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