Cells and Tissues

Epithelial Tissue Covers body surfaces and lines body

cavities. Functions include lining, protecting, and forming glands. Three types of epithelium occur: Squamous epithelium is flattened cells. Cuboidal epithelium is cube-shaped

cells. Columnar epithelium consists of

elongated cells.

• Any epithelium can be simple or stratified. Simple epithelium has only a single cell layer. Stratified epithelium has more than one layer of cells.

•Pseudostratified epithelium is a single layer of cells so shaped that they appear at first glance to form two layers.

Epithelial Tissue

Functions of epithelial cells include

movement materials in, out, or around the body.

protection of the internal environment against the external environment.

Secretion of a product.

glands

Glands can be single epithelial cells, such as the goblet cells that line the intestine.

Vertebrates have

keratin in their skin cells to reduce water loss.

Many other animals secrete mucus or other materials from their skin, such as earthworms do.

Connective tissue serves many purposes in the body:

binding supporting protecting forming blood storing fats filling space

Connective cells are separated from one another by a non-cellular matrix. The matrix may be solid (as in bone), soft (as in loose connective tissue), or liquid (as in blood).

Adipose tissue has enlarged fibroblasts storing fats and reduced intracellular matrix. Adipose tissue facilitates energy storage and insulation.

Cartilage and bone are "rigid" connective tissues. Cartilage has structural proteins deposited in the matrix between cells

Bone has calcium salts in the matrix, giving it greater strength. Bone also serves as a reservoir (or sink) for calcium.

Blood is a connective tissue of cells separated by a liquid (plasma) matrix. Two types of cells occur. Red blood cells (erythrocytes) carry oxygen. White blood cells (leukocytes) function in the immune system

Muscle tissue facilitates movement of the animal by contraction of individual muscle cells (referred to as muscle fibers). Three types of muscle fibers occur in animals skeletal (striated) smooth cardiac

Nervous tissue functions in the integration of

stimulus and control of response to that stimulus. Nerve cells are called neurons. Each neuron has a cell body, an axon, and many dendrites. Nervous tissue is composed of two main cell types: neurons and ganglial cells. Neurons transmit nerve messages

Organs and Organ Systems

THE INTEGUMENTARY SYSTEM THE CIRCULATORY SYSTEM LYMPHATIC SYSTEM AND IMMUNITY THE DIGESTIVE SYSTEM THE NERVOUS SYSTEM THE ENDOCRINE SYSTEM THE REPRODUCTIVE SYSTEM THE MUSCULAR AND SKELETAL SYSTEMS THE RESPIRATORY SYSTEM THE EXCRETORY SYSTEM