Classification of Tissues Based on the Functions Performed

Scientists divide animal tissues into four classes based on the functions they perform.

The first class includes all those tissues that serve an animal’s needs for growth, repair and energy. Tissues that secure oxygen and excrete carbon dioxide are extremely variable in the animal kingdom. In many invertebrates gas exchange takes place through the body wall or external gills, but in species adapted to a terrestrial life, an internal sac capable of expansion and contraction served this purpose, and gradually became more complex over evolutionary time as animals’ demand for oxygen increased.

The tissues of the second class fall into two groups: physical (nervous and sensory tissues), which operate via electrical impulses along nerve fibers; and the chemical (endocrine tissues), which release hormones into the bloodstream. In vertebrates the same tissues perform both physical and chemical coordination because the nervous tissues also serve as hormone sources. In vertebrates most endocrine functions are isolated in specialized glands, several of which are derived from nervous tissue. The basic unit of all nervous tissues is the neuron, aggregations of which are called ganglia. The bundles of axons along which neurons transmit and receive impulses are called nerves.

The third class of tissues serves to bind the other tissues and organs together and to support the body. They are derived mainly from certain embryonic cells that have numerous delicate protoplasmic processes. Tissues of this group later become of diverse form and usually produce much intercellular substance, so that the cells themselves are less conspicuous.

Muscle tissue is primarily responsible for movement. It consists of contractile cells. There are two general types of muscle: striated muscle, which moves the skeleton and is under voluntary control; and smooth muscle; which surrounds the walls of many internal organs and cannot normally be controlled voluntarily.

The fourth class of tissues includes reproductive tissues, hemopoietic tissues, and tissues fluids. The most important reproductive tissues are the gonads (ovaries and testes), which produce the gametes (eggs and sperm respectively). Hemopoietic tissues produce the cellular components of the blood.

Among the important tissues fluids are lymph, cerebrospinal fluid, and milk (in mammals).

Дайте відповіді на запитання.

1.What is a tissue?

2.What structure does it have?

3.How are tissues divided?

4.What are the main methods of tissues classification?

5.How many classes of animal tissues do scientists usually determine?

6.What does the first class of animal tissues include?

7.Can you describe both groups into which the tissues of the second class fall?

8.What purpose does the third class of tissues serve?

9.What is the basic unit of all nervous tissues?

10.What is the primary responsibility of muscle tissues?

11.How many general types of muscle exist?

12.What kinds of tissues are in the fourth class?

13.Where one can find the most important reproductive tissues?

14.What components of the blood do hemopoietic tissues produce?

Вправи

I. Згрупуйте подані нижче слова за частинами мови.

Іменник	Дієслово	Прикметник
tissue	compose	terrestrial

tissue, compose, epithelial, cell, include, variable, derive, origin, transmit, composition, terrestrial, receive, bind, compose, external, support, demand, increase, fall into, fluid, endodermal, exchange, adapt, embryonic, divide, perform, growth, repair, energy, secure, excrete, glands, unit, substance, expansion, lymph.

II. Заповніть пропуски словами some або any.

1. I have _____ English journals at home.

2. We have not received ______ offers from British companies.

3. My colleagues have ______ good pictures of embryonic cells movement.

4. Do you have ______ scientific papers about tissues structure and function to look through today?

5. Ann does not have _______ books about London.

6. There are _______ exotic animals in our city zoo.

7. Our dean is going to buy _______ new equipment for biochemical labs.

8. Would you like _______ tea with milk?

9. Do you know _______ recreation zones in Kyiv?

10. I would like _______ mineral water.

III. Заповніть пропуски у реченнях, використовуючи слова у дужках.

1. Tissues (in physiology) is a level of __________ in multicellular organism.

2. An early scientific ___________ of tissues divided them on the basis of the organ system.

3. Scientists divide animal tissues into four classes based on the _________ they perform.

4. In vertebrates, the same tissues _________ both physical and chemical coordination.

5. The basic unit of all __________is the neuron, aggregations of which are called ganglia.

6. Muscle tissue is primarily responsible _________; it consists of contractile cells.

7. The most important __________ tissues are the gonads.

(1.classification; 2.organization; 3.functions; 4.nervous tissues;5. perform; 6.for movement; 7.reproductive).

IV. Складіть речення.