b. Types of Bone Tissues. There are two major types of bone tissue. One is
compact bone CT, which is dense. The other is cancellous bone CT, which is spongy.
Compact bone CT forms the hard outer layers of bones as organs. Cancellous bone
CT forms the inner, lighter portion of bones.
2-12. FAT CONNECTIVE TISSUE
a. Fat Cells. A large fraction of the volume of a fat cell is occupied by a droplet
of fat. This droplet has its own membrane, in addition to the outer membrane of the cell.
The remaining components of the fat cell, including the nucleus, are found in an outer
layer of cytoplasm surrounding the droplet of fat.
b. Matrix. Fat connective tissue has a matrix of lipid (oil or fat). There may be
yellow fat CT or brown fat CT.
c. Functions. Fat CT acts as a packing material among the organs, nerves,
and vessels. Fat CT also helps to insulate the body from both heat and cold. Some fat
CT serves as a high-energy storage area.
2-13. BLOOD "CONNECTIVE TISSUE"
Some experts consider blood to be a type of connective tissue. Blood will be
discussed in lesson 9.
Section IV. MUSCLE TISSUES
There are muscle tissues and there are organs called muscles. Muscles are
made up of muscle tissues. Muscle tissues and the muscles they make up are
specialized to contract. Because of their ability to shorten (contract), muscles are able
to produce motion.
2-15. TYPES OF MUSCLE TISSUES
See figure 2-3 for the three types of muscle tissue.
a. Skeletal Muscle Tissue. The cells (muscle fibers) of skeletal muscle tissue
are long and cylindrical and have numerous nuclei. The arrangement of the cellular
contents is very specific and results in a striated appearance when viewed with the
microscope. This type of muscle tissue is found mainly in the skeletal muscles.