Exam 2: Blood worksheet

Describe the steps in blood clotting.

1. In a damaged vessel, the smooth muscle in the wall contracts to reduce the vessel diameter. 2. exposed collagen in the damaged wall stimulates platelets to stick and break, and to release their chemicals, which attracts more platelets and through a positive-feedback cycle forms a platelet plug. 3. Platelet chemicals initiate the clotting cascade that activates plasma clotting proteins from their inactive to active forms, eventually causing thrombin to turn fibrinogen molecules into fibrin threads, which trap blood cells and form a gel-like clot. 4. the clot retracts, pulling the wall of the vessel closed. 5. eventually, the clot will dissolve as chemicals in the clot activate plasminogen into plasmin, which digests the fibrin threads.

Describe the structure of a hemoglobin molecule, and relate it to its function in a red blood cell.

A hemoglobin molecule consists of 4 subunits assembled into a functional molecule. The two alpha and two beta chains are proteins, made of amino acids. Each protein contains a non-protein heme unit. The heme unit has an iron molecule bound to it, which is the site where oxygen binds. Thus, a hemoglobin molecule has 4 iron units and can bind a maximum of 4 oxygen molecules. When red blood cells are broken down, the 3 parts (protein subunit, heme unit, and iron) are processed differently by the body. The proteins are broken down and the amino acids reused. Iron is transported back to the marrow to make new red cells. Heme is broken down to biliverdin and bilirubin, which is processed by the liver into bile and excreted from the body.

What is the role of fibrin?

Assembles into threads which form a net and trap blood cells in clot

Name the 3 types of granular leukocytes; which is the most common?

Basophils, eosinophils, and neutrophils. Neutrophils comprise approximately 60% of the WBCs.

What is the role of plasmin?

Digest fibrin threads and causes clot to break up

Which of the following is a pluripotent stem cell involved in hemopoiesis? Leukocyte Hemocytoblast Erythrocyte Fibroblast

Hemocytoblast

Where are most plasma proteins produced?

Liver

In lymphoid leukemia, the bone marrow may be taken over by cells of an abnormal ______________ cell line. A. erythrocyte B. basophil C. neutrophil D. lymphocyte

Lymphocyte

Describe some roles for white blood cells in the body.

Lymphocytes are responsible for giving the body immunity. Neutrophils and macrophages are major phagocytic cells, engulfing and digesting foreign and abnormal material. Other cells release the chemicals stored in their cytoplasmic granules to cause inflammation (basophils) or attack parasites (eosinophils). All WBCs travel in the blood but may squeeze out of the bloodstream and crawl through tissue to get to sites of injury or disease.

How is a platelet related to a megakaryocyte? What is the function of platelets?

Megakaryocytes are the large marrow cell that gives rise to platelets. Platelets are pieces broken off from the megakaryocyte, membrane bound collections of chemicals that induce the blood clotting process.

Name the 2 types of agranular leukocytes; which class of cells comprises your immune system?

Monocytes and lymphocytes. Lymphocytes comprise your immune system.

What are the two main fractions of blood, and what are their approximate percentages?

Plasma: approximately 55% Formed elements = red and white blood cells and platelets: 45%

Describe the life span of a red blood cell (you don't need to name the intermediate forms, but know what happens as it grows to maturity and beyond), and relate its mature structure to its function. (hint: both shape and contents)

Red blood cells are produced in the marrow; for the first few days of development they produce large amounts of hemoglobin until the cell is little more than a bag of hemoglobin. At that point, the cell extrudes its nucleus and organelles and is a passive carrier of hemoglobin. The mature cell thus has no nucleus, and has the shape of a biconcave disc - flattened in the middle. This shape gives it a high surface area to volume ratio, maximizing its ability to exchange gases between the hemoglobin in its cytoplasm and the fluid around it.

The process of fibrinolysis describes A. The breakdown of a blood clot B. The formation of an embolus C. The formation of a thrombus D. The destruction of red blood cells following a mis-matched blood transfusion

The breakdown of a blood clot

Describe 4 functions of the blood.

Transporting oxygen, carbon dioxide, nutrients, wastes Regulating pH and ion composition in body tissues Regulating heat distribution Prevention of fluid loss (clotting) and defense against disease

What are the main components of plasma? What approximate percentages do they comprise?

Water - 92% Proteins - 7% Everything else - ions, nutrients, wastes - 1%

A fragment of a megakaryocyte

Which of the following best describes a platelet? A. A fragment of a megakaryocyte B.A lymphocyte involved in blood clotting C.A biconcave disc containing hemoglobin D.A plasma protein produced by the liver

What is the role of plasma proteins?

albumins are largely transport proteins globulins are transport proteins and also antibodies used to fight disease fibrinogen and other clotting proteins that can be activated when needed

Why is tissue plasminogen activator used in the emergency room

tPA is used in the ER for patients who have had a heart attack or stroke, to speed the breakup of a clot and restore blood flow to heart or brain.

In a sample of plasma, most of the volume is: nutrients. water. ions. proteins.

water