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Tissues, Glands and Membranes A tissue is a group of cells that have a similar structure and function The microscopic study of tissues is called histology Four Types of Tissue Epithelial Connective Muscle Nervous Epithelial Tissue Epitihelial – “ Covering Lining” Covers internal and external surfaces throughout the body Three parts: free surface basement membrane very little extracellular space Functions of the epithelial cell Protects the underlying structures- for example the skin Acts as a barrier to certain substance- for example water, toxic molecules, and microorganisms Also allows the passage of certain substances – for example oxygen and carbon dioxide Secretes substance – for example secretions from sweat glands Absorbs substances – for example vitamins, minerals Classified according to the number of layers and the cell shape #of layers Simple (one layer) Pseudo stratified Stratified Transitional Cell shape Squamous Cuboidal Columnar Columnar Squamous Keratinized Non Keratinized Roughly cuboidal to columnar when not stretched,squamous when stretched The structure relates to the function Simple epithelium- found in movement epithelium - gasses across wall of alveoli - filtration of fluid across kidneys - secretion of glands - nutrient absorption Sratified epithelium well adapted for its protective function as outer layers are damaged , they are replaced by deeper cell layers Found where abrasions may occur, such as skin, anal canal and vaginal canal Differences also reflected in the cell shape Flat and thin cells – for diffusion in lungs and filtration in kidneys Cuboidal or columnar cells are cells with major functions of secretion or absorption. They are larger because they contain more organelles for all the functions they must perform e.g. columnar cells of the stomach lining have secretory vesicles that secrete mucus. Free Surface of the cell Cell Connections Cell Connections Tight Junctions Desmosoes Hemidesmosomes Gap junctions Glands Glands- A gland is a multicellular structure that secretes substances on to a surface, into a cavity or into the blood Most are made of epithelial cells Types of Glands Exocrine- glands that have ducts - simple- no branches -compound- branches ends- 1-tubular straight tubular coiled tubular 2- acinar/ alvoelar or saclike 3- both tubuloacinar Types of Exocrine Glands Endocrine Glands Endocrine-have no ducts and empty their secretions directly into the blood Secretions are called hormones and these hormones are carried to other parts of the body by the blood Connective Tissue Connective Tissue Connective Tissue structure – large amounts of extracellular materials that separate cells from one another This extracellular matrix is divided into three parts: -protein fibers - ground substance consisting of non fibrous protein and other molecules - fluid Connective Tissue Matrix Protein Fibers - Collagen Fibers- resemble microscopic ropes, flexible but resist bending - Reticular Fibers- very fine short collagen fibers that branch to form the supporting network - Elastic Fibers- structure similar to coiled metal bed springs but after being stretched , elastic fibers recoil to their original shape Connective Tissue Matrix Ground Substance Ground Substance is the shapeless background against which cells and collagen fibers are seen in the light microscope Made up of highly structured molecules Consists of Proteoglycans (proteins and carbohydrates that trap water) Connective Tissue Matrix Cells of the matrix How Do We Name Connective Tissue ? According to Their Functions examples: Blast- produces the matrix Cyte – maintains the matrix Clast-break down the matrix for remodeling Macrophage Mast Cell Functions of the Connective Tissue Encloses and Separates Connecting tissue to one another Supporting and Moving Storing Cushioning and insulating Transporting Protecting Classification of Connective Tissue Loose (areolar) Adipose Dense Connective Tissue - Dense collagenous connective A) Collagen arranged in same direction B) Collagen arranged in many directions Dense elastic connective tissue A)Elastic arranged in many directions b) Elastic fibers arranged in same direction Cartilage Hyaline FIbrocartilage Elastic Cartilage Bone Blood Loose Areolar Tissue -mostly collagen, few elastic and widely separated from each other Produced by the fibroblast This is the tissue that fills in the spaces Loose Connective TISSUE Adipose Tissue Has very little collagen and elastic fibers Large cells filled with lipids Pads of protection and thermal insulation Dense Connective Tissue Densely packed fibers that produced by the fibroblast Dense Collagenous- mostly collagen tendons, ligaments, capsules around organs same direction in tendons, different in organs Dense Elastic Tissue- abundant elastic fibers among collagen fibers vocal cords, walls of large arteries Dense Elastic Cartilage Composed of cartilage cells or Chondrocytes Located in the matrix along with collagen Amongst the extracellular matrix It gives the matrix resilience Hyaline Fibro Elastic Hyaline Cartilage The most abundant type of cartilage Ends of bones where they come together to form joints. It is the smooth and resilient Surfaces that withstand repeated compression Costal , respiratory, and nasal cartilges Fibrocartilage Has more fibrous tissue than does hyaline cartilage , bundles of collagen Resists pulling or tearing Found in the disks between vertebrae and in some joints Elastic Cartilage Has elastic fibers, collagen proteoglycans Coiled fibers amongst bundles of collagen fibers Can recoil to its original shape when bent External ear, epiglottis, auditory tube Bone Is hard connective tissue that consists of cells and a mineralized matrix Osteoblasts secrete the matrix called lamellae osteocytes are located in lacune The Osteon ( Haversion system) consist of central canal with blood vessels, osteocytes and lamellae Haversion System/Osteon Blood Here the matrix is a liquid which enables the blood to move through the vessels to carry nutrients and other materials Muscle Tissue Main Characteristic is its ability to contract , making movement possible Contractile proteins in the muscle cells themselves, called actin and myosin Muscle cells are called muscle fibers because they resemble tiny threads Three Types of Muscle Tissue Skeletal Muscle Cardiac Muscle Smooth Muscle Skeletal Muscle Normally thought of as “muscle” Meat of animals, 40% of persons body weight Attaches to the skeletal system and enables body movement Long and cylindrical cells with several nuclei per cell Some cells are the entire length of the muscle Striated, Vountary Smooth Muscle Forms the hollow walls of the organs and is also in the skin and eyes Movement of food and emptying of the Urinary Bladder Involuntary Tapered at each end , have a single nucleus and are not striated Cardiac Muscle Muscle of the heart and is responsible for Involuntary control Cylinder in shape and shorter than skeletal Striated and one nucleus Connected by intercalated disks Classification of Muscles Skeletal Voluntary Striated >1nuclei Smooth involuntary not striated 1 nuclei Cardiac involuntary striated 1 nuclei Nervous Tissues Forms the brain, spinal cord and nerves Coordinates and controls many body activities Conscious and unconscious Awareness, emotion, reasoning Communicate through action potentials Cell= neuron or nerve cell responsible for conduction of action potentials Neuron – cell body , dendrites and axons Neuroglia surrounding support cells Neurons and Glial cells Membranes Serous Membranes simple squamous epithelium resting on delicate layers of loose connective tissue cavities and cover the organs inside these cavities secretes serous fluid which lines the cavitites prevents trauma and damage Membranes Pleural- lungs Pleuritis Pericardium- heart - Pericarditis Peritoneal other - Peritonitis Other Membranes Cutaneous Synovial Periosteal