Deck 1: Introduction

Question 1

What cellular component of blood can be involved in disorders of hemostasis?

Answer 1

The term Hemostasis comes from the Greek roots, heme referring to blood and stasis referring to halt. It is the stoppage of bleeding through the injured blood vessels or the tissue. It is the inbuilt property of the circulatory system that maintains the blood in liquid form within the blood vessels.
Hemostasis occurs in the following two stages:
1. Primary hemostasis : It involves formation of blood clot. The smooth muscles of blood vessels contract at the site of injury and exposed collagen protein attracts platelets.
2. Secondary hemostasis: Platelets release chemicals that make other platelets sticky with the help of coagulation factors, calcium ions, and vitamin K form prothrombin activator. This prothrombin activator cleaves prothrombin to generate thrombin which further induces the generation of fibrin from fibrinogen. Fibrin forms a mesh that traps RBCs and platelets forming the clot.
3. Fibrinolysis - At last when the vessel is repaired, dissolution of clot takes place. This ensures the normal blood flow by means of plasmin that split fibrin into fibrin degradation product (FDP) that is swept away in circulation.
Decrease in any of these factors (platelets, coagulation protein, calcium and vitamin K) can cause upset in the stages of hemostasis. This can further result in excessive bleeding or abnormal clotting of blood (thrombosis- platelet plug at the site other than injury). Platelet is the main cellular component of blood involved in disorder of hemostasis.

Question 2

Aaron, a 2-year-old male, was seen by his pediatrician because he had a fever of 102 to 104ºF over the past 24 hours. Aaron was lethargic. Before this, he had been in good health except for two episodes of otitis.
Consider why the pediatrician might order laboratory tests and how this child's condition might affect the composition of his blood.
If Aaron was diagnosed with otitis media, what cellular component(s) in his blood would be playing a central role in fighting this infection?

Answer 2

Otitis media is an infection that occurs in the middle ear. In this case, the ear is infected or clogged with fluid behind the eardrum. The three vital cellular constituents of blood are RBCs (red blood cells), WBCs (white blood cells) and platelets (thrombocytes).
Every cellular component has its own function. RBCs are involved in the transportation of oxygen to the lungs and all the tissues of the body. WBCs are further classified as eosinophil, basophils, neutrophils, lymphocytes, and monocytes.
All these have specific functions in protecting the body from foreign bodies. Thrombocytes have a role in maintaining homeostasis of the body. In the present case, Aaron is suffering from otitis media. It is the case of infection; the cellular components responsible for playing a central role in fighting this infection are WBCs.
In simple words, leukocytes or WBCs are known as scavengers of the body. These are the important cellular components, which protect the body by fighting against foreign pathogens (bacteria and virus), which are the cause of infection.

Question 3

In which group of individuals would you expect to find the highest reference intervals for hemoglobin, hematocrit, and erythrocyte count? (Objective 1)

A) newborns
B) males older than 12 years of age
C) females older than 17 years of age
D) children between 1 and 5 years of age

Answer 3

Reference intervals refer to the physiological differences in the concentration of cellular elements, which depends on race, age, sex, and geographic location. Erythrocytes are also known as red blood cells (RBCs).
RBC contains a vital protein called hemoglobin. It is responsible for transport of oxygen as well as carbon dioxide between the body tissues and the lungs. The hematocrit measures the volume of RBCs compared to the total blood volume.
Erythrocytes, hemoglobin and hematocrit are linked with each other. An increase in the concentration of any of these would lead to an increase in the concentration of the other.
After puberty, males have higher hemoglobin, hematocrit, and erythrocyte levels than females.
Hence, the options B, C and D are incorrect.
Newborns have a higher erythrocyte concentration than any other age group. The erythrocyte concentration decreases gradually 6 months after the birth and then slowly increases from 5 to 17 years of age.
Hence, the correct answer is option .

Question 4

A 13-year-old female saw her physician for complaints of a sore throat, lethargy, and swollen lymph nodes. A CBC was performed with the following results: Hb 9.0 g/dL (90 g/L); Hct 30% (0.30 L/L);
On the basis of these results, should reflex testing be performed?

Question 5

Aaron, a 2-year-old male, was seen by his pediatrician because he had a fever of 102 to 104ºF over the past 24 hours. Aaron was lethargic. Before this, he had been in good health except for two episodes of otitis.
Consider why the pediatrician might order laboratory tests and how this child's condition might affect the composition of his blood.
Aaron's physician ordered a complete blood count (CBC). The results are Hb 11.5 g/dL (115 g/L); Hct 34% (0.34 L/L).
What parameters, if any, are outside the reference intervals? Why do you have to take Aaron's age into account when evaluating these results?

Question 6

Which cells are important in transporting oxygen and carbon dioxide between the lungs and body tissues?
(Objective 2)

A) platelets
B) leukocytes
C) thrombocytes
D) erythrocytes

Question 7

Forty-five percent of the volume of blood is normally composed of: (Objective 3)

A) erythrocytes
B) leukocytes
C) platelets
D) plasma

Question 8

Alterations in the concentration of blood cells generally are the result of: (Objective 4)

A) laboratory error
B) amount of exercise before blood draw
C) a disease process
D) variations in analytical equipment

Question 9

Leukocytes are necessary for: (Objective 2)

A) hemostasis
B) defense against foreign pathogens
C) oxygen transport
D) excretions of cellular metabolites

Question 10

Laboratories can use which type of testing to help direct the physician's selection of appropriate testing after screening tests are performed? (Objective 5)

A) reflexive based on results of screening tests
B) manual repeat of abnormal results
C) second test by a different instrument
D) standing orders for all inpatients

Question 11

Screening tests used to evaluate the hemostasis system include: (Objective 6)

A) PT and APTT
B) CBC
C) hemoglobin
D) WBC count

Question 12

A patient blood specimen is stored in a car for 2 hours with the outside temperature of 95°. This is an example of error in which component of testing? (Objective 8)

A) pre-examination
B) examination
C) post-examination