Tissues and Membranes Chapter 6 PDF

Chapter 6: Tissues and Membranes LECTURE NOTES 1. Definitions 1. Tissue Tissues are group of cells that are similar to each other in structure and function. 2. Membranes are thin sheets of tissue that cover surfaces, line body cavities, and surround organs. There are four major ty...

Chapter 6: Tissues and Membranes LECTURE NOTES 1. Definitions 1. Tissue Tissues are group of cells that are similar to each other in structure and function. 2. Membranes are thin sheets of tissue that cover surfaces, line body cavities, and surround organs. There are four major types of tissues: a) Epithelial b) Connective c) Nervous d) Muscular 2. Histology Histology is the study of tissues. 2.Epithelial Tissue Epithelial tissue covers surfaces, lines cavities, and engages in secretion, absorption, and protective functions. A. Classification according to shape (Figure 6-2). It is classified according to cell shape (squamous, cuboidal, and columnar) and layers (simple and stratified) a. Squamous Cells are thin and flat like fish scales b. Cuboidal Cells are cubelike and look like dice c. Columnar Cells are tall and narrow and look like columns B. Classification according to layers a. Simple One layer b. Stratified Two or more layers C. Simple epithelia a. Simple squamous  b. Simple cuboidal c. Simple columnar d. Pseudostratified columnar epithelium D. Where is it found? SIMPLE.- One layer a) Simple squamous-Walls of blood vessels -Alveoli -Kidneys b) Simple cuboidal-Lining of kidney tubules -Various glands ( thyroid, pancreas, salivary) c) Simple columnar-Digestive tract  d) Pseudostratified columnar-lining of respiratory tract -Lining of reproductive tubes ( fallopian tubes) E. Stratified epithelia (transitional) a. Multilayered b. Transitional F. STRATIFIED.- Two or more layers Stratified epithelia are multilayered and therefore stronger than simple epithelia. They perform a protective function and are found in tissue exposed to everyday wear and tear, such as the mouth, esophagus, and skin. a) Stratified squamous-Outer layer of the skin -Lining of mouth, esophagus, anus, and vagina Most common of the stratified epithelia. Esphagus b) Transitional-Urinary bladder It is found primarily in organs that need to stretch such as the urinary bladder. The cells appear stratified when the urinary bladder is empty (unscratched) and simple when the bladder is full ( stretched. G. What is its Function? a. Protection -The skin protects the body from sunlight and from invasion by disease-producing bacteria. -The epithelial tissue lining the respiratory passages helps clean Inhaled air. -The epithelium of the respiratory tract secretes mucus and is lined with cilia. The mucus traps the dust inhaled in the air, and the constantly waving cilia move the dust and mucus toward the throat. The dust and mucus are then either coughed or swallowed and eliminated in the stools. b. Absorption Epithelium in the digestive tract, absorb large amounts of water and digested food. c. Filtration Epithelium tissue also functions in the transport of substances across membranes. d. Secretion Epithelial tissue forms glands that secrete a variety of hormones and enzymes. H. What is it like? a. Continuous sheets (Figure 6-1)  The cells fit together snugly like tiles. b. One surface is always unattached Epithelial tissue has two surfaces. One surface is always unattached, like the surface of the outer skin or the inner lining of the mouth. The undersurface is attached to a basement membrane. c. It is avascular Epithelial tissue has no blood supply of its own. For its nourishment depends on the blood supply of underlying connective tissue. d. It is able to regenerate Because epithelial tissue is so well nourished from the underlying connective tissue, it is able to regenerate, or repair itself, quickly if injured. I. Glandular epithelia a. Exocrine glands i. Secrete into ducts which carry the secretions onto a surface ii. Examples: saliva, sweat, digestive enzymes b. Endocrine glands i. Secrete into the blood that transports the hormones throughout the body  ii. Considered ductless glands iii. Examples: insulin, growth hormone, steroids 3. Connective Tissue 1. Where is it found/What does it do? a. Most abundant of the tissue types It is found in: 1) The blood 2) Under the skin 3) In bone 4) Around many organs Function: b. Connects or binds together c. Protection d. Stores fat e. Transport 2. What does it look like? a. Blood supply: good except for ligaments and tendons An injury in tendons or ligaments heals very slowly due to poor blood supply. Cartilage does not have blood supply b. Intercellular matrix It is what makes the various types of connective tissue so different. The intercellular matrix is material located outside the cell. It fills the spaces between the cells (intercellular space) The cell makes the matrix and secretes it into the Intercellular spaces. i. Large amount The amount of matrix varies from one cell type to the next: Fat tissue, has little intercellular matrix. Bone and cartilage have few cells and large amounts of intercellular matrix. ii. Great variety (examples: liquid in blood/hard in bone) The Intercellular matrix may be liquid as in blood; gel-like as in fat tissue; or hard as, as in bone. c. Fibers Protein fibers are found in the matrix of most connective tissue. i. Collagen.-Fibers are strong and flexible but not easily stretched. Injections of collagen have been used cosmetically to remove unwanted lines and wrinkles. ii. Elastin fibers are not very strong, but they are stretchy, like a rubber band. iii. Reticular-Is a fine collagen. 3. Types a. Loose connective (areolar)/adipose Contains fibers that are loosely arranged around cells. Three types i. Areolar- Beneath skin and most epithelial layers; between muscles. Made up of collagen and elastin. fibers in a gel-like intercellular matrix. It protects, provides cushion, acts like "tissue glue". ii. Adipose-Beneath skin (subcutaneous), around kidneys and heart, behind eye balls. Stores fat. Insulate the body from extremes of outside temperature. iii. Reticular-Lymphoid tissue such as lymph nodes, spleen, and bone marrow -It forms the internal framework for lymphoid tissue such as the spleen, lymph nodes and bone marrow. b. Dense fibrous connective This tissue is composed of an intercellular matrix that contains many collagen and elastic fibers. i. Tendons-Attach muscles to bones ii. Ligaments-Attach bones to other bones iii. Fascia--Covers muscles, blood vessels and nerves.  iv. Capsules- Protective cover of some organs such as liver and kidneys c. Cartilage i. Chondrocytes Cartlage cells. Although the matrix is soilid, it is not as hard as that of the bone. Most cartilage is covered by perichondrium. ii. Types and location a. Hyaline cartilage-end of long bones at joints, , connects ribs to sternum, ring s in trachea b. Elastic cartilage, external ear and part of larynx c. Fibrocartilage-Intervertebral discs, pads in knee joints, pad between pubic bones d. Bone i. Osseous tissue ii. Hard intercellular matrix iii. Forms skeletal system: protection and movement iv. Storage of minerals, especially calcium e. Blood and lymph Watery intercellular matrix. D. Nervous Tissue  1. Neurons a. Parts: dendrites, cell body, axons b. Conducts the electrical signal 2. Neuroglia a. Cells that support and take care of neurons E. Muscle Tissue: Muscle tissue is composed of cells that shorten, or contract. In doing so, they cause movement of a body part. (Pag 83) 1. Skeletal muscle-Generally attached to the bone 2. Smooth muscle-Generally found in the walls of the viscera, such as the stomach, intestines, and urinary bladder. 3. Cardiac muscle-It is found only in the heart F. Tissue Regeneration Two types: a) Regeneration.-Refers to the replacement of injured tissue by cells that are identical to the original cells. Occurs only in tissues whose cell undergo mitosis, such as the skin b) Fibrosis.- Is the replacement of the injured tissue by the formation of fibrous connective tissue, or scar tissue. The fibers of scar tissue pull the edges of the wound together and strengthen the area. Damaged skeletal muscle, cardiac muscle, and nervous tissue are replaced by scar tissue. G. Membranes Membranes are thin sheets of tissue that cover surfaces, line body cavities, and surround organs. 1. Epithelial membranes a. Cutaneous (skin): -The outer layer of the skin b. Mucous membranes-Secret mucus to keep the membrane moist and also lubricated i. Line all cavities that open to the outside ii. Examples: digestive tract, respiratory tract, genitourinary tracts c. Serous membranes Serous membranes secrete a thin , watery, serous  fluid. The fluid allows the membrane to slide past one another with little friction. i. Pleura: visceral and parietal ii. Pericardium iii. Peritoneum: visceral and parietal 2. Connective tissue membranes a. Synovial b. Periosteum c. Perichondrium d. Meninges e. Fascia Practice Unit Exam (available to students on Evolve with answers) Matching Directions. Using the following words, fill in the blanks. Some words may be used more than once. a. epithelial tissue b. connective tissue c. nervous tissue d. muscle tissue 1. ______ smooth, skeletal, and cardiac 2. ______ areolar, tendons, ligaments 3. ______ blood, cartilage, and bone 4. ______ arranged like floor tiles 5. ______ squamous, cuboidal, and columnar 6. ______ intercellular matrix: liquid, gel, hard 7. ______ include endocrine and exocrine glandular tissue 8. ______ contracts and causes movement 9. ______ hyaline, fibro-, and elastic 10. ______ adipose, blubber, and insulation