mammary gland. Some authorities regard the female breast as one of the secondary sex characteristics anatomical features whose function lies primarily in their appeal to the opposite sex. The mammary glands, by contrast, are the milk-producing glands that develop within the female breast only...

Cystic Fibrosis

The significance of chloride pumps becomes especially evident in cystic fibrosis CF , a hereditary disease especially affecting white children of European descent. CF is usually caused by a defect in which cells make chloride pumps but fail to install them in the plasma membrane. Consequently, there is an inadequate saline layer on the cell surface and the mucus is dehydrated and overly sticky. This thick mucus plugs the ducts of the pancreas and prevents it from secreting digestive enzymes...

Monomers and Polymers

Since carbon can form long chains, some organic molecules are gigantic macromolecules with molecular weights that range from the thousands as in starch and proteins to the millions as in DNA . Most macromolecules are polymers14 molecules made of a repetitive series of identical or similar subunits called monomers MON-oh-murs . Starch, for example, is a polymer of about 3,000 glucose monomers. In starch, the monomers are identical, while in other polymers they have a basic structural similarity...

Credits

Yorgos Nikas SPL Photo Researchers, Inc. 1.1, 1.2 National Library of Medicine Peter Arnold, Inc. 1.3 SPL Photo Researchers, Inc. 1.4a,b Kathy Talaro Visuals Unlimited 1.5a Courtesy of the Armed Forces Institute of Pathology 1.5b Corbis-Bettmann 1.7 Tim Davis Photo Researchers, Inc. 1.15a U.H.B. Trust Tony Stone Images 1.15b Custom Medical Stock 1.16top Alexander Tsiaras Photo Researchers, Inc. 1.16bottom Scott Camazine Sue Trainor Photo Researchers, Inc. 1.17 CNR Phototake 1.18 Tony Stone...

Carbon Compounds and Functional Groups

Organic chemistry is the study of compounds of carbon. By 1900, biochemists had classified the organic molecules of life into four primary categories carbohydrates, lipids, Table 2.5 Energy-Transfer Reactions in the Human Body Reactions in which there is a net release of energy. The products have less total free energy than the reactants did. An exergonic reaction in which electrons are removed from a reactant. Electrons may be removed one or two at a time and may be removed in the form of...

Muscular Strength and Conditioning

We have far more muscular strength than we normally use. The gluteus maximus can generate 1,200 kg of tension, and all the muscles of the body can produce a total tension of 22,000 kg nearly 25 tons . Indeed, the muscles can generate more tension than the bones and tendons can withstand a fact that accounts for many injuries to the patellar and cal-caneal tendons. Muscular strength depends on a variety of anatomical and physiological factors Muscle size. The strength of a muscle depends...

Response to Stretch

Stretch alone sometimes causes smooth muscle to contract by opening mechanically gated calcium channels in the sarcolemma. Distension of the esophagus with food or the colon with feces, for example, evokes a wave of contraction called peristalsis PERR-ih-STAL-sis that propels the contents along the organ. Saladin Anatomy amp I 11. Muscular Tissue I Text I The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition Smooth muscle exhibits a reaction called the...

Embryonic Tissues

Human development begins with a single cell, the fertilized egg, which soon divides to produce scores of identical, smaller cells. The first tissues appear when these cells start to organize themselves into layers first two, and soon three strata called the primary germ layers, which give rise to all of the body's mature tissues. The three layers are called ectoderm, mesoderm, and endoderm. The ectoderm3 is an outer layer that gives rise to the epidermis and nervous system. The inner layer, the...

Stratum Granulosum

The stratum granulosum consists of two to five layers of flat keratinocytes more in thick skin than in thin skin. These keratinocytes contain coarse, dark-staining kerato-hyalin granules that give this layer its name. These granules consist of a protein that combines with intermediate filaments of the cytoskeleton and converts them to keratin. Keratinocytes in the stratum spinosum and stratum granulosum also produce lipid-filled membrane-coating vesicles. Here in the stratum granulosum, these...

The Healing of Fractures

An uncomplicated fracture heals in about 8 to 12 weeks, but complex fractures take longer and all fractures heal Saladin Anatomy amp I 7. Bone Tissue I Text I I The McGraw-Hill Physiology The Unity of Companies, 2003 Form and Function, Third Edition Table 7.2 Agents Affecting Calcium and Bone Metabolism Table 7.2 Agents Affecting Calcium and Bone Metabolism Little effect in adults promotes mineralization and lowers blood Ca2 concentration in children may prevent bone loss in pregnant and...

The Muscle Fiber

In order to understand muscle function, you must know how the organelles and macromolecules of a muscle fiber are arranged. Perhaps more than any other cell, a muscle fiber exemplifies the adage, Form follows function. It has a complex, tightly organized internal structure in which even the spatial arrangement of protein molecules is closely tied to its contractile function. Muscle fibers have multiple flattened or sausage-shaped nuclei pressed against the inside of the plasma membrane. This...