chapter 7

Question 1

The system consisting of the heart, blood vessels, and the blood that circulates through them.

Answer 1

circulatory system

Question 2

List the three formed elementsof blood

Answer 2

Red blood cells (RBCs), representing the bulk of the formed elements, settle to the bottom. White blood cells (WBCs) and platelets appear just above red blood cells in a thin, grayish-white layer

Question 3

List the liquid component of blood

Answer 3

plasma

Question 4

About what percentage of blood volume is plasma

Answer 4

55 percent

Question 5

Nearly two-thirds of plasma proteins, which primarily serve to maintain the proper water balance between blood and the interstitial fluid. Manufactured in the liver, also bind to certain molecules (such as bilirubin and fatty acids) and drugs (such as penicillin) and assist in their transport in blood

Answer 5

albumins

Question 6

a diverse group of proteins that transport various substances in the blood. Many beta globulins bind to lipid (fat) molecules, such as cholesterol. When a protein attaches to one of these molecules, it creates a complex called a lipoprotein. Two medically important lipoproteins are the low-density lipoproteins (LDLs) and high-density lipoproteins (HDLs), and medical exams often include taking a blood sample to measure LDL and HDL relative proportions. The LDLs are sometimes called “bad cholesterol” because high blood levels of these lipoproteins are associated with increased risk of cardiovascular health problems. High levels of HDLs often indicate a lower risk of cardiovascular disease. We discuss lipoproteins and the health implications of high blood cholesterol levels when we discuss the heart and blood vessels. Gamma globulins function as part of the body’s defense system, helping to protect against infections and illness.

Answer 6

Globulins

Question 7

a third group of plasma proteins, play an important role in the process of blood clotting. As we see later in this chapter, blood clotting minimizes blood loss and helps maintain homeostasis after injury. In addition to plasma proteins, plasma transports a variety of other molecules, including ions (also called electrolytes), hormones, nutrients, waste products, and gases. Electrolytes such as sodium and potassium contribute to the control of cell function and cell volume. Hormones, which are chemical “messengers” from the endocrine system, transport information throughout the body. Nutrients such as carbohydrates, amino acids, vitamins, and other substances are absorbed from the digestive tract or produced by cells’ metabolic reactions. Waste products in plasma include carbon dioxide, urea, and lactic acid. Gases dissolved in plasma include oxygen, which is necessary for metabolism, and carbon dioxide, a waste product of metabolism.

Answer 7

Clotting proteins

Question 8

List the three major classes of plasma proteins

Answer 8

Albumina, Globulins, Clotting proteins

Question 9

What is the main function of red blood cells?

Answer 9

red blood cells (RBCs), also called erythrocytes (“red cells” in Greek). Red blood cells function primarily as carriers of oxygen and carbon dioxide. Each cubic millimeter of blood contains approximately 5 million red blood cells. They give blood its color and are the major reason why it is viscous.

Question 10

What is the function of hemoglobin? Where is hemoglobin located?

Answer 10

hemoglobin. Hemoglobin consists of four polypeptide chains, each containing a heme group (Figure 7.4). At the center of each heme group is an iron atom, which can readily form a bond with an oxygen molecule (O2). In total, a single red blood cell can carry up to 1.2 billion molecules of oxygen

Question 11

Define hematocrit.

Answer 11

The percentage of blood that consists of red blood cells is called the hematocrit (review Figure 7.2b). The hematocrit is a relative measure of the oxygen-carrying capacity of blood, and thus it is often of interest to the health care professional. The normal hematocrit range is 43–49% in men and 37–43% in women. A related number is the amount of hemoglobin in the blood, expressed in units of grams per 100 ml of blood (abbreviated Hb gm%). Normal values for hemoglobin are 14–18 gm% in men and 12–14 gm% in women.

Question 12

Why would it be bad if a person had too low of a hematocrit?

Answer 12

It can be a sign of anemia

Question 13

Where are all formed elements of blood produced at?

Answer 13

All blood cells and platelets originate from cells in the red marrow of certain bones. These cells, called stem cells, divide repeatedly throughout our lives, continually producing immature blood cells. These immature cells develop into platelets and the various types of mature red and white blood cells described in

Question 14

What type of cell destroy and digest old RBCs in the liver and spleen?

Answer 14

Old and damaged RBCs are removed from the circulating blood and destroyed in the liver and spleen by large cells called macrophages. Macrophages are derived from monocytes, the largest of the white blood cells.

Question 15

The heme group of hemoglobin is converted by the liver to a yellowish pigment called what?

Answer 15

The heme groups (minus the iron) are converted by the liver to a yellowish pigment called bilirubin. If you’ve ever noticed how a bruise slowly changes color as it heals, from purple to blue to green to yellow, you have observed the chemical breakdown of the heme groups to bilirubin at the site of damage.

Question 16

What is the name of the condition in which a person’s skin and eyes look yellow due to a buildup of this pigment?

Answer 16

When the liver fails to secrete bilirubin into the bile properly or when the bile duct from the liver to the intestines is blocked, bilirubin may accumulate in blood plasma. High circulating levels of bilirubin make skin and mucous membranes look yellowish and can turn the whites of the eyes yellow. This condition is called jaundice (from jaune, French for “yellow”). Jaundice may also be caused by an increase in the rate of RBC breakdown

Question 17

What is the name of the hormone that stimulates the production of RBCs?

Answer 17

If oxygen availability falls for any reason, these cells cause the kidneys to secrete a hormone called erythropoietin.

Erythropoietin is transported in the blood to the red bone marrow, where it stimulates stem cells to produce more red blood cells. When the oxygen carrying capacity of blood returns to an appropriate level as monitored by kidney cells, the cells cut back on their production of erythropoietin, and RBC production returns to normal. Thus, the body maintains homeostasis of oxygen availability by adjusting the production rate of the RBCs that transport it.

Question 18

What is the stimulus for the release of erythropoietin hormone? .

Answer 18

If oxygen availability falls for any reason

Question 19

What organ is the erythropoietin hormone released from?

Answer 19

kidneys

Question 20

Is RBC production due to the erythropoietin hormone an example of negative or positive feedback?

Answer 20

Regulation of RBC production is a negative feedback control loop that maintains homeostasis

Question 21

Summarize the function of WBCs. (in general, not each specific type of WBC)

Answer 21

Approximately 1% of whole blood consists of white blood cells (WBCs or leukocytes). Larger than red blood cells, they are also more diverse in structure and function. They have a nucleus but no hemoglobin. Because they are translucent, they are difficult to identify under the microscope unless they have been stained. Each cubic millimeter of blood contains only about 7,000 of them, and there is only one WBC for every 700 RBCs. White blood cells play a number of crucial roles in defending against disease and injury.

Question 22

About what percentage of blood is WBCs?

Answer 22

1 percent

Question 23

Summarize the function of platelets

Answer 23

Less than 1% of whole blood consists of platelets. Platelets are derived from megakaryocytes, which are large cells derived from stem cells in the bone marrow (review Figure 7.5). Megakaryocytes never circulate—they remain in the bone marrow. Platelets are just small pieces of megakaryocyte cytoplasm and cell membrane. Because platelets are not living cells, they last only about five to nine days in circulation. When a blood vessel is injured and leaks blood, platelets participate in the clotting process, thereby limiting the vascular and tissue damage. We examine the clotting process in the next section. Once the bleeding is stopped, platelets also participate in the repair process by releasing proteins that promote blood vessel growth and repair.

Question 24

Define hemostasis

Answer 24

Hemostasis (Figure 7.8), the natural process of stopping the flow or loss of blood, proceeds in three stages:
1 vascular spasm, or intense contraction of blood vessels in the area,
2 formation of a platelet plug, and
3 blood clotting, also called coagulation. Once blood loss has stopped, tissue repair can begin.

Question 25

What is the name of the protein that creates threads that wind around a platelet pug and form a clot?

Answer 25

Fibrin

Question 26

Summarize hemophilia

Answer 26

An inherited condition caused by a deficiency of one or more clotting factors. People with the most common form of the condition, hemophilia A, lack a protein known as clotting factor VIII. When a vessel is breached, blood clots slowly or not at all. Even if the skin is not broken, severe bruising can spread into joints and muscles. Fifty years ago, most people with hemophilia did not survive to adulthood. Today, many bleeding episodes can be controlled by administering another of the clotting factors, factor VIIa. Clotting factor VIIa was initially in short supply because it had to be purified from donor blood, but with genetic engineering techniques it is now possible to produce factor VIIa in the laboratory and in large quantities.

Question 27

List the four possible ABO blood types

Answer 27

A, B, AB, or O

Question 28

Differentiate between and state the roles of antigens and antibodies

Answer 28

An antigen (anti means “against,” and the Greek word gennan means “to generate”) is a “nonself” cell protein that stimulates the immune system of an organism to defend the organism. As part of this defense, the immune system produces an opposing protein called an antibody (“against” + “body”). Produced by lymphocytes, antibodies belong to the class of plasma proteins called gamma globulins, mentioned earlier. Antibodies mount a counterattack on antigens they recognize as “nonself” (Figure 7.10a). There are many antibodies, each one specialized to attack one particular antigen. This response has been compared to a lock and key: Only a specific antibody key can fit a specific antigen lock. Antibodies float freely in the blood and lymph until they encounter an invader with the matching antigen. They bind to the antigen molecule to form an antigen-antibody complex that marks the foreigner for destruction. The formation of an antigen-antibody complex often causes the foreign cells to clump together, effectively inactivating them (Figure 7.10b)

Question 29

If a person has type A antigen what blood type do they have?

Answer 29

A

Question 30

If a person has type A antigen what plasma antibody do they have?

Answer 30

B

Question 31

What would happen if a person with type A antibody received blood that had type A antigens?

Answer 31

A transfusion reaction

Question 32

What blood type doesn't have A or B antigens?

Answer 32

O

Question 33

What antibodies would a person with this type of blood have in their plasma?

Answer 33

none

Question 34

What blood type would allow a person to receive all other blood types without negative consequences?

Answer 34

type O

Question 35

What is Rh factor?

Answer 35

Another red blood cell surface antigen, called Rh factor because it was first discovered in rhesus monkeys, is also important in blood transfusions. Approximately 85% of Americans are Rh-positive, meaning they carry the Rh antigen on their red blood cells. About 15% are Rh-negative—they do not have the Rh antigen, and consequently their immune systems respond to any foreign Rh antigen by making antibodies against it.

Question 36

Describe how Rh factor incompatibility can affect a fetus.

Answer 36

the mother starts producing anti-Rh antibodies. These maternal antibodies can cross the placenta and attack the fetus’s red blood cells. The result may be hemolytic disease of the newborn (HDN), a disorder characterized by a reduced number of red blood cells and toxic levels of hemoglobin breakdown products in the newborn. HDN can lead to mental retardation or even death.

Question 37

Which mothers can RH factor incompatibility affect? (Rh+ or Rh-)

Answer 37

Rh-

Question 38

Mononucleosis is a contagious infection of lymphocytes in blood and lymph tissues caused by the Epstein–Barr virus, a relative of the virus that causes herpes. Most common during adolescence, “mono” is nicknamed the “kissing disease” because it’s frequently spread through physical contact. Symptoms of mononucleosis can mimic those of the flu: fever, headache, sore throat, fatigue, and swollen tonsils and lymph nodes. A blood test reveals increased numbers of monocytes and lymphocytes. The disease is called mononucleosis because many of the lymphocytes enlarge and begin to resemble monocytes. There is no known cure for mononucleosis, but almost all patients recover on their own within four to six weeks. Extra rest and good nutrition help the body overcome the virus.

Answer 38

Mononucleosis

Question 39

Although blood normally is well defended by the immune system, occasionally bacteria may invade the blood, overwhelm its defenses, and multiply rapidly in blood plasma. The bacteria may be toxic themselves, or they may secrete toxic chemicals as by-products of their metabolism. A bacterial infection of blood is called blood poisoning, or septicemia. Blood poisoning may develop from infected wounds (especially deep puncture wounds), severe burns, urinary system infections, or major dental procedures. To help prevent it, wash wounds and burns thoroughly with soap and water. Consult your doctor immediately when an infection is accompanied by flushed skin, chills and fever, rapid heartbeat, or shallow breathing. An early sign of some blood poisonings is the sudden appearance of red streaks on healthy skin near the site of an infection (Figure 7.14). The red streaks are due to inflammation of veins or lymph vessels in the area, indicating that the infection is spreading toward the systemic circulation. Although blood poisonings can be very dangerous (even fatal) if left untreated, in most cases they can be treated effectively with antibiotics.

Answer 39

Blood poisoning

Question 40

Anemia is a general term for reduction in the oxygencarrying capacity of blood. All causes of anemia produce similar symptoms: pale skin, headaches, fatigue, dizziness, difficulty breathing, and heart palpitations—the uncomfortable feeling that one’s heart is beating too fast as it tries to compensate for the lack of oxygen delivery. Major types of anemia include the following: ● Iron-deficiency anemia. Recall that every hemoglobin molecule contains four molecules of iron. When the body is deficient in iron, hemoglobin cannot be synthesized properly. The result is fewer hemoglobin molecules per red blood cell, and thus a decreased ability to transport oxygen. Iron-deficiency anemia is the most common form of anemia worldwide. Usually, it is due to too little iron in the diet, but it can also be caused by an inability of the digestive tract to absorb iron properly. Generally, it can be treated by taking pills that contain iron or by eating foods rich in iron such as leafy green vegetables and meat. ● Hemorrhagic anemia. Anemia due to blood loss (hemorrhage) may be caused by injuries, bleeding ulcers, excessive menstrual flow, and even certain parasites. Treatment includes finding and treating the underlying cause of blood loss, if possible, and making sure one has enough iron in the diet to replenish the lost red blood cells. ● Pernicious anemia. Pernicious anemia is caused by a deficiency of vitamin B12 absorption by the digestive tract. Vitamin B12 is important for the production of normal red blood cells. Pernicious anemia can be treated by injections of B12. ● Hemolytic anemia. Hemolytic anemia is the result of rupture (lysis) or early destruction of red blood cells. One cause is sickle-cell disease, an inherited disorder in which the red blood cells take on an abnormal sickle shape when the oxygen concentration is low. Because of their abnormal shape, sickled red blood cells become damaged as they travel through small blood vessels. Once damaged, they are destroyed by the body. Sicklecell anemia is most prevalent in Africans who live near the equator and in African Americans. Another common cause of hemolytic anemia is the parasite that causes malaria. ● Anemia due to renal failure. When the kidneys fail, they do not produce enough erythropoietin to maintain normal red blood cell production. In this case, the anemia is secondary to the renal failure and the attendant decline in erythropoietin, not the primary problem. This type of anemia is easily corrected by treatment with exogenous erythropoietin, called EPO, which maintains red blood cell production within normal limits.

Answer 40

anemia

Question 41

Leukemia refers to any of several types of blood cancer. Their common characteristic is uncontrolled proliferation of abnormal or immature white blood cells in the bone marrow. Overproduction of abnormal WBCs crowds out the production of normal white blood cells, red cells, and platelets. Huge numbers of leukemia cells enter and circulate in the blood, interfering with normal organ function.

Answer 41

Leukemia

Question 42

Thrombocytopenia is a reduction in the number of platelets in the blood. Thrombocytopenia can occur for a number of reasons, such as viral infection, anemia, leukemia, other blood disorders, exposure to X-rays or radiation, and even as a reaction to certain drugs. Sometimes platelet levels decline for no apparent reason, in which case, they often rise again after several weeks.

Answer 42

Thrombocytopenia