4 Components Of Blood And Their Functions PdfBy Alfred D. In and pdf 25.11.2020 at 11:41 5 min read
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- Different Types of Blood Cells and Their Roles in the Human Body
- Overview of blood components and their preparation
- Components of Blood
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See also Overview of Blood. Plasma is the liquid component of blood, in which the red blood cells, white blood cells, and platelets are suspended. It constitutes more than half of the blood's volume and consists mostly of water that contains dissolved salts electrolytes and proteins. The major protein in plasma is albumin. Albumin helps keep fluid from leaking out of blood vessels and into tissues, and albumin binds to and carries substances such as hormones and certain drugs.
Different Types of Blood Cells and Their Roles in the Human Body
Blood , fluid that transports oxygen and nutrients to the cells and carries away carbon dioxide and other waste products. Technically, blood is a transport liquid pumped by the heart or an equivalent structure to all parts of the body, after which it is returned to the heart to repeat the process.
Blood is both a tissue and a fluid. It is a tissue because it is a collection of similar specialized cells that serve particular functions. These cells are suspended in a liquid matrix plasma , which makes the blood a fluid. If blood flow ceases, death will occur within minutes because of the effects of an unfavourable environment on highly susceptible cells. The constancy of the composition of the blood is made possible by the circulation , which conveys blood through the organs that regulate the concentrations of its components.
In the lungs , blood acquires oxygen and releases carbon dioxide transported from the tissues. The kidneys remove excess water and dissolved waste products. Nutrient substances derived from food reach the bloodstream after absorption by the gastrointestinal tract.
Glands of the endocrine system release their secretions into the blood, which transports these hormones to the tissues in which they exert their effects. Many substances are recycled through the blood; for example, iron released during the destruction of old red cells is conveyed by the plasma to sites of new red cell production where it is reused.
Each of the numerous components of the blood is kept within appropriate concentration limits by an effective regulatory mechanism. In many instances, feedback control systems are operative; thus, a declining level of blood sugar glucose leads to accelerated release of glucose into the blood so that a potentially hazardous depletion of glucose does not occur.
Unicellular organisms, primitive multicellular animals, and the early embryos of higher forms of life lack a circulatory system.
Because of their small size, these organisms can absorb oxygen and nutrients and can discharge wastes directly into their surrounding medium by simple diffusion. Sponges and coelenterates e. In larger and more-complex animals, transport of adequate amounts of oxygen and other substances requires some type of blood circulation. In most such animals the blood passes through a respiratory exchange membrane , which lies in the gills , lungs, or even the skin. There the blood picks up oxygen and disposes of carbon dioxide.
The cellular composition of blood varies from group to group in the animal kingdom. Most invertebrates have various large blood cells capable of amoeboid movement. Some of these aid in transporting substances; other are capable of surrounding and digesting foreign particles or debris phagocytosis. Compared with vertebrate blood, however, that of the invertebrates has relatively few cells. Among the vertebrates, there are several classes of amoeboid cells white blood cells, or leukocytes and cells that help stop bleeding platelets , or thrombocytes.
Oxygen requirements have played a major role in determining both the composition of blood and the architecture of the circulatory system. In some simple animals, including small worms and mollusks , transported oxygen is merely dissolved in the plasma. Larger and more-complex animals, which have greater oxygen needs, have pigments capable of transporting relatively large amounts of oxygen.
The red pigment hemoglobin , which contains iron, is found in all vertebrates and in some invertebrates. In almost all vertebrates, including humans, hemoglobin is contained exclusively within the red cells erythrocytes.
The red cells of the lower vertebrates e. Red cells vary markedly in size among mammals; those of the goat are much smaller than those of humans, but the goat compensates by having many more red cells per unit volume of blood. The concentration of hemoglobin inside the red cell varies little between species. Hemocyanin , a copper -containing protein chemically unlike hemoglobin, is found in some crustaceans. Hemocyanin is blue in colour when oxygenated and colourless when oxygen is removed.
Some annelids have the iron-containing green pigment chlorocruorin, others the iron-containing red pigment hemerythrin. In many invertebrates the respiratory pigments are carried in solution in the plasma, but in higher animals, including all vertebrates, the pigments are enclosed in cells; if the pigments were freely in solution, the pigment concentrations required would cause the blood to be so viscous as to impede circulation.
This article focuses on the main components and functions of human blood. For full treatment of blood groups, see the article blood group. For information on the organ system that conveys blood to all organs of the body, see cardiovascular system. For additional information on blood in general and comparison of the blood and lymph of diverse organisms, see circulation. In humans, blood is an opaque red fluid, freely flowing but denser and more viscous than water.
The characteristic colour is imparted by hemoglobin , a unique iron-containing protein. Hemoglobin brightens in colour when saturated with oxygen oxyhemoglobin and darkens when oxygen is removed deoxyhemoglobin. For this reason, the partially deoxygenated blood from a vein is darker than oxygenated blood from an artery.
The red blood cells erythrocytes constitute about 45 percent of the volume of the blood, and the remaining cells white blood cells, or leukocytes , and platelets , or thrombocytes less than 1 percent.
The fluid portion, plasma , is a clear, slightly sticky, yellowish liquid. After a fatty meal, plasma transiently appears turbid. Within the body the blood is permanently fluid, and turbulent flow assures that cells and plasma are fairly homogeneously mixed. The total amount of blood in humans varies with age, sex, weight, body type, and other factors, but a rough average figure for adults is about 60 millilitres per kilogram of body weight.
An average young male has a plasma volume of about 35 millilitres and a red cell volume of about 30 millilitres per kilogram of body weight. There is little variation in the blood volume of a healthy person over long periods, although each component of the blood is in a continuous state of flux. In particular, water rapidly moves in and out of the bloodstream, achieving a balance with the extravascular fluids those outside the blood vessels within minutes.
The normal volume of blood provides such an adequate reserve that appreciable blood loss is well tolerated. Withdrawal of millilitres about a pint of blood from normal blood donors is a harmless procedure. Blood volume is rapidly replaced after blood loss; within hours, plasma volume is restored by movement of extravascular fluid into the circulation. Replacement of red cells is completed within several weeks. The vast area of capillary membrane, through which water passes freely, would permit instantaneous loss of the plasma from the circulation were it not for the plasma proteins—in particular, serum albumin.
Capillary membranes are impermeable to serum albumin, the smallest in weight and highest in concentration of the plasma proteins. The osmotic effect of serum albumin retains fluid within the circulation, opposing the hydrostatic forces that tend to drive the fluid outward into the tissues.
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External Websites. Articles from Britannica Encyclopedias for elementary and high school students. Robert S. See Article History. In a circuit through the cardiovascular system, red blood cells transport oxygen from the lungs to the body tissues and carry carbon dioxide from the body tissues back to the lungs. Britannica Quiz. Blood: Fact or Fiction? This specialized fluid enlivens the human body, but how much do you really know about blood? From blood cells to blood types, sink your vampire teeth into this quiz.
In a circuit through the cardiovascular system, red blood cells transport oxygen from the lungs to the body tissues and transport carbon dioxide from the body tissues to the lungs.
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Overview of blood components and their preparation
Blood is made of of several components, including red blood cells, white blood cells, platelets, and the plasma, which contains coagulation factors and serum. Blood helps maintain homeostasis by stabilizing pH, temperature, osmotic pressure, and by eliminating excess heat. Blood supports growth by distributing nutrients and hormones, and by removing waste. These cells deliver oxygen to the cells and remove carbon dioxide. Blood plays a protective role by transporting clotting factors and platelets to prevent blood loss after injury.
Blood , fluid that transports oxygen and nutrients to the cells and carries away carbon dioxide and other waste products. Technically, blood is a transport liquid pumped by the heart or an equivalent structure to all parts of the body, after which it is returned to the heart to repeat the process. Blood is both a tissue and a fluid. It is a tissue because it is a collection of similar specialized cells that serve particular functions. These cells are suspended in a liquid matrix plasma , which makes the blood a fluid. If blood flow ceases, death will occur within minutes because of the effects of an unfavourable environment on highly susceptible cells.
Components of Blood
Blood is a specialized body fluid. It has four main components: plasma, red blood cells, white blood cells, and platelets. Blood has many different functions, including:. The blood that runs through the veins, arteries, and capillaries is known as whole blood, a mixture of about 55 percent plasma and 45 percent blood cells. About 7 to 8 percent of your total body weight is blood.
Blood is composed of plasma and three types of cells: red blood cells, white blood cells, and platelets. Left tube: after standing, the RBCs have settled at the bottom of the tube. Blood is a circulating tissue composed of fluid, plasma, and cells.
Blood is a combination of plasma and cells that circulate through the entire body.
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Find GPs in Australia. The formed elements are so named because they are enclosed in a plasma membrane and have a definite structure and shape. All formed elements are cells except for the platelets, which are tiny fragments of bone marrow cells. Leukocytes are further classified into two subcategories called granulocytes which consist of neutrophils, eosinophils and basophils; and agranulocytes which consist of lymphocytes and monocytes. The formed elements can be separated from plasma by centrifuge, where a blood sample is spun for a few minutes in a tube to separate its components according to their densities. This volume is known as the haematocrit. WBCs and platelets form a narrow cream-coloured coat known as the buffy coat immediately above the RBCs.
Blood Components. In adults, this amounts to 4. This essential fluid carries out the critical functions of transporting oxygen and nutrients to our cells and getting rid of carbon dioxide, ammonia, and other waste products. In addition, it plays a vital role in our immune system and in maintaining a relatively constant body temperature. Blood is a highly specialized tissue composed of more than 4, different kinds of components. Four of the most important ones are red cells, white cells, platelets, and plasma. All humans produce these blood components--there are no populational or regional differences.
The heart pumps blood through the arteries, capillaries and veins to provide oxygen and nutrients to every cell of the body. The blood also carries away waste products. The adult human body contains approximately 5 liters of blood. It makes up 7 to 8 percent of a person's body weight. Approximately 2. Plasma is the liquid portion of the blood.
Describe the structure and function of blood in the body
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