Muscles and their Structure in the Human Body

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The muscular system is the biological system of humans that produces movement. The muscular system is controlled through the nervous system, but some muscles, like cardiac muscle, can be completely autonomous. Muscle is contractile tissue and is derived from the mesodermal layer of embryonic germ cells. Its function is to produce force and cause motion, either locomotion or movement within internal organs. Much of muscle contraction occurs without conscious thought and is necessary for survival, like the contraction of the heart or peristalsis, which pushes food through the digestive system. Voluntary muscle contraction is used to move the body and can be controlled, such as movements of fingers or movements of biceps and triceps.

Muscle is composed of muscle cells (sometimes known as " muscle fibers" ). The bundles of muscle cells are grouped together to form muscle. Skeletal muscles, which involve muscles from the skeletal tissue, are arranged in groups. An example is the biceps brachii. It is connected by tendons to processes of the skeleton. In contrast, smooth muscle occurs in almost every organ, from the skin (in which it controls straightening of body hair) to the blood vessels and digestive tract (in which it controls peristalsis).

Types of Body Muscles

There are approximately 640 skeletal muscles in the human body. There are three basic types of muscles in the body (smooth, cardiac, and skeletal). They differ in many regards and can create contraction and relaxation. In skeletal muscle, contraction is stimulated at each cell by nervous impulses, Muscular activity accounts for most of the body's energy consumption. Muscles store energy for their own use in the form of glycogen, which represents about 1% of their mass. Glycogen can be rapidly converted to glucose when more energy is necessary.

Smooth muscle or " involuntary muscle" is found within the walls of organs and structures such as the esophagus, stomach, intestines, bronchi, bladder, and blood vessels. Smooth muscle cells contain only one nucleus.

Cardiac muscle is also an " involuntary muscle" but it is striated in structure. Like smooth muscle, cardiac muscle cells contain only one nucleus. Cardiac muscle is found only within the heart.

Skeletal muscle or " voluntary muscle" is fixed by tendons to the bone and is used to produce skeletal movement such as locomotion. Skeletal muscle cells are multinucleated with the nuclei peripherally located. Skeletal muscle is called 'striated' because of the longitudinally striped appearance under light microscopy.

Blood Groups and Transfusion

Blood transfusion is a very common hospital procedure nowadays. But this is more than just taking blood from one person and using it to help another. Although all blood contains the same basic components (red cells, white cells, platelets, and plasma), not everyone has the same types ofmarkerson the surface of their red blood cells. These markers (also calledantigens) are proteins and sugars that our bodies use to identify the blood cells as the cells of our own system. So, medical experts group blood into four types based on the different markers. The four main blood groups are: blood group A has a marker known as " A", blood group B has a marker known as " B." In blood group AB the blood cells have both A and B markers. Blood group O has neither A or B markers.

Blood cell markers are microscopic. Each unit of blood goes through a dozen tests to check for infectious diseases and establish the blood type. Only after these tests the blood transfusion can be given to the recipient. About 5 million Americans need blood transfusions every year, for all sorts of reasons. Sometimes, a transfusion is an emergency (like losing blood after an accident). Sometimes it's expected (as with treatment for cancer).

Lymphatic System and Lymph Organs

The lymphatic system consists of organs, ducts, and nodes. The lymph vessels form a network in the body as the blood network. It transports a watery clear fluid called lymph. This fluid distributes immune cells and other factors throughout the body. It also interacts with the blood circulatory system to drain fluid from cells and tissues.

Lymph organs are found in every part of the body except the central nervous system. The major parts of the system are the bone marrow, spleen, thymus gland, lymph nodes, and the tonsils. The other organs of the body, including the heart, lungs, intestines, liver, and skin also contain lymphatic tissue. The ducts of the lymphatic system provide transportation for proteins, fats, and other substances in lymph. The lymph is drained from the tissue in microscopic blind-ended vessels called lymph capillaries.

Lymph nodes are filters of lymph. They may become enlarged due to a tumor or infection. The spleen is a filter of blood.

The lymphatic system contains immune cells called lymphocytes, which protect the body against antigens (viruses, bacteria, etc.) that invade the body and, in such a way, it defends the body against diseases.

Classification of Tissues

Cells are the smallest units of life. In complex organisms, cells group together with one another and function to form tissues. Tissues provide the numerous functions of organs. They maintain biological life. The study of tissues is called histology, and is important to the understanding of how the human body is able to function as a unit.

The human body is composed of four basic types of tissues; epithelium, connective, muscular, and nervous tissues.

These tissues vary in their composition and their function. Epithelium forms the coverings of surfaces of the body. As such, it serves many purposes, including protection, adsorption, excretion, secretion, filtration, and sensory reception. Connective tissue is the most widely distributed tissue type found in the human body. The role of connective tissue is to protect, support, and bind together parts of the body. Muscular tissue is a tissue characterized by the ability to contract upon stimulation; its three varieties are skeletal, cardiac, and smooth. It is an extremely elastic one that can shorten or elongate to produce movement. Nervous tissue receives stimuli and conducts impulses. It is the main component of the nervous system and the brain.

VIII. Tasks on Speaking

Speak on the following:

1. About myself and my studies at a higher medical school.

2. A higher medical school where I study.

3. Students’ studies and how they spend their free time.

4. Medical education in Russia.

5. Medical education in the USA and the UK.

6. Features of medical education in Russia and English-speaking countries (the USA and UK).

7. Names of different medical specialties and jobs of different specialists.

8. Daily routine of physicians.

9. Specific jobs of different specialists.

10. Healthcare system in the UK and the USA.

11. Features of healthcare system in Russia and English-speaking countries.

12. Ethics, medical ethics and bioethics.

13. The main principles and rules of medical bioethics.

14. Types of medical institutions providing health care.

15. Hospital departments and hospital jobs.

16. The work of the hospital staff.

17. Duties of a doctor in the hospital.

18. The procedure of clinical examination of patients.

19. The results of the physical examination of patients.

20. Different types of medical emergencies.

21. First aid procedures, instructions how to give first aid.

22. Different types of pharmacy.

23. The work of chemist’s shops.

24. Types and forms of medications and ways of their storage.

25. Different types of medications.

26. The routes of drug administration.

27. Directions for drug use.

28. Nutritional value of different foods.

29. Balanced and unbalanced diet.

30. Role of balanced diet for person’s health.

31 Give recommendations as for healthy nutrition

32 The structure of the human body.

33. The organs of the oral, thoracic and pelvic cavities.

34. The structure of the extremities.

35. The structure of the cell.

36. Chemical substances of the cell.

37. Basic types of tissues.

38. The structure of the organs of the human body.

39. The main bones of the human body.

40. The processes of bone formation and growth.

41. Types of muscles.

42. The functions of three types of muscles.

43. Composition of blood.

44. Functions of three types of blood cells.

45. Blood types in the ABO system.

46. Mechanism of blood transfusion and indications for blood transfusion.

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