The human body is rather like a highly technical and sophisticated machine. It operates as a single entity, but it is made up of several systems that work interdependently. Each system is associated with a specific function that is normally essential for the well-being of the individual. If one system fails means the consequences or impact can extend to others, and may greatly reduce the ability of the body to function normally.
Before studying anatomy and physiology should know the meaning of these which is normal as well as the need to know abnormality, are below -
• Anatomy - Anatomy is the study of the structure of the body and the physical relationships between its constituent parts.
• Physiology - Physiology is the study of how the body systems work and how their integrated activities maintain the life and health of the individual.
• Pathology and pathophysiology - Pathology is the study of abnormalities and Pathophysiology is the study of how they (abnormality) affect body functions, often causing illness.
For survival, many essential processes must be carried out within the body. Some involve communication and transport, others relate to taking in raw materials and getting rid of wastes and yet others ensure the body remains able to protect itself and that the human species survive.
The use of standardized anatomical terminology enables the physical relationships between structures within the body to be described accurately and communicated consistently.
Most body systems become less efficient with age. The physiological decline is a normal part of aging and should not be confused with illness or disease, although some conditions do become more common in older life. Maintaining a healthy lifestyle can not only slow the effects of aging but also protect against illness.
Survival needs of the body and related body activities:-
• Communication - Communication requires transport systems to ensure that all body cells are supplied with the very many substances needed to support them, as well as allowing for waste excretion; this involves the blood and the cardiovascular and lymphatic systems.
Communication systems receive, collate and respond to information that may originate either within the body(internally)or from its environment(externally). Internal communication involves mainly the nervous and endocrine systems; these are important in the maintenance of homeostasis (A property of cells, tissues, and organisms that allows the maintenance and regulation of the stability and constancy needed to function properly. Homeostasis is a healthy state that is maintained by the constant adjustment of biochemical and physiological pathways.) and regulation of vital body functions. Communication with the external environment involves the special senses and verbal and non-verbal activities, and all of these also depend on the nervous system.
° Transport systems-
(I) Blood:- The blood transports substances around the body through a large network of blood vessels. In adults, the body contains 5-6 liters of blood. It consists of two parts: a fluid called plasma and blood cells suspended in the plasma.
=> Plasma-
This is 90% water with a wide range of substances dissolved or suspended in it. These include:-
• Nutrients absorbed from the alimentary canal
• Oxygen absorbed from the lungs
• Chemical synthesized by body cells, e.g. hormones
• Waste materials produced by all cells to be eliminated from the body by excretion.
=> Blood cells-
There are three distinct groups, classified according to their functions.
• Erythrocyte - Also known as red blood cells(RBC), RBC transports oxygen and to a lesser extent, carbon dioxide between the lungs and all body cells.
• Leukocytes- Also known as white blood cells (WBC), are mainly concerned with the protection of the body against infection and foreign substances. There are several types of leukocytes, which carry out their protective functions in different ways. These cells are larger and less numerous than erythrocytes.
• Thrombocytes -Also known as platelets, are tiny cell fragments that play an essential part in blood clotting.
(II) Cardiovascular system-
The cardiovascular system consists of a network of blood vessels and the heart.
=> Blood vessels:-
There are three types :
• Arteries - which carry blood away from the heart.
• Veins- which return blood to the heart.
• Capillaries- which link the arteries and veins.
Capillaries are tiny blood vessels with very thin walls consisting of only one layer of cells, which enables the exchange of substances,
Such as nutrients, oxygen, and cellular waste products, between the blood and body tissues. Blood vessels form a massive network that transports blood to - (i) The lungs(pulmonary circulation), where oxygen is absorbed from the air in the lungs and at the same time, carbon dioxide is excreted from the blood into the air. (ii) Cells in all other parts of the body (general or systemic circulation).
=> Heart:-
The heart is a muscular sac with four chambers, which pumps blood around the body and maintains blood pressure.
The heart muscles are not under conscious (voluntary) control. At rest the heart contracts, or beats, between 60 and 100 times per minute. The rate is greatly increased when the body oxygen requirements are increasing, e.g. during exercise.
The rate at which the heart beats can be counted by raking the pulse. The pulse can be felt most easily where a superficial artery can be pressed gently against a. Bone, usually at the wrist.
(III) Lymphatic system:-
The lymphatic system consists of a series of lymph vessels, which begin as blind-ended tubes in the tissue spaces between the blood capillaries and tissue cells.
Structurally, they are similar to veins and blood capillaries but the pores in the walls of the lymph capillaries are larger than those of the blood capillaries. Lymph is tissue fluid that also contains material drained from tissue spaces, including plasma proteins and sometimes, bacteria or cell debris. It is transported along lymph vessels and returned to the bloodstream near the heart.
There are collections of lymph nodes situated at various points along the length of the lymph vessels. Lymph is filtered as it passes through these nodes, removing microbes and other materials. Other lymphatic organs include the spleen and the thymus.
The lymphatic system also provides the sites for the formation and maturation of lymphocytes, which are also known as white blood cells involved in immunity.
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