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Tissues: Living Communities

Tissues: Living Communities. Chapter 4. Introduction. Since cells are __________________, they have lost ability to perform all metabolic functions required to sustain life as an isolated entity. Cells exist in cooperative communities in multicellular organisms

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Tissues: Living Communities

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  1. Tissues: Living Communities Chapter 4

  2. Introduction • Since cells are __________________, they have lost ability to perform all metabolic functions required to sustain life as an isolated entity. • Cells exist in cooperative communities in multicellular organisms • Cells of similar ____________ and _____________ cluster together to form tissues. • Tissues cluster to form organs. • Organs form systems.

  3. Classification of Tissues • Epithelial tissue • Covers and lines • Connective tissue • Provides support • Muscle tissue • Enables movement • Nervous tissue • Controls work • Most organs contain all 4 tissue types. • The study of microscopic structures of tissues and organs is called _________

  4. Epithelial Tissue • Composed of sheets of cells that cover and line other tissues. • Lines bladder, blood vessels, thorax, etc. • Has a surface that is exposed to the surrounding environment or to the inner openings of chambers and ducts (lumen). • Functions: • protects, covers, lines • filters • May be absorptive • May play an important role in sensory input • Secretes and excretes • Glandular epithelia- manufacture and release secretions

  5. Characteristics of Epithelia • Organized into tightly packed groups that form ___________ of tissue. • Can be composed of single layer or multiple layers depending on location. • Epithelial cells share the following characteristics: • ________- Each epithelial cell has an apical surface and a basal surface • Apical surface faces the lumen or body cavity • Basal surface faces the underlying connective tissue • Lateral surfaces are connected to neighboring cells by ________________ complexes • All epithelial cells are ______________. • Rely on underlying connective tissue for oxygen and nutrients • Most epithelial cells are _____________.

  6. Junctional Complexes – specialized attachments between epithelial cells at their plasma membranes. Give epithelial tissue strength. Tight junctions Prevent ____________ Bladder, GI tract Desmosomes Welded plaque Tough, resist __________ and stretching (like Velcro). Consist of intermediate fibers (tonofilaments) Skin, heart, uterus Gap junctions Cytoplasm continuous between cells Linked by tubular channel proteins called _______________. Allow exchange of ions, nutrients, and transport signals Intestines, cardiac, and smooth muscles

  7. Epithelial Cells: Basement Membrane Foundation of epithelial cells, made by epithelial cells Meshwork of fibers that cements epithelial cell to underlying _____________________ tissue (CT) Its strength and elasticity help to prevent the epithelial cell from being torn away Also called basal _________ Varies in thickness Oxygen and nutrients diffuse up to epithelium through the basement membrane from the connective tissue. Absorbed substances and waste products produced by epithelium diffuse down through basement membrane to the connective tissue.

  8. Surface Specialization • Surfaces vary depending on location in body and function • May be smooth or contain ___________(fingerlike projections) or _______(hairs) • Cilia found in respiratory and reproductive tracts • Microvilli in intestines and urinary tract • If the cell contains microvilli, it is said to have a __________ border. • Brush border helps to increase _____________ area, which aids in absorption. (can add up to 20 times of surface area). • Epithelial cells of the skin are filled with a waterproof substance called __________. • Accumulate as cell matures

  9. Classifications of Epithelia • Classified according to 3 characteristics: • Number of cell layers. • Single layer is called __________ • Found in protected parts of body where they provide minimal protection to underlying structures • More than one layer is called __________ • Thicker and stronger and are on parts of body that are subjected to mechanical or chemical stress. • Shape of cells • Based on shape that is on exposed or _________ surface • Squamous, cuboidal, and columnar • Presence of surface specializations • Keratinized, ciliated, etc.

  10. Simple Squamous Epithelium • Fragile and thin • Flat and smooth; reduce friction • Often found lining surfaces involved in the passage of either _____ or ________ • lining of lungs, kidneys • ______thelium – lining of chest (pleura), abdomen (peritoneum), and pericardium • ______thelium – lining of blood vessels

  11. Simple Cuboidal Epithelium • Single layer of cubical cells • Round, dark-staining nuclei aligned in a single row • Occurs in areas of the body where absorption and secretion take place • Glands (endocrine and exocrine): salivary glands, ovaries, liver, kidneys, pancreas

  12. Simple Columnar Epithelium • Elongated and closely packed together – thick and protective • Nuclei aligned in a row (not central) at the base of the cell near the basement membrane • Also found in areas of absorption and secretion • Line the GI tract from stomach to rectum • ____________ cell- apical surface is blanketed by dense microvilli that maximize absorption by increasing surface contact with nutrient-filled lumen. • __________ cell- manufacture and store mucin (component of mucus) for lubrication

  13. Stratified SquamousEpithelium • Multilayered • Continually worn away or sloughed off • Replaced by cells from deeper layers • Cuboidal cells are attached to the basement membrane. As they mature, they are pushed to the surface away from nutrients. • Lose their cytoplasm and nuclei and become squamous. • Occur in areas of the body subject to __________ or ___________ stresses • Mouth, esophagus, vagina, rectum • Skin (keratinized)

  14. Stratified CuboidalEpithelium • Usually two layers of cuboidal cells • Provides protection to deeper, delicate tissues • Found primarily along large ducts of salivary glands, mammary glands, and sweat glands

  15. Stratified Columnar Epithelium • RARE • Basal cells are cuboidal • Function in secretion and protection

  16. Pseudostratified Columnar Epithelium • “_______” stratified – truly simple epithelium • Cell nuclei are found at different levels across the length of the tissue • Some cells do not reach luminal surface, but ALL attach to basement membrane. • Usually ________ and often associated with ______ cells. • Found in respiratory tract

  17. Transitional Epithelium • Stratified epithelium • Basal layer of cuboidal or columnar cells • Superficial layer of cuboidal or squamous cells • Ability to _______ - found in areas where changes in volume occur • Urinary tract • As epithelia stretches, layers often thin depending on how much volume is present • Forms a _____-proof barrier

  18. Glandular Epithelia • Gland- a cell or group of cells that have ability to manufacture and discharge a secretion. • _____________- specialized protein molecules that are produced in the RER, packaged by the golgi and discharged from the cell. • Glandular epithelial cells have prominent ER, Golgi • Secretions may be sent far away in the body for use. • Multicellular glands form in utero • A layer of epithelial cells folds inward (___________). • Form __________ that lead to the epithelial surface • Some glands (__________) lose the duct and become separated from the original epithelium

  19. Glands can be classified by the following factors: • Presence or absence of ducts • Endocrine vs. Exocrine • Number of cells that compose them • Unicellular vs multicellular • Shape of secreting ducts • Simple or compound • Complexity of glandular structure • Tubular, acinar, tubuloacinar • Type of secretion made • Mucoid or serous • Manner in which secretion is stored and discharged • Merocrine, apocrine, or holocrine

  20. Endocrine Glands NO DUCTS (cells die) Produce and secrete _____________ Regulate body functions (growth, maturity, sex cycle) Blood stream delivers secretions to entire body ___________ within the gland bring secretions to the circulatory system Endocrine glands are part of the Endocrine System

  21. Exocrine Glands Contain ducts (except for ________ cells) Have local effect. Discharge secretions via ducts directly into nearby areas. Secretions act locally and do not enter into the circulatory system Examples of secretions: Saliva Bile Pancreatic and liver digestive enzymes Sweat Egg/Sperm Scent glands

  22. Unicellular Exocrine Gland: Goblet Cell • Only unicellular exocrine gland • _____less • Composed of a modified ___________ epithelial cell. • Found interspersed among the columnar cells of the respiratory and digestive tracts and conjunctiva of eye • Secretes _______: (polysaccharides, proteins, and glycoproteins) • when mixed with water → mucus • Mucus functions to protect and lubricate the apical surface of the epithelial cell and traps microorganisms and foreign particles

  23. Multicellular Exocrine Glands • Contain 2 distinct components: • 1) ___________ Unit • Secretory cells usually surrounded by connective tissue rich in blood vessels and nerve fibers that provides nourishment and structural support to the unit. • 2) ________ • carries secretion to its deposit site • _____epithelial cells may be present that assist with the discharge of secretions into the glandular duct. • Rate of secretion production is controlled by hormonal and nervous influences.

  24. Classification of Multicellular Exocrine Glands: Shape • Based on shape and number of tubes • If main duct is unbranched, the gland is ________ • If main duct is branched, gland is __________ • If secretory cells form a long channel of even width, gland is _________ • If cells form a rounded sac, it is _________ or acinar • Glands with both tubular and alveolar qualities are tubuloalveolar or tubuloacinar

  25. Classification of Exocrine Glands: Manner of secretion • How much of a cell is sacrificed in the act of secretion determines its classification: • _______________ • Glands package their secretions and release them via exocytosisas they are manufactured • Secretory cells remain intact • Majority of glands • (ex: pancreas, sweat glands, salivary glands) • _______________ • Glands store their secretions in the apex of the secretory cell after they are manufactured. When apex is full, it is pinched off and released with the secretions into the duct system. Cell is repaired and process is repeated. • (ex: mammary glands, some sweat glands) • ________________ • Glands store their secretions until they are needed. The cell lyses, releasing its contents. Cell dies and is replaced via mitosis. • (ex: sebaceous glands)

  26. Classification of Exocrine Glands:Type of Secretions Produced • Serous secretions • Watery • Contain a high concentration of enzymes • Pancreatic secretion • Mucous secretions • Thick, viscous • Composed of glycoproteins • Mucus membranes (GI and respiratory tracts) • Mixed exocrine glands contain both mucous and serous components • Salivary glands

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