What are Tissues? Tissues are groups of cells – Similar in structure – Characteristic in pattern – Specialized for the performance of specifictasks Histology The study of tissues - Histo means tissue Epithelial tissue • Covers surfaces • Lines cavities • Forms glands Connective tissue • Supports and forms the framework of all parts of thebody Muscle tissue • Contracts • Produces movement Nervous tissue • Conducts nerve impulses What is the Function of Epithelium • Forms a protective covering for the body • Main tissue of skin’s outer layer • Forms membranes and ducts • Lines body cavities and hollow organs What is the structure of Epithilium • Tightly packed to protect underlying tissue or toform barriers • Repairs itself quickly • Can become stronger if subjected to wear & tear – i.e. calluses in skin Epithelial Cell Structure - 3 different shapes • Squamous - flat • Cuboidal - square • Columnar - long and narrow Epithelial Cell Structure - 3 Different layers • Simple – single layer • Stratified – many layers • Pseudostratified – staggered, so appear to be multilayered but are not Transitional epithelium Capable of great expansion but returns to original size - bladder Special Functions of Epithelial Tissue 1. Produce secretions • Digestive juices • Sweat • Goblet Cells - epithelial cells in respiratory & digestive tract that produce mucus 2. Protect by trapping particles • Secrete mucus • Cilia projections trap particles 3. Glands – an organ specialized to produce a substance that is sent out to other parts of the body • Manufactures secretions from materials removed from blood Describe the Exocrine Gland • Have tubes or ducts to carry secretions away from glands • Effective in a limited area near the source • Structure • Single cell – goblet • Multiple cells • Simple tubular - intestine • Branched tubular - stomach • Coiled tubular - skin • Simple saclike - skin • Compound formation of tubes and sacs – mouth Some Examples • Gastrointestinal glands secrete digestive juices • Sebaceous glands in skin produce oil • Lacrimal glands produce tears Decsribe the Endocrine Gland • Ductless glands that secrete directly into the blood • Hormones have effects on specific target tissues • Structure – an extensive network of capillaries Examples • Pituitary • Thyroid • Adrenal Function & Structure of Connective Tissue (overview) Function • Supporting fabric of all parts of the body • Most extensive and widely distributed tissue of the body Structure • Matrix - large amounts of nonliving material between cells • Fibers – generally give matrix some structure Structure of Connective Tissue Classifications Classified according to composition of the intracellular matrix • Liquid connective tissue • Blood & lymph • Cells suspended in fluid matrix • Soft connective tissue • Adipose and areolar tissue • Cells loosely held together with semi-liquid matrix • Fibrous connective tissue • Ligaments, tendons, capsules • Cells held together with densely packed fibrous matrix • Hard connective tissue • Bone or cartilage • Cells held together with a hardened matrix that contains minerals Name the two Soft Connective Tissue types 2 types • Areolar (loose) Tissue • Most common type of connective tissue in the body • Intercellular matrix is jelly-like - Examples • Membranes around vessels & organs • Between muscles • Under skin • Adipose Tissue • Fatty tissue for storing energy and providing protective padding • Cells store fat What are Fibroblasts cells that produce fibrous connective tissue Describe Fibrous Connective Tissue • Structure -very dense with large numbers of fibers • Collagen is most common fiber • Elastin fibers allow tissue to stretch and return to original length • Vocal cords • Arterial walls • Function – cover various organs • Capsules – very strong coverings for organs • Kidneys • All fibers arranged in same direction to allow for pulling in one direction • Tendons • Ligaments • Fibroblasts – cells that produce fibrous connective tissue Collagen • The Body’s Scaffolding • Most abundant protein in body • 25% of total protein • 19 types of collagen • Collagen fibers give intercellular matrix both strength and flexibility • Stronger than steel fibers of same size Hard Connective Tissue - Cartilage Structure • strong & flexible Function – • Structural material • Reinforcement • Shock absorber • Surface that reduces friction Cartilage - 3 types Hyaline cartilage – aka gristle • End of long bones • Tip of nose • Fibrocartilage – not elastic • Between spinal bones and pelvic bones • Elastic cartilage – can spring back into original shape • Outer ear Chondrocytes cells that produce cartilage Hard Connective Tissue Bone aka osseous tissue • Structure - connective tissue with intercellular matrix hardened by minerals • Osteocytes – bone cells • Blood vessels, nerves in intercellular matrix • Bone marrow • Function • Support • Produce red blood cells Osteoblasts cells that form bone Muscle Tissue • Function • Produce movement through contraction of its cells • Structure - cells are long thread-like fibers • Skeletal muscle • Cardiac muscle • Smooth muscle • After injury • repairs itself only with difficulty • Often replaced with scartissue 3 Types of Muscle Tissue 1. Skeletal Muscle • Voluntary – can consciously contract skeletal muscle • Function - moves the body • Structure – • Very large cells • More than one nucleus • Striated (striped) pattern 2. Cardiac Muscle • Involuntary – contracts without conscious thought • Function – produces regular contractions, causing the heart to pump blood • Structure – • Cells are branched and interwoven • Membranes between cells also act to interconnect cells 3. Smooth Muscle • Involuntary • Function contract to produce movement of fluids or substances • Walls of hollow organs and vessles Nervous Tissue function and structure • Function – control and communications • Brain – control center of body • Spinal Cord – information superhighway • Nerves – direct communication between brain and body • Structure • Neuron – nerve cell • Neuroglia – support cell Neurons Nerve cell • Cell Body – transmits nerve impulses • Dendrite – branched tail that receives impulses for cell body • Axon – single tail that sends impulses away from cell body • Can be several feet long • Myelin – coating that Insulates axon Neuroglia nerve support cell • Protect nerves from harmful substances • Remove foreign material & debris • Form the myelin insulation Membranes function ans structure Function • Coverings • Dividers • Linings • To Anchor Structure • Epithelial membranes - layered • Serous membranes • Mucous membranes • Cutaneous membranes - skin • Connective tissue membranes • Synovial membranes • Meninges • Superficial fascia • Deep fascia • Fibrous pericardium • Periosteum • Perichondrium Epithelial Membranes – Structure Layered • Outer epithelial layer • Strengthened by connective tissue layer and sometimes smooth muscle layer Closely packed cells • Manufacture secretions • Protect deeper layers from invasion Serous Membranes aka Mesothelium Structure • Layered - One layer lines the walls of a body cavity and then it folds in on itself to line the outermost layer of the organ • Although in 2 layers, the membrane is continuous • Parietal layer – attaches to wall of body cavity • Visceral layer – attaches to organ • Does not connect with the outside of the body Function • Secretes a thin watery fluid that decreases friction on organs during movement