Blood, Ch19

Question 1

The percentage of blood that is composed of erythrocytes is called what?

Answer 1

Hematocrit

Question 2

What are the seven main functions of blood?

Answer 2

Exchanging gases, distributing solutes, performing immune functions, maintaining body temperature, functioning in blood clotting, preserving acid-base homeostasis, and stabilizing blood pressure.

Question 3

What are the three formed elements found in blood?

Answer 3

Erythrocytes/red blood cells. Leukocytes/white blood cells. Cellular fragments called platelets.

Question 4

What relatively large plasma protein is produced by the liver? What is it responsible for?

Answer 4

Albumin. Responsible for blood’s colloid osmotic pressure, or the pressure that draws water into the blood via osmosis.

Question 5

What kind plasma proteins include globular alpha and beta globulins and lipoproteins? What do they do?

Answer 5

Transport proteins, which are hydrophilic and can associate with water molecules. Hydrophobic molecules bind to them so that they can be transported throughout blood without clumping up.

Question 6

A blood clot is a collection of what?

Answer 6

Platelets and plasma protein clotting proteins.

Question 7

What are some characteristics of erythrocytes?

Answer 7

Biconcave, giving them a large surface area for gas exchange. Mature ones are anucleate and also lack most other organelles. Little more than plasma membrane surrounding cytosol filled with enzymes and protein hemoglobin, or Hb.

Question 8

What does the large protein hemoglobin consist of?

Answer 8

Four polypeptide subunits, 2 alpha chains and 2 beta chains. Each polypeptide is bound to an iron-containing heme group.

Question 9

What does the iron ion in each heme group of erythrocytes do?

Answer 9

It binds to oxygen in parts of the body where oxygen concentration is high, forming the molecule oxyhemoglobin (HbO2). When oxygen concentrations are low, Hb releases oxygen to become deoxyhemoglobin.

Question 10

What happens to iron ions in Hb when it binds to oxygen?

Answer 10

It becomes oxidized, losing an electron, changing from 2+ to 3+. Oxyhemoglobin.

Question 11

In tissue spaces where oxygen levels are low, Hb binds to what?

Answer 11

Carbon dioxide, forming carbaminohemoglobin. Approx 23% of carbon dioxide in blood is transported this way. When it combines to carbon monoxide (CO) it forms carboxyhemoglobin.

Question 12

What occurs in red bone marrow?

Answer 12

Hematopoiesis. Red marrow houses all the cells from which formed elements arise, the hematopoietic stem cells, or HSCs.

Question 13

How does erythropoiesis happen?

Answer 13

HSCs differentiate into progenitor erythrocyte CFUs. These differentiate into proerythroblasts, which become erythroblasts. As they mature their nuclei shrink and are ejected, so now they’re reticulocytes. Remaining organelles are ejected through exocytosis, and then they enter the bloodstream.

Question 14

What hormone is required from the kidneys for erythrocyte CFUs to differentiate into proerythroblasts? What are some of its effects?

Answer 14

Erythropoietin, or EPO. Speeds up the rate of erythropoiesis and reduces time needed for new erythrocytes to mature. Can trigger replacement of yellow bone marrow with red.

Question 15

What occurs in the negative feedback loop governing erythropoiesis?

Answer 15

Blood levels of oxygen fall below normal, which chemoreceptor kidney cells detect. Kidneys produce more erythropoietin and release it into the blood, which causes increased production of erythrocytes. Blood levels of oxygen rise to normal.

Question 16

In addition to erythropoietin, what chemicals can increase production of erythrocytes? What else about them?

Answer 16

Growth factors, which are produced by cell types such as endothelial cells in blood vessels and fibroblasts in connective tissue. They aid in the transition from yellow to red marrow, and trigger mitosis of hematopoietic stem cells.

Question 17

How does erythrocyte destruction and death occur?

Answer 17

Erythrocytes become trapped in the sinusoids of the spleen. Spleen leukocyte macrophages digest erythrocytes. Hemoglobin is broken down into amino acids, iron ions, and biliverdin which becomes bilirubin. Iron ions and amino acids are recycled and used to make new Hb in red marrow. Bilirubin is sent to the liver for excretion.

Question 18

Decreased oxygen-carrying capacity of the blood. Symptoms? Possible effects?

Answer 18

Anemia. “An”-without, “emia”-blood. Pallor, fatigue, weakness, shortness of breath, rapid heart rate . May cause elevated numbers of reticulocytes in the blood as the body boosts erythrocyte production.

Question 19

What is the most common type of anemia, in which erythrocytes are pale and small? What are some of the causes?

Answer 19

Iron-deficiency anemia. Due to inadequate dietary iron, reduced intestinal absorption, slow blood loss like menstruation. Decreased Hb may also be due to malnutrition, vitamin B6 deficiency, certain drugs, pregnancy, heavy metal poisoning.

Question 20

What kind of anemia is caused by an underlying condition such as cancer produces chemicals that interfere with the transport of iron from the liver to the red marrow?

Answer 20

Anemia of chronic disease

Question 21

What type of anemia results from vitamin B12 deficiency, which interferes with DNA synthesis of rapidly dividing cells, including hematopoietic cells?

Answer 21

Pernicious anemia

Question 22

Erythrocytes destruction can lead to this kind of anemia. Causes?

Answer 22

Hemolytic anemia. Causes include bacterial infections, diseases of the immune system or liver, and lead poisoning.

Question 23

Anemia in which the red bone marrow may stop producing erythrocytes.

Answer 23

Aplastic anemia. “A”-without. “Plasis”-formation.

Question 24

What is the most common cause of abnormal Hb? Individuals with a single of this defective gene have what?

Answer 24

Sickle-cell disease. Single gene is sickle-cell trait, and individuals are generally resistant to malaria.

Question 25

Individuals with two copies of the defective gene have sickle-cell disease. Explain?

Answer 25

They reproduce an abnormal Hb called HbS. When oxygen levels are low, HbS molecules line up in a row, forcing the erythrocytes into a curved sickle shape. They get stuck in capillary beds, which leads to ischemia and tissue damage. The cells are eventually destroyed, lowering the number of erythrocytes and causing anemia.

Question 26

Describe the qualities and physical characteristics of leukocytes?

Answer 26

Larger than erythrocytes and have prominent nuclei. WBCs don’t function within blood but use it as a transport vehicle. When they reach their destination they adhere to walls of capillaries or venules and exit the blood by squeezing between the endothelial cells of the vessels.

Question 27

What are the two basic types of leukocytes?

Answer 27

Granulocytes that contain cytoplasmic granules that the cells release when activated. These include neutrophils, eosinophils, and basophils. Agranulocytes lack visible cytoplasmic granules. Lymphocytes and monocytes.

Question 28

This the most common type of leukocyte, making up 60-70% of total leukocytes in the blood. Takes up both basic and acidic dyes, staining the cytoplasm a light lilac color. Explain them?

Answer 28

Neutrophils. 3-5 lobes in nuclei, giving the other name of polymorphonucleocytes, or PMNs/polys. Attracted to injured cells through chemotaxis. Granule contents directly kill bacterial cells, enhance inflammation, and attract more neutrophils and leukocytes. Active phagocytes.

Question 29

These leukocytes takes up the dye eosin and therefore appear red. Relatively rare and account for less than 4% in the blood. Explain them?

Answer 29

Eosinophils. Bilobed nuclei, with two circular loves connected by a thin strand of nuclear material. Involved in the response to infection with parasitic worms and allergic reactions. Granules contain substance for these, as well as enzymes and toxins specific to parasites and chemicals that mediate inflammation. Phagocytes.

Question 30

Least common leukocytes, less than 1% of the total in the blood. Their granules take up the basic dye methylene blue, staining them dark purple-blue.

Answer 30

Basophils. The granules in these cells almost completely obscure their typically S-shaped nuclei. Granules release chemicals that mediate inflammation.

Question 31

The second most numerous type of leukocyte, at 20-25%. Contain large, spherical nuclei and generally a thin rim of light blue cytoplasm that is visible when stained. 2 types?

Answer 31

B lymphocytes/B cells and T lymphocytes/T cells. Both are activated by cellular markers called antigens, which are present on all cells and most biological molecules.

Question 32

What type of lymphocyte produces proteins called antibodies that bind to antigens and remove them from tissues?

Answer 32

B cells. Each population secretes antibodies with a specific structure that allows them to bind to only one unique antigen.

Question 33

What type of lymphocyte has specific receptors for individual antigens? Once bound, the lymphocytes activate other components of the immune system and directly destroy abnormal body cells.

Answer 33

T cells

Question 34

These are the largest leukocytes, accounting for 3-8%. Large, U-shaped nuclei and light blue or purple cytoplasm that becomes visible when the cells are stained.

Answer 34

Monocytes. Remain in blood for a few days before exiting capillaries and entering the tissues, where some mature into macrophages. Ingest dead and dying cells, bacteria, antigens, and cellular debris. Activate other parts of the immune system by displaying phagocytosed antigens to other leukocytes.

Question 35

Leukocytes form in the bone marrow by this process. Arose from HSCs, which divide and split into two lines. One produces most of the formed elements, including erythrocytes and platelets. The other forms lymphocytes.

Answer 35

Leukopoiesis. Myeloid cell line. Lymphoid cell line.

Question 36

This cell line differentiates early into blasts that are committed to becoming monocytes or granulocytes. Explain further?

Answer 36

Myeloid cell line. Agranulated monocytes develop from committed monoblasts and precursor promonocytes. All granulocytes come from myeloblasts that differentiate into precursor promyelocytes. In the final precursor stage, cells are called band cells or stab cells.

Question 37

How does the lymphoid cell line mature?

Answer 37

Differentiate first into committed lymphoblasts. Then precursor prolymphocytes, which become mature B and T cells. B cells mature in bone marrow, while T cells travel to and mature in the thymus gland in the mediastinum.

Question 38

These are not true cells, but are instead small fragments of cells surrounded by a plasma membrane. They lack nuclei and most other organelles. What else do they contain?

Answer 38

Platelets. Multiple types of granules that house clotting factors and enzymes, mitochondria, and glycogen deposits that enable them to carry out oxidative catabolism. These also contain cytoskeleton elements, including microtubules.

Question 39

Explain megakaryocyte formation, after beginning as HSCs?

Answer 39

Precursors cells called megakaryoblasts derive from the myeloid cell line. They become megakaryocytes, which undergo lots of mitosis w/out cytokinesis. End result is a cell w/ multiple copies of DNA in a nucleus.

Question 40

How do megakaryocytes produce platelets?

Answer 40

Under the influence of hormones like thrombopoietin, megakaryocytes extend arms filled with cytosol, granules, and organelles, through clefts in the bone marrow sinusoids and into the bloodstream. The force of the blood moving past the arms lops off small pieces that become platelets.

Question 41

This involves a series of events that form a gelatinous blood clot to plug a broken vessel. What are the five steps?

Answer 41

Hemostasis. Vascular spasm. Platelets plug formation. Coagulation. Clot retraction. Thrombolysis.

Question 42

What is involved in vascular spasm in hemostasis, and what step number is it?

Answer 42

Step 1. When blood leaks into the ECF, vasoconstriction and increased tissue pressure occur. These decrease blood vessel diameter, minimizing blood loss from the injured vessel.

Question 43

What first happens in platelet plug formation during hemostasis and what step is it?

Answer 43

Step 2. When the vessel is injured, collagen fibers and chemicals in the tunica adventitia are exposed. The injured endothelial cells release the glycoproteins von Willebrand factor (vWF), which binds to receptors on the surface of the platelets membranes. This makes the platelets sticky so they adhere to once another and the vessel wall.

Question 44

During hemostasis, the binding of vWF and collagen to platelets triggers a series of events within platelets known as what, which causes what?

Answer 44

Platelet activation. The activated platelets release the contents of their granules by exocytosis. Many of these factors attract and activate nearby platelets and cause them to clump together, or aggregate. This forms the platelet plug.

Question 45

Fibrin converts the soft, liquid platelet plug into a more solid mass by the process of what? It is converted into fibrin by what process, a series of reactions that occur at the surface of the platelets and/or damaged endothelial cells?

Answer 45

Coagulation. Coagulation cascade.

Question 46

The coagulation cascade relies relies on what, which are enzymes produced by the liver that circulate in the blood in their inactive forms?

Answer 46

Clotting factors

Question 47

What four clotting factors depend on the presence of vitamin K for synthesis?

Answer 47

2, 7, 9, 10. II, VII, IX, X

Question 48

What happens after the coagulation cascade in hemostasis? What step is it?

Answer 48

Step 4, clot retraction. The actin and myosin fibers in platelets contract, which brings the edges of the wounded vessel closer together. It also squeezes serum (plasma minus the clotting proteins) out of the clot.

Question 49

What is the last step in hemostasis and how does it work?

Answer 49

The blood clot dissolves through thrombolysis. Endothelial cells release tissue plasminogen activator (tPA). Can also be initiated by urokinase, produced by the kidney. tPA activates the enzyme plasminogen, which binds to fibrin as it’s incorporated into the clot. It catalyzes the reaction that converts it to plasmin, which degrades fibrin, dissolving the clot.

Question 50

What are two chemicals are produced by endothelial cells to regulate the first and second stages of clot formation? What do they do?

Answer 50

Prostacyclin, which inhibits platelet aggregation. Nitric oxide, which causes vasodilation.

Question 51

What anticoagulant molecules are produced by endothelial cells and hepatocytes?

Answer 51

Antithrombin-III, binds and inhibits activity of factor Xa and thrombin, prevents new thrombin formation. Heparan sulfate, enhances activity of antithrombin-III. Active protein C, catalyzes reactions that degrade factors Va and VIIIa.