Structural Organisation in Animals Test - 4

In all connective tissues except blood, the cells secrete fibres of structural proteins called collagen or elastin.

The connective tissues have soft tissues to specialised types, which include cartilage, bone, adipose, and blood.

The cuboidal epithelium is composed of a single layer of cube-like cells found in ducts of glands and tubular parts of nephrons in kidneys and its main functions are secretion and absorption.

The columnar epithelium is found in the lining of stomach and intestine and help in secretion and absorption. It also provides barrier against harmful micro organisms.

In between cardiac muscle fibres, there are communication junctions which are made up of intercalated discs.

The ciliated epithelium is mainly present in the inner surface of hollow organs like bronchioles and fallopian tubes.

The figure is identified as salivary gland. It is multicellular and is lined with glandular epithelium cells. These types of cells are specialized in production and release of particular kind of digestive juices or sweat or oil. Salivary gland secretes alkaline fluid called saliva.

Smooth muscles are ‘involuntary’ muscles as they can't be directly controlled. We usually are not able to make it contract merely by thinking about it as we can do with skeletal muscles. Involuntary muscles are under control of medulla oblongata and part of cerebrum.  Smooth muscles are spindle shaped or fusiform, uninucleated and unstraited fibres.The wall of internal organs such as the blood vessels, stomach and intestine contains this type of muscle tissue.

Apart from being connective tissue, Areolar tissue is also protective in nature. It has large number of fibroblast cells which produce fibres. Mast cells, plasma cells and macrophages help to protect against pathogens and aid in tissue repair.

The squamous epithelium is made of a single thin layer of flattened cells with irregular boundaries. They are found in the walls of blood vessels and air sacs of lungs and are involved in functions like forming a diffusion boundary.

Blood, bone, lymph forms the connective tissue that connects the different parts of the bodyNerve cells are parts of neural system or nervous system that transmit information from one part of the body to others.

Tight junctions hold cells together. They are narrow belts that circle around the upper part of lateral surfaces of the adjacent epithelial cells to create a fusion point.  They stop substances from leaking across a tissue as they prevent passage of molecules and ions through space between adjacent cells.

Dense irregular connective tissue provide strength to body parts. Hence the cells and fibres are packed compactly.

Tendons are dense connective tissue which provide strength and attach  muscles to bones.

The neuroglial cells which constitute the rest of the neural system protect and support neurons. Neuroglia makes up more than one-half the volume of neural tissue in our body.