Chemistry Of Blood

Question 1

What are the main components of blood?

Answer 1

red blood cells, white blood cells platelets and plasma

Question 2

Describe the red blood cell component of blood

Answer 2

Also known as erythrocytes.
Main function is to transport oxygen.
Life span of 120 days and thereafter, they get destroyed in the RES.
No cellular organelles. They have no mitochondria and therefore do not carry out oxidative metabolism.
They metabolize glucose in glycolysis for ATP production. The reduced NADH produced in glycolysis converts pyruvate to lactate in order to sustain glycolysis.
Glucose is also metabolized in the RBCs in the pentose phosphate pathway to produce NADPH which is used to detoxify peroxides that can damage the membrane. Reduced NADP is also important in keeping iron in the ferrous state

Question 3

How do the red blood cells metabolize glucose?

Answer 3

They metabolize glucose in glycolysis for ATP production. The reduced NADH which is produced in glycolysis converts pyruvate to lactate in order to sustain glycolysis.
Glucose is also metabolized in the RBCs in the pentose phosphate pathway to produce NADPH which is used to detoxify peroxides that can damage the membrane.

Question 4

Describe the white blood cell component of blood

Answer 4

Also called leukocytes and their primary function is to phagocytosis and destruction of particulate matter.
They carry out oxidative metabolism because they have all the cellular organelles.

Question 5

Briefly describe the platelet component of blood

Answer 5

They are involved in the blood clotting mechanism. Most of the energy comes from glycolysis

Question 6

Describe the plasma component of blood

Answer 6

This made up of 90% water . It also contains various molecules such as proteins, hormones and nutrients e.g sugars, lipids vitamins and minerals. The proteins include enzymes, clotting factors, immunoglobulins . Some of the proteins transport compounds in the blood.

Question 7

State and describe the major functions of blood

Answer 7

1. Respiration: Transportation of oxygen from the lungs to the tissues and carbon dioxide from the tissues to the lungs.
2. Nutrition:Transportation of the nutrients.
3. Excretion: Transportation of metabolic waste to kidneys, lungs, skin, and intestines for removal.
4. Acid-base balance: The blood is important in the maintenance of the acid base balance in the body.
5. Water balance: blood is also involved in the regulation of water balance through the exchange of fluid in the circulation system and the tissue fluid.
6. Temperature: It regulates temperature by the distribution of body heat.
7. Defence: This is the function of the white blood cells and the immunoglobulins.
8. Regulation of metabolism: It transports hormones that are involved in the regulation of metabolic pathways.
9. Transportation of metabolites. For example, metabolites like fatty acids are transported in the blood bound to albumin from the adipose tissue to skeletal muscle where they are broken down to produce energy in the process of beta oxidation.
10. Coagulation: Blood is involved in the formation of blood clots that stop the bleeding.

Question 8

List the plasma proteins

Answer 8

albumin,
alpha 1 and alpha 2 globulins,
beta globulins and
gamma globulins
They also include fibrinogen, transferrin and blood coagulation factors

Question 9

Describe the plasma proteins

Answer 9

Plasma proteins are rich in disulphide bonds and they are mainly glycoproteins and lipoproteins.
They are synthesized in the liver except gamma globulin which is synthesized in the lymphocytes.
The concentration of plasma proteins is 7 to 7.5g/100mls

Question 10

What is the main function of plasma proteins?

Answer 10

to maintain the oncotic pressure which is important in drawing fluid from the interstitial to the vascular system.

Question 11

State the types of plasma proteins and their respective functions

Answer 11

1. Blood clotting - Fibrinogen, coagulation factors.
2. Enzymes - Functional and non-functional plasma enzymes.
3. Immune defense - Immunoglubulins.
4. Transport binding - Albumin, lipoprotein, transferrin, Haptoglobulins
5. Inflammatory reaction - C reactive proteins, acute phase proteins

Question 12

Which is the main plasma protein?

Answer 12

Albumin

Question 13

Describe albumin

Answer 13

The main plasma protein and contributes to 75 to 80% of the oncotic pressure. It is made up of a single polypeptide chain.
If albumin concentration is low e.g in Protein Energy Malnutrition, the fluid accumulates in the extravascular space causing edema. Liver disease also causes low albumin.
Albumin transports molecules such as fatty acids, hormones, unconjugated bilirubin. It also transports drugs.

Question 14

What are functional enzymes?

Answer 14

These are enzymes are present at all times in the circulation of normal individuals and perform physiologic functions in blood. They include enzymes of blood coagulation and blood clot dissolution. Majority of functional plasma enzymes are synthesized and secreted by the liver.

Question 15

What are non functional enzymes?

Answer 15

These are enzymes found in the blood with no known physiological function . They are released in the blood due to the normal destruction of erythrocytes, leukocytes, and other tissues and are in circulation in insignificant amounts

Question 16

What is the significance of non-functional enzymes?

Answer 16

when there is tissue damage or disease, excessive release of these non-functional enzymes in plasma occurs resulting in significant elevation of their levels. Detection of significantly increased levels of these non-functional plasma enzymes is therefore of diagnostic of some disease conditions.

Question 17

What are the subunits of immunoglobulins made up of?

Answer 17

the H chain( heavy chain) and L chain( light chain)

Question 18

List the types of immunoglobulins

Answer 18

IgA, IgG, IgD, IgE and IgM

Question 19

Which components make up the immune response?

Answer 19

B lymphocytes, T lymphocytes and immunoglobulins

Question 20

Describe immunoglobulins

Answer 20

These are oligomeric proteins made up of multiple chains.
They are glycoproteins and are made up of 2 types of subunits: the H chain( heavy chain) and L chain( light chain). The classification into the H and L chains is based on the immigration in electrophoresis.
There are 5 types of immunoglobulins: IgA, IgG, IgD, IgE and IgM.
They have a Y shaped structure.
They are produced in response to the invasion of foreign compounds such as bacteria, protein. There are 3 components of immune response, B lymphocytes, T lymphocytes and immunoglobulins.

Question 21

State the composition and function of IgA

Answer 21

15%-dimer
produced in extra vascular secretion. d Prevents attachment of bacteria and viruses in the mucous membranes such as nasal, bronchial, intestinal mucosa.

Question 22

State the composition and function of IgG

Answer 22

75%-monomer
Main antibody in the plasma. Response takes longer than that of IgM. It promotes phagocytosis by macrophages leukocytes.

Question 23

State the composition and function of IgM

Answer 23

9%- pentamer
Produces the primary response to an antigen in the plasma. They promote phagocytosis by macrophages and leukocytes.

Question 24

State the composition and function of IgD

Answer 24

0.2%- monomer
Found on the surface of the B cells where it acts as a receptor for antigens

Question 25

State the composition and function of IgE

Answer 25

0.004%-monomer
Mediates the hypersensitivity reaction. It causes anaphylactic reaction , hay fever and asthma. Increased production in worm infestation causes increase of eosinophils.