Chapter 19 Flashcards
What are the three components of the cardiovascular system?
- Blood
- The heart
- Blood vessels
Blood
A liquid connective tissue that consists of cells surrounded by blood plasma.
Interstitial fluid
The fluid that bathes body cells and is constantly renewed by the blood.
What are the three general functions of blood?
- Transportation
- Regulation
- Protection
Briefly describe some of the physical characteristics of blood
- Is denser and more viscous (thicker) than water and feels slightly sticky.
- Its temperature is ~38°C (100.4°F).
- Has a slightly alkaline pH (7.4).
- Its color varies with its oxygen content (when saturated with oxygen, it is bright red. When unsaturated with oxygen, it is dark red).
- Constitutes about 20% of extracellular fluid, and 8% of the total body mass.
- Volume is 5-6 liters (1.5 gal) in an average-sized adult male and 4-5 liters (1.2 gal) in an average-sized adult female.
What are the two main components of blood?
- Blood plasma (watery liquid extracellular matrix that contains dissolved substances) (55%)
- Formed elements (cells and cell fragments - eg. RBCs and WBCs) (45%)
Buffy coat
A thin layer of WBCs between the RBCs and blood plasma.
Blood plasma
A straw-colored liquid in blood. Is about 91.5% water and 8.5% solutes, most of which (7% by weight) are proteins.
Plasma proteins
Most produced by liver. Responsible for colloid osmotic pressure. Major contributors to blood viscosity. Transport hormones (steroid), fatty acids, and calcium. Help regulate blood pH.
What are the three types of plasma proteins? What percentage of the plasma proteins do they make up?
- Albumins (54%)
- Globulins (38%)
- Fibrinogens (7%)
Albumins
Smallest and most numerous plasma proteins. Help maintain osmotic pressure, an important factor in the exchange of fluids across blood capillary walls.
Globulins
Large proteins (plasma cells produce immunoglobulins). Immunoglobulins (AKA antibodies) help attack viruses and bacteria. Alpha and beta globulins transport iron, lipids, and fat-soluble vitamins.
Fibrinogen
Large protein. Plays essential role in blood clotting
Antibodies
AKA immunoglobulins; a type of plasma protein that develops into a cell that produces gamma globulins (an important type of globulin). Produced during certain immune responses. Production of antibodies is stimulated by foreign substances (antigens) such as bacteria and viruses.
What are the three types of formed elements?
- Red blood cells (RBCs)
- White blood cells (WBCs)
- Platlets
Red blood cells (RBCs)
AKA erythrocytes; 4.8 million/μL in females and 5.4 million/μL in males; 7–8 μm diameter, biconcave discs, without nuclei; live for about 120 days. Hemoglobin within RBCs transports most oxygen and part of carbon dioxide in blood.
White blood cells (WBCs)
AKA leukocytes; 5000–10,000/μL. Most live for a few hours to a few days. Combat pathogens and other foreign substances that enter body.
Platelets
150,000–400,000/μL. 2–4 μm diameter cell fragments that live for 5–9 days; contain many vesicles but no nucleus. Form platelet plug in hemostasis; release chemicals that promote vascular spasm and blood clotting.
Hematocrit
The percentage of total blood volume occupied by RBCs (Eg. A hematocrit of 40 indicates that 40% of the volume of blood is composed of RBCs). The normal range of hematocrit for adult females is ~42%; for adult males, it is 47%.
Hemopoiesis
AKA hematopoiesis; the process by which the formed elements of blood develop. Before birth, hemopoiesis first occurs in the yolk sac of an embryo and later in the liver, spleen, thymus, and lymph nodes of a fetus. Red bone marrow becomes the primary site of hemopoiesis in the last 3 months before birth and continues as the source of blood cells after birth and throughout life.
Red bone marrow
A highly vascularized connective tissue located in the microscopic spaces between trabeculae of spongy bone tissue. It is present mainly in bones of the axial skeleton, pectoral and pelvic girdles, and the proximal epiphyses of the humerus and femur.
Pluripotent stem cells
AKA hemocytoblasts; red bone marrow cells that are derived from mesenchyme. Have the capacity to develop into many different types of cells.
Myeloid stem cells
Begin their development in red bone marrow and give rise to red blood cells, platelets, monocytes, neutrophils, eosinophils, basophils, and mast cells.
Lymphoid stem cells
Give rise to lymphocytes. Begin their development in red bone marrow but complete it in lymphatic tissues. Lymphoid stem cells also give rise to natural killer (NK) cells.
Progenitor cells
What some of the myeloid stem cells differentiate into during hemopoiesis. They are no longer capable of reproducing themselves and are committed to giving rise to more specific elements of blood.
Precursor cells
AKA blasts; over several cell divisions these cells develop into the actual formed elements of blood (Eg. Monoblasts develop into monocytes).
Hemopoietic growth factors
Hormones that regulate the differentiation and proliferation of particular progenitor cells.
Erythropoietin (EPO)
Increases the number of red blood cell precursors. Is produced primarily by cells in the kidneys that lie between the kidney tubules (peritubular interstitial cells).
Thrombopoietin (TPO)
A hormone produced by the liver that stimulates the formation of platelets from megakaryocytes.
Cytokines
Small glycoproteins that are typically produced by cells such as red bone marrow cells, leukocytes, macrophages, fibroblasts, and endothelial cells. They generally act as local hormones. Cytokines stimulate proliferation of progenitor cells in red bone marrow and regulate the activities of cells involved in nonspecific defenses (such as phagocytes) and immune responses (such as B cells and T cells). Two important families of cytokines that stimulate white blood cell formation are colony-stimulating factors (CSFs) and interleukins.
Hemoglobin
A pigment that gives whole blood its red color. Found in RBCs - each RBC contains about 280 million hemoglobin molecules. Consists of globin. Transports oxygen and carbon dioxide (a waste product of metabolism). Also plays a role in the regulation of blood flow and blood pressure.
Briefly describe RBC anatomy
- Are biconcave discs with a diameter of 7–8 μm.
- Have a simple structure – their plasma membrane is both strong and flexible, which allows them to deform without rupturing as they squeeze through narrow blood capillaries.
- Lack a nucleus and other organelles and can neither reproduce nor carry on extensive metabolic activities.
- Hemoglobin is found in their cytosol, and constitute ~33% of the cell’s weight.
Briefly describe RBC physiology
- Are highly specialized for their oxygen transport function.
- Because they have no nucleus, all of their internal space is available for oxygen transport.
- Because they lack mitochondria and generate ATP anaerobically (without oxygen), they do not use up any of the oxygen they transport.
- The shape of an RBC facilitates its function – a biconcave disc has a much greater surface area for the diffusion of gas molecules into and out of the RBC than would, say, a sphere or a cube.
Globin
Type of protein that makes up hemoglobin molecules. Composed of four polypeptide chains (two alpha and two beta chains).
Heme
A ringlike nonprotein pigment that is bound to each of the four chains of globin. At the center of each heme is an iron ion (Fe2+) that can combine reversibly with one oxygen molecule, allowing each hemoglobin molecule to bind four oxygen molecules.
Nitric oxide (NO)
A gaseous hormone that is produced by the endothelial cells that line blood vessels. Binds to hemoglobin. Under some circumstances, hemoglobin releases NO - the released NO causes vasodilation (an increase in blood vessel diameter that occurs when the smooth muscle in the vessel wall relaxes). Vasodilation improves blood flow and enhances oxygen delivery to cells near the site of NO release.
What are the 14 steps involved in the recycling of RBCs?
- Macrophages in the spleen, liver, or red bone marrow phagocytize ruptured and worn-out red blood cells.
- The globin and heme portions of hemoglobin are split apart.
- Globin is broken down into amino acids, which can be reused to synthesize other proteins.
- Iron is removed from the heme portion in the form of Fe3+, which associates with the plasma protein transferrin, a transporter for Fe3+ in the bloodstream.
- In muscle fibers, liver cells, and macrophages of the spleen and liver, Fe3+ detaches from transferrin and attaches to an iron-storage protein called ferritin.
- On release from a storage site or absorption from the gastrointestinal tract, Fe3+ reattaches to transferrin.
- The Fe3+–transferrin complex is then carried to red bone marrow, where RBC precursor cells take it up through receptor-mediated endocytosis for use in hemoglobin synthesis. Iron is needed for the heme portion of the hemoglobin molecule, and amino acids are needed for the globin portion. Vitamin B12 is also needed for the synthesis of hemoglobin.
- Erythropoiesis in red bone marrow results in the production of red blood cells, which enter the circulation.
- When iron is removed from heme, the non-iron portion of heme is converted to biliverdin, a green pigment, and then into bilirubin, a yellow-orange pigment.
- Bilirubin enters the blood and is transported to the liver.
- Within the liver, bilirubin is released by liver cells into bile, which passes into the small intestine and then into the large intestine.
- In the large intestine, bacteria convert bilirubin into urobilinogen.
- Some urobilinogen is absorbed back into the blood, converted to a yellow pigment called urobilin, and excreted in urine.
- Most urobilinogen is eliminated in feces in the form of a brown pigment called stercobilin, which gives feces its characteristic color.
Erythropoiesis
The production of RBCs. Starts in the red bone marrow with proerythroblasts.
Proerythroblast
A precursor cell. Divides several times and produces cells that begin to synthesize hemoglobin.
Reticulocyte
A cell near the end of the development sequence that turns into a mature blood cell.
Hypoxia
An oxygen deficiency at the tissue level. Occurs if not enough oxygen enters the blood. Stimulates the kidneys to step up the release of erythropoietin - as the number of circulating RBCs increases, more oxygen can be delivered to body tissues.
Neutrophils
60–70% of all WBCs. 10–12 μm diameter; nucleus has 2–5 lobes connected by thin strands of chromatin; cytoplasm has very
fine, pale lilac granules. Phagocytosis. Destruction of bacteria with lysozyme, defensins, and strong oxidants, such as superoxide anion, hydrogen peroxide, and hypochlorite anion.
Eosinophils
2-4% of all WBCs. 10–12 μm diameter; nucleus usually has 2 lobes connected by thick strand of chromatin; large, red-orange granules fill cytoplasm. Combat effects of histamine in allergic reactions, phagocytize antigen–antibody complexes, and destroy certain parasitic worms.
Basophils
0.5–1% of all WBCs. 8–10 μm diameter; nucleus has 2 lobes; large cytoplasmic granules appear deep blue-purple. Liberate heparin, histamine, and serotonin in allergic reactions that intensify overall inflammatory response.
Lymphoctyes
Include T cells, B cells, and natural killer cells. 20–25% of all WBCs. Small lymphocytes are 6–9 μm in diameter; large lymphocytes are 10–14 μm in diameter; nucleus is round or slightly indented; cytoplasm forms rim around nucleus that looks sky blue; the larger the cell, the more cytoplasm is visible. Mediate immune responses, including antigen–antibody reactions. B cells develop into plasma cells, which secrete antibodies. T cells attack invading viruses, cancer cells, and transplanted tissue cells. Natural killer cells attack wide variety of infectious microbes and certain spontaneously arising tumor cells.
Monocytes
3–8% of all WBCs. 12–20 μm diameter; nucleus is kidney-or horseshoe-shaped; cytoplasm is blue-gray and appears foamy. Phagocytosis (after transforming into fixed or wandering macrophages).
Emigration
AKA diapedesis; a process in which RBCs are contained within the bloodstream and WBCs leave the bloodstream. WBCs leave by rolling along the endothelium, sticking to it, and then squeezing between endothelial cells.
Adhesion molecules
Help WBCs stick to the endothelium.
What are the two types of adhesion molecules?
- Selectins
- Integrins
Describe the three stages of the platelet plug formation mechanism
- Platelet adhesion: platelets stick to the parts of the damaged blood vessel.
- Platelet release reaction: due to adhesion, the platelets become activated.
- Platelet aggregation: platelets stick together. The accumulation of platelets turns into a platelet plug.
Describe the three stages of the blood clotting (coagulation) mechanism
- Two pathways, called the extrinsic pathway and the intrinsic pathway, lead to the formation of prothrombinase. Once prothrombinase is formed, the steps involved in the next two stages of clotting are the same for both the extrinsic and intrinsic pathways, and together these two stages are referred to as the common pathway.
- Prothrombinase converts prothrombin (a plasma protein formed by the liver) into the enzyme thrombin.
- Thrombin converts soluble fibrinogen (another plasma protein formed by the liver) into insoluble fibrin. Fibrin forms the threads of the clot.
People whose RBCs display only antigen A have ______ blood. Those who have only antigen B are ______. Individuals who have both A and B antigens are ______; those who have neither antigen A nor B are ______.
Type A; type B; type AB; type O (universal donor)
The ______ reacts with antigen A, and the ______ reacts with antigen B.
Anti-A antibody; anti-B antibody
