Animal Tissue

Epithelial tissueConnective tissue

Muscle tissueNervous tissue

Organs in animals are composed of a number of different tissue

types.

Epithelial Tissue

covers body surfaces and lines body cavities. Functions include lining, protecting, and forming glands.

• Squamous epithelium is flattened cells. • Cuboidal epithelium is cube-shaped cells. • Columnar epithelium consists of elongated

cells.

Note the single layer of simple cuboidal epithelium lining either side of a tubule.

one of the columnar epithelium cells

Functions of epithelial cells

• movement materials in, out, or around the body.

• protection of the internal environment against the external environment.

• Secretion of a product.

Connective Tissue

• binding • supporting • protecting • forming blood • storing fats • filling space

Loose Connective Tissue (LCT)

• Fibroblasts • occurs beneath

epithelium in skin and many internal organs

• forms a protective layer over muscle, nerves, and blood vessels.

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

• Fibrous Connective Tissue

• many fibers of collagen

occurs in • tendons, connect

muscle to bone. • Ligaments connect

bone to bone at a joint.

Solid connective tissue (bone)

Note the haversian canal and surrounded by osteocytes and a mineralized matrix.

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

Liquid(plasma) connective tissue (Blood)

• Red blood cells (erythrocytes) carry oxygen.

• White blood cells (leukocytes) function in the immune system.

• Plasma transports dissolved glucose, wastes, carbon dioxide and hormones, as well as regulating the water balance for the blood cells.

• Platelets are cell fragments that function in blood clotting.

(erythocytes = red; platelets = yellow; T-lymphocyte = light green)

Muscle Tissue

• skeletal (striated) • smooth • cardiac • Muscle fibers are multinucleated,

with the nuclei located just under the plasma membrane. Most of the cell is occupied by striated, thread-like myofibrils.

Skeletal (striated) muscle

• These cells function in conjunction with the skeletal system for voluntary muscle movements.

Smooth muscle • These cells function in

involuntary movements and/or autonomic responses (such as breathing, secretion, ejaculation, birth, and certain reflexes).

• spindle shaped cells that form masses. These fibers are components of structures in the digestive system, reproductive tract, and blood vessels.

Cardiac muscle

• a type of striated muscle found only in the heart.

• The cell has a bifurcated (or forked) shape, usually with the nucleus near the center of the cell.

• The cells are usually connected to each other by intercalated disks.

Nervous Tissue

• Dendrites receive information from another cell and transmit the message to the cell body. The cell body contains the nucleus, mitochondria and other organelles typical of eukaryotic cells. The axon conducts messages away from the cell body.

Pyramidal Neurons from the Central Nervous System (SEM x3,960).