Blood is a fluid connective tissue critical to the transportation of nutrients, gases, and wastes throughout the body; to defend the body against infection and other threats; and to the homeostatic regulation of pH, temperature, and other internal conditions. Blood is composed of formed elements—erythrocytes, leukocytes, and cell fragments called platelets—and a fluid extracellular matrix called plasma. More than 90 percent of plasma is water. The remainder is mostly plasma proteins—mainly albumin, globulins, and fibrinogen—and other dissolved solutes such as glucose, lipids, electrolytes, and dissolved gases. Because of the formed elements and the plasma proteins and other solutes, blood is sticky and more viscous than water. It is also slightly alkaline, and its temperature is slightly higher than normal body temperature.
albumin
most abundant plasma protein, accounting for most of the osmotic pressure of plasma
antibodies
(also, immunoglobulins or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
blood
liquid connective tissue composed of formed elements—erythrocytes, leukocytes, and platelets—and a fluid extracellular matrix called plasma; component of the cardiovascular system
buffy coat
thin, pale layer of leukocytes and platelets that separates the erythrocytes from the plasma in a sample of centrifuged blood
fibrinogen
plasma protein produced in the liver and involved in blood clotting
formed elements
cellular components of blood; that is, erythrocytes, leukocytes, and platelets
globulins
heterogeneous group of plasma proteins that includes transport proteins, clotting factors, immune proteins, and others
hematocrit
(also, packed cell volume) volume percentage of erythrocytes in a sample of centrifuged blood
immunoglobulins
(also, antibodies or gamma globulins) antigen-specific proteins produced by specialized B lymphocytes that protect the body by binding to foreign objects such as bacteria and viruses
packed cell volume (PCV)
(also, hematocrit) volume percentage of erythrocytes present in a sample of centrifuged blood
plasma
in blood, the liquid extracellular matrix composed mostly of water that circulates the formed elements and dissolved materials throughout the cardiovascular system
platelets
(also, thrombocytes) one of the formed elements of blood that consists of cell fragments broken off from megakaryocytes
red blood cells (RBCs)
(also, erythrocytes) one of the formed elements of blood that transports oxygen
white blood cells (WBCs)
(also, leukocytes) one of the formed elements of blood that provides defense against disease agents and foreign materials
Visit this site for a list of normal levels established for many of the substances found in a sample of blood. Serum, one of the specimen types included, refers to a sample of plasma after clotting factors have been removed. What types of measurements are given for levels of glucose in the blood?
There are values given for percent saturation, tension, and blood gas, and there are listings for different types of hemoglobin.
1. Which of the following statements about blood is true?
A) Blood is about 92 percent water.
B) Blood is slightly more acidic than water.
C) Blood is slightly more viscous than water.
D) Blood is slightly more salty than seawater.
C
2. Which of the following statements about albumin is true?
A) It draws water out of the blood vessels and into the body’s tissues.
B) It is the most abundant plasma protein.
C) It is produced by specialized leukocytes called plasma cells.
D) All of the above are true.
B
3. Which of the following plasma proteins is not produced by the liver?
A) fibrinogen
B) alpha globulin
C) beta globulin
D) immunoglobulin
D
1. A patient’s hematocrit is 42 percent. Approximately what percentage of the patient’s blood is plasma?
The patient’s blood is approximately 58 percent plasma (since the buffy coat is less than 1 percent).
2. Why would it be incorrect to refer to the formed elements as cells?
The formed elements include erythrocytes and leukocytes, which are cells (although mature erythrocytes do not have a nucleus); however, the formed elements also include platelets, which are not true cells but cell fragments.
3. 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.