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Blood Physiology and Functions
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Blood Physiology and Functions
Blood Physiology and Functions
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1
Question
What are the functions of blood?
Answer
Blood maintains homeostasis in several ways: transport of gases, nutrients, waste products; transport of processed molecules; transport of regulatory molecules; regulation of pH and osmosis; maintenance of body temperature; protection against foreign substances such as microorganisms and toxins; and blood clotting to prevent fluid and cell loss and to aid in tissue repair.
2
Question
What is blood classified as?
Answer
Blood is a connective tissue consisting of plasma and formed elements. It is the body's only fluid tissue, composed of liquid plasma and formed elements.
3
Question
What are the formed elements of blood?
Answer
Formed elements include erythrocytes (red blood cells), leukocytes (white blood cells), and platelets.
4
Question
What is hematocrit?
Answer
Hematocrit is the percentage of red blood cells (RBCs) out of the total blood volume.
5
Question
What is the approximate total blood volume in adults?
Answer
Total blood volume is approximately 5 liters.
6
Question
What is the average pH of blood?
Answer
The pH of the blood is between 7.35 and 7.45.
7
Question
What is the average temperature of blood?
Answer
The average temperature of blood is 38°C.
8
Question
What percentage of body weight does blood account for?
Answer
Blood accounts for approximately 8% of body weight.
9
Question
What are the characteristics of plasma?
Answer
Plasma is a pale yellow fluid containing over 100 solutes, mostly water (91%), and contains proteins (6%): Albumin (58% of plasma proteins), Globulins (38%), and Fibrinogen (4%). Other substances include ions, nutrients, waste products, and respiratory gases.
10
Question
What are erythrocytes?
Answer
Erythrocytes, or red blood cells (RBCs), are about 95% of formed elements, have no nuclei or organelles, and are dedicated to respiratory gas transport.
11
Question
What is the structure of hemoglobin (Hb)?
Answer
Hemoglobin (Hb) accounts for about a third of the cell's volume and consists of the protein globin, made up of two alpha and two beta chains, each bound to a heme group that can bind to one oxygen molecule.
12
Question
What is the function of hemoglobin in RBCs?
Answer
Hemoglobin transports oxygen and carbon dioxide; 98.5% of oxygen is transported bound to hemoglobin, while 1.5% is dissolved in plasma.
13
Question
What is the process of erythropoiesis?
Answer
Erythropoiesis is the production of RBCs, starting from a hemocytoblast transforming into proerythroblasts, which develop into early erythroblasts, and then proceed through three phases: 1. Ribosome synthesis in early erythroblasts, 2. Hb accumulation in intermediate and late erythroblasts, 3. Ejection of the nucleus from late erythroblasts and formation of reticulocytes.
14
Question
What triggers the release of erythropoietin (EPO)?
Answer
EPO release by the kidneys is triggered by hypoxia due to decreased RBCs, decreased oxygen availability, or increased tissue demand for oxygen.
15
Question
What happens to old erythrocytes?
Answer
Old RBCs become rigid and fragile, and their hemoglobin begins to degenerate. They are engulfed by macrophages in the spleen or liver, where heme and globin are separated, iron is salvaged, and bilirubin is produced.
16
Question
What are the functions of white blood cells (WBCs)?
Answer
WBCs protect the body against invading microorganisms and remove dead cells and debris from tissues by phagocytosis.
17
Question
What are the two categories of white blood cells?
Answer
White blood cells are categorized into granulocytes (neutrophils, eosinophils, basophils) and agranulocytes (lymphocytes and monocytes).
18
Question
What is the function of platelets?
Answer
Platelets function in clotting by forming platelet plugs and contributing to the formation of clots to seal off larger wounds.
19
Question
What are the phases of blood clotting?
Answer
The three phases of blood clotting include vascular spasms (immediate vasoconstriction), platelet plug formation, and coagulation (blood clotting).
20
Question
What is the ABO blood group system?
Answer
The ABO blood group system consists of two antigens (A and B) on the surface of RBCs and two antibodies in the plasma (anti-A and anti-B).
21
Question
What is hemolytic disease of the newborn?
Answer
Hemolytic disease of the newborn occurs when an Rh-negative mother is exposed to Rh-positive blood, leading to the production of antibodies that can affect the fetus.
22
Question
What is the lifespan of an erythrocyte?
Answer
The lifespan of an erythrocyte is 100-120 days.
23
Question
Where does hematopoiesis occur in the body?
Answer
Hematopoiesis occurs in different locations before and after birth: in the fetus, hematopoiesis occurs in the liver, thymus, spleen, lymph nodes, and red bone marrow; after birth, it occurs in the red bone marrow of the axial skeleton and girdles.
24
Question
What are the two mechanisms by which platelets prevent blood loss?
Answer
The two mechanisms are the formation of platelet plugs to seal small breaks in blood vessels and the formation of clots to seal larger wounds.
25
Question
What is clot retraction?
Answer
Clot retraction is the stabilization of the clot by squeezing serum from the fibrin strands, which helps pull the edges of damaged tissue closer together.
26
Question
What is fibrinolysis?
Answer
Fibrinolysis is the process of dissolving fibrin in a clot, activated by thrombin and tissue plasminogen activator, which activates plasmin.