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Chapter 20 Unifying Concept of Animal Structure and Function Microscopic hairs on the toes of a gecko Structure and Function in Animal Tissues The structure hierarchy in an animal begins with cells and tissues, whose forms correlate with their functions. Organs and Organ Systems Tissues are arranged into organs, which may be functionally correlated in organ systems. External Exchange and Internal Regulation Complex animals have internal surface that facilitate exchange with the environment. Feedback control maintains homeostasis in many animals. Structure fits function at all levels of organization in the animal body Anatomy is the study of structure. 解剖學 Histology is the study of the microscopic anatomy of cells and tissues. 組織學 Physiology is the study of function. 生理學 Animals consist of a hierarchy of levels or organization. 組織 - Tissues are an integrated group of similar cells that perform a common function. 器官 - Organs perform a specific task and consist of two or more tissues. 器官系統 - Organ systems consist of multiple organs that together perform a vital body function. The structure hierarchy in an animal A. Cellular level Muscle cell B. Tissue level Muscle tissue C. Organ level Heart Muscle tissue D. Organ system level Circulatory system Nervous tissue Epithelial tissue Connective tissue Heart Blood Blood vessels (arteries, veins, capillaries) E. Organism level Many organ systems functioning together An animal’s form reflects natural selection The body plan or design of an organism - reflects the relationship between form and function. - results from natural selection. - does not imply a process of conscious invention. Streamlined and tapered bodies - increase swimming speeds. - have similarly evolved in fish, sharks, and aquatic birds and mammals, representing convergent evolution. 趨同演化 Convergent evolution: the evolution of similar features in different evolutionary lineages, which can result from living in very similar environments. Shark Penguin Seal Convergent evolution of body shape in fast swimmers. Tissues are groups of cells with a common structure and function 組織 (weave) Tissues are an integrated group of similar cells that perform a common function and combine to form organs. Animals have four main categories of tissues: 上皮組織 (1) epithelial tissue. 結締組織 (2) connective tissue. 肌肉組織 (3) muscle tissue. 神經組織 (4) nervous tissue. Epithelial tissue covers the body and lines its organs and cavities Epithelial tissues, or epithelia, are sheets of closely packed cells - cover body surfaces. - line internal organs and cavities. Epithelial tissues are named according to the (1) number of cell layers they have. - simple epithelium 單層上皮組織 - stratified epithelium 複層上皮組織 - pseudostratified epithelium 偽複層上皮組織 (2) shape of the cells on their apical surface. - squamous 鱗狀(扁平)上皮 - cuboidal 立方上皮 - columnar 柱狀上皮 基底層 Types of epithelial tissue Apical surface of epithelium Basal lamina (extracellular matrix) Underlying tissue Cell nuclei A. Simple squamous epithelium E. Pseudostratified ciliated columnar epithelium (capillaries, air sacs of the lung) (lining the respiratory track) B. Simple cuboidal epithelium (thyroid gland, salivary gland, tube in the kidney) D. Stratified squamous epithelium (lining the esophagus and mouth) C. Simple columnar epithelium (lining in the intestine) Connective tissue binds and supports other tissues Connective tissues consists of a sparse population of cells scattered throughout an extracellular material called a matrix.基質 The cells produce and secrete the matrix. Connective tissue can be grouped into six major types: (1) Loose connective tissue 疏鬆性結締組織. - is the most widespread. - consists of ropelike collagen and elastic fibers that are strong and resilient. - mainly to bind epithelia to underlying tissues and hold organs in place. (2) Fibrous connective tissue 纖維(緻密)結締組織 - has densely packed collagen fibers. - forms tendons that attach muscle to bone; ligaments connect bones at joints. (3) Adipose tissue 脂肪組織 - stores fat in large, closely packed adipose cells held in a matrix of fibers. - this tissue pads and insulates your body and store energy. (4) Cartilage 軟骨組織 - is a strong and flexible skeletal material. - Consists of collagen fibers embedded in a rubbery material. - commonly surrounds the ends of bones. (5) Bone 骨組織 - has a matrix of collagen fibers. - embedded in a hard mineral substance containing calcium, magnesium, and phosphate. (6) Blood 血液組織 - transports substances throughout the body. - its extensive ECM (extracellular matrix) is liquid called plasma. Types of connective tissue White blood cells Red blood cell Central canal Plasma Cell nucleus Collagen fiber Elastic fibers Matrix F. Blood E. Bone A. Loose connective tissue (under the skin) Cell nucleus Collagen fibers Fat droplets adipose cells B. Fibrous connective tissue C. Adipose tissue (forming a tendon, ligament) Boneforming cells Cartilageforming cells Matrix D. Cartilage (at the end of a bone, ear, nose cushioning disks between vertebrate) Muscle tissue functions in movement Muscle tissue is the most abundant tissue in most animals. There are three types of vertebrate muscle tissue: 骨骼肌 - Skeletal muscle causes voluntary movements. 心肌 - Cardiac muscle pumps blood. 平滑肌 - Smooth muscle moves walls of internal organs, such as the intestines. Muscle fiber Unit of muscle contraction Muscle fiber (cell) Nuclei Junction between two cells Nucleus B. Cardiac muscle Muscle fiber Nucleus A. Skeletal muscle C. Smooth muscle Skeletal muscle Cardiac muscle Smooth muscle Striped/Striated Yes Yes No Nucleus location Peripheral Central Central Nucleus number Multiple Single Single Branched No Yes No Voluntary movement Yes No No Contraction speed Fast - Slow Contraction time Short - Long Nervous tissue forms a communication network Nervous tissue - senses stimuli. - rapidly transmits information. 神經元 Neurons carry signals by conducting electrical impulses. 樹突 Dendrites 細胞本體 Cell body 軸突 Axon 神經膠細胞 Other cells (glial cell) in nervous tissue - insulate axons. - nourish neurons. - regulate the fluid around neurons. Organs are made up of tissues Each tissue performs specific functions. The small intestine - is lined by a columnar epithelium that secrete digestive juices and absorbs nutrients. Lumen - the inner surface of the Epithelial tissue small intestine has many (columnar epithelium) fingerlike projections that increase the surface area Connective tissue for absorption. - includes connective tissues that contain blood vessels. Smooth muscle - has two layers of smooth muscle tissue (two layers) that help propel food. Connective tissue Epithelial tissue Small intestine Bioengineers are learning to produce tissues and organs for transplants 生物工程 Bioengineering is seeking ways to repair or replace damaged tissues and organs. New tissues and organs are being grown using a patient’s own cells. These techniques - remove the risk of tissue rejection. - may reduce the shortage of organs available for transplants. A laboratory-grown bladder Artificial skin Artificial skin Human skin Organ systems work together to perform life’s functions Each organ system typically consists of many organs, has one or more functions, and works with other organ systems to create a functional organism. 循環系統 A. Circulatory system 呼吸系統 B. Respiratory system Nasal cavity Heart Pharynx Larynx Trachea Bronchus Lung Blood vessels Exchanges gases O2 in CO2 out O2, nutrients body cells CO2 lungs Metabolic wastes kidneys 體被系統 C. Integumentary system 骨骼系統 D. Skeletal system Hair Skin Bone Nails Cartilage Against - physical injury - infection - excessive heat or cold - drying out Supports body Protects organs Provides the frameworks for muscle E. Muscular system 肌肉系統 Moves body Maintains posture Produces heat 泌尿系統 F. Urinary system Skeletal muscles G. Digestive system 消化系統 Mouth Remove waste products from blood Ingests & digests food Excretes urine Esophagus Absorbs nutrients Liver Eliminates undigested material Kidney Stomach Small Ureter intestine Urinary Large bladder intestine Urethra Anus Returns excess body fluid circulation system Part of the immune system I. Lymphatic system 淋巴系統 H. Endocrine system 內分泌系統 Hypothalamus Pituitary gland Thymus Adrenal gland Pancreas Testis (male) Lymph Thyroid gland nodes Parathyroid gland Appendix Ovary (female) Secrete hormones To maintain homeostasis Bone marrow Thymus Spleen Lymphatic vessels 免疫系統 J. Immune system Against infection & cancer 神經系統 K. Nervous system Brain Sense organ (ear) Spinal cord Nerves Detecting stimuli Integrating information Directing the body’s responses L. Reproductive system 生殖系統 Supports a developing embryo Products milk Seminal vesicles Female Male Oviduct Prostate gland Ovary Vas deferens Uterus Penis Vagina Testis Produces gametes and sex hormones Urethra New imaging technology reveals the inner body New technologies - are used in medical diagnosis and research. - allow physicians to examine organ systems without surgery. (1) X-rays X光照射 (2) CT: computed tomography 電腦斷層掃描 (3) MRI: magnetic resonance imaging 核磁共振造影 (4) PET: positron-emission tomography 正子斷層顯影術 (1) X-rays X-rays - high-energy radiation. - passes readily through soft tissues. - shadows of hard structures (bone, teeth, dense tumors). (2) CT: computed tommography A newer X-ray technology called computed tomography (CT). - produces high-resolution images of a series of thin cross section of the body. - can detect small differences between normal and abnormal tissues in many organs (abdomen, brain). (3) MRI: magnetic resonance imaging Magnetic resonance imaging (MRI) - takes advantage of the behavior of the hydrogen atoms in water molecules. - visualize soft tissues well. (water is the major component of soft tissues) - provides three-dimensional images of very small structures. Femur (thigh bone) Torn meniscus Tibia (shin bone) (4) PET: positron-emission tomography PET helps identify metabolic processes at specific body locations. The patient is injected with a small amount of radioactive isotope labeled molecule (glucose). Examples of PET CT and PET images can be combined for an even more informative image CT: better anatomical representation. PET: metabolic information. A combined CT-PET scan showing tumors (bright white) in the upper left lung and lower abdomen The integumentary system protects the body (skin, hair and nails) The skin consists of two layers: 1. The epidermis 表皮 - is a stratified squamous epithelium. - forms the surface of the skin. 2. The dermis 真皮 - forms a deeper skin layer and - is composed of dense connective tissue with many resilient elastic fibers and strong collagen fibers. - the dermis contains hair follicles, oil and sweat glands, muscle cells, nerves, sensory receptors, and blood vessels. A section of skin, the major organ of the integumentary system Hair Epidermis Sweat pore Muscle Dermis Nerve Sweat gland Hypodermis (under the skin) Adipose tissue Blood vessels Oil gland Hair follicle Sensory receptors in the human skin Heat Light touch Pain Cold Hair Epidermis Dermis Nerve to brain Connective tissue Hair movement Strong pressure Skin has many functions. - The epidermis resists physical damage, decreases water loss, and prevents penetration by microbes. - The dermis collects sensory information, synthesizes vitamin D, and helps regulate body temperature. Exposure of the skin to ultraviolet light. - causes skin cells to release melanin, which contributes to a visible tan. - damages DNA of skin cells and can lead to a. premature aging of the skin. b. cataracts. c. skin cancers. Hair and Nails Hair - produced by a hair follicle. - helps to insulate their bodies. - consists of a shaft of flattened keratin-filled dead cells. 油脂腺 Oil glands release oils that - are associated with hair follicles. - lubricate hair. - condition surrounding skin. - inhibit the growth of bacteria. Fingernails and toenails - composed of keratin. - protective coverings. - facilitates fine manipulation. Structural adaptations enhance exchange with the environment Every organism is an open system that must exchange matter and energy with its surroundings. Cells in small and flat animals can exchange materials directly with the environment. Hydra Organisms increase in size, the surface area - is too small for the corresponding volume. - too far away from the deepest cells of the body. In these organisms, evolutionary adaptations - consist of extensively branched or folded surfaces, which increase the area of these surfaces. - provide for sufficient environmental exchange. Indirect exchange between the environment and the cells EXTERNAL ENVIRONMENT CO2 O Food 2 Mouth of a complex animal Digestive system Blo o ANIMAL d Respiratory system Interstitial fluid Heart Nutrients Circulatory system Body cells Urinary system Intestine Anus Unabsorbed matter (feces) Metabolic waste products (urine) Interstitial fluid: An aqueous solution that surrounds body cells and through which materials pass back and forth between the blood and the body tissues. Trachea A resin model of the finely branched air tubes (white) and blood vessels (red) of the human lungs Animals reguate their internal nvironment Two environments: - external environment - internal environment the interstitial fluid that fills the spaces around the cells. Claude Bernard The father of Physiology 不變的; 變動性很少的; 靜恆狀態的 Homeostasis is the active maintenance of a steady state within the body. - external environmental conditions may fluctuate wildly. - homeostatic mechanisms regulate internal conditions. 恆定 External environment Homeostatic mechanisms Large fluctuations Internal environment Small fluctuations A model of homeostasis in a white-tailed ptarmigan in its snowy habitat Homeostasis depends on negative feedback Control systems - detect change. - direct responses. 負回饋 Negative-feedback mechanisms - keep internal variables steady. - permit only small fluctuations around set points. Negative feedback is a common control mechanism in which a chemical reaction, metabolic pathway, or hormone-secreting gland is inhibited by the products of the reaction, pathway, or gland. Sweat evaporates, cooling the body. Brain activates cooling mechanisms. Blood vessels dilate. Temperature decreases Cooling mechanisms shut off. Temperature rises above set point Homeostasis: Body temperature approximately 37°C Temperature increases Warming mechanisms shut off. Temperature falls below set point Blood vessels constrict. Brain activates warming mechanisms. Shivering generates heat. Feedback control of body temperature