Tissues are groups of cells with a common structure (form) and function. The study of tissues is known as histology. The study of tissues in connection with diseases of tissues is known as histopathology.
There are four main tissues in the body – epithelial tissue, connective tissue, muscular tissue, and nervous tissue.
Epithelial Tissue. Epithelial tissue is commonly referred to as epithelium. It covers body surfaces and internal organs and lines body cavities. Functions include lining, protecting, and forming glands. Epithelial tissue may be classified by shape into: a) squamous - flat-like; b) cuboidal - tall and wide; c) columnar - column-shaped; d) ciliated. Ciliated epithelium performs the function of moving particles or fluid over the epithelial surface in such structures as trachea, bronchial tubes, and nasal cavities.
Schematic view of simple squamous epithelium
Epithelial tissue may be also classified by cell arrangement into a) simple epithelium and b) compound epithelium. Simple epithelium consists of a single layer of cells. Compound epithelium is made of two or more cell layers. It functions as a protective covering, as it does in our skin, for example.
Connective tissues. Connective tissues are the most abundant tissues in animal body. Connective tissues serve many purposes: binding, supporting, protecting, forming blood, storing fats, filling space. The connective tissues include cartilage, bone, adipose, and blood. All connective tissues, except blood, secrete structural proteins called collagen or elastin. Connective tissues are classified into three types: Loose Connective tissue, Dense Connective tissue, and Specialized Connective tissue. Loose Connective tissues have cells and fibers that are loosely arranged in a semi-fluid ground substance. Loose Connective tissue includes Areolar tissue, Adipose tissue and Reticular tissue. Areolar tissue is present beneath the skin and serves as a framework support for epithelium, it also attaches epithelium to underlying tissues. Adipose tissue specializes in storing fats, it is found around organs and in subcutaneous layer (between skin and muscle). Reticular connective tissue is found around liver, kidney, spleen and lymph nodes. It provides support for these soft organs. Dense Connective tissues have fibers and fibroblasts that are packed compactly. It provides connection between different tissues in the human body. Tendons are dense regular tissue that attach skeletal muscle to bones and ligaments attach bone to another bone. Collagen is the dense irregular tissue present in the skin. Specialized Connective Tissue. Cartilage, bones and blood are types of specialized connective tissue. Cartilage is solid, pliable tissue. Cartilage is present in the tip of the nose, outer ear joints, between bones of vertebral column. Bones are hard and non-pliable, rich in calcium salts and collagen fibers. They provide structural frame to the body. The bone marrow in some bones is the place where blood cells are produced. Blood is a fluid connective tissue. It contains plasma, RBCs, WBCs and platelets.
Muscular Tissue. Muscle tissue is a soft tissue that composes muscles in animal bodies. Muscle tissues are tissues made of cells able to perform contractions and therefore generate movement. Muscle tissue varies with function and location in the body. In mammals, there are three types of muscle tissue: skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscle is found in the muscles that move bones. The walls of internal organs contain smooth muscles. Cardiac muscle tissue is present only in the heart. The main function of cardiac tissue is pumping blood through the body.
Nervous tissue is composed of two main cell types: neurons and glial cells. Neurons transmit nerve messages. Glial cells are in direct contact with neurons and often surround them. The function of nervous tissue is to receive and to transmit nervous impulses (the reception and transmission of information).
Exercise 1. Complete the table on Tissues.
| Type of tissue | Location | Function |
| Epithelial tissue | ||
| Connective tissue | ||
| Loose connective tissue | ||
| Areolar tissue | ||
| Adipose tissue | ||
| Reticular tissue | ||
| Dense connective tissue | ||
| Specialized connective tissue | ||
| Muscular tissue | ||
| Skeletal tissue | ||
| Smooth tissue | ||
| Cardiac tissue | ||
| Nervous tissue |
Exercise 2. Complete the following sentences. Choose the ending according to the text.
1. There are four main tissues in the body – ….
2. Epithelial tissue may be classified by shape into: ….
3. Connective tissues serve many purposes: ….
4. Connective tissues are classified into three types: ….
5. Loose Connective tissue includes ….
6. Dense connective tissue provides....
7. Muscle tissue is a soft tissue that composes….
8. The function of nervous tissue is ….
Exercise 3. a) Make up collocations using the words from both columns.
| subcutaneous | epithelium |
| pliable | muscle |
| bone | organs |
| internal | tissue |
| ciliated | layer |
| cardiac | marrow |
b) Fill in the gaps with the words from the table above.
1. Cartilage is solid, …. Cartilage is present in the tip of the nose, outer ear joints, between bones of vertebral column.
2. The … in some bones is the place where blood cells are produced.
3. … performs the function of moving particles or fluid over the epithelial surface in such structures as trachea, bronchial tubes, and nasal cavities.
4. Epithelial tissue is commonly referred to as epithelium. It covers body surfaces and … and lines body cavities.
5. In mammals there are three types of muscle tissue: skeletal muscle, smooth muscle and ….
6. Adipose tissue specializes in storing fats, it is found around organs and in … (between skin and muscle).
Exercise 4. Translate the derivatives.
1. To protect, protecting, protection, protective.
2. To classify, classification, classifying, classifiable.
3. To arrange, arranging, arrangement, arranger.
4. To digest, digesting, digestion, digestive.
Exercise 5. Give the English equivalents of the Russian words in brackets.
1. Muscle tissues are tissues made of cells able (производить сокращения и вызывать движение). 2. Muscle tissue varies (функции и расположение в теле). 3. Loose Connective tissue includes (ареолярная ткань, жировая ткань и ретикулярная ткань). 4. Compound epithelium (состоять из двух или более слоев клеток).5. Soft muscle is found in various parts of the body (таких как артерии, мочевой пузырь, пищеварительный тракт) as well as in many other organs. 6. The function of nervous tissue is (получать и передавать нервные импульсы).
Exercise 6. The answers to the following questions are the summary of the text. Answer these questions and give the summary of the text.
1. What are the main types of animal tissue?
2. What are epithelial tissues?
3. What is their function?
4. What are the different types of epithelium based on the number of cell layers?
5. What are the different types of epithelium based on cell shape?
6. What are the general functions of connective tissues?
7. What are the three types of loose connective tissue?
8. What type of tissue composes cartilage and bones?
9. What are the reticular fibers of connective tissue and where can they be found? 10. What structures in the body are made primarily of dense regular connective tissue?
11. Which cells is nervous tissue made of?
VOCABULARY LIST TO TEXT B
| anemia n | [əˈniː.mi.ə] | анемия |
| arteriole n | ɑːˈtɪə.ri.əʊl] | мелкая артери |
| artery n | [ˈɑː.tər.i] | артерия |
| capillary n | [kəˈpɪl.ər.i] | капилляр |
| carbon dioxide n | [ˈkɑː.bən daɪˈɒk.saɪd] | углекислый га | |||
| chamber n | [ˈtʃeɪmbə(r)] | камера | |||
| clot v | [klɒt] | свертываться | |||
| constitute v | [ˈkɒn.stɪ.tjuːt] | составлять | |||
| dissolve v | [dɪˈzɒlv] | растворить | |||
| germ n | [dʒɜːm] | микроб |
| heart (attack) n | [hɑːt] | сердечный приступ |
| liquid n | [ˈlɪkwɪd] | жидкость |
| lymphocyte n | [ˈlim.fə.saɪt] | лимфоцит |
| monocyte n | [ˈmɒnə.sait] | моноцит |
| polycythemia n | [polisaiˈthimiə] | полицитемия |
| stroke n | [strəʊk] | инсульт |
| thrombocythemia n | [thrɑmbōˌsai-ˈthimiə] | тромбоцитемия |
| thrombocytopenia n | [thrɑmbəˌsaitə-ˈpiniə] | тромбоцитопения |
| venule n | [ˈvēnyül] | маленькая вена |
| volume n | [ˈvɒljuːm] | объем |
BLOOD
Blood is a specialized type of connective tissue. It is found inside the blood vessels (arteries, arterioles, capillaries, venules and veins) and also within the chambers of the heart. Some of the blood cells are also found in other types of body tissues, for example, lymphocytes are found in the lymphatic system. The main components of blood include: plasma, red blood cells, white blood cells and platelets. Blood plasma is a pale colored liquid, which constitutes 55% of blood fluid, is mostly water (92% of its volume), and contains dissolved glucose, hormones, carbon dioxide and blood cells themselves.
Erythrocytes. The red blood cells (also called erythrocytes) make up about 40% of the blood's volume. Red blood cells contain hemoglobin, a protein that gives blood its red color and enables it to carry oxygen from the lungs and deliver it to all body tissues. Oxygen is used by cells to produce energy that the body needs, leaving carbon dioxide as a waste product. Red blood cells carry carbon dioxide away from the tissues and back to the lungs. When the number of red blood cells is too low (anemia), blood carries less oxygen, and fatigue and weakness develop. When the number of red blood cells is too high (polycythemia), blood can become too thick, which may cause the blood to clot more easily and increase the risk of heart attacks and strokes. Leucocytes. White blood cells (also called leukocytes) are fewer in number than red blood cells. White blood cells are responsible primarily for defending the body against infection. There are five main types of white blood cells: neutrophils, lymphocytes, monocytes, eosinophils and basophils. All of them have different functions within the immune system: protect the body against infections, produce antibodies, etc.
Thrombocytes. Blood platelets (more formally called “thrombocytes”) are very small disc-shaped cell-like particles that are smaller than red or white blood cells. They have an important role in blood clotting and so they gather at locations of injury. When the number of platelets is too low (thrombocytopenia), bruising and abnormal bleeding become more likely. When the number of platelets is too high (thrombocythemia), blood may clot excessively, causing a stroke or heart attack.
Functions of blood. 1. Transportation. Blood is the primary means of transport in the body. It is responsible for transporting oxygen, nutrients, enzymes and hormones to and from the cells that make up our body and removing wastes.
2. Protection. Blood performs the important task of protecting the body from infections. The white blood cells found in blood are responsible for producing antibodies and proteins, which are capable of fighting off and killing the germs and viruses that can cause serious damage to the body cells. 3. Regulation. Blood is also a regulator of many factors in the body. It regulates the temperature of the body, body pH and water balance.
