anatomy and physiology guided chapter 4 cards
Objective #6: Define gland, and differentiate between exocrine and endocrine. See Pages 87-88, Table 4.2
A gland is a single cell or a mass of epithelial cells adapted for secretion. Endocrine glands are ductless; their secretory products (hormones) enter the extracellular fluid and diffuse into the blood. Exocrine glands (sweat, oil, and digestive glands) secrete their products into ducts that empty at the surface of the covering and lining of the epithelium or directly onto a free surface.
Objective #1: Define the term tissue. See Page 78
A tissue is a group of similar cells that usually have a similar embryological origin and are specialized for a particular function.
Objective #8: Explain how CTs are composed of cells plus an extracellular matrix composed of ground substance and fibres. See Pages 88-90
Connective tissue consists of the following three basic elements: cells ground substance protein fibres (The latter two combine to form the matrix.)
Objective #7: Describe the general characteristics of connective tissues (CTs) and discuss their major structural differences from epithelial tissue. See Page 88
Connective tissue is the most abundant and widely distributed tissue in the body. Unlike epithelia, connective tissues do not occur on free surfaces. Unlike epithelium, connective tissue is highly vascular (except for cartilage and tendons). Except for cartilage, connective tissue like epithelium has a nerve supply.
Objective #2: Name the four primary adult tissue types, and give a brief description of each. See Page 79
Depending on their function and structure, the various tissues of the body are classified into the following four principal types: Epithelial tissue covers body surfaces; lines hollow organs, body cavities, and ducts; and forms glands. Epithelial tissue provides external protection for underlying tissue. Connective tissue protects and supports the body and its organs, binds organs together, stores energy reserves as fat, and provides immunity. Muscle tissue is responsible for movement and generation of force. Nervous tissue initiates and transmits action potentials (nerve impulses) that help coordinate body activities, monitors the external environment, and contributes to homeostasis.
Objective #10: For each of the following CTs, describe its structure, name a key body location, and identify its function(s): Mesenchyme, Areolar CT, Adipose Tissue, Reticular CT, Dense Regular CT, Dense Irregular CT, Elastic CT, Hyaline Cartilage, Fibrocartilage, Elastic Cartilage, Bone, and Blood. See Pages 89-96; Tables 4.3, 4.4, 4.5
Five types of CT include: Loose connective tissue Dense connective tissue Cartilage Bone Liquid (blood and lymph) Loose connective tissue consists of all three types of fibres, several types of cells, and a semi-fluid ground substance. Loose Connective Tissue Areolar connective tissue is a prime example of loose connective tissue. It presents all of the typical loose connective tissue features. The ground substance aids the passage of nutrients from the blood vessels of the connective tissue to adjacent cells and tissues. It is found in the subcutaneous layer. Adipose tissue is a loose CT consisting of adipocytes, which are specialized for storing triglycerides. It reduces heat loss through the skin; serves as an energy reserve; and supports, protects, and generates considerable heat to help maintain proper body temperature in newborns (brown fat). Reticular connective tissue consists of a fine interlacing of reticular fibres and reticular cells. It forms the stroma of certain organs, and helps to bind together the cells of smooth muscle. Dense Connective Tissue Dense connective tissue contains thicker, denser, and more numerous fibres than loose connective tissue, but considerably fewer cells. Dense regular connective tissue consists of bundles of collagen fibres in a regular, orderly, and parallel arrangement that confers great strength. Dense irregular connective tissue contains collagen fibres that are irregularly arranged; it is found in parts of the body where tensions are exerted in various directions. It usually occurs in sheets, such as the dermis of the skin. It also is found in the heart valves, the perichondrium, the tissue surrounding cartilage, and the periosteum. Elastic connective tissue consists of elastic fibres and fibroblasts. It is quite strong and can recoil back to its original shape after being stretched. It is found in lung tissue and elastic arteries. Cartilage Cartilage consists of a dense network of collagen fibres and elastic fibres embedded in chondroitin sulfate. Its collagen fibres give it strength, and its chondroitin sulfate gives it resilience. Chondrocytes occur within spaces called lacunae in the matrix. Cartilage is surrounded by a dense irregular connective tissue membrane called the perichondrium. Unlike other connective tissues, cartilage has no blood vessels or nerves (except in the perichondrium). The three major types of cartilage are the following: Hyaline cartilage is the most abundant but weakest type of cartilage. It has fine collagen fibres embedded in a gel-type matrix. It provides flexibility and support, and at the joints, reduces friction and absorbs shock. Fibrocartilage contains bundles of collagen fibres in its matrix. It does not have a perichondrium. Due to its combined strength and rigidity, it is the strongest of the three types of cartilage. Elastic cartilage contains a threadlike network of elastic fibres within the matrix. A perichondrium is present. Elastic cartilage provides strength and elasticity and maintains the shape of certain organs. Cartilage growth is accomplished by interstitial (endogenous—from within) growth and appositional (exogenous—from without) growth. Bone Bone (osseous tissue) consists of a matrix containing mineral salts and collagenous fibres and cells called osteocytes.Bone is classified as either compact or spongy, depending on how the matrix and cells are organized. The basic unit of compact bone is the osteon or Haversian system, which consists of four parts. The lamella are concentric rings of matrix that consist of mineral salts that give bone its hardness, and collagen fibres that give bone its strength. Lacunae are small spaces between the lamellae that contain mature bone cells called osteocytes. Canaliculi are minute canals—containing the processes of osteocytes—which provide routes for nutrient and waste transport. A central (Haversian) canal contains the blood vessels and nerves. Spongy bone has trabeculae rather than osteons. Bone supports, protects, helps to provide movement, stores minerals, and houses blood-forming tissue. Blood Blood (vascular tissue) consists of a liquid matrix called plasma, and formed elements. Formed elements include erythrocytes, leukocytes, and thrombocytes, and each has specific functions: Red blood cells (erythrocytes) function in transporting respiratory gases. White blood cells (leukocytes) are involved in phagocytosis, immunity, and allergic reactions. Platelets (thrombocytes) function in blood clotting. Lymph Lymph is the interstitial fluid flowing in the lymph vessels.
Objective #3: Describe the features, location, and function of epithelial tissue. See Page 79
General Features of Epithelial Tissues Epithelial cells are arranged in sheets, in either single or multiple layers. The epithelium consists mostly of packer cells with little extracellular material. In epithelial tissues, 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 through a thin extracellular layer called the basement membrane. Epithelia have a nerve supply and a high capacity for renewal (a high mitotic rate). Epithelial tissue is avascular; the exchange of materials between epithelium and adjacent connective tissue is by diffusion. Functions of epithelia include protection, filtration, lubrication, secretion, digestion, absorption, transportation, excretion, sensory reception, and reproduction.
Objective #13: Define the term epithelial membrane; and discuss the structure, location, and function of its four different types—cutaneous, mucous, serous, and synovial. See Pages 96-98, Fig 4.3
Membranes are flat sheets of pliable tissue that cover or line a part of the body. Epithelial membranes consist of an epithelial layer and an underlying connective tissue layer. These membranes include mucous membranes, serous membranes, and the cutaneous membrane or skin. Synovial membranes line joints and contain only connective tissue. Mucous membranes (mucosae) line cavities that open to the exterior, such as the gastrointestinal tract. 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. The connective tissue layer of a mucous membrane is called the lamina propria. A serous membrane, or serosa, lines a body cavity that does not open directly to the exterior, and covers the organs that lie withi the cavity. Examples of this membrane include the pleura, pericardium, and peritoneum. These membranes consist of parietal and visceral portions. The epithelial layer secretes a lubricating serous fluid that reduces friction between organs and the walls of the cavities in which they are located. Synovial membranes line joint cavities, bursae, and tendon sheaths, and do not contain epithelium; they also secrete a lubricating synovial fluid.
Objective #11: Compare and contrast the three types of muscle tissue in terms of their structure, control, location in the human body, and function. See Pages 98, 198
Muscle tissue consists of fibres (cells) that are modified for contraction, and thus provide motion, maintenance of posture, and heat production. Skeletal muscle tissue is attached to bones, is striated, and is voluntary. Cardiac muscle tissue forms most of the heart wall, is striated, and is usually involuntary. Smooth (visceral) muscle tissue is found in the walls of hollow internal structures (blood vessels and viscera), is nonstriated, and is usually involuntary. It provides motion (e.g., constriction of blood vessels and airways, propulsion of foods through the gastrointestinal tract, and contraction of the urinary bladder and gallbadder).
Objective #4: Discuss the classification scheme for epithelia. See Pages 79-80, Fig 4.1
The covering and lining of the epithelia can be classified as a combination of layers and shapes of cells. The name of the specific type of stratified epithelium depends on the shape of the surface cells. Layers are arranged as simple (one layer), stratified (several layers), or pseudostratified (one layer that appears as several). Cell shapes include squamous (flat), cuboidal (cube-like), columnar (rectangular), and transitional (variable).
Objective #9: Describe matrix and ground substance; list the three CT fibre types; and name the types of cells of which CT can be composed. See Pages 88-90, Fig 4.2
The matrix is abundant with relatively few cells, and tends to prevent tissue cells from touching one another. The matrix of a connective tissue—which can be fluid, semifluid, gelatinous, fibrous, or calcified—is usually secreted by the connective tissue cells and adjacent cells and determines the qualities of tissues. Immature cells have names that end in blast (e.g., fibroblast, chondroblast), whereas mature cells have names that end in cyte (e.g., osteocyte). Most mature cells have a reduced capacity for cell division and matrix formation, and are mostly involved in maintaining the matrix. The types of cells found in various connective tissues include fibroblasts (which secrete fibres and matrix), macrophages or histiocytes (which develop from monocytes and are phagocytic), mast cells (which are abundant alongside blood vessels and produce histamine), and adipocytes or fat cells (which store energy in the form of fat). The ground substance and fibres, deposited in the space between the cells, comprise the matrix of connective tissue. Substances found in the ground substance include hyaluronic acid, chondroitin sulfate, dermatan sulfate, and keratan sulfate. The three types of fibres embedded in the matrix between the cells of connective tissues are the following: Collagen fibres, composed of the protein collagen, are very tough and resistant to stretching, yet allow some flexibility in the tissue; they are found in bone, cartilage, tendons, and ligaments. Elastic fibres, composed of the protein elastin, provide strength and stretching capacity and are found in the skin, blood vessels, and lungs. Reticular fibres, consisting of collagen and glycoprotein, provide support in the walls of the blood vessels and form a strong, supporting network around fat cells, nerve fibres, and skeletal and smooth muscle fibres.
Objective #12: Identify the major cell of nervous tissue; denote the location of nervous tissue in the body; and discuss its function. See Page 98
The nervous system is composed of only two principal kinds of cells: neurons (nerve cells) and neuroglia (protective and supportin g cells). Most neurons consist of a cell body and two types of processes called dendrites and axons. Neurons are sensitive to stimuli; convert stimuli into nerve impulses; and conduct nerve impulses to other neurons, muscle fibres, or glands. Neuroglia protect and support neurons and are often the sites of tumours of the nervous system.
Objective #5: For each of the following epithelial tissues, give a structural description, denote a key body location, and identify its function(s): Simple Squamous, Simple Cuboidal, Simple Columnar, Pseudostratified Columnar, Transitional, Stratified Squamous (both keratinized and non-keratinized), Glandular and Stratified Cuboidal. Page 80, Table 4.1 a-i
The 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. The endothelium lines the heart and blood vessels. The mesothelium lines the thoracic and abdominopelvic cavities, and covers the organs within them. The simple cuboidal epithelium consists of a simple layer of cube-shaped cells and performs the functions of secretion and absorption. The simple columnar epithelium consists of a single layer of rectangular cells, which can exist in two forms: nonciliated simple columnar epithelium ciliated simple columnar epithelium Nonciliated simple columnar epithelium contains microvilli to increase surface area. Goblet cells secrete mucus. Ciliated simple columnar epithelium contains cells with cilia, motile, hair-like processes that help to move fluids or particles along a surface. Stratified epithelium has at least two layers of cells. It is a more durable and protective tissue. The name of the specific kind of stratified epithelium depends on the shape of the surface cells. Pseudostratified epithelium has only one layer but gives the appearance of many. All cells are attached to the basement membrane, but some do not reach the apical surface. In pseudostratified cilated columnar epithelium, the cells that reach the surface either secrete mucus (goblet cells) or bear cilia that sweep away mucus and trapped foreign particles. Pseudostratified nonciliated columnar epithelium contains no cilia or goblet cells. Stratified squamous epithelium consists of several layers of cells in which the top layer of cells is flat and the deeper layers of cells vary in shape from cuboidal to columnar. The basal cells replicate by mitosis and ultimately work their way to the surface. In keratinized stratified squamous epithelium, a tough layer of keratin (a protein resistant to friction with a capacity to repel bacteria) is deposited in the surface cells. Nonkeratinized stratified squamous epithelium does not contain keratin and remains moist. Stratified cuboidal epithelium is a rare tissue that consists of two or more layers of cube-shaped cells with mainly a protective function. Stratified columnar epithelium consists of several layers of cells of which only the top layer is columnar. It is somewhat rare and functions in protection and secretion. Transitional epithelium consists of several layers of cells; their appearance is variable. It is capable of stretching and thus permits the distention of an organ. It lines the urinary bladder and portions of the ureters and the urethra.
Objective #14: Describe the role of tissue repair in restoring homeostasis. See Pages 98-99
Tissue repair is the process of replacing dead or damaged cells. Repair can occur only if inflammation is complete. This repair process will be discussed in greater detail in Chapter 17, which is examined in BIOL 1693 Anatomy and Physiology II. In your textbook page 99, read the "Focus on Wellness" section.