![\"14.5.1\"](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2019\/06\/vampire_PNG32-2.png\")
Figure 14.5.1 \"I want to suck your blood.\"<\/em>[\/caption]\r\n\r\nVampires<\/h1>\r\n<\/div>\r\nFrom Bram Stoker\u2019s famous novel about Count Dracula, to films such as Van Helsing<\/em> and the Twilight<\/em> Saga,<\/em> fantasies featuring vampires (like the one in Figure 14.5.1) have been popular for decades. Vampires, in fact, are found in centuries-old myths from many cultures. In such myths, vampires are generally described as creatures that drink blood \u2014 preferably of the human variety \u2014 for sustenance. Dracula, for example, is based on Eastern European folklore about a human who attains immortality (and eternal damnation) by drinking the blood of others.\r\n\r\nWhat Is Blood?<\/h1>\r\n<\/div>\r\n\r\n[caption id=\"attachment_4489\" align=\"alignleft\" width=\"397\"]![\"14.5.2](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Blood-centrifugation-scheme-2.png\")
Figure 14.5.2 If blood is centrifuged (spun at high speed), it separates into its major components based on density, as shown here: plasma, leukocytes (white blood cells) and platelets, and erythrocytes (red blood cells). All blood normally contains these components in about the same proportions.[\/caption]\r\n\r\nThe average adult body contains between 4.7 and 5.7 litres of blood. More than half of that amount is fluid. Most of the rest of that amount consists of blood cells. The relative amounts of the various components in blood are illustrated in Figure 14.5.2. The components are also described in detail below.\r\n\r\n\r\n[pb_glossary id=\"2702\"]Blood<\/strong>[\/pb_glossary]\u00a0is a fluid connective tissue that circulates throughout the body through blood vessels of the cardiovascular system. What makes blood so special that it features in widespread myths? Although blood accounts for less than 10% of human body weight, it is quite literally the elixir of life. As blood travels through the vessels of the [pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary], it delivers vital substances (such as nutrients and oxygen) to all of the [pb_glossary id=\"5665\"]cells[\/pb_glossary], and carries away their metabolic wastes. It is no exaggeration to say that without blood, cells could not survive. Indeed, without the oxygen carried in blood, cells of the [pb_glossary id=\"5915\"]brain[\/pb_glossary] start to die within a matter of minutes.<\/span>\r\nFunctions of Blood<\/h1>\r\n<\/div>\r\nBlood performs many important functions in the body. Major functions of blood include:\r\n\r\n \t- Supplying tissues with oxygen, which is needed by all cells for [pb_glossary id=\"5877\"]aerobic cellular respiration[\/pb_glossary].<\/li>\r\n \t
- Supplying cells with nutrients, including [pb_glossary id=\"5451\"]glucose[\/pb_glossary], [pb_glossary id=\"5707\"]amino acids[\/pb_glossary], and fatty acids.<\/li>\r\n \t
- Removing metabolic wastes from cells, including carbon dioxide, urea, and lactic acid.<\/li>\r\n \t
- Helping to defend the body from [pb_glossary id=\"5799\"]pathogens[\/pb_glossary] and other foreign substances.<\/li>\r\n \t
- Forming clots to seal broken blood vessels and stop bleeding.<\/li>\r\n \t
- Transporting [pb_glossary id=\"5661\"]hormones[\/pb_glossary] and other messenger molecules.<\/li>\r\n \t
- Regulating the [pb_glossary id=\"4330\"]pH[\/pb_glossary] of the body, which must be kept within a narrow range (7.35 to 7.45).<\/li>\r\n \t
- Helping regulate body temperature (through [pb_glossary id=\"3942\"]vasoconstriction[\/pb_glossary] and [pb_glossary id=\"2756\"]vasodilation[\/pb_glossary]).<\/li>\r\n<\/ul>\r\n\r\n
Blood\u00a0Plasma<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4395\"]Plasma[\/pb_glossary]<\/strong> is the liquid component of human blood. It makes up about 55% of blood by volume. It is about 92% water, and contains many dissolved substances. Most of these substances are [pb_glossary id=\"5813\"]proteins<\/span>[\/pb_glossary]<\/span>, but plasma also contains trace amounts of glucose, mineral ions, hormones, carbon dioxide, and other substances. In addition, plasma contains blood cells. When the cells are removed from plasma, as in Figure 14.5.2 above, the remaining liquid is clear but yellow in colour.<\/span>\r\n\r\nBlood Cells<\/h1>\r\n<\/div>\r\nThe cells in blood include [pb_glossary id=\"4398\"]erythrocytes[\/pb_glossary], [pb_glossary id=\"5623\"]leukocytes[\/pb_glossary], and [pb_glossary id=\"4399\"]thrombocytes[\/pb_glossary]. These different types of blood cells are shown in the photomicrograph (Figure 14.5.3) and described in the sections that follow.\r\n\r\n[caption id=\"attachment_4490\" align=\"aligncenter\" width=\"402\"]![\"14.5.3](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/SEM_blood_cells-2.jpg\")
Figure 14.5.3 Highly magnified blood cells in this image include doughnut-shaped red blood cells, rough-surfaced white blood cells, and small disc-shaped platelets.<\/em>[\/caption]\r\nErythrocytes<\/h2>\r\nThe most numerous cells in blood are\u00a0red blood cells,<\/strong>\u00a0also called [pb_glossary id=\"4398\"]erythrocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>. One microlitre of blood contains between 4.2 and 6.1 million red blood cells, and red blood cells make up about 25% of all the cells in the human body. The cytoplasm of a mature erythrocyte is almost completely filled with hemoglobin, the iron-containing protein that binds with oxygen and gives the cell its red colour. In order to provide maximum space for hemoglobin, mature erythrocytes lack a cell [pb_glossary id=\"5797\"]nucleus[\/pb_glossary] and most [pb_glossary id=\"5557\"]organelle<\/span>s<\/span>[\/pb_glossary]<\/span>. They are little more than sacks of hemoglobin.<\/span>\r\n\r\nErythrocytes also carry proteins called antigens that determine blood type. [pb_glossary id=\"2703\"]Blood type[\/pb_glossary] is a genetic characteristic. The best known human blood type systems are the ABO and Rhesus systems.\r\n\r\n \t- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"]
![\"14.5.4](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/ABO_blood_type.svg_-1-3.png\")
Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\nLeukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
What Is Blood?<\/h1>\r\n<\/div>\r\n\r\n[caption id=\"attachment_4489\" align=\"alignleft\" width=\"397\"] Figure 14.5.2 If blood is centrifuged (spun at high speed), it separates into its major components based on density, as shown here: plasma, leukocytes (white blood cells) and platelets, and erythrocytes (red blood cells). All blood normally contains these components in about the same proportions.[\/caption]\r\n\r\nThe average adult body contains between 4.7 and 5.7 litres of blood. More than half of that amount is fluid. Most of the rest of that amount consists of blood cells. The relative amounts of the various components in blood are illustrated in Figure 14.5.2. The components are also described in detail below.\r\n\r\n\r\n[pb_glossary id=\"2702\"]Blood<\/strong>[\/pb_glossary]\u00a0is a fluid connective tissue that circulates throughout the body through blood vessels of the cardiovascular system. What makes blood so special that it features in widespread myths? Although blood accounts for less than 10% of human body weight, it is quite literally the elixir of life. As blood travels through the vessels of the [pb_glossary id=\"5927\"]cardiovascular system[\/pb_glossary], it delivers vital substances (such as nutrients and oxygen) to all of the [pb_glossary id=\"5665\"]cells[\/pb_glossary], and carries away their metabolic wastes. It is no exaggeration to say that without blood, cells could not survive. Indeed, without the oxygen carried in blood, cells of the [pb_glossary id=\"5915\"]brain[\/pb_glossary] start to die within a matter of minutes.<\/span>\r\nFunctions of Blood<\/h1>\r\n<\/div>\r\nBlood performs many important functions in the body. Major functions of blood include:\r\n\r\n \t- Supplying tissues with oxygen, which is needed by all cells for [pb_glossary id=\"5877\"]aerobic cellular respiration[\/pb_glossary].<\/li>\r\n \t
- Supplying cells with nutrients, including [pb_glossary id=\"5451\"]glucose[\/pb_glossary], [pb_glossary id=\"5707\"]amino acids[\/pb_glossary], and fatty acids.<\/li>\r\n \t
- Removing metabolic wastes from cells, including carbon dioxide, urea, and lactic acid.<\/li>\r\n \t
- Helping to defend the body from [pb_glossary id=\"5799\"]pathogens[\/pb_glossary] and other foreign substances.<\/li>\r\n \t
- Forming clots to seal broken blood vessels and stop bleeding.<\/li>\r\n \t
- Transporting [pb_glossary id=\"5661\"]hormones[\/pb_glossary] and other messenger molecules.<\/li>\r\n \t
- Regulating the [pb_glossary id=\"4330\"]pH[\/pb_glossary] of the body, which must be kept within a narrow range (7.35 to 7.45).<\/li>\r\n \t
- Helping regulate body temperature (through [pb_glossary id=\"3942\"]vasoconstriction[\/pb_glossary] and [pb_glossary id=\"2756\"]vasodilation[\/pb_glossary]).<\/li>\r\n<\/ul>\r\n\r\n
Blood\u00a0Plasma<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4395\"]Plasma[\/pb_glossary]<\/strong> is the liquid component of human blood. It makes up about 55% of blood by volume. It is about 92% water, and contains many dissolved substances. Most of these substances are [pb_glossary id=\"5813\"]proteins<\/span>[\/pb_glossary]<\/span>, but plasma also contains trace amounts of glucose, mineral ions, hormones, carbon dioxide, and other substances. In addition, plasma contains blood cells. When the cells are removed from plasma, as in Figure 14.5.2 above, the remaining liquid is clear but yellow in colour.<\/span>\r\n\r\nBlood Cells<\/h1>\r\n<\/div>\r\nThe cells in blood include [pb_glossary id=\"4398\"]erythrocytes[\/pb_glossary], [pb_glossary id=\"5623\"]leukocytes[\/pb_glossary], and [pb_glossary id=\"4399\"]thrombocytes[\/pb_glossary]. These different types of blood cells are shown in the photomicrograph (Figure 14.5.3) and described in the sections that follow.\r\n\r\n[caption id=\"attachment_4490\" align=\"aligncenter\" width=\"402\"] Figure 14.5.3 Highly magnified blood cells in this image include doughnut-shaped red blood cells, rough-surfaced white blood cells, and small disc-shaped platelets.<\/em>[\/caption]\r\nErythrocytes<\/h2>\r\nThe most numerous cells in blood are\u00a0red blood cells,<\/strong>\u00a0also called [pb_glossary id=\"4398\"]erythrocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>. One microlitre of blood contains between 4.2 and 6.1 million red blood cells, and red blood cells make up about 25% of all the cells in the human body. The cytoplasm of a mature erythrocyte is almost completely filled with hemoglobin, the iron-containing protein that binds with oxygen and gives the cell its red colour. In order to provide maximum space for hemoglobin, mature erythrocytes lack a cell [pb_glossary id=\"5797\"]nucleus[\/pb_glossary] and most [pb_glossary id=\"5557\"]organelle<\/span>s<\/span>[\/pb_glossary]<\/span>. They are little more than sacks of hemoglobin.<\/span>\r\n\r\nErythrocytes also carry proteins called antigens that determine blood type. [pb_glossary id=\"2703\"]Blood type[\/pb_glossary] is a genetic characteristic. The best known human blood type systems are the ABO and Rhesus systems.\r\n\r\n \t- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"] Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\n
Leukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
Functions of Blood<\/h1>\r\n<\/div>\r\nBlood performs many important functions in the body. Major functions of blood include:\r\n\r\n \t- Supplying tissues with oxygen, which is needed by all cells for [pb_glossary id=\"5877\"]aerobic cellular respiration[\/pb_glossary].<\/li>\r\n \t
- Supplying cells with nutrients, including [pb_glossary id=\"5451\"]glucose[\/pb_glossary], [pb_glossary id=\"5707\"]amino acids[\/pb_glossary], and fatty acids.<\/li>\r\n \t
- Removing metabolic wastes from cells, including carbon dioxide, urea, and lactic acid.<\/li>\r\n \t
- Helping to defend the body from [pb_glossary id=\"5799\"]pathogens[\/pb_glossary] and other foreign substances.<\/li>\r\n \t
- Forming clots to seal broken blood vessels and stop bleeding.<\/li>\r\n \t
- Transporting [pb_glossary id=\"5661\"]hormones[\/pb_glossary] and other messenger molecules.<\/li>\r\n \t
- Regulating the [pb_glossary id=\"4330\"]pH[\/pb_glossary] of the body, which must be kept within a narrow range (7.35 to 7.45).<\/li>\r\n \t
- Helping regulate body temperature (through [pb_glossary id=\"3942\"]vasoconstriction[\/pb_glossary] and [pb_glossary id=\"2756\"]vasodilation[\/pb_glossary]).<\/li>\r\n<\/ul>\r\n\r\n
Blood\u00a0Plasma<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4395\"]Plasma[\/pb_glossary]<\/strong> is the liquid component of human blood. It makes up about 55% of blood by volume. It is about 92% water, and contains many dissolved substances. Most of these substances are [pb_glossary id=\"5813\"]proteins<\/span>[\/pb_glossary]<\/span>, but plasma also contains trace amounts of glucose, mineral ions, hormones, carbon dioxide, and other substances. In addition, plasma contains blood cells. When the cells are removed from plasma, as in Figure 14.5.2 above, the remaining liquid is clear but yellow in colour.<\/span>\r\n\r\nBlood Cells<\/h1>\r\n<\/div>\r\nThe cells in blood include [pb_glossary id=\"4398\"]erythrocytes[\/pb_glossary], [pb_glossary id=\"5623\"]leukocytes[\/pb_glossary], and [pb_glossary id=\"4399\"]thrombocytes[\/pb_glossary]. These different types of blood cells are shown in the photomicrograph (Figure 14.5.3) and described in the sections that follow.\r\n\r\n[caption id=\"attachment_4490\" align=\"aligncenter\" width=\"402\"] Figure 14.5.3 Highly magnified blood cells in this image include doughnut-shaped red blood cells, rough-surfaced white blood cells, and small disc-shaped platelets.<\/em>[\/caption]\r\nErythrocytes<\/h2>\r\nThe most numerous cells in blood are\u00a0red blood cells,<\/strong>\u00a0also called [pb_glossary id=\"4398\"]erythrocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>. One microlitre of blood contains between 4.2 and 6.1 million red blood cells, and red blood cells make up about 25% of all the cells in the human body. The cytoplasm of a mature erythrocyte is almost completely filled with hemoglobin, the iron-containing protein that binds with oxygen and gives the cell its red colour. In order to provide maximum space for hemoglobin, mature erythrocytes lack a cell [pb_glossary id=\"5797\"]nucleus[\/pb_glossary] and most [pb_glossary id=\"5557\"]organelle<\/span>s<\/span>[\/pb_glossary]<\/span>. They are little more than sacks of hemoglobin.<\/span>\r\n\r\nErythrocytes also carry proteins called antigens that determine blood type. [pb_glossary id=\"2703\"]Blood type[\/pb_glossary] is a genetic characteristic. The best known human blood type systems are the ABO and Rhesus systems.\r\n\r\n \t- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"] Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\n
Leukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
\r\nBlood\u00a0Plasma<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4395\"]Plasma[\/pb_glossary]<\/strong> is the liquid component of human blood. It makes up about 55% of blood by volume. It is about 92% water, and contains many dissolved substances. Most of these substances are [pb_glossary id=\"5813\"]proteins<\/span>[\/pb_glossary]<\/span>, but plasma also contains trace amounts of glucose, mineral ions, hormones, carbon dioxide, and other substances. In addition, plasma contains blood cells. When the cells are removed from plasma, as in Figure 14.5.2 above, the remaining liquid is clear but yellow in colour.<\/span>\r\n
Blood\u00a0Plasma<\/h1>\r\n<\/div>\r\n[pb_glossary id=\"4395\"]Plasma[\/pb_glossary]<\/strong> is the liquid component of human blood. It makes up about 55% of blood by volume. It is about 92% water, and contains many dissolved substances. Most of these substances are [pb_glossary id=\"5813\"]proteins<\/span>[\/pb_glossary]<\/span>, but plasma also contains trace amounts of glucose, mineral ions, hormones, carbon dioxide, and other substances. In addition, plasma contains blood cells. When the cells are removed from plasma, as in Figure 14.5.2 above, the remaining liquid is clear but yellow in colour.<\/span>\r\n\r\nBlood Cells<\/h1>\r\n<\/div>\r\nThe cells in blood include [pb_glossary id=\"4398\"]erythrocytes[\/pb_glossary], [pb_glossary id=\"5623\"]leukocytes[\/pb_glossary], and [pb_glossary id=\"4399\"]thrombocytes[\/pb_glossary]. These different types of blood cells are shown in the photomicrograph (Figure 14.5.3) and described in the sections that follow.\r\n\r\n[caption id=\"attachment_4490\" align=\"aligncenter\" width=\"402\"] Figure 14.5.3 Highly magnified blood cells in this image include doughnut-shaped red blood cells, rough-surfaced white blood cells, and small disc-shaped platelets.<\/em>[\/caption]\r\nErythrocytes<\/h2>\r\nThe most numerous cells in blood are\u00a0red blood cells,<\/strong>\u00a0also called [pb_glossary id=\"4398\"]erythrocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>. One microlitre of blood contains between 4.2 and 6.1 million red blood cells, and red blood cells make up about 25% of all the cells in the human body. The cytoplasm of a mature erythrocyte is almost completely filled with hemoglobin, the iron-containing protein that binds with oxygen and gives the cell its red colour. In order to provide maximum space for hemoglobin, mature erythrocytes lack a cell [pb_glossary id=\"5797\"]nucleus[\/pb_glossary] and most [pb_glossary id=\"5557\"]organelle<\/span>s<\/span>[\/pb_glossary]<\/span>. They are little more than sacks of hemoglobin.<\/span>\r\n\r\nErythrocytes also carry proteins called antigens that determine blood type. [pb_glossary id=\"2703\"]Blood type[\/pb_glossary] is a genetic characteristic. The best known human blood type systems are the ABO and Rhesus systems.\r\n\r\n \t- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"] Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\n
Leukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
Blood Cells<\/h1>\r\n<\/div>\r\nThe cells in blood include [pb_glossary id=\"4398\"]erythrocytes[\/pb_glossary], [pb_glossary id=\"5623\"]leukocytes[\/pb_glossary], and [pb_glossary id=\"4399\"]thrombocytes[\/pb_glossary]. These different types of blood cells are shown in the photomicrograph (Figure 14.5.3) and described in the sections that follow.\r\n\r\n[caption id=\"attachment_4490\" align=\"aligncenter\" width=\"402\"] Figure 14.5.3 Highly magnified blood cells in this image include doughnut-shaped red blood cells, rough-surfaced white blood cells, and small disc-shaped platelets.<\/em>[\/caption]\r\nErythrocytes<\/h2>\r\nThe most numerous cells in blood are\u00a0red blood cells,<\/strong>\u00a0also called [pb_glossary id=\"4398\"]erythrocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>. One microlitre of blood contains between 4.2 and 6.1 million red blood cells, and red blood cells make up about 25% of all the cells in the human body. The cytoplasm of a mature erythrocyte is almost completely filled with hemoglobin, the iron-containing protein that binds with oxygen and gives the cell its red colour. In order to provide maximum space for hemoglobin, mature erythrocytes lack a cell [pb_glossary id=\"5797\"]nucleus[\/pb_glossary] and most [pb_glossary id=\"5557\"]organelle<\/span>s<\/span>[\/pb_glossary]<\/span>. They are little more than sacks of hemoglobin.<\/span>\r\n\r\nErythrocytes also carry proteins called antigens that determine blood type. [pb_glossary id=\"2703\"]Blood type[\/pb_glossary] is a genetic characteristic. The best known human blood type systems are the ABO and Rhesus systems.\r\n\r\n \t- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"] Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\n
Leukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
- \r\n \t
- In the ABO system, there are two common antigens, called antigen A and antigen B. There are four ABO blood types, A (only A antigen), B (only B antigen), AB (both A and B antigens), and O (neither A nor B antigen). The ABO antigens are illustrated in Figure 14.5.4.<\/li>\r\n \t
- In the Rhesus system, there is just one common antigen. A person may either have the antigen (Rh+) or lack the antigen (Rh-).<\/li>\r\n<\/ul>\r\n[caption id=\"attachment_4491\" align=\"aligncenter\" width=\"856\"] Figure 14.5.4 Each of the ABO blood types is characterized by different glycoproteins on red blood cells.<\/em>[\/caption]\r\n\r\nBlood type\u00a0is important for medical reasons. A person who needs a blood transfusion must receive blood of a compatible type. Blood that is compatible lacks antigens that the patient's own blood also lacks. For example, for a person with type A blood (no B antigen), compatible types include any type of blood that lacks the B antigen. This would include type A blood or type O blood, but not type AB or type B blood. If incompatible blood is transfused, it may cause a potentially life-threatening reaction in the patient\u2019s blood.\r\n
Leukocytes<\/h2>\r\n[pb_glossary id=\"5623\"]Leukocyte<\/strong>s<\/strong>[\/pb_glossary]<\/strong>\u00a0(also called white blood cells)<\/span> are cells in blood that defend the body against invading microorganisms and other threats. There are far fewer leukocytes than red blood cells in blood. There are normally only about 1,000 to 11,000 white blood cells per microlitre of blood. Unlike erythrocytes, leukocytes have a nucleus. White blood cells are part of the body\u2019s [pb_glossary id=\"4242\"]immune system[\/pb_glossary]. They destroy and remove old or abnormal cells and cellular debris, as well as attack pathogens and foreign substances. There are five main types of white blood cells, which are described in Table 14.5.1: neutrophils, eosinophils, basophils, lymphocytes, and monocytes. The five types differ in their specific immune functions.<\/span>\r\n
![\"14.5.5](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Blood_clot_in_scanning_electron_microscopy-2.jpg\")
Figure 14.5.5 Erythrocytes become trapped in a coagulating clot so they cannot escape through a break in a blood vessel.<\/em>[\/caption]\r\n\r\n[caption id=\"attachment_4496\" align=\"alignleft\" width=\"311\"]![\"14.5.6](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Blausen_0740_Platelets-2.png\")
Figure 14.5.6 The shape of platelets (thrombocytes) after they are activated helps them to stick together and form a plug for a damaged blood vessel.<\/em>[\/caption]\r\n\r\nCoagulation begins almost instantly after an injury occurs to the endothelium of a blood vessel. Thrombocytes become activated and change their shape from spherical to star-shaped, as shown in Figure 14.5.6. This helps them aggregate with one another (stick together) at the site of injury to start forming a plug in the vessel wall. Activated thrombocytes also release substances into the blood that activate additional thrombocytes and start a sequence of reactions leading to fibrin formation. Strands of fibrin crisscross the platelet plug and strengthen it, much as rebar strengthens concrete.\r\n\r\n[caption id=\"attachment_4651\" align=\"aligncenter\" width=\"675\"]![\"Platelet](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Platelet_Party_900x-2.png\")
Figure 14.5.7 Image by Nick Seluk\/ ![\"14.5.7](\"https:\/\/pressbooks.ccconline.org\/acchumanbio\/wp-content\/uploads\/sites\/152\/2023\/10\/Symptoms_of_anemia.svg_-2.png\")
Figure 14.5.8 Anemia has wide-ranging effects on the human body because oxygen is essential for normal functioning of cells in every organ system.<\/em>[\/caption]\r\n\r\n![Blood-centrifugation-scheme<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Blood-centrifugation-scheme.png\"){kind=link}
![SEM_blood_cells<\/a> by Bruce Wetzel and Harry Schaefer (Photographers)\/](\"https:\/\/commons.wikimedia.org\/wiki\/File:SEM_blood_cells.jpg\"){kind=link}
![ABO_blood_type.svg<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:ABO_blood_type.svg\"){kind=link}
![Blood_clot_in_scanning_electron_microscopy<\/a> by Janice Carr from CDC\/ Public Health Image LIbrary](\"https:\/\/commons.wikimedia.org\/wiki\/File:Blood_clot_in_scanning_electron_microscopy.jpg\"){kind=link}
![Blausen_0740_Platelets<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Blausen_0740_Platelets.png\"){kind=link}
![Symptoms_of_anemia.svg<\/a> by](\"https:\/\/commons.wikimedia.org\/wiki\/File:Symptoms_of_anemia.svg\"){kind=link}