Tissues

The cells of this tissue are called nerve cells or neurons.

The brain, spinal cord and nerves are all composed of the nervous tissue. The cells of this tissue are called nerve cells or neurons. Many nerve fibres bound together by the connective tissue make up a nerve.

In desert plants, epidermis has a thick waxy coating of cutin. Cutin checks loss of water in desert plants.

The lateral meristem is concerned with secondary growth. Its meristematic activity adds cells to the primary body, which is derived from the apical meristems.

In the xylem, the substances move only in the upward direction, but in the phloem, substances move in both the directions.

Epithelial tissues are formed by layers of cells that cover organ surfaces such as the surface of the skin, the airways and the inner lining of the digestive tract.

Xylem is responsible for the transport of water and soluble mineral nutrients from the roots to all the parts of the plant. Along with that, it is also responsible for replacing water lost during transpiration and photosynthesis.

Blood is a highly specialised circulating tissue consisting of several types of cells suspended in a fluid medium known as plasma.

Phloem complex tissue is composed of sieve tubes, companion cells, phloem fibres and phloem parenchyma. The main function of the seive tube is to transport organic compounds.

Muscle tissue consists of elongated cells called muscle fibres which have the ability to contract and relax. Muscle tissues are responsible for the movement in our body.

Apical meristem is present at the growing tips of stems and roots and increases the length of the stem and the root.

Large air cavities are present in the simple parenchyma of the aquatic plants. These cavities gives buoyancy to the aquatic plants to help them float in water. This type of parenchyma is known as aerenchyma.

Xylem is a dead, complex permanent tissue of plants. It is composed of tracheids, vessels, xylem fibres and xylem parenchyma. Xylem parenchyma is the only living tissue of the xylem responsible for the storage of food.

Phloem complex tissue is composed of sieve tubes, companion cells, phloem fibres and phloem parenchyma. Companion cells regulate the metabolic activities of the sieve tube elements.

Ciliated epithelium is cuboidal or columnar epithelium bearing several hundred cilia on its free end. It lines the respiratory passage, oviducts, etc.

Bone is the hardest tissue in the body and its hardness is due to calcification of its matrix. Bone is the main constituent of the skeleton.

Bone is a calcified connective tissue. Bone cells are embedded in a hard matrix that is composed of calcium and phosphorus compounds. It has lacunae and haversian canal in its structure.

Cardiac muscles are found only in the heart. These muscles show rapid rhythmical contraction and relaxation, long refractory period and do not show fatigue.

Epithelial tissue forms the protective covering of the animal body. It gets modified to perform various functions such as:
1. Protection: It acts as a barrier between the outer world (or inner spaces) and our bodies.
2. Absorption and secretion: When absorption and secretion occurs, the epithelial tissue facilitates movement across the epithelial barrier.
3. Excretion: Epithelial tissue even lines the excretory lumina, like the tracts from the kidneys to the urethra.

Smooth muscles or the involuntary muscles are the spindle shaped striated muscle fibres found in the iris of the eye, uterus and bronchi of the lungs. Smooth muscle fibres control the involuntary movement in these organs.

The periderm protects the plant from injuries, pathogens and also from excessive water loss.

Cuboidal epithelium is composed of cube shaped cells that provide mechanical support to the various organs such as kidney tubules, ducts of salivary glands, etc. The nuclei of these cells are usually located at the centre.

The growth in plants is limited to certain regions, thus meristmatic tissue or dividing tissue in plants is localised to these regions. However, cell growth in animals is more uniform. So, there is is no demarcation of dividing and non-dividing regions in animals.

Parenchyma cells also control plant's metabolism like photosynthesis, respiration, protein synthesis.

It is dead with hollow cells and consists of only the cell wall.