Essentials of Human Anatomy Body Tissues Tissue Level of Organization • Group of similar cells – common embryonic origin – common function • Histology – study.
Download ReportTranscript Essentials of Human Anatomy Body Tissues Tissue Level of Organization • Group of similar cells – common embryonic origin – common function • Histology – study.
Essentials of Human Anatomy Body Tissues Tissue Level of Organization • Group of similar cells – common embryonic origin – common function • Histology – study of tissues 4 Basic Tissues (1) 1. Epithelial Tissue – covers surfaces because cells are in contact – lines hollow organs, cavities and ducts – forms glands when cells sink under the surface 2. Connective Tissue – supports and binds structures together – stores energy as fat – provides immunity to disease 4 Basic Tissues (2) 3. Muscle Tissue – cells shorten in length producing movement 4. Nerve Tissue – cells that conduct electrical signals – detects changes inside and outside the body – responds with nerve impulses Biopsy • Removal of living tissue for microscopic examination • Useful for diagnosis, especially cancer • Tissue preserved, sectioned and stained before microscopic viewing Epithelial Tissue • Functions – Protection – Sensory functions – Secretion – Absorption – Excretion Epithelial Tissues General characteristics • cover organs and the body • line body cavities • line hollow organs • have a free ( apical ) surface • have a basement membrane • avascular • cells readily divide • cells tightly packed • cells often have desmosomes • classified according to cell shape and number of cell layers Types of Epithelium • Covering and lining epithelium – epidermis of skin – lining of blood vessels and ducts – lining respiratory, reproductive, urinary & GI tract • Glandular epithelium – secreting portion of glands – thyroid, adrenal, and sweat glands Classification Cell Shapes 1. Squamous 2. Cuboidal 3. Collumnar Arrangement 1. Simple 2. Stratified 3. Pseudostratified Simple Epithelial Tissues • • • • Simple Squamous Simple cuboidal Simple columnar Pseudostratified columnar Epithelial Tissues Simple Squamous • single layer of flat cells • substances pass easily through • line air sacs • line blood vessels • line lymphatic vessels Simple Squamous Epithelial Tissues Simple cuboidal • single layer of cube-shaped cells • line kidney tubules • cover ovaries • line ducts of some glands Simple Cuboidal Epithelial Tissues Simple columnar • single layer of elongated cells • nuclei usually near the basement membrane at same level • sometimes possess cilia • sometimes possess microvilli • often have goblet cells • line uterus, stomach, intestines Simple Columnar Epithelium Simple Columnar Epithelium with cilia Epithelial Tissues Pseudostratified columnar • single layer of elongated cells • nuclei at two or more levels • appear striated • often have cilia • often have goblet cells • line respiratory passageways Pseudostratified Columnar Epithelium Stratified Epithelial Tissues • Stratified squamous • Stratified cuboidal • Stratified columnar Epithelial Tissues Stratified Squamous • many cell layers • top cells are flat • can accumulate keratin • outer layer of skin • line oral cavity, vagina, and anal canal Stratified Squamous Epithelium Epithelial Tissues Stratified cuboidal • 2-3 layers • cube-shaped cells • line ducts of mammary glands, sweat glands, salivary glands, and the pancreas Stratified Cuboidal Epithelium Epithelial Tissues Stratified columnar – • top layer of elongated cells • cube-shaped cells in deeper layers • line part of male urethra and part of pharynx Stratified Columnar Epithelium Epithelial Tissues Transitional • many cell layers • cube-shaped and elongated cells • line urinary bladder, ureters, and part of urethra Transitional Epithelium Glandular Epithelium Composed of cells that are specialized to produce and secrete substances Endocrine Glands • Lack ducts and secrete their products directly into the interstitial fluid and bloodstream. • Hormones act as chemical messengers to influence cell activities elsewhere in the body. Exocrine Glands – Usually maintain their contact with the epithelial surface by means of a duct. – Duct secretes materials onto the surface of the skin or onto an epithelial surface lining an internal passageway. Connective Tissues General characteristics • most abundant tissue type • many functions • bind structures • provide support and protection • serve as frameworks • fill spaces • store fat • produce blood cells • protect against infections • help repair tissue damage • have a extra-cellular matrix • have varying degrees of vascularity • have cells that usually divide Extra-Cellular Matrix • Cells rarely touch due to extracellular matrix • Matrix(fibers & ground substance secreted by cells • Consistency varies from liquid, gel to solid Connective Tissue Major Cell Types Fibroblasts • fixed cell • most common cell • large, star-shaped • produce fibers Mast cells • fixed cell • release heparin • release histamine Macrophages • wandering cell • phagocytic • important in injury or infection Connective Tissue Fibers Collagenous fibers • thick • composed of collagen • great tensile strength • abundant in dense CT • hold structures together • tendons, ligaments Reticular fibers • very thin collagenous fibers • highly branched • form supportive networks Elastic fibers • bundles of microfibrils embedded in elastin • fibers branch • elastic • vocal cords, air passages Connective Tissues Connective tissue proper • loose connective tissue • adipose tissue • reticular connective tissue • dense connective tissue • elastic connective tissue Specialized connective tissue • cartilage • bone • blood Connective Tissues Loose connective tissue • mainly fibroblasts • fluid to gel-like matrix • collagenous fibers • elastic fibers • bind skin to structures • beneath most epithelia • blood vessels nourish nearby epithelial cells • between muscles Adipose tissue • adipocytes • cushions • insulates • store fats • beneath skin • behind eyeballs • around kidneys and heart Connective Tissues Reticular connective tissue • composed of reticular fibers • supports internal organ walls • walls of liver, spleen, lymphatic organs Dense connective tissue • packed collagenous fibers • elastic fibers • few fibroblasts • bind body parts together • tendons, ligaments, dermis • poor blood supply Connective Tissues Elastic connective tissue • abundant in elastic fibers • some collagenous fibers • fibroblasts • attachments between bones • walls of large arteries, airways, heart Bone (Osseous Tissue) • solid matrix • supports • protects • forms blood cells • attachment for muscles • skeleton • osteocytes in lacunae Cartilage Connective Tissue Characteristics: – Weaker than bone – More flexible than bone • Cells in an abundant matrix. • Cell Types – Chondroblasts – Chondrocytes in lacunae • Avascular 3 Major Functions of Cartilage • Supporting soft tissues. • Providing a gliding surface at articulations (joints) • Providing a model for the formation of most of the bones in the body. Types of Cartilage • Three types of cartilage: – Hyaline cartilage • • • • Most abundant kind Has a perichondrium (membrane) Associated with synovial joints Most bones first modeled in hyaline cartilage – Fibrocartilage • Has collagen fibers • Intervertebral discs, pubic symphysis – Elastic cartilage • Has elastic fibers • Ear, respiratory tubing Muscle Tissues Skeletal muscle General characteristics • muscle cells called muscle fibers • contractile • three types • skeletal • smooth • cardiac • attached to bones • striated • voluntary Smooth muscle • walls of organs • skin • walls of blood vessels • involuntary • not striated Cardiac muscle • heart wall • involuntary • striated • intercalated discs Muscle Tissues Skeletal Muscle Smooth Muscle Cardiac Muscle Nervous Tissue • Sometimes termed neural tissue. • Found in brain, spinal cord, and peripheral nerves • Consists of neurons, or nerve cells, and glial cells that support, protect, and provide a framework for neurons. Neurons • Detect stimuli, process information quickly, and rapidly transmit electrical impulses from one region of the body to another. • Prominent cell body functions in control; information processing, storage, and retrieval; internal communication. Neurons • Processes extend from the nerve cell body. – Dendrite – Axon THE END