Module 5: The Blood

Lesson 1: An Overview of Blood

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Mỗi bài học (lesson) bao gồm 4 phần chính: Thuật ngữ, Luyện Đọc, Luyện Nghe, và Bàn Luận.
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Dưới đây là danh sách những thuật ngữ Y khoa của module The Blood.
Khái quát được số lượng thuật ngữ sẽ xuất hiện trong bài đọc và nghe sẽ giúp bạn thoải mái tiêu thụ nội dung hơn. Sau khi hoàn thành nội dung đọc và nghe, bạn hãy quay lại đây và luyện tập (practice) để quen dần các thuật ngữ này. Đừng ép bản thân phải nhớ các thuật ngữ này vội vì bạn sẽ gặp và ôn lại danh sách này trong những bài học (lesson) khác của cùng một module.

Medical Terminology: The Blood

ABO blood group
blood-type classification based on the presence or absence of A and B glycoproteins on the erythrocyte membrane surface
agglutination
clustering of cells into masses linked by antibodies
agranular leukocytes
leukocytes with few granules in their cytoplasm; specifically, monocytes, lymphocytes, and NK cells
albumin
most abundant plasma protein, accounting for most of the osmotic pressure of plasma
anemia
deficiency of red blood cells or hemoglobin
antibodies
(also, immunoglobulins or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
anticoagulant
substance such as heparin that opposes coagulation
antithrombin
anticoagulant that inactivates factor X and opposes the conversion of prothrombin (factor II) into thrombin in the common pathway
B lymphocytes
(also, B cells) lymphocytes that defend the body against specific pathogens and thereby provide specific immunity
basophils
granulocytes that stain with a basic (alkaline) stain and store histamine and heparin
bilirubin
yellowish bile pigment produced when iron is removed from heme and is further broken down into waste products
biliverdin
green bile pigment produced when the non-iron portion of heme is degraded into a waste product; converted to bilirubin in the liver
blood
liquid connective tissue composed of formed elements—erythrocytes, leukocytes, and platelets—and a fluid extracellular matrix called plasma; component of the cardiovascular system
bone marrow biopsy
diagnostic test of a sample of red bone marrow
bone marrow transplant
treatment in which a donor’s healthy bone marrow with its stem cells replaces diseased or damaged bone marrow of a patient
bruise
localized bleeding under the skin due to damaged blood vessels
buffy coat
thin, pale layer of leukocytes and platelets that separates the erythrocytes from the plasma in a sample of centrifuged blood
carbaminohemoglobin
compound of carbon dioxide and hemoglobin, and one of the ways in which carbon dioxide is carried in the blood
clotting factors
group of 12 identified substances active in coagulation
coagulation
formation of a blood clot; part of the process of hemostasis
colony-stimulating factors (CSFs)
glycoproteins that trigger the proliferation and differentiation of myeloblasts into granular leukocytes (basophils, neutrophils, and eosinophils)
common pathway
final coagulation pathway activated either by the intrinsic or the extrinsic pathway, and ending in the formation of a blood clot
cross matching
blood test for identification of blood type using antibodies and small samples of blood
cytokines
class of proteins that act as autocrine or paracrine signaling molecules; in the cardiovascular system, they stimulate the proliferation of progenitor cells and help to stimulate both nonspecific and specific resistance to disease
defensins
antimicrobial proteins released from neutrophils and macrophages that create openings in the plasma membranes to kill cells
deoxyhemoglobin
molecule of hemoglobin without an oxygen molecule bound to it
diapedesis
(also, emigration) process by which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues
embolus
thrombus that has broken free from the blood vessel wall and entered the circulation
emigration
(also, diapedesis) process by which leukocytes squeeze through adjacent cells in a blood vessel wall to enter tissues
eosinophils
granulocytes that stain with eosin; they release antihistamines and are especially active against parasitic worms
erythrocyte
(also, red blood cell) mature myeloid blood cell that is composed mostly of hemoglobin and functions primarily in the transportation of oxygen and carbon dioxide
erythropoietin (EPO)
glycoprotein that triggers the bone marrow to produce RBCs; secreted by the kidney in response to low oxygen levels
extrinsic pathway
initial coagulation pathway that begins with tissue damage and results in the activation of the common pathway
ferritin
protein-containing storage form of iron found in the bone marrow, liver, and spleen
fibrin
insoluble, filamentous protein that forms the structure of a blood clot
fibrinogen
plasma protein produced in the liver and involved in blood clotting
fibrinolysis
gradual degradation of a blood clot
formed elements
cellular components of blood; that is, erythrocytes, leukocytes, and platelets
globin
heme-containing globular protein that is a constituent of hemoglobin
globulins
heterogeneous group of plasma proteins that includes transport proteins, clotting factors, immune proteins, and others
granular leukocytes
leukocytes with abundant granules in their cytoplasm; specifically, neutrophils, eosinophils, and basophils
hematocrit
(also, packed cell volume) volume percentage of erythrocytes in a sample of centrifuged blood
hematopoietic stem cell
type of pluripotent stem cell that gives rise to the formed elements of blood (hemocytoblast)
heme
red, iron-containing pigment to which oxygen binds in hemoglobin
hemocytoblast
hematopoietic stem cell that gives rise to the formed elements of blood
hemoglobin
oxygen-carrying compound in erythrocytes
hemolysis
destruction (lysis) of erythrocytes and the release of their hemoglobin into circulation
hemolytic disease of the newborn (HDN)
(also, erythroblastosis fetalis) disorder causing agglutination and hemolysis in an Rh+ fetus or newborn of an Rh− person
hemophilia
genetic disorder characterized by inadequate synthesis of clotting factors
hemopoiesis
production of the formed elements of blood
hemopoietic growth factors
chemical signals including erythropoietin, thrombopoietin, colony-stimulating factors, and interleukins that regulate the differentiation and proliferation of particular blood progenitor cells
hemorrhage
excessive bleeding
hemosiderin
protein-containing storage form of iron found in the bone marrow, liver, and spleen
hemostasis
physiological process by which bleeding ceases
heparin
short-acting anticoagulant stored in mast cells and released when tissues are injured, opposes prothrombin
hypoxemia
below-normal level of oxygen saturation of blood (typically <95 percent)
immunoglobulins
(also, antibodies or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
interleukins
signaling molecules that may function in hemopoiesis, inflammation, and specific immune responses
intrinsic pathway
initial coagulation pathway that begins with vascular damage or contact with foreign substances, and results in the activation of the common pathway
jaundice
yellowing of the skin or whites of the eyes due to excess bilirubin in the blood
leukemia
cancer involving leukocytes
leukocyte
(also, white blood cell) colorless, nucleated blood cell, the chief function of which is to protect the body from disease
leukocytosis
excessive leukocyte proliferation
leukopenia
below-normal production of leukocytes
lymphocytes
agranular leukocytes of the lymphoid stem cell line, many of which function in specific immunity
lymphoid stem cells
type of hematopoietic stem cells that gives rise to lymphocytes, including various T cells, B cells, and NK cells, all of which function in immunity
lymphoma
form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes, the spleen, the liver, and other tissues
lysozyme
digestive enzyme with bactericidal properties
macrophage
phagocytic cell of the myeloid lineage; a matured monocyte
megakaryocyte
bone marrow cell that produces platelets
memory cell
type of B or T lymphocyte that forms after exposure to a pathogen
monocytes
agranular leukocytes of the myeloid stem cell line that circulate in the bloodstream; tissue monocytes are macrophages
myeloid stem cells
type of hematopoietic stem cell that gives rise to some formed elements, including erythrocytes, megakaryocytes that produce platelets, and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes (neutrophils, eosinophils, and basophils)
natural killer (NK) cells
cytotoxic lymphocytes capable of recognizing cells that do not express “self” proteins on their plasma membrane or that contain foreign or abnormal markers; provide generalized, nonspecific immunity
neutrophils
granulocytes that stain with a neutral dye and are the most numerous of the leukocytes; especially active against bacteria
oxyhemoglobin
molecule of hemoglobin to which oxygen is bound
packed cell volume (PCV)
(also, hematocrit) volume percentage of erythrocytes present in a sample of centrifuged blood
plasma
in blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system
plasmin
blood protein active in fibrinolysis
platelet plug
accumulation and adhesion of platelets at the site of blood vessel injury
platelets
(also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes
pluripotent stem cell
stem cell that derives from totipotent stem cells and is capable of differentiating into many, but not all, cell types
polycythemia
elevated level of hemoglobin, whether adaptive or pathological
polymorphonuclear
having a lobed nucleus, as seen in some leukocytes
positive chemotaxis
process in which a cell is attracted to move in the direction of chemical stimuli
red blood cells (RBCs)
(also, erythrocytes) one of the formed elements of blood that transports oxygen
reticulocyte
immature erythrocyte that may still contain fragments of organelles
Rh blood group
blood-type classification based on the presence or absence of the antigen Rh on the erythrocyte membrane surface
serum
blood plasma that does not contain clotting factors
sickle cell disease
(also, sickle cell anemia) inherited blood disorder in which hemoglobin molecules are malformed, leading to the breakdown of RBCs that take on a characteristic sickle shape
T lymphocytes
(also, T cells) lymphocytes that provide cellular-level immunity by physically attacking foreign or diseased cells
thalassemia
inherited blood disorder in which maturation of RBCs does not proceed normally, leading to abnormal formation of hemoglobin and the destruction of RBCs
thrombin
enzyme essential for the final steps in formation of a fibrin clot
thrombocytes
platelets, one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes
thrombocytopenia
condition in which there are too few platelets, resulting in abnormal bleeding (hemophilia)
thrombocytosis
condition in which there are too many platelets, resulting in abnormal clotting (thrombosis)
thrombopoietin
hormone secreted by the liver and kidneys that prompts the development of megakaryocytes into thrombocytes (platelets)
thrombosis
excessive clot formation
thrombus
aggregation of fibrin, platelets, and erythrocytes in an intact artery or vein
tissue factor
protein thromboplastin, which initiates the extrinsic pathway when released in response to tissue damage
totipotent stem cell
embryonic stem cell that is capable of differentiating into any and all cells of the body; enabling the full development of an organism
transferrin
plasma protein that binds reversibly to iron and distributes it throughout the body
universal donor
individual with type O− blood
universal recipient
individual with type AB+ blood
vascular spasm
initial step in hemostasis, in which the smooth muscle in the walls of the ruptured or damaged blood vessel contracts
white blood cells (WBCs)
(also, leukocytes) one of the formed elements of blood that provides defense against disease agents and foreign materials
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Dưới đây là các bài văn nằm ở bên trái. Ở bên phải là các bài luyện tập (practice) để đánh giá khả năng đọc hiểu của bạn. Sẽ khó khăn trong thời gian đầu nếu vốn từ vựng của bạn còn hạn chế, đặc biệt là từ vựng Y khoa. Hãy kiên nhẫn và đọc nhiều nhất có kể, lượng kiến thức tích tụ dần sẽ giúp bạn đọc thoải mái hơn.
Recall that blood is a connective tissue. Like all connective tissues, it is made up of cellular elements and an extracellular matrix. The cellular elements—referred to as the formed elements—include red blood cells (RBCs), white blood cells (WBCs), and cell fragments called platelets. The extracellular matrix, called plasma, makes blood unique among connective tissues because it is fluid. This fluid, which is mostly water, perpetually suspends the formed elements and enables them to circulate throughout the body within the cardiovascular system.
The primary function of blood is to deliver oxygen and nutrients to and remove wastes from body cells, but that is only the beginning of the story. The specific functions of blood also include defense, distribution of heat, and maintenance of homeostasis.

A. Transportation

Nutrients from the foods you eat are absorbed in the digestive tract. Most of these travel in the bloodstream directly to the liver, where they are processed and released back into the bloodstream for delivery to body cells. Oxygen from the air you breathe diffuses into the blood, which moves from the lungs to the heart, which then pumps it out to the rest of the body. Moreover, endocrine glands scattered throughout the body release their products, called hormones, into the bloodstream, which carries them to distant target cells. Blood also picks up cellular wastes and byproducts, and transports them to various organs for removal. For instance, blood moves carbon dioxide to the lungs for exhalation from the body, and various waste products are transported to the kidneys and liver for excretion from the body in the form of urine or bile.

B. Defense

Many types of WBCs protect the body from external threats, such as disease-causing bacteria that have entered the bloodstream in a wound. Other WBCs seek out and destroy internal threats, such as cells with mutated DNA that could multiply to become cancerous, or body cells infected with viruses.

When damage to the vessels results in bleeding, blood platelets and certain proteins dissolved in the plasma, the fluid portion of the blood, interact to block the ruptured areas of the blood vessels involved. This protects the body from further blood loss.

C. Maintenance of Homeostasis

Recall that body temperature is regulated via a classic negative-feedback loop. If you were exercising on a warm day, your rising core body temperature would trigger several homeostatic mechanisms, including increased transport of blood from your core to your body periphery, which is typically cooler. As blood passes through the vessels of the skin, heat would be dissipated to the environment, and the blood returning to your body core would be cooler. In contrast, on a cold day, blood is diverted away from the skin to maintain a warmer body core. In extreme cases, this may result in frostbite.

Blood also helps to maintain the chemical balance of the body. Proteins and other compounds in blood act as buffers, which thereby help to regulate the pH of body tissues. Blood also helps to regulate the water content of body cells.
You have probably had blood drawn from a superficial vein in your arm, which was then sent to a lab for analysis. Some of the most common blood tests—for instance, those measuring lipid or glucose levels in plasma—determine which substances are present within blood and in what quantities. Other blood tests check for the composition of the blood itself, including the quantities and types of formed elements.

One such test, called a hematocrit, measures the percentage of RBCs, clinically known as erythrocytes, in a blood sample. It is performed by spinning the blood sample in a specialized centrifuge, a process that causes the heavier elements suspended within the blood sample to separate from the lightweight, liquid plasma (Figure 1). Because the heaviest elements in blood are the erythrocytes, these settle at the very bottom of the hematocrit tube. Located above the erythrocytes is a pale, thin layer composed of the remaining formed elements of blood. These are the WBCs, clinically known as leukocytes, and the platelets, cell fragments also called thrombocytes. This layer is referred to as the buffy coat because of its color; it normally constitutes less than 1 percent of a blood sample. Above the buffy coat is the blood plasma, normally a pale, straw-colored fluid, which constitutes the remainder of the sample.

The volume of erythrocytes after centrifugation is also commonly referred to as packed cell volume (PCV). In normal blood, about 45 percent of a sample is erythrocytes. The hematocrit of any one sample can vary significantly, however, about 36–50 percent, according to gender and other factors. Normal hematocrit values for females range from 37 to 47, with a mean value of 41; for males, hematocrit ranges from 42 to 52, with a mean of 47. The percentage of other formed elements, the WBCs and platelets, is extremely small so it is not normally considered with the hematocrit. So the mean plasma percentage is the percent of blood that is not erythrocytes: for females, it is approximately 59 (or 100 minus 41), and for males, it is approximately 53 (or 100 minus 47).
When you think about blood, the first characteristic that probably comes to mind is its color. Blood that has just taken up oxygen in the lungs is bright red, and blood that has released oxygen in the tissues is a more dusky red. This is because hemoglobin is a pigment that changes color, depending upon the degree of oxygen saturation.

Blood is viscous and somewhat sticky to the touch. It has a viscosity approximately five times greater than water. Viscosity is a measure of a fluid’s thickness or resistance to flow, and is influenced by the presence of the plasma proteins and formed elements within the blood. The viscosity of blood has a dramatic impact on blood pressure and flow. Consider the difference in flow between water and honey. The more viscous honey would demonstrate a greater resistance to flow than the less viscous water. The same principle applies to blood.

The normal temperature of blood is slightly higher than normal body temperature—about 38 °C (or 100.4 °F), compared to 37 °C (or 98.6 °F) for an internal body temperature reading, although daily variations of 0.5 °C are normal. Although the surface of blood vessels is relatively smooth, as blood flows through them, it experiences some friction and resistance, especially as vessels age and lose their elasticity, thereby producing heat. This accounts for its slightly higher temperature.

The pH of blood averages about 7.4; however, it can range from 7.35 to 7.45 in a healthy person. Blood is therefore somewhat more basic (alkaline) on a chemical scale than pure water, which has a pH of 7.0. Blood contains numerous buffers that actually help to regulate pH.

Blood constitutes approximately 8 percent of adult body weight. Adult males typically average about 5 to 6 liters of blood. Females average 4–5 liters.
Like other fluids in the body, plasma is composed primarily of water: In fact, it is about 92 percent water. Dissolved or suspended within this water is a mixture of substances, most of which are proteins. There are literally hundreds of substances dissolved or suspended in the plasma, although many of them are found only in very small quantities.

A. Plasma Proteins

About 7 percent of the volume of plasma—nearly all that is not water—is made of proteins. These include several plasma proteins (proteins that are unique to the plasma), plus a much smaller number of regulatory proteins, including enzymes and some hormones. The major components of plasma are summarized in Figure 2.

The three major groups of plasma proteins are as follows:

  • Albumin is the most abundant of the plasma proteins. Manufactured by the liver, albumin molecules serve as binding proteins—transport vehicles for fatty acids and steroid hormones. Recall that lipids are hydrophobic; however, their binding to albumin enables their transport in the watery plasma. Albumin is also the most significant contributor to the osmotic pressure of blood; that is, its presence holds water inside the blood vessels and draws water from the tissues, across blood vessel walls, and into the bloodstream. This in turn helps to maintain both blood volume and blood pressure. Albumin normally accounts for approximately 54 percent of the total plasma protein content, in clinical levels of 3.5–5.0 g/dL blood.
  • The second most common plasma proteins are the globulins. A heterogeneous group, there are three main subgroups known as alpha, beta, and gamma globulins. The alpha and beta globulins transport iron, lipids, and the fat-soluble vitamins A, D, E, and K to the cells; like albumin, they also contribute to osmotic pressure. The gamma globulins are proteins involved in immunity and are better known as antibodies or immunoglobulins. Although other plasma proteins are produced by the liver, immunoglobulins are produced by specialized leukocytes known as plasma cells. (Seek additional content for more information about immunoglobulins.) Globulins make up approximately 38 percent of the total plasma protein volume, in clinical levels of 1.0–1.5 g/dL blood.
  • Fibrinogen is the third of the three major groups of plasma proteins. Like albumin and the alpha and beta globulins, fibrinogen is produced by the liver. It is essential for blood clotting, a process described later in this chapter. Fibrinogen accounts for about 7 percent of the total plasma protein volume, in clinical levels of 0.2–0.45 g/dL blood.

B. Other Plasma Solutes

In addition to proteins, plasma contains a wide variety of other substances. These include various electrolytes, such as sodium, potassium, and calcium ions; dissolved gases, such as oxygen, carbon dioxide, and nitrogen; various organic nutrients, such as vitamins, lipids, glucose, and amino acids; and metabolic wastes. All of these nonprotein solutes combined contribute approximately 1 percent to the total volume of plasma.

OpenStax. (2022). Anatomy and Physiology 2e. Rice University. Retrieved June 15, 2023. ISBN-13: 978-1-711494-06-7 (Hardcover) ISBN-13: 978-1-711494-05-0 (Paperback) ISBN-13: 978-1-951693-42-8 (Digital). License: Attribution 4.0 International (CC BY 4.0). Access for free at openstax.org.

The cellular elements of blood include a vast number of erythrocytes and comparatively fewer leukocytes and platelets. Plasma is the fluid in which the formed elements are suspended. A sample of blood spun in a centrifuge reveals that plasma is the lightest component. It floats at the top of the tube separated from the heaviest elements, the erythrocytes, by a buffy coat of leukocytes and platelets. Hematocrit is the percentage of the total sample that is comprised of erythrocytes. Depressed and elevated hematocrit levels are shown for comparison.

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Xem video và cảm nhận nội dung bài. Bạn có thể thả trôi, cảm nhận dòng chảy ngôn ngữ và không nhất thiết phải hiểu toàn bộ bài. Bên dưới là script để bạn khái quát nội dụng và tra từ mới.
Script:
  1. Blood is a fluid connective tissue critical to the transportation of nutrients, gases, and wastes throughout the body.
  2. It also helps to defend the body against infection and other threats.
  3. Furthermore, it plays an important role in the homeostatic regulation of pH, temperature, and other internal conditions.
  4. Blood is composed of formed elements and a fluid extracellular matrix called plasma.
  5. The formed elements include erythrocytes, leukocytes, and cell fragments called platelets.
  6. More than 90 percent of plasma is water.
  7. The remainder is plasma proteins which are mainly albumin, globulins, and fibrinogen, and other dissolved solutes such as glucose, lipids, electrolytes, and dissolved gases.
  8. Because of the formed elements and the plasma proteins and other solutes, blood is sticky and more viscous than water.
  9. It is also slightly alkaline, and its temperature is slightly higher than normal body temperature.
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