Tissue and Membranes ST110 Concorde Career College. INTRODUCTION. Tissue : group of similar cells that perform a common function Matrix : nonliving intercellular material Histology: The study of the structure, composition and functions of tissues. Four Major Types of Human Tissue.
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INTRODUCTION • Tissue: group of similar cells that perform a common function • Matrix: nonliving intercellular material • Histology: The study of the structure, composition and functions of tissues
Four Major Types of Human Tissue • Epithelial • Connective • Muscle • Nervous
EPITHELIAL TISSUE • Types • Epithelium is divided into two types: • Membranous (covering or lining) epithelium • Glandular epithelium
Epithelial tissue • Locations • Membranous epithelium: covers the body and some of its parts and lines the serous cavities; blood and lymphatic vessels; and respiratory, digestive, and genitourinary tracts • Glandular epithelium: secretory units of endocrine and exocrine glands • Along with connective are bound together by a basement membrane.
Epithelial Tissues • Functions include: • Protection • Skin • Excretion and Secretion • endocrine glands • Mucous glands • Kidneys • Sweat glands • Diffusion • Alveolar wall • Cleaning • Intestinal tract (Ciliated) • Absorption • Intestinal tract • Kidneys • Sensation • Skin • Tongue
EPITHELIAL TISSUE (cont.) • Generalizations about epithelial tissue • Limited amount of matrix material • Membranous type attached to a basement membrane • Avascular • Cells are in closely packed together, with many desmosomes and tight junctions • Capable of reproduction
EPITHELIAL TISSUE: MEMBRANOUS • Classification of epithelial tissue • Membranous (covering or lining) epithelium • Classification based on cell shape • Squamous • Cuboidal • Columnar • Transitional • Pseudostratified columnar
EPITHELIAL TISSUE: MEMBRANOUS • Epithelial and Connective tissue are bound together by basement membrane
EPITHELIAL TISSUE Classification based on layers of cells: Simple epithelium • Simple squamous epithelium • One-cell layer of flat cells • Permeable to many substances • Examples: Alveoli of the lungs and lining of blood vessels • Simple cuboidal epithelium • One-cell layer of cells that are as tall as they are wide • Found in many glands and ducts (secretion & absorption)
Simple squamous • Found in the lining of the heart, blood and lymphatic vessels, body cavities, and alveoli of the lungs.
EPITHELIAL TISSUE (cont.) • Classifications based on layers of cells (cont.) • Simple columnar epithelium • Single layer of tall, column-shaped cells • Cells often modified for certain functions such as goblet cells (secretion), cilia (movement), microvilli (absorption) • Often lines hollow visceral structures • Pseudostratified columnar epithelium • Columnar cells of differing heights • All cells rest on basement membrane but may not reach the free surface above • Cell nuclei at odd and irregular levels • Found lining air passages and segments of male reproductive system • Motile cilia and mucus are important modifications
Cilia • Hair-like extensions of cells in the respiratory tract and female reproductive system.
EPITHELIAL TISSUE (cont.) Classifications based on layers of cells (cont.) • Stratified epithelium • Keratinized stratified squamous epithelium • Multiple layers of flat, squamous cells • Cells filled with keratin • Covering outer skin on body surface • Nonkeratinized stratified squamous epithelium • Lining vagina, mouth, and esophagus • Free surface is moist • Primary function is protection • Stratified cuboidal epithelium • Two or more rows of cells are typical • Basement membrane is indistinct • Located in sweat gland ducts and pharynx
Keratinized stratified squamous • Found in covering outer skin on body surface.
Nonkeratinized stratified squamous • Found in lining of vagina, mouth and esophagus.
EPITHELIAL TISSUE (cont.) Classifications based on layers of cells (cont.) • Stratified columnar epithelium • Multiple layers of columnar cells • Only most superficial cells are typical in shape • Rare • Located in segments of male urethra and near anus • Transitional epithelium • Located in lining of hollow viscera subjected to stress (e.g., urinary bladder) • Often 10 or more layers thick • Protects organ walls from tearing • Has varying shapes and is capable of stretching (found in urinary bladder)
EPITHELIAL TISSUE: GLANDULAR EPITHELIUM • Glandular epithelium • Glands are usually composed of simple cuboidal cells • Specialized for secretory activity • Exocrine glands: discharge secretions into ducts • Simple exocrine glands- only has one duct leading to the surface • Compound exocrine glands- only has two or more ducts leading to the surface • Endocrine glands: “ductless” glands; discharge secretions directly into blood or interstitial fluid • Goblet cells- glandular epithelial cells that secrete mucous to lubricate the intestinal wall
EPITHELIAL TISSUE: GLANDULAR EPITHELIUM (cont.) • Structural classification of exocrine glands • Multicellular exocrine glands are classified by the shape of their ducts and the complexity of their duct system • Shapes include tubular and alveolar • Simple exocrine glands: only one duct leads to the surface • Compound exocrine glands: have two or more ducts
EPITHELIAL TISSUE: GLANDULAR EPITHELIUM (cont.) • Functional classification of exocrine glands (Figure 5-12) • Apocrine glands • Secretory products collect near apex of cell and are secreted by pinching off the distended end • Secretion process results in some damage to cell wall and some loss of cytoplasm • Mammary glands are good examples • Holocrine glands • Secretion products, when released, cause rupture and death of the cell • Sebaceous glands are holocrine • Merocrine glands • Secrete directly through cell membrane • Secretion proceeds with no damage to cell wall and no loss of cytoplasm • Most numerous gland type Mast= cell that produces heparin and histamine
CONNECTIVE TISSUE • Has large amounts of intracellular matrix • Most varied and abundant tissue in the body • Functions, characteristics, and types • General function: • Support – holds organ together • Bind together tissues • Mechanical framework (skeleton) • General characteristics • ECM predominates in most connective tissues and determines its physical characteristics • Consists of fluid, gel, or solid matrix, with or without extracellular fibers (collagenous, reticular, and elastic) and proteoglycans or other compounds that thicken and hold together the tissue
CONNECTIVE TISSUE • Types • Three subgroups: • Loose connective Tissue • Dense Connective Tissue • Specialized Connective Tissue
CONNECTIVE TISSUE (cont.) • Loose Connective Tissue • Areolar • Adipose • Reticular • Dense Connective Tissue • Fibrous • Elastic • Specialized Connective Tissue • Bone • Compact bone • Cancellous bone • Cartilage • Hyaline • Fibrocartilage • Elastic • Blood
CONNECTION TISSUE cont. • Areolar connective tissue • One of the most widely distributed of all tissues • Intercellular substance is prominent and consists of collagenous and elastic fibers loosely interwoven and embedded in soft viscous ground substance • Several kinds of cells present, notably fibroblasts and macrophages, also mast cells, plasma cells, fat cells, and some white blood cells • Function: stretchy, flexible connection
CONNECTION TISSUE (cont.) • Adipose tissue • Similar to loose connective tissue but contains mainly fat cells • Functions: protection, insulation, support, and food reserve • Reticular tissue • Forms framework of spleen, lymph nodes, and bone marrow • Consists of network of branching reticular fibers with reticular cells overlying them • Functions: defense against microorganisms and other injurious substances; reticular meshwork filters out injurious particles and reticular cells phagocytose them
Dense CONNECTIVE TISSUE • Dense Connective Tissue • Matrix consists mainly of densely packed fibers and relatively few fibroblast cells • Irregular: fibers intertwine irregularly to form a thick mat • Regular: bundles of fibers are arranged in regular parallel rows • Fibrous(Collagenous): mostly collagenous fibers in ECM • Elastic: mostly elastic fibers in ECM
Dense CONNeCTIVETISSUE (cont.) • Locations: structures that need great tensile strength, such as tendons and ligaments; also dermis and the outer capsule of the kidney and spleen • Function: furnishes flexible connections that are strong or stretchy
DAY 2 Membranes and Wound Healing
Specialized CONNECTIVE TISSUE: BONE TISSUE • Bone tissue • Uniquely hard and strong connective tissue type • Cells (osteocytes) embedded in a calcified matrix • Inorganic component of matrix accounts for 65% of total bone tissue • Functions • Support • Protection • Point of attachment for muscles • Reservoir for minerals • Supports blood-forming tissue • Provide movement
Specialized CONNECTIVE TISSUE:BONE TISSUE (cont.) • Compact bone • Osteon (Haversian system) • Structural unity of bone • Spaces for osteocytes called lacunae • Matrix present in concentric rings called lamellae • Canaliculi are canals that join lacunae with the central Haversiancanal (communication passageway) • Cell types • Osteocyte: mature, inactive bone cell • Osteoblast: active bone-forming cell • Osteoclast: bone-destroying cell
Specialized CONNECTIVE TISSUE: BONE TISSUE (cont.) • Cancellous bone made up of trabeculae • Trabeculae: thin beams of bone • Supports red bone marrow • Myeloid tissue: a type of reticular tissue • Produces blood cells • Called spongy bone because of its spongelikeappearance • Endochondrial ossification- the conversion of cartilage to bone • Periosteum- membrane that surrounds bone