Unit 4A Exam

The first heart sound represents which portion of the cardiac cycle?

closing of the atrioventricular valves

People with ABO blood type O ________.

lack both antigens A and B on their erythrocytes

Of the three germ layers that give rise to all adult tissues and organs, which gives rise to the heart?

mesoderm

Interleukins are associated primarily with which of the following?

production of various lymphocytes immune responses inflammation (all of the above)

CT: A patient was admitted to the burn unit the previous evening suffering from a severe burn involving his left upper extremity and shoulder. A blood test reveals that he is experiencing leukocytosis. Why is this an expected finding?

Any severe stress can increase the leukocyte count, resulting in leukocytosis. A burn is especially likely to increase the proliferation of leukocytes in order to ward off infection, a significant risk when the barrier function of the skin is destroyed.

CT: A patient has thalassemia, a genetic disorder characterized by abnormal synthesis of globin proteins and excessive destruction of erythrocytes. This patient is jaundiced and is found to have an excessive level of bilirubin in his blood. Explain the connection.

Bilirubin is a breakdown product of the non-iron component of heme, which is cleaved from globin when erythrocytes are degraded. Excessive erythrocyte destruction would deposit excessive bilirubin in the blood. Bilirubin is a yellowish pigment, and high blood levels can manifest as yellowed skin.

CT: True or false: The buffy coat is the portion of a blood sample that is made up of its proteins.

False. The buffy coat is the portion of blood that is made up of its leukocytes and platelets.

CT: Explain why administration of a thrombolytic agent is a first intervention for someone who has suffered a thrombotic stroke.

In a thrombotic stroke, a blood vessel to the brain has been blocked by a thrombus, an aggregation of platelets and erythrocytes within a blood vessel. A thrombolytic agent is a medication that promotes the breakup of thrombi.

CT: Following a motor vehicle accident, a patient is rushed to the emergency department with multiple traumatic injuries, causing severe bleeding. The patient's condition is critical, and there is no time for determining his blood type. What type of blood is transfused, and why?

In emergency situations, blood type O− will be infused until cross matching can be done. Blood type O− is called the universal donor blood because the erythrocytes have neither A nor B antigens on their surface, and the Rh factor is negative.

Which of the following statements about erythropoietin is true?

It facilitates the proliferation and differentiation of the erythrocyte lineage.

Which of the following statements about albumin is true?

It is the most abundant plasma protein.

CT: In preparation for a scheduled surgery, a patient visits the hospital lab for a blood draw. The technician collects a blood sample and performs a test to determine its type. She places a sample of the patient's blood in two wells. To the first well she adds anti-A antibody. To the second she adds anti-B antibody. Both samples visibly agglutinate. Has the technician made an error, or is this a normal response? If normal, what blood type does this indicate?

The lab technician has not made an error. Blood type AB has both A and B surface antigens, and neither anti-A nor anti-B antibodies circulating in the plasma. When anti-A antibodies (added to the first well) contact A antigens on AB erythrocytes, they will cause agglutination. Similarly, when anti-B antibodies contact B antigens on AB erythrocytes, they will cause agglutination.

The process in which antibodies attach to antigens, causing the formation of masses of linked cells, is called ________.

agglutination

T and B lymphocytes ________.

are involved with specific immune function

Most blood enters the ventricle during ________.

atrial diastole

A patient has been experiencing severe, persistent allergy symptoms that are reduced when she takes an antihistamine. Before the treatment, this patient was likely to have had increased activity of which leukocyte?

basophils

A molecule of hemoglobin ________.

consists of four globin proteins, each bound to a molecule of heme

The production of healthy erythrocytes depends upon the availability of ________.

copper, zinc, and vitamin B12

The earliest organ to form and begin function within the developing human is the ________.

heart

Which valve separates the left atrium from the left ventricle?

mitral

Which of the following lists the valves in the order through which the blood flows from the vena cava through the heart?

tricuspid, pulmonary semilunar, bicuspid, aortic semilunar

Hemolytic disease of the newborn is a risk during a subsequent pregnancy in which ________.

an Rh− mother is carrying a second Rh+ fetus

Hemophilia is characterized by ________.

inadequate production of clotting factors

The cardiovascular centers are located in which area of the brain?

medulla oblongata

Thrombocytes are more accurately called ________.

platelets

Which chamber initially receives blood from the systemic circuit?

right atrium

The first step in hemostasis is ________.

vascular spasm

CT: One of the more common adverse effects of cancer chemotherapy is the destruction of leukocytes. Before his next scheduled chemotherapy treatment, a patient undergoes a blood test called an absolute neutrophil count (ANC), which reveals that his neutrophil count is 1900 cells per microliter. Would his healthcare team be likely to proceed with his chemotherapy treatment? Why?

A neutrophil count below 1800 cells per microliter is considered abnormal. Thus, this patient's ANC is at the low end of the normal range and there would be no reason to delay chemotherapy. In clinical practice, most patients are given chemotherapy if their ANC is above 1000.

Which of the following statements about blood is true?

Blood is slightly more viscous than water.

Which of the following is unique to cardiac muscle cells?

Only cardiac muscle is capable of autorhythmicity

CT: A young woman has been experiencing unusually heavy menstrual bleeding for several years. She follows a strict vegan diet (no animal foods). She is at risk for what disorder, and why?

She is at risk for anemia, because her unusually heavy menstrual bleeding results in excessive loss of erythrocytes each month. At the same time, her vegan diet means that she does not have dietary sources of heme iron. The non-heme iron she consumes in plant foods is not as well absorbed as heme iron.

CT: Why is it so important for the human heart to develop early and begin functioning within the developing embryo?

The human embryo is rapidly growing and has great demands for nutrients and oxygen, while producing waste products including carbon dioxide. All of these materials must be received from or delivered to the mother for processing. Without an efficient early circulatory system, this would be impossible.

Which of the following statements about mature, circulating erythrocytes is true?

They have no nucleus.

CT: A lab technician collects a blood sample in a glass tube. After about an hour, she harvests serum to continue her blood analysis. Explain what has happened during the hour that the sample was in the glass tube.

When blood contacts glass, the intrinsic coagulation pathway is initiated. This leads to the common pathway, and the blood clots. Within about 30 minutes, the clot begins to shrink. After an hour, it is about half its original size. Its heavier weight will cause it to fall to the bottom of the tube during centrifugation, allowing the lab technician to harvest the serum remaining at the top.