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Vertebrate Tissues Dr. Strong’s Zoology Class OMHS Tissues • Groups of cells that have specialized structural and functional roles • 4 basic types of tissues: epithelial, connective, muscle, and nervous A. Epithelial Tissue • Protects, secretes, absorbs • Cover body surfaces, cover and line internal organs, compose glands • Always has a free surface (an exposed surface) Classification of Tissues • Based upon shapes, arrangements, and functions - Simple – single layer - Stratified – many layers - Squamous - flattened - Cuboidal –cube shaped - Columnar – elongated shape Simple Squamous Epithelium •single layer of thin, flat cells •Allows for rapid diffusion of substances; also filtration, osmosis • Found in alveoli of lungs, lines inside of blood vessels •Thin and delicate – easily damaged Simple Squamous Epithelium Simple Cuboidal Epithelium • single layer of cube-shaped cells • Absorption & secretion • lines kidney tubules, etc. Simple Cuboidal Epithelium Simple Columnar Epithelium •Single layer of tall, narrow cells • lines most organs of digestive tract •Secretes digestive fluids & absorbs nutrients from food Simple Columnar Epithelium Often have microvilli and secrete mucous Pseudostratified Ciliated Columnar Epithelium •Single row of cells- not all reach the free surface, but each cell borders the basement membrane •Protects, secretes, & moves mucous • lines respiratory system, mucous traps dust, etc; cilia move mucous out Pseudostratified Ciliated Columnar Epithelium Cilia Goblet Cellssecrete mucus Basement Membrane Stratified Squamous Epithelium •many layers of cells; cells divide in deeper layers and push older cells outward •Layering = protection (prevents water loss and entry of chemicals, microorganisms, etc.) •forms epidermis; lines throat & mouth Stratified Squamous Epithelium Basement Membrane Stratified Squamous ● Keratinized – extra, tougher layers of dead skin cells to add protection. Thickest on the palms of hands and soles of feet. ● Nonkeratinized – layers of living cells found in areas where friction occurs such as in the mouth and throat where food is chewed and swallowed. Transitional epithelium • Changes in response to tension (can stretch) • Inner lining of bladder • Protects – prevents contents of urinary tract from diffusing back into internal environment 4 Basic Tissue Types B.Connective Tissue – Supports, binds together, protects – Most widely distributed tissue in body – Usually well-vascularized – Has a matrix - material between cells • Consists of fibers and a ground substance 1. Loose connective tissue (Areolar Tissue) • Cells are mainly fibroblasts (cells that produce fibers in the matrix) • Matrix = gel-like ground substance and many collagen and elastin fibers • Binds skin to organs & fills space between muscles • Has many blood vessels that nourish nearby epithelial cells Loose Connective Tissue 2. Adipose Tissue (fat) • Made up of cells that store fat • Beneath skin; between muscles; around kidneys; surface of heart; around joints • Cushions joints and organs • Insulates • Stores energy Adipose Tissue Large, empty-looking cells with thin margins; nucleus pressed against cell membrane • 3. Dense Connective Tissue • Densely packed, parallel collagen fibers (white) with only a few fibroblasts • Very strong; makes up tendons and ligaments • Low blood supply injuries slow to heal Dense Connective Tissue fibroblasts 4. Cartilage • Cartilage cells = chondrocytes 3 types of cartilage found in the body: a. Hyaline Cartilage • Very fine collagen fibers in matrixlooks like glass. • Found on ends of bones, soft part of nose, rings that support airway, fetal skeleton. b. Elastic Cartilage ● Very flexible. Found in ear. c. Fibrocartilage • Can act as a shock absorber in knee. 5. Bone •Hardness due to mineral salts and many collagen fibers in matrix. Bone cells are called osteocytes. Function - support, attachment for muscles, mineral storage, protection (cranial & thoracic cavities), forms blood cells Found in skeleton. Bone Haversian Canal Osteocytes in lacunae 6. Blood •Transports materials (nutrients and oxygen) throughout body; helps maintain homeostasis •Matrix is fluid (called plasma) Blood Leucocytes Thrombocytes Erythrocytes Six types of connective tissue C. Muscle Tissue • Made up of elongated cells (muscle fibers) that can contract • Functions in movement of body parts • 3 types –Skeletal Muscle –Smooth Muscle –Cardiac Muscle Skeletal Muscle •multi-nucleated; striated – light and dark bands • Voluntary – can be controlled by conscious effort • Found: attached to bones Skeletal Muscle striations Smooth Muscle • one nucleus; unstriated • Found: walls of hollow internal organssuch as esophagus, intestines, stomach, blood vessels, etc. • Involuntary • Move food through digestive tract, blood through blood vessels, etc. Smooth Muscle Nuclei Cardiac Muscle • Striated, one nucleus, branched • Has intercalated disks (where cells are connected) • involuntary • Found: only in heart • Pumps blood through heart chambers and into blood vessels Cardiac Muscle Intercalated disc 3 Types of Muscle Tissue D. Nerve Tissue • Sensory reception and conduction of nerve impulses; allows for communication and coordination of body functions • Found in brain, spinal cord, nerves • Cells called neurons Nerve Tissue Cell Body Nucleus Axon Dendrites Tissues form Organs Most organs are made of several types of tissues.