Transcript Tissues
Tissues Anatomy and Physiology Four tissue types • • • • Epithelium Connective Muscle Nervous Epithelium • Functions: protection, secretes, absorbs, excretes • Location: covers body surfaces, lines internal organs, glands • Is found anywhere the body has an outside link Epithelium • Is anchored to connective tissue • Does not contain blood vessels • How, then, would epithelium get needed materials? Epithelium • Reproduces rapidly • Heals quickly • Tightly packed Epithelium • Classified by cell shape and layers • Three general groups: simple—one layer of cells stratified—layered glands—produce and secrete substances Epithelium • Three shapes or forms: 1. squamous: flat cells • May be simple or stratified (usually simple) Simple squamous Epithelium • Shape 2: cuboidal • Cube shaped, but may have rounded edges • May be simple or stratified Epithelium • Shape 3: columnar • Longer, oval or rectangular, tall cells • May be simple or stratified Connective Tissue • Very diverse • Functions include: to bind, support, store fat, blood and immune cells • Though they appear to unrelated, they have the same structure microscopically Structure Good blood supply (must support epithelium) Cells farther apart than epithelium Have fibers in between the cells Background of either fluid, solid or semi-solid Structure • Solid background: bone • Semi-solid background: cartilage, loose connective • Fluid background: blood Major Cell Types • Fibroblasts: produce 3 types of connective fibers 1. collagenous (made from collagen); a tough white fiber as in tendons Fibroblasts produce • 2. Elastic fibers: most abundant, appear yellow, made from elastin, are weaker, can stretch. • Found in vocal chords and walls of blood vessels Fibroblasts produce • 3. Reticular: found in lymph organs, digestive and respiratory passages Major Cell Types • Macrophages (engulfers) • Mast Cells: produce heparin, which prevents blood clotting and histamine, which reacts in allergies and inflammation Examples of Connective • Loose fibrous connective: binds epithelium to under layers Examples of Connective • Adipose: fat storing • Cells get larger as fat is added Examples of Connective • Dense fibrous connective: closely packed fibers • Ligaments Examples of Connective • Bone: most rigid • Made in concentric circles Examples of Connective • Blood: consists of plasma, red blood cells, white blood cells, many dissolved substances and fibers Examples of Connective • Cartilage: fibers and background make it flexible; • 3 types of cartilage Muscle Tissue • • • • Three types: 1. Skeletal 2. Smooth 3. Cardiac • Can contract Skeletal Muscle • • • • Voluntary Attaches to bone Long threadlike fibers Striated (appears striped) • Each cell has many nuclei Smooth Muscle • Involuntary • Not striated (smooth) • Spindle shaped cells with one large nucleus • Found in walls of internal organs and blood vessels Cardiac Muscle • • • • Only in the heart Involuntary Striated Special branches to interconnect cells • This makes the message to contract reach all cells at about the same time • Cell to cell communication proteins help with this also Nervous Tissue • Found in brain, spinal cord, and nerves • Basic cell is the neuron • Neurons can respond to a stimulus and send an impulse Neuron Nervous Tissue • Mixed in with the neurons are support cells called Neuroglial cells • They support, bind, and contain the blood supply • Neuroglial cells do not receive and send impulses The purple are axons from neurons; the pink cells are neuroglial cells