Chapter 6

Question 1

What are the three functions of blood?

Answer 1

Transport - Blood is the primary transport medium of the body. Blood transports gases and nutrients and carries away wastes from all parts of the body. Hormones are also transported in the blood.

Defense - Blood defends the body against pathogen invasion and blood loss.

Regulation - Blood has regulatory functions for temperature, water-salt balance, and pH.

Question 2

What are the two components of blood? Name the cellular components found in the blood. What are pluripotent stem cells?

Answer 2

Blood is a tissue that contains cells and cell fragments suspended in a liquid called plasma.

The formed elements are: red blood cells, white blood cells, and platelets.
Red blood cells are two to three times smaller than white blood cells, but there are many more of them.

Pluripotent stem cells in red bone marrow give rise to the different types of blood cells and may have the potential to treat human diseases.

Question 3

What types of components are found in blood plasma? Describe the functions of the following: albumins, globulins, gamma globulins, fibrinogen.

Answer 3

Plasma is the liquid portion of blood. It’s mostly made up of water, but it also contains salts, small organic molecules, hormones, and plasma proteins.

The liver makes most plasma proteins that function to buffer the blood, transport molecules, and maintain osmotic pressure. Each protein also has specific functions.

Albumins contribute most to plasma’s osmotic pressure, and they help transport other organic molecules.

Globulins include alpha and beta globulins, which also help transport substances in the blood, and gamma globulins, which are the antibodies of immunity.

Fibrinogen is involved in blood clotting.

Question 4

Describe the structure of a red blood cell (erythrocyte).

Answer 4

Red blood cells (erythrocytes) are small, biconcave disks that lack a nucleus when mature. There are 4 to 6 million red blood cells per microliter of whole blood.

Question 5

What substance carries the oxygen in red blood cells?

Answer 5

Red blood cells contain hemoglobin, the respiratory pigment that transports oxygen.

Question 6

How is carbon dioxide transported in the blood?

Answer 6

Hemoglobin directly transports about 23% of carbon dioxide, which binds to the terminal amino groups of the globin molecules.

The remaining carbon dioxide is transported as the bicarbonate ion in the plasma. When blood containing bicarbonate ions reaches the lungs, carbon dioxide diffuses out of the blood into the lungs and is exhaled. The enzyme carbonic anhydrase, contained in red blood cells, catalyzes the reaction of carbon dioxide and water to form carbonic acid

Question 7

Where are blood cells produced? What is the average life span of a red blood cell? What is EPO?

Answer 7

Red blood cells are produced in the bone marrow. Red blood cells live only about 120 days and are destroyed in the liver and the spleen. Hemoglobin is released when blood cells are broken down. Iron is recovered and recycled to the bone marrow. Pigments from hemoglobin are excreted as bile pigments. The kidneys release the erythropoietin hormone (EPO), which stimulates bone marrow stem cells to make more red blood cells.

Question 8

Describe the following disorders involving red blood cells: anemia, sickle-cell disease.

Answer 8

Anemia results from too few red blood cells and/or insufficient hemoglobin.
Sickle-cell disease is a hereditary condition in which the hemoglobin molecule is abnormal and the individual has sickle-shaped red blood cells that tend to rupture as they pass through the narrow capillaries.

Question 9

Describe the structure of white blood cells (leukocytes). What are their functions?

Answer 9

White blood cells (leukocytes) are large and nucleated, and they function in immunity. They squeeze through capillaries and invade tissues when needed. Some white blood cells are very good at phagocytosis, while others produce antibodies.

Question 10

What are colony-stimulating factors?

Answer 10

Colony-stimulating factors (CSFs) are proteins that regulate the production of white blood cells. The immune system defends the body against pathogens, cancer cells, and foreign proteins.

Question 11

What is an antigen?

Answer 11

An antigen is a cell or other foreign substance that provokes an immune response.

Question 12

What are the functions of the following granular leukocytes: neutrophils, eosinophils, basophils.

Answer 12

Neutrophils (or polymorphonuclear leukocytes) engulf bacteria and debris through phagocytosis.
Eosinophils are numerous during allergic reactions or parasitic infections.
Basophils and similar cells called mast cells release histamine associated with allergic reactions.

Question 13

What are the functions of the following agranular leukocytes: monocytes, lymphocytes

Answer 13

Agranular leukocytes include monocytes, which become macrophages that phagocytize pathogens and cellular debris in tissues, and lymphocytes (B cells and T cells), which are responsible for specific immunity to particular pathogens and toxins.

Question 14

Briefly describe the following disorders of white blood cells: severe combined immunodeficiency (SCID), leukemia, mononucleosis.

Answer 14

Inherited immune deficiencies such as severe combined immunodeficiency (SCID) result from disorders with the production and/or function of white blood cells. Cancer of white blood cells is called leukemia. Infectious mononucleosis, one of the most common human viruses, is a disease in which a virus infects lymphocytes.

Question 15

Describe the structure and function of platelets (thrombocytes).

Answer 15

Platelets (thrombocytes) result from the fragmentation of megakaryocytes in the red bone marrow. These are involved in the process of blood clotting.

Question 16

Briefly describe the process of blood clotting.

Answer 16

When tissues are damaged, platelets stick to the damaged area, partially sealing torn blood vessels. Injured tissues release prothrombin activator, which converts prothrombin to thrombin. This step requires calcium ions. Thrombin functions as an enzyme to convert fibrinogen into long threads of insoluble fibrin.

Question 17

What are following disorders related to blood clotting: thrombocytopenia, hemophilia.

Answer 17

An insufficient number of platelets is called thrombocytopenia.
Hemophilia is an inherited clotting disorder carried on the X chromosome that results in the deficiency of a clotting factor. Injections of this factor can treat the disease.

Question 18

Describe the ABO blood groups in humans. What blood type is the universal donor?
What blood type is the universal recipient? What is agglutination?

Answer 18

A blood transfusion is the transfer of blood from one individual into the blood of another. Blood typing involves determining the ABO blood group and Rh factor so that the transfusion can be done safely.

ABO Blood Groups
The most common system for typing blood is the ABO system. Blood types A, B, and AB correspond with having specific antigens on the surface of RBCs; type O is an absence of these antigens. All persons have antibodies in their plasma for the A and/or B antigen not carried on their own RBCs. If the corresponding antigen and antibody are combined, clumping, or agglutination, occurs. This crossmatching test is done to determine the blood type of an individual for the purposes of transfusion

Blood Compatibility
Type O is sometimes called the universal donor because it has neither type A nor type B antigens on the red blood cells, and type AB blood is sometimes called the universal recipient because this blood type has neither anti-A nor anti-B antibodies in the plasma.

Question 19

What is the Rh factor? What problems can arise if an Rh-negative mother carries an Rh-positive baby? What is RHOgam?

Answer 19

The Rh system represents a different antigen on the surface of RBCs. Rh-positive indicates presence of the antigen; Rh-negative indicates its absence. Rh factor is especially important in Rh-negative mothers who carry Rh-positive fetuses because of the possibility of hemolytic disease of the newborn (HDN) also known as erythroblastosis fetalis. RhoGAM injections are given to Rh-negative women who give birth to an Rh-positive child.

Question 19

Tie together how the various systems of the body work in concert to maintain the homeostasis of the blood.

Answer 19

All of the human systems work together to maintain homeostasis. The cardiovascular system delivers oxygen and nutrients to, and takes away metabolic wastes from, the interstitial fluid that surrounds cells. The lymphatic system returns interstitial fluid to the bloodstream. The muscular system makes essential contributions to body movement. In the skeletal system, bones contribute calcium ions, which are important to blood clotting. The urinary system regulates acid-base and water-salt balance of blood and interstitial fluid.