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 Cells farther apart than epithelium Have fibers in between the cells Background of either fluid, solid or semi-solid Good blood supply (must support epithelium)

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