Introduction Tissue – cells organized into groups that are specialized to carry out a specific function Four major tissue types (table 5.1) – Epithelial – Connective – Muscular – Nervous

Epithelial Tissue Covers organs, forms inner lining of body cavities, and lines hollow organs Underside anchored to connective tissue by a thin, nonliving layer called the basement membrane Lack blood vessels, readily divides and is tightly packed Carcinomas pp. 101

Epithelial Tissue Classified according to shape and number of layers of cells – Squamous – thin, flattened cells – Cuboidal – cube-shaped cells – Columnar – tall, elongated cells – Simple – single layer of cells – Stratified – two or more layers of cells – Psuedostratified – falsely stratified

Epithelial Tissue Simple Squamous Epithelium – Single layer of thin flattened cells – Fit together like floor tiles – Common at sites of diffusion and filtration Lines air sacs (alveoli) of the lungs Forms walls of capillaries Lines the inside of blood and lymph vessels Covers membranes that line body cavities

Epithelial Tissue Simple Squamous Epithelium

Epithelial Tissue Simple Cuboidal Epithelium – Single layer of cube-shaped cells – Common at sites of secretion and absorption Covers the ovaries Lines the kidney tubules Lines the ducts of the salivary glands, thyroid gland, pancreas and liver

Epithelial Tissue Simple Cuboidal Epithelium

Epithelial Tissue Simple Columnar Epithelium – Single layer of elongated cells – May be ciliated (microvilli) Increase surface area – Common at sites of secretion and absorption Lines uterus and most organs of the digestive tract Goblet Cells – flask shaped cells imbedded in simple columnar epithelium that secrete protective mucous on the free surface of the tissue

Epithelial Tissue Simple Columnar Epithelium

Epithelial Tissue Psuedostratified Columnar Epithelium – Only appears layered – Contain cilia and goblet cells – Lines the passageways of the respiratory system

Epithelial Tissue Psuedostratified Columnar Epithelium

Epithelial Tissue Stratified Squamous Epithelium – Relatively thick – Forms outer layer of the epidermis As skin cells age the accumulate keratin, harden and die Prevents water and nutrient loss, and damage from chemicals and microorganisms – Lines the oral cavity, esophagus, vagina, and anal canal Not keratinized

Epithelial Tissue Stratified Squamous

Epithelial Tissue Stratified Cuboidal – Two or three layers of cuboidal cells that form the lining of a lumen – Lines the large ducts of the mammary glands, sweat glands, salivary glands, and pancreas

Epithelial Tissue Stratified Cuboidal Epithelium

Epithelial Tissue Stratified Columnar Epithelium – Consists of several layers of columnar cells – Found in the male urethra, ductus deferens and in parts of the pharynx

Epithelial Tissue Stratified Columnar Epithelium

Epithelial Tissue Transitional Epithelium – Specialized to change in response to increase tension – Forms the inner lining of the urinary bladder and lines the ureters

Epithelial Tissue Transitional Epithelium

Connective Tissue Functions – Binds structures – Provides support and protection – Serves as framework – Fill spaces – Stores fat – Produces blood cells – Protects against infections – Helps repair tissue damage

Connective Tissue Contain extracellular matrix – Consistency varies from fluid to solid Most contain good supply of blood vessels and are well nourished May be rigid or flexible Contain a variety of cells and fibers

Connective Tissue Major Cell Types – Fibroblasts – most common type of “fixed cell” in connective tissue Produce fibers by secreting proteins into the extracellular matrix – Macrophages – originate as white blood cells Specialized to carry on phagocytosis – Mast Cells – release heparin, which prevents blood clotting and histamine, which promotes reactions associated with inflammation and allergies

Connective Tissue Connective Tissue Fibers – Collagenous Fibers Thick threads of the protein collagen Flexible but only slightly elastic Posses great tensile strength Important components of ligaments and tendons – Elastic Fibers Composed of the protein elastin Stretch easily Common in areas that are routinely stretched

Connective Tissue Connective Tissue Fibers – Reticular Fibers Very thin collagenous fibers Highly branched Form delicate supporting networks in a variety of tissues

Connective Tissue Loose Connective Tissue – Areolar Tissue – forms delicate, thin membranes throughout the body Found beneath most layers of epithelium Nourishes nearby epithelium cells

Connective Tissue Loose Connective Tissue Adipose Tissue – (fat) lies beneath the skin, in spaces b/w muscles, around the kidneys, behind the eyeballs, in certain abdominal membranes, on the surface of the heart, and around certain joints – Cushion joints, insulates and stores energy

Connective Tissue Loose Connective Tissue – Reticular Connective Tissue Composed of thin collagenous fibers in a three- dimensional network Provides framework for the liver and spleen Dense Connective Tissue – Fibers are very strong enabling the tissue to withstand pulling forces – Poor blood supply – Forms parts of tendons and ligaments

Connective Tissue Dense Connective Tissue

Connective Tissue Cartilage – Rigid connective tissue that provides support, frameworks, attachments, protects underlying tissues, and forms structural models for developing bones Chondrocytes – (cartilage cells) occupy small chambers called lacunae and lie completely with the extracellular matrix – Three types of cartilage recognized based on their extracellular matrix

Connective Tissue Cartilage – Hyaline Cartilage Found on the ends of bones in many joints, in the soft part of the nose, and in the supporting rings of the respiratory passages

Connective Tissue Cartilage – Elastic Cartilage Provides framework for the external ear and larynx

Connective Tissue Cartilage – Fibrocartilage Shock absorber for structures that are subjected to pressure Forms pads b/w discs of the spinal column and cushions bones of the knee

Connective Tissue Bone – Most rigid connective tissue (CaCO 3 CaPO 4 ) – Supports body structures, protects vital parts of cranial and thoracic body cavities, and is an attachment for muscles – Osteocytes – bone cells embedded in lacunae – Osteocytes form hollow cylinder-shaped tubes called osteons within bone tissue

Connective Tissue Bone – Canaliculi – cytoplasmic process that extend outward and pass through very small tubes in the extracellular matrix – Injured bone is thus highly vascularized and heals more rapidly than injured cartilage

Connective Tissue Bone

Connective Tissue Blood – Transports a variety of materials b/w interior body cells and those that exchange substances with the external environment – Composed of formed elements suspended in a extracellular matrix called blood plasma Formed elements include RBC’s WBC’s and platelets – Most blood forms in red marrow within the hollow parts of long bones

Connective Tissue Blood

Muscle Tissue Skeletal Muscle Tissue – Found in muscles that attach to bones and is controlled by conscious effort (voluntary) – Contain light and dark cross markings called striations – Move the head, trunk and limbs – Enable us to make facial expressions, write, talk, sing, chew, swallow and breathe

Muscle Tissue Skeletal Muscle

Muscle Tissue Smooth Muscle Tissue – Involuntary, Do not contain striations – Comprises the walls of hollow internal organs Cardiac Muscle Tissue – Found only in the heart – Involuntary, striated

Muscle Tissue Smooth Muscle Tissue

Muscle Tissue Cardiac Muscle Tissue

Nervous Tissue Found in the brain, spinal cord, and peripheral nerves – Neuron – basic nerve cell Sense and respond to changes Coordinate, regulate and integrate many body functions – Neuroglial Cells – support and bind the components of the nervous tissue, carry on phagocytosis and help supply nutrients to neurons by connecting them to blood vessels

Nervous Tissue Nerve Cell