《生物学》课程参考书籍文献（英文版，Chapter 49 - Chapter 60）Part XIII Animal Form and Function、Part XIV Regulating the Animal Body

Sternum Heart Pelvis Testis Fem Skeletal system Endocrine system Spinal Nervous system Respiratory system Lymphatic/Immune syste FIGURE 49.5 Vertebrate organ systems. The 11 principal organ systems of the human body are shown, including both male and female reproductive 986 Part XIlI Animal Form and Function

986 Part XIII Animal Form and Function Skull Sternum Pelvis Femur Brain Spinal cord Nerves Skeletal system Circulatory system Endocrine system Nervous system Respiratory system Lymphatic/Immune system Trachea Lungs Lymph nodes Spleen Lymphatic vessels Testis (male) Ovary (female) Pituitary Thyroid Thymus Adrenal gland Pancreas Arteries Veins Heart FIGURE 49.5 Vertebrate organ systems. The 11 principal organ systems of the human body are shown, including both male and female reproductive systems

Pectoralis Liver Biceps Stomach Kidney Smal stine Ureter abdominus Bladde Sartorius Digestive system Urinary system Muscular system Hair fallopian Vas deferens Testis Uterus P Vair Reproductive system Reproductive system Integumentary system FIGURE 49.5(continued) Chapter 49 Organization of the Animal Body 987

Chapter 49 Organization of the Animal Body 987 Salivary glands Esophagus Liver Stomach Small intestine Large intestine Vas deferens Testis Penis Digestive system Urinary system Muscular system Reproductive system (male) Reproductive system (female) Integumentary system Ovary Fallopian tube Uterus Vagina Hair Skin Fingernails Gastrocnemius Pectoralis major Biceps Rectus abdominus Sartorius Quadriceps Ureter Bladder Urethra Kidney FIGURE 49.5 (continued)

49.2 Epithelial tissue forms membranes and glands Characteristics of Epithelial Tissue capillaries, for example, where the thin, delicate nature of these membranes permits the rapid movement of molecules An epithelial membrane, or epithelium, covers every sur-(such as the diffusion of gases). A simple cuboidal epithelium face of the vertebrate body. Epithelial membranes are de- lines the small ducts of some glands, and a simple columna rived from all three germ layers. The epidermis, derived epithelium is found in the airways of the respiratory tract from ectoderm, constitutes the outer portion of the skin. and in the gastrointestinal The inner surface of the digestive tract is lined by an ep- terspersed among the columnar epithelial cells are numer ithelium derived from endoderm, and the inner surfaces of ous goblet cells, specialized to secrete mucus. The columnar the body cavities are lined with an epithelium derived from epithelial cells of the respiratory airways contain cilia on their apical surface(the surface facing the lumen, or cavity), Because all body surfaces are covered by epithelial mem- which move mucus toward the throat. In the small intes- branes, a substance must pass through an epithelium in tine, the apical surface of the columnar epithelial cells form order to enter or leave the body. Epithelial membranes fingerlike projections called microvilli, that increase the sur- thus provide a barrier that can impede the passage of some face area for the absorption of food. substances while facilitating the passage of others. For Stratified epithelial membranes are several cell layers land-dwelling vertebrates, the relative impermeability of thick and are named according to the features of their up- the surface epithelium(the epidermis) to water offers es- permost layers. For example, the epidermis is a stratified sential protection from dehydration and from airborne squamous epithelium. In terrestrial vertebrates it is further athogens(disease-causing organisms). On the other hand, characterized as a keratinized epithelium, because its upper the epithelial lining of the digestive tract must allow selec- layer consists of dead squamous cells and filled with a tive entry of the products of digestion while providing a water-resistant protein called keratin. The deposition of barrier to toxic substances, and the epithelium of the lungs keratin in the skin can be increased in response to abrasion, must allow for the rapid diffusion of gases producing calluses. The water-resistant property of keratin Some epithelia become modified in the course of em- is evident when the skin is compared with the red portion bryonic development into glands, which are specialized for of the lips, which can easily become dried and chapped be- secretion. A characteristic of all epithelia is that the cells cause it is covered by a nonkeratinized, stratified squamous are tightly bound together, with very little space between epithelium them. As a consequence, blood vessels cannot be interposed The glands of vertebrates are derived from invaginated between adjacent epithelial cells. Therefore, nutrients and epithelium. In exocrine glands, the connection between oxygen must diffuse to the epithelial cells from blood ves- the gland and the epithelial membrane is maintained as a sels in nearby tissues. This places a limit on the thickness of duct. The duct channels the product of the gland to the epithelial membranes; most are only one or a few cell layers surface of the epithelial membrane and thus to the external environment(or to an interior compartment that opens Epithelium possesses remarkable regenerative powers, the exterior, such as the digestive tract). Examples of constantly replacing its cells throughout the life of the ani- ocrine glands include sweat and sebaceous (oil) glands, mal. For example, the liver, a gland formed from epithelial which secrete to the external surface of the skin, and acces- tissue, can readily regenerate after substantial portions of it sory digestive glands such as the salivary glands, liver, and have been surgically removed. The epidermis is renewed pancreas, which secrete to the surface of the epithelium lin- every two weeks, and the epithelium inside the stomach is ing the digestive tract. replaced every two to three days. Endocrine glands are ductless glands; their connections There are two general classes of epithelial membranes: with the epithelium from which they were derived are lost simple and stratified. These classes are further subdivided during development. Therefore their secretions, called into squamous, cuboidal, and columnar, based upon the hormones, are not channeled onto an epithelial membrane shape of the cells(table 49.2). Squamous cells are flat, Instead, hormones enter blood capillaries and thus stay cuboidal cells are about as thick as they are tall, and colum- within the body endocrine glands are discussed in more nar cells are taller than they are wide detail in chapter 56 ypes of Epithelial Tissues Epithelial tissues include membranes that cover all Simple epithelial membranes are one cell layer thick. a body surfaces and glands. The epidermis of the skin is simple, squamous epithelium is composed of squamous ep an epithelial membrane specialized for protection, thelial cells that have an irregular, flattened shape with ta- whereas membranes that cover the surfaces of hollow pered edges. Such membranes line the lungs and ble organs are often specialized for transport. 988 Part XIlI Animal Form and Function

Characteristics of Epithelial Tissue An epithelial membrane, or epithelium, covers every sur￾face of the vertebrate body. Epithelial membranes are de￾rived from all three germ layers. The epidermis, derived from ectoderm, constitutes the outer portion of the skin. The inner surface of the digestive tract is lined by an ep￾ithelium derived from endoderm, and the inner surfaces of the body cavities are lined with an epithelium derived from mesoderm. Because all body surfaces are covered by epithelial mem￾branes, a substance must pass through an epithelium in order to enter or leave the body. Epithelial membranes thus provide a barrier that can impede the passage of some substances while facilitating the passage of others. For land-dwelling vertebrates, the relative impermeability of the surface epithelium (the epidermis) to water offers es￾sential protection from dehydration and from airborne pathogens (disease-causing organisms). On the other hand, the epithelial lining of the digestive tract must allow selec￾tive entry of the products of digestion while providing a barrier to toxic substances, and the epithelium of the lungs must allow for the rapid diffusion of gases. Some epithelia become modified in the course of em￾bryonic development into glands, which are specialized for secretion. A characteristic of all epithelia is that the cells are tightly bound together, with very little space between them. As a consequence, blood vessels cannot be interposed between adjacent epithelial cells. Therefore, nutrients and oxygen must diffuse to the epithelial cells from blood ves￾sels in nearby tissues. This places a limit on the thickness of epithelial membranes; most are only one or a few cell layers thick. Epithelium possesses remarkable regenerative powers, constantly replacing its cells throughout the life of the ani￾mal. For example, the liver, a gland formed from epithelial tissue, can readily regenerate after substantial portions of it have been surgically removed. The epidermis is renewed every two weeks, and the epithelium inside the stomach is replaced every two to three days. There are two general classes of epithelial membranes: simple and stratified. These classes are further subdivided into squamous, cuboidal, and columnar, based upon the shape of the cells (table 49.2). Squamous cells are flat, cuboidal cells are about as thick as they are tall, and colum￾nar cells are taller than they are wide. Types of Epithelial Tissues Simple epithelial membranes are one cell layer thick. A simple, squamous epithelium is composed of squamous ep￾ithelial cells that have an irregular, flattened shape with ta￾pered edges. Such membranes line the lungs and blood capillaries, for example, where the thin, delicate nature of these membranes permits the rapid movement of molecules (such as the diffusion of gases). A simple cuboidal epithelium lines the small ducts of some glands, and a simple columnar epithelium is found in the airways of the respiratory tract and in the gastrointestinal tract, among other locations. In￾terspersed among the columnar epithelial cells are numer￾ous goblet cells, specialized to secrete mucus. The columnar epithelial cells of the respiratory airways contain cilia on their apical surface (the surface facing the lumen, or cavity), which move mucus toward the throat. In the small intes￾tine, the apical surface of the columnar epithelial cells form fingerlike projections called microvilli, that increase the sur￾face area for the absorption of food. Stratified epithelial membranes are several cell layers thick and are named according to the features of their up￾permost layers. For example, the epidermis is a stratified squamous epithelium. In terrestrial vertebrates it is further characterized as a keratinized epithelium, because its upper layer consists of dead squamous cells and filled with a water-resistant protein called keratin. The deposition of keratin in the skin can be increased in response to abrasion, producing calluses. The water-resistant property of keratin is evident when the skin is compared with the red portion of the lips, which can easily become dried and chapped be￾cause it is covered by a nonkeratinized, stratified squamous epithelium. The glands of vertebrates are derived from invaginated epithelium. In exocrine glands, the connection between the gland and the epithelial membrane is maintained as a duct. The duct channels the product of the gland to the surface of the epithelial membrane and thus to the external environment (or to an interior compartment that opens to the exterior, such as the digestive tract). Examples of ex￾ocrine glands include sweat and sebaceous (oil) glands, which secrete to the external surface of the skin, and acces￾sory digestive glands such as the salivary glands, liver, and pancreas, which secrete to the surface of the epithelium lin￾ing the digestive tract. Endocrine glands are ductless glands; their connections with the epithelium from which they were derived are lost during development. Therefore, their secretions, called hormones, are not channeled onto an epithelial membrane. Instead, hormones enter blood capillaries and thus stay within the body. Endocrine glands are discussed in more detail in chapter 56. Epithelial tissues include membranes that cover all body surfaces and glands. The epidermis of the skin is an epithelial membrane specialized for protection, whereas membranes that cover the surfaces of hollow organs are often specialized for transport. 988 Part XIII Animal Form and Function 49.2 Epithelial tissue forms membranes and glands

Table 49.2 Epithelial Tissue Simple epithelium SQUAMOUS Cuboidal Typical Location Lining of lungs, capillary walls, and blood vessels Function Cells very thin; provides thin layer across which diffusion can readily occur Characteristic Cell Types Epithelial cells CUBOIDAL Columna Typical Location epithelial Lining of some glands and kidney tubules; covering of ovaries Nucleus Cells rich in specific transport channels; functions in secretion and absorption Characteristic Cell Types Goblet cell Gland cells COLUMNAR Surface lining of stomach, intestines, and parts of respiratory tract Function Thicker cell layer; provides protection and functions in secretion and Characteristic Cell Types Epithelial cells Stratified Epithelium columnar 就心武 Tough layer of cells; provide Goblet cell Characteristic Cell Types epitheli PSEUDOSTRATIFIED COLUMNAR Typical location helial Secretes mucus: dense with cilia that aid in movement of Characteristic Cell T7 Gland cells; ciliated epithelial cells Nucleus Chapter 49 Organization of the Animal Body 989

Chapter 49 Organization of the Animal Body 989 Table 49.2 Epithelial Tissue Simple Epithelium SQUAMOUS Typical Location Lining of lungs, capillary walls, and blood vessels Function Cells very thin; provides thin layer across which diffusion can readily occur Characteristic Cell Types Epithelial cells CUBOIDAL Typical Location Lining of some glands and kidney tubules; covering of ovaries Function Cells rich in specific transport channels; functions in secretion and absorption Characteristic Cell Types Gland cells COLUMNAR Typical Location Surface lining of stomach, intestines, and parts of respiratory tract Function Thicker cell layer; provides protection and functions in secretion and absorption Characteristic Cell Types Epithelial cells Stratified Epithelium SQUAMOUS Typical Location Outer layer of skin; lining of mouth Function Tough layer of cells; provides protection Characteristic Cell Types Epithelial cells PSEUDOSTRATIFIED COLUMNAR Typical Location Lining parts of the respiratory tract Function Secretes mucus; dense with cilia that aid in movement of mucus; provides protection Characteristic Cell Types Gland cells; ciliated epithelial cells Cuboidal epithelial cells Nucleus Cytoplasm Cilia Pseudo– stratified columnar cell Goblet cell Simple squamous epithelial cell Nucleus Columnar epithelial cells Nucleus Goblet cell Nuclei

49.3 Connective tissues contain abundant extracellular material Connective Tissue Proper Connective tissues are derived from embryonic meso- derm and occur in many different forms(table 49.3) These various forms are divided into two major classes connective tissue proper, which is further divided into loose and dense connective tissues; and special connec tive tissues that include cartilage, bone. and blood. At first glance, it may seem odd that such diverse tissues are placed in the same category. Yet all connective tissues do share a common structural feature: they all have abun ant extracellular material because their cells are spaced widely apart. This extracellular material is generically known as the matrix of the tissue. In bone. the extracel lular matrix contains crystals that make the bones hard in blood, the extracellular matrix is plasma, the fluid por- tion of the blood Loose connective tissue consists of cells scattered FIGURE 49.6 within an amorphous mass of proteins that form a ground Collagen fibers. Each fiber is composed of many individual substance. This gelatinous material is stre ed by loose scattering of protein fibers such as collagen(figure 49.6), elastin, which makes the tissue elastic, and reticulin which supports the tissue by forming a collagenous mesh work. The flavored gelatin we eat for dessert consists of the extracellular material from loose connective tissues. The ells that secrete collagen and other fibrous proteins are known as fibroblasts Loose connective tissue contains other cells as well. in- cluding mast cells that produce histamine(a blood vessel lator)and heparin(an anticoagulant) and macrophages, the immune systems first defense against invading organisms as will be described in detail in chapter 57 Adipose cells are found in loose connective tissue, usually in large groups that form what is referred adipose tissue(figure 49.7). Each adipose cell contains a droplet of fat (triglycerides) within a storage vesicle When that fat is needed for energy, the adipose cell hy- drolyzes its stored triglyceride and secretes fatty acids into the blood for oxidation by the cells of the muscles, liver, and other organs. The number of adipose cells in FIGURE 49.7 an adult is generally fixed. When a person gains weight, Adipose tissue. Fat is stored in globules of adipose tissue, a type the cells become larger, and when weight is lost, the cells of loose connective tissue. As a person gains or loses weight, the size of the fat globules increases or decreases. A person cannot Dense connective tissue contains tightly packed colla- decrease the number of fat cells by losing weight. gen fibers, making it stronger than loose connective tis- sue. It consists of two types: regular and irregular. The collagen fibers of dense regular connective tissue are the capsules of the kidneys and adrenal glands. It also cow lined up in parallel, like the strands of a rope. This is the ers muscle as epimysium, nerves as perineurium, and bones structure of tendons, which bind muscle to bone, and liga as periosteum. ments. which bind bone to bone. In contrast the collagen fibers of dense irregular connective tissue have many Connective tissues are characterized by abundant different orientations. This type of connective tissue pro- extracellular materials in the matrix between cells duces the tough coverings that package organs, such as Connective tissue proper may be either loose or dense 990 Part XIlI Animal Form and Function

Connective Tissue Proper Connective tissues are derived from embryonic meso￾derm and occur in many different forms (table 49.3). These various forms are divided into two major classes: connective tissue proper, which is further divided into loose and dense connective tissues; and special connec￾tive tissues that include cartilage, bone, and blood. At first glance, it may seem odd that such diverse tissues are placed in the same category. Yet all connective tissues do share a common structural feature: they all have abun￾dant extracellular material because their cells are spaced widely apart. This extracellular material is generically known as the matrix of the tissue. In bone, the extracel￾lular matrix contains crystals that make the bones hard; in blood, the extracellular matrix is plasma, the fluid por￾tion of the blood. Loose connective tissue consists of cells scattered within an amorphous mass of proteins that form a ground substance. This gelatinous material is strengthened by a loose scattering of protein fibers such as collagen (figure 49.6), elastin, which makes the tissue elastic, and reticulin, which supports the tissue by forming a collagenous mesh￾work. The flavored gelatin we eat for dessert consists of the extracellular material from loose connective tissues. The cells that secrete collagen and other fibrous proteins are known as fibroblasts. Loose connective tissue contains other cells as well, in￾cluding mast cells that produce histamine (a blood vessel dilator) and heparin (an anticoagulant) and macrophages, the immune system’s first defense against invading organisms, as will be described in detail in chapter 57. Adipose cells are found in loose connective tissue, usually in large groups that form what is referred to as adipose tissue (figure 49.7). Each adipose cell contains a droplet of fat (triglycerides) within a storage vesicle. When that fat is needed for energy, the adipose cell hy￾drolyzes its stored triglyceride and secretes fatty acids into the blood for oxidation by the cells of the muscles, liver, and other organs. The number of adipose cells in an adult is generally fixed. When a person gains weight, the cells become larger, and when weight is lost, the cells shrink. Dense connective tissue contains tightly packed colla￾gen fibers, making it stronger than loose connective tis￾sue. It consists of two types: regular and irregular. The collagen fibers of dense regular connective tissue are lined up in parallel, like the strands of a rope. This is the structure of tendons, which bind muscle to bone, and liga￾ments, which bind bone to bone. In contrast, the collagen fibers of dense irregular connective tissue have many different orientations. This type of connective tissue pro￾duces the tough coverings that package organs, such as the capsules of the kidneys and adrenal glands. It also cov￾ers muscle as epimysium, nerves as perineurium, and bones as periosteum. Connective tissues are characterized by abundant extracellular materials in the matrix between cells. Connective tissue proper may be either loose or dense. 990 Part XIII Animal Form and Function 49.3 Connective tissues contain abundant extracellular material. FIGURE 49.6 Collagen fibers. Each fiber is composed of many individual collagen strands and can be very strong under tension. FIGURE 49.7 Adipose tissue. Fat is stored in globules of adipose tissue, a type of loose connective tissue. As a person gains or loses weight, the size of the fat globules increases or decreases. A person cannot decrease the number of fat cells by losing weight