Download Tissue Level of Organization in Human Anatomy and Physiology | Bisc 206 and more Study notes Physiology in PDF only on Docsity! Chapter 4 Chapter Objectives INTRODUCTION 1. Define the relation of the cellular level to the major structures of tissues that endow tissues with distinct properties. A tissue is a group of similar cells that usually have a similar embryological origin and are specialized for a particular function. The nature of the extracellular material that surrounds the connections between the cells that compose the tissue influence the structure and properties of a specific tissue. 2. Describe how the tissue level of organization is utilized by pathologists when examining organ biopsies. Pathologists, physicians who specialize in laboratory studies of cells and tissues, aid other physicians in making diagnoses; they also perform autopsies. Analysis of biopsies, samples of living tissue removed for microscopic examination, is a chief responsibility of a pathologist. TYPES OF TISSUES AND THEIR ORIGINS 3. Classify the tissues of the body into four major types. 1. Epithelial tissue covers body surfaces, lines hollow organs, body cavities, and ducts; and forms glands. Epithelial=Lines 2. Connective tissue protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity. Connective=Binds 3. Muscle tissue is responsible for movement and generation of force. 4. Nervous tissue initiates and transmits action potentials (nerve impulses) that help coordinate body activities. 1. Describe the type of tissues derived from the three embryonic germ layers. All tissues and organs of the body develop from one or more of the three primary germ layers: ectoderm, endoderm, and mesoderm. Table 29.1: Endoderm- Epithelial lining of gastrointestinal tract Epithelial lining of urinary bladder, gallbladder, and liver Epithelial lining of pharynx, auditory tubes, tonsils, larynx, trachea, bronchi, and lungs Epithelium of thyroid gland, parathyroid glands, pancreas, and thymus Epithelial lining of prostate and bulbourethral glands, vagina, vestibule, urethra, and associated glands such as greater vestibular and lesser vestibular glands 4. Hemidesmosomes connect cells to extracellular material such as the basement membrane (Figure 4.1d). 5. Gap junctions allow cells in a tissue to rapidly communicate through connexons, transmembrane protein channels that connect cells together (Figure 4.1e). EPITHELIAL TISSSUE 8. Describe the general features of epithelial tissue and describe their functions Epithelial cells are arranged in sheets, in either single or multiple layers Epithelium consists of mostly packer cells with little extracellular material Many cell junctions are present, providing secure attachments among cells An epithelial cell has an apical surface and a basal surface attached to a base membrane Epithelia adhere firmly to nearby connective tissue via a thin extracellular layer, the basement membrane Epithelial tissue is avascular; exchange of materials between epithelium and adjacent connective tissue is by diffusion Epithelia have a nerve supply Epithelia have a high capacity for renewal (high mitotic rate) 7. Describe the general functions of epithelial tissues. Protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory reception, and reproduction 9. Discuss the role of the basement in disease In untreated cases of diabetes, the basement membrane of capillaries thickens, especially in the eyes and kidneys. Because of this the blood vessels cannot function properly and blindness and kidney failure may result. Covering and Lining Epithelium 10. Note that the tissue structure is directly related to the job it has in an organ. 1. Define the terminology that indicates the types of cell layering. Layers are arranged as simple (1 layer), stratified (several layers), and pseudostratified ( 1 layer that appears as several) 2. Relate the terms for the variety of cell shapes with their appearance and general character. Cell shapes include squamous (flat), cuboidal (cube-like), columnar (rectangular) and transitional (variable) 13. Considering the layers and cell shapes in combination, outline the classification of covering and lining epithelium. Covering and lining the epithelia may be classified as a combination of arrangement of layers and shape of the cells. The name of the specific type of stratified epithelium depends on the shape of the surface cells. Each of the epithelial tissues described is illustrated in table 4.3 Simple Epithelium 14. Illustrate the structure of the different simple epithelial tissues in addition to showing histological representations and examples of organs that contain them. Simple Squamous Epithelium consists of a single layer of flat, scalelike cells. It is adapted for diffusion and filtration and is found in the lungs and kidneys. It is found in parts of the body that are subject to little wear and tear. Endothelium lines the heart and blood vessels. Mesothelium lines the thoracic and abdominopelvic cavities and covers the organs within them. Simple Cuboidal Epithelium consists of a simple layer of cube-shaped cells and performs the functions of secretion and absorption. Simple Columnar Epithelium consists of a single layer of rectangular cells and can exist in two forms: 1. Nonciliated columnar epithelium contains microvilli to increase surface area and the rate of absorption and goblet cells that secrete mucus 2. Ciliated simple columnar epithelium contains cells with cilia, motile, hair-like processes that help to move fluids or particles along a surface Stratified Epithelium Exocrine glands (sweat, oil, and digestive glands) secrete their products into ducts that empty at the surface of covering and lining epithelium or directly onto a free surface. Structural Classification of Exocrine Glands 19. Indicate how structural classification is based on numbers of associated cells and describe the single type of unicellular gland. Exocrine glands are either unicellular (single-celled; e.g. goblet cell) or multicellular (composed of cells that form a distinctive microscopic structure or macroscopic organ such as: sweat, oil, and salivary glands.) Functional Classification of Exocrine Glands 20. Show how functional classification is related to the mode used by the cells to deliver their secretory products. Based on whether a secretion is a product of a cell or consists of entire or partial glandular cells themselves. Merocrine glands form the secretory products and discharge it by exocytosis Apocrine glands accumulate their secretory product at the apical surface of the secreting cell; that portion then pinches off from the rest of the cell to form the secretion with the remaining part of the cell repairing itself and repeating the process. Holocrine glands accumulate the secretory product in the cytosol; when the cell dies, it and its products are discharged as the glandular secretion, with the discharged cell being replaced by a new one. CONNECTIVE TISSUE 21. Describe the important and prominent characteristics of connective tissue. Connective Tissue is the most abundant and widely distributed tissue in the body. General Features of Connective Tissue 22. Describe the two basic elements of connective tissue. Cells and the extracellular matrix. The matrix consists of protein fibers and ground substance, the material between the cells and fibers. The extracellular matrix is usually secreted by the connective tissue cells and determines the tissue’s qualities. Connective Tissue Cells 23. Discuss the cells that compose connective tissue in terms of origin, function, and mobility 1. Cells in connective tissue are derived from mesenchyme. a. Immature cells have names that end in -blast( e.g., fibroblast, chondroblast) while mature cells have names that end in -cyte (e.g., osteocyte). a. Most mature cells have reduced capacity for cell division and matrix formation and are mostly involved in maintaining the matrix. 2. Types of cells found in various connective tissues include fibroblasts (which secrete fibers and matrix), macrophages (or histiocytes, which develop from monocytes and are phagocytic), plasma cells (which develop into antibody- producing B lymphocytes, or B cells), mast cells (which are abundant alongside blood vessels and produce histamine), adipocytes (or fat cells, which store energy in the form of fat), and white blood cells (or leukocytes). (Figure 4.5) Connective Tissue Matrix 24. Describe the two factors of a connective tissue matrix that bestow specific properties on the tissue. The ground substance and fibers, deposited in the space between the cells, comprise the matrix of connective tissue. Ground Substance 25. Name the chemical components of ground substance and how each is responsible for differing physical consistencies of connective tissues. a. Substances found in the ground substance include hyaluronic acid, chondroitin sulfate, dermatan sulfate, and keratan sulfate. b. The function of ground substance is that it supports, binds, and provides a medium for the exchange of b. Loose connective tissue consists of all three types of fibers, several types of cells, and a semifluid ground substance. Types of Mature Connective Tissue 30. Discuss the three features of mature connective tissue. Loose Connective Tissue 31. List the structure, function, and location of loose connective tissue. Loose connective Tissue: Areolar connective tissue is a prime example of loose connective tissue. It shows all of the typical loose connective tissue features. (Table 4.3A) a. The ground substance aids the passage of nutrients from the blood vessels of the connective tissue into adjacent cells and tissues. b. It is found in the subcutaneous layer. 2. Adipose tissue consists of adipocytes which are specialized for storage of triglycerides. (Table 4.3B) a. It is found wherever areolar connective tissue is located. b. It reduces heat loss through the skin, serves as an energy reserve, supports, protects, and generates considerable heat to help maintain proper body temperature in newborns (brown fat). 3. Reticular connective tissue consists of fine interlacing reticular fibers and reticular cells (Table 4.3C). a. It forms the stroma of certain organs. It helps to bind together the cells of smooth muscle. a. 32. Discuss liposuction in terms of the connective tissue involved, locations, and possible complications. Dense Connective Tissue List the structure, function, and location of dense connective tissue. Dense connective tissue contains more numerous, thicker, and dense fibers but considerably fewer cells than loose connective tissue. 1. Dense regular connective tissue consists of bundles of collagen fibers in a regular and orderly, parallel arrangement that confers great strength (Table 4.3D). 2. Dense irregular connective tissue contains collagen fibers that are irregularly arranged and is found in parts of the body where tensions are exerted in various directions (Table 4.3E). a. It usually occurs in sheets, such as the dermis of the skin. b. It is also found in heart valves, the perichondrium, the tissue surrounding cartilage, and the periosteum. 3. Elastic connective tissue consists of elastic fibers and fibroblasts (Table 4.3F). a. It is quite strong and can recoil back to its original shape after being stretched. b. It is found in lung tissue and elastic arteries. Cartilage 34. List the structure, function, and location of cartilage connective tissue. d. Cartilage consists of a dense network of collagen fibers and elastic fibers embedded in chondroitin sulfate. its hardness and collagen fibers that give bone its strength. a. Lacunae are small spaces between lamellae that contain mature bone cells called osteocytes. b. Canaliculi are minute canals containing processes of osteocytes that provide routes for nutrient and waste transport. c. A central (Haversian) canal contains blood vessels and nerves. 3. Spongy bone has trabeculae rather than osteons. 3. Bone supports, protects, helps provide movement, stores minerals, and houses blood- forming tissue. 1. Explain how tissue engineering has allowed scientists to grow new tissues in the laboratory for replacement of damaged tissues in the body Liquid connective Tissue List the structure, function, and location of blood connective tissue. Blood (vascular tissue) consists of a liquid matrix called plasma and formed elements. (Table 4.3K) 1. Formed elements include erythrocytes, leukocytes, and thrombocytes. a. Red blood cells (erythrocytes) function in transporting respiratory gases. a. White blood cells (leukocytes) are involved in phagocytosis, immunity, and allergic reactions. b. Platelets (thrombocytes) function in blood clotting. c. Lymph is interstitial fluid flowing in lymph vessels. g. Tissue engineering has allowed scientists to grow new tissues in the laboratory for the replacement of damaged tissues. 2. List the structure, function, and location of lymph tissue. Lymph tissue consists of several types of cells in a clear liquid extracellular matrix that is similar to blood plasma but with less protein. MEMBRANES 3. Describe an epithelial membrane general structure. Epithelial membranes consist of an epithelial layer and an underlying connective tissue layer and include mucous membranes, serous membranes, and the cutaneous membrane or skin. 4. Distinguish between an epithelial and a synovial membrane. 1. Epithelial membranes consist of an epithelial layer and an underlying connective tissue layer and include mucous membranes, serous membranes, and the cutaneous membrane or skin. 2. Synovial membranes line joints and contain only connective tissue. Mucous Membranes 39. List the location and function of mucous membranes. 1. Mucous membranes (mucosae) line cavities that open to the exterior, such as the gastrointestinal tract. a. The epithelial layer of a mucous membrane is an important aspect of the body's defense mechanisms, acting as a barrier to pathogens and a trapping surface for particles. a. The connective tissue layer of a mucous membrane is called the lamina propria. Serous Membranes 5. List the location and function of serous membranes 2. A serous membrane, or serosa, lines a body cavity that does not open directly to the exterior and covers the organs that lie within the cavity. Examples include the pleura, pericardium, and peritoneum. a. These membranes consist of parietal and visceral portions. b. The epithelial layer secrets a lubricating serous fluid that reduces friction between organs and the walls of the cavities in which they are located.