1. Components of Blood

2. 1. What is blood composed of?
Blood is a liquid tissue composed of 55% fluid and 45% blood cells or formed elements.

3. 2.What is the hematocrit?
Hematocrit is the percentage of red blood cells found in blood.

4. 3. What is plasma and what does it contain?
Plasma is the liquid portion of blood.  It is composed of approximately 90% fluid along with blood proteins, glucose, vitamins, minerals, dissolved gases, and waste products of cell metabolism.

5. 4.Why is blood considered a tissue?
Blood is considered a fluid tissue because it contains water and cells

6. 5. What are the 3 groups of proteins found in the blood and what is their function?
The albumins work together with inorganic minerals to maintain body fluid levels by drawing water via osmosis back into the capillaries
The globulins assist in protecting the body from foreign invaders
The fibrinogens play an important role in blood clotting. 

7. 6. What are erythrocytes?
Erythrocytes are red blood cells whose job is to carry oxygen.

8. 7. What function does haemoglobin serve in our blood?
Hemoglobin is an iron-containing protein that significantly increases the ability of the red blood cells to carry oxygen.  Due to the presence of hemoglobin, red blood cells can increase their carry capacity by a factor of 7.

10. 8. How long can your cells survive without oxygen?
Cells can survive without oxygen for about five minutes.  After this they begin to die.

11. 9. What is oxyhemoglobin?
Oxyhemoglobin is a compound formed when oxygen molecules bind with iron molecules in the hemoglobin

12. 10. Why does blood look blue in your veins?
Blood in your veins appears blue due to the fact that veins carry blood that is low in oxygen and the loss of oxygen changes the shape of the hemoglobin molecule causing it to reflect blue light.

13. 11. Why are red blood cells bioconcave?
Red blood cells are biconcave in shape which increases their surface area for gas exchange by 20 to 30%. 

14. 12. How long do erythrocytes live and where are they produced?
Erythrocytes live for approximately 120 days and they are produced in the bone marrow by stem cells.

15. 13. How many red blood cells does the average male and female contain
13. How many red blood cells does the average male and female contain? Can anything affect this number?
Red blood cell counts are different on average for males and females.  Males tend to carry about 5.5 billion red blood cells per millimetre of blood while females have about 4.5 billion per millimetre of blood.  The red blood cell count can be affected by altitude.  People living at high altitudes may contain as many as 8 billion red blood cells per millimetre.

16. 14. What happens when red blood cells die?
As red blood cells age their outer membranes become brittle and can rupture as the cells travel through narrow capillaries.  The liver and spleen monitor the age of red blood cells and remove them and the debris from the blood.  As they are broken down haemoglobin is released and the iron from the haemoglobin is recovered and stored in the bone marrow for future use and the heme is changed into bile pigments.

17. 15. What is the most common cause of anemia? Are there any other causes?
Anemia is a condition characterized by low energy levels that result from deficient levels of haemoglobin or red blood cells.  The most common cause of this deficiency is hemorrhage or heaving bleeding.  Anemia can also be caused by a deficiency of dietary iron.

18. 16. Does your body contain more leukocytes or erythrocytes?
Humans contain significantly less leukocytes than erythrocytes.  Estimation shows that white blood cells (leukocytes) are outnumbered by red blood cells by a ratio of 700 to 1.

19. 17. What is one major structural difference between white and red blood cells?
A major difference in structure between red blood cells and white blood cells is the presence of a nucleus in white cells and the absence of the nucleus in red cells.

20. 18. How do leukocytes function to fight invaders?
One method of fighting invaders is through the process of phagocytosis.  The leukocytes squeeze out of the capillaries and into the tissue where the microbe (invader) is located and engulfs the microbe.  Once it has ingested the microbe the leukocyte will release digestive enzymes that will digest the microbe and itself. The left over material is known as pus.

22. 19.What other form of defence besides engulfing invaders do white blood cells have?
 The other method used by leukocytes is the formation of special proteins known as antibodies which interfere with invading microbes and toxins.

23. 20. How are platelets similar to red blood cells?
Platelets are similar to red blood cells in that they both are produced in the bone marrow and neither contain a nucleus

24. 21. How are platelets formed?
Platelets are formed when small fragments of cytoplasm break away from a large cell in the bone marrow called a megakaryocyte.

25. 22. What is the function of platelets?
Platelets play a crucial role in blood clotting.  They break open when they come in contact with the sharp edge of a broken blood vessel and release chemicals which begin the blood clotting process