Term Paper on Blood: Definition and Functions | Body Fluids | Biology

Here is a term paper on ‘Blood’. Find paragraphs, long and short term papers on ‘Blood’ especially written for college and paramedical students.

1. Term Paper on the Definition of Blood
2. Term Paper on the Physical Characteristics of Blood
3. Term Paper on the Composition of Blood
4. Term Paper on the Functions of Blood
5. Term Paper on the Components of Blood
6. Term Paper on the Physiology of Blood

Term Paper # 1. Definition of Blood:

Blood is a specialized bodily fluid that delivers necessary substances to the body’s cells — such as nutrients and oxygen — and transports waste products away from those same cells.

Normally, 7-8% of human body weight is from blood. In adults, this amounts to 4-5 quarts of blood. This essential fluid carries out the critical functions of transporting oxygen and nutrients to our cells and getting rid of carbon dioxide, ammonia, and other waste products.

In addition, it plays a vital role in our immune system and in maintaining a relatively constant body temperature. Blood is a highly specialized tissue composed of many different kinds of components. Four of the most important ones are red cells, white cells, platelets, and plasma.

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Term Paper # 2. Physical Characteristics of Blood:

i. Opaque

ii. Metallic taste

iii. Red color (intensity dependent upon amount of dissolved oxygen present)

iv. More dense and more viscous than water

v. pH ~ 7.35 – 7.45

vi. Temperature is always slightly higher than body temperature

vii. Average volume ~ 5L

viii. Approximately 8% of body weight

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Term Paper # 3. Composition of Blood (Cells, Plasma):

Blood is the fluid constituent of the body that flows through the vascular channels and transport vital requirement and waste product of the body.

Other function of the constituent of blood includes body defense through immunological response, stoppage of bleeding and maintenance of body temperature.

The blood has two major components:

1. Cellular

2. Fluid

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Term Paper # 4. Functions of Blood:

1. Transport of Respiratory Gases:

It carries oxygen from lungs to the tissue and carbon dioxide from the tissue to lung.

2. Transport of Nutrition:

It carry digestive food materials absorbed from the intestine to the tissue cell for utilization.

3. It act as a medium through which hormones, vitamins and other important chemical are brought to their place of activity.

4. Drainage of Waste Material:

Blood carries, the waste product of cellular activity and bring them to the organs excretion (kidney/ skin/ lung/ Intestine)

5. Blood maintain the water balance in the body.

6. Blood maintain acid Base equilibrium of the body because it has buffering capacity.

7. It maintains ions of the body by maintaining the ions between the cells and surrounding fluid.

8. It regulates body temperature.

9. Defensive Function:

Blood act as a great defensive mechanism by two ways:

a. WBC of blood due to the phagocytes capacity engulfs foreign particle and back and digests them.

b. It develops antibodies which can react against the infection.

10. Blood has a property of blood coagulation due to presence of blood coagulation factor thus guards our body against hemorrhage or bleeding.

11. Plasma proteins of blood have different functions.

12. It regulates the blood volume and blood pressure.

I. RBC (Erythrocyte)

II. WBC (Leukocyte)

III. Platelets (Thrombocyte)

a. Neutrophil

b. Eosinophil and Basophil

c. Monocyte

d. Lymphocyte

They are middle sized measuring (7.2-7.5 micron), they have biconcave shape. Protein fraction of RBC is 85%. They don’t have the nucleus. They contain hemoglobin and are the heaviest of all the solid component of the blood. The shape of erythrocytes is a biconcave disc.

The hemoglobin is responsible for carrying Oxygen from the lungs to the tissue cell’s and bring back on its return carbon dioxide which is formed as a result of cellular metabo­lism. Internal fluid connection of RBC is equivalent to 0.85% Nacl (sodium chloride).

If RBC is dropped in water endo-osmosis occur and hemolysis happens. If RBC is dropped into concentrated solution exo-osmosis occurs and RBC will shrink. That is why physiological saline (Nacl in water) has a concentration of 0.85% Nacl (sodium chloride).

Hemoglobin is the iron-containing protein attached to red blood cells that transports oxygen from the lungs to the rest of the body. Hemoglobin bonds with oxygen in the lungs, exchanges it for carbon dioxide at cellular level, and then transports the carbon dioxide back to the lungs to be exhaled.

Whether hemoglobin binds with oxygen or carbon dioxide depends on the relative con­centration of each around the red blood cell. When it reaches the oxygen-rich lungs, it releases the less-abundant carbon dioxide to bind with oxygen; when it goes back out into the body where cells are producing carbon dioxide, it releases the oxygen and binds with carbon dioxide. This is called the Bohr Effect.

When carbon monoxide is present, it competes with oxygen at the haem binding sites, and since hemoglobin is 200 times more likely to bond with carbon monoxide, forming a very bright red form of hemoglobin called carboxyhemoglobin.

A concentration of carbon monoxide as low as 0.02% in the air can cause nausea and headache; 0.1% causes uncon­sciousness and death, (compare that with the normal 20% oxygen saturation of the air!) Heavy smokers, who expose themselves regularly to carbon monoxide, may have as many as 20% of their hemoglobin’s oxygen sites blocked by carbon monoxide.

Hemoglobin abnormalities result in very serious hereditary diseases, such as sickle- cell anemia and thalassemia.

Hemoglobin is made up of four subunits, with a haem (iron-containing) group in each for oxygen binding. There are slightly different haemoglobins in adults when compared to children and fetus.

They are group of nucleated cell which help in the defense mechanism of the body in response to attack by pathogenic organism. Two types of leukocyte is found in blood circu­lation granulocyte (Neutrophil, Eosinophils, Basophil) and agranulocyte (lymphocyte and monocyte).

It is also called polymorphs (they can change their shape) and main function is to phagocyte pathogen Hence neutrohilia is commonly seen in presence of an infection.

Protect the body by release of Histamine and Heparin that start an inflammatory response at the concerned site of infection. Allergic reaction and parasitic reaction involve eosinophilia and Basophilia.

Lymphocyte involved one of the major defense system by which body fights infections, they are involved in the immunological responses of the body. Immunological response means killing the infective micro-organism either directly or by providing antibodies against their concerned antigens. The antibod­ies are produced by B lymphocyte.

It is the largest cell found in peripheral blood. They are referred to as macro phages and main function is to remove particulate matters of dead and dy­ing cells. Cellular debris carrying RBC and antigen antibodies. These cells are mainly located in liver followed by bone marrow, intestine, brain and other tissues of the blood.

White blood cells perform several functions in the body as:

1. Phagocytosis:

The neutrophils and the monocytes engulf foreign particles and bacteria through their phagocytic action, thereby destroying their action.

W.B.C. manufactures anti-bodies and immune bodies to increase the power of resistance against any infection.

Lymphocytes may be converted to fibroblast in the area of inflammation and help the process of tissue repair and regeneration.

The basophil leucocytes are supposed to secrete heparin (a substance of liver), which prevent, intravascular clothing.

The eosinophils are very rich in histamine. They are believed to defend the body against allergic conditions in which histamine like bod­ies are produced in excess.

Due to the production of such sub­stances, the process of coagulation and the deposit of clot are facilitated.

Leucocytes manufacture certain substances called trephones from plasma protein, which exert great influence on the nutrition, growth and repair of tissues.

Platelet assists in the stoppage of bleeding with the help of coagulation factor. These are the smallest cells of the blood and the sticky in character and form the haemostatic plug which effectively seal the vessels and then stop the hemorrhage. Platelets are irregularly-shaped, colorless bodies that are present in blood. Their sticky surface lets them, along with other substances, form clots to stop bleeding.

When bleeding from a wound suddenly occurs, the platelets gather at the wound and attempt to block the blood flow. The mineral calcium, vitamin K, and a protein called fi­brinogen help the platelets to form a clot.

Clot begins to form when the blood is exposed to air. They react with the fibrinogen to begin forming fibrin, which resembles tiny threads. The fibrin threads then begin to form a web-like mesh that traps the blood cells within it. This mesh of blood cells hardens as it dries, forming a clot, or “scab”.

Calcium and vitamin K must be present in blood to support the formation of clots. If blood is lacking these nutrients, it will take longer than normal for blood to clot. If these nutrients are missing, patient could bleed to death. A healthy diet provides most people with enough vitamins and minerals, but vitamin supplements are sometimes needed.

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Term Paper # 6. Physiology of Blood:

I. Components of Blood:

A. Major Components of Blood:

1. Formed elements – the actual cellular components of blood (special connective tissue)

a. Erythrocytes – red blood cells

b. Leukocytes – white blood cells

c. Platelets – cell fragments for clotting

2. Blood plasma – complex non-cellular fluid surrounding formed elements; protein and electrolytes

B. Separation of Components in a Centrifuge:

II. Erythrocytes (Red Blood Cells; RBCs):

A. Structure:

1. 7.5 micron diameter; 2.0 micron thick

2. Biconcave disk shape; ideal for gas exchange

i. Spectrin – elastic protein; allows shape change

3. Mature cells are anucleate (no nucleus)

4. Very few organelles; mainly a hemoglobin carrier

i. Hemoglobin – 33% of cell mass; carries oxygen

5. No mitochondria; only anaerobic respiration

6. Ratio erythrocytes:leukocytes = 800:1

7. Red blood cell count: # cells per cubic millimeter

i. Normal male count – 5.1 to 5.8 million

ii. Normal female count – 4.3 to 5.2 million

B. Functions (Oxygen and Carbon Dioxide Transport):

1. Hemoglobin – large molecules with globin and hemes

a. Globin – complex protein with 4 polypeptides (2 α and 2 β polypeptides)

b. Heme group – IRON containing pigment part of hemoglobin to which oxygen binds

i. Each polypeptide has one heme group; each heme carries one O₂

c. Normal hemoglobin levels (grams/100 ml blood)

i. Infants 14-20 grams/100 ml

ii. Adult female 12-16 grams/100 ml

iii. Adult male 13-18 grams/100 ml

2. States of Hemoglobin:

a. Oxyhemoglobin – when oxygen is bound to IRON

b. Deoxyhemoglobin – no oxygen bound to IRON

c. Karbaminohemoglobin – when carbon dioxide bound (to polypeptide chain)

b. Iron – Essential for Hemoglobin to Carry Oxygen:

i. 65% of Fe in body is in hemoglobin

ii. Liver and spleen store most excess Fe bound to ferritin and hemosiderin

iii. Fe in blood bound to transferrin

iv. Daily Fe loss: 0.9 mg men/1.7 mg women

v. women also lose Fe during menstrual flow

c. B-complex Vitamins – Vitamin B₁₂ and Folic Acid essential for DNA synthesis in early mitotic divisions leading to erythrocytes

III. Leukocytes (White Blood Cells; WBCs):

A. General Structure and Function:

1. Protection from microbes, parasites, toxins, cancer

2. 1% of blood volume; 4-11,000 per cubic mm blood

3. Diapedesis – can “slip between” capillary wall

4. Amoeboid motion – movement through the body

5. Chemotaxis – moving in direction of a chemical

6. Leukocytosis – increased “white blood cell count” in response to bacterial/viral infection

7. Granulocytes – contain membrane-bound granules (neutrophils, eosinophils, basophils)

8. Agranulocytes – NO membrane-bound granules (lymphocytes, monocytes)

B. Granulocytes – Granules in Cytoplasm can be Stained with Wright’s Stain; Bilobar Nuclei; 10-14 Micron Diameter; all are Phagocytic Cells (Engulf Material):

1. Neutrophils – destroy and ingest bacteria and fungi (polymorphonuclear leuks.; “polys”)

a. Most numerous WBC

b. Basophilic (blue) and acidophilic (red)

c. Defensins – antibiotic-like proteins (granules)

d. Polymorphonuclear – many-lobed nuclei

e. Causes lysis of infecting bacteria/fungi

f. HIGH poly count —> likely infection

2. Eosinophils – Lead Attack Against Parasitic Worms:

a. Only 1-4% of all leukocytes

b. Two-lobed, purplish nucleus

c. Acidophilic (red) granules with digest enzymes

d. Phagocytose antigens and antigen/antibody complex

e. Inactivate chemicals released during allergies

3. Basophils – Releases Histamine Which Causes Inflammation, Vasodilation, and Attraction of WBCs:

a. RAREST of all leukocytes (0.5%)

b. Deep purple U or S shaped nucleus

c. Basophilic (blue) granules with HISTAMINE

d. Related to “mast cells” of connective tissue

e. BOTH release Histamine with “IgE” signal

f. Antihistamine – blocks the action of Histamine in response to infection or allergic antigen

C. Agranulocytes – WBCs without Granules in Cytoplasm:

1. Lymphocytes – two types of Lymphocytes:

a. T lymphocytes – (thymus) respond against virus infected cells and tumor cells

b. B lymphocytes – (bone marrow) differentiate into different “plasma cells” which each produce antibodies against different antigens

c. Lymphocytes primarily in lymphoid tissues

d. Very large basophilic (purple) nucleus

e. Small lymphocytes in blood (5-8 microns)

f. Larger lymphocytes in lymph organs (10-17 microns)

2. Monocytes – differentiate to become macrophages; serious appetites for infectious microbes

a. Largest of all leukocytes (18 microns)

b. Dark purple, kidney shaped nucleus

IV. Platelets (Thrombocytes – “Clotting”):

A. General Characteristics:

1. Very small, 2-4 microns in diameter

2. Approximately 250-500,000 per cubic millimeter

3. Essential for clotting of damaged vasculature

4. Thrombopoietin – regulates platelet production

V. Plasma (The Liquid Part of Blood):

A. General Characteristics:

1. Plasma makes up 55% of normal blood by volume

2. Water is 90% of the plasma by volume

3. Many different SOLUTES in the plasma

a. Albumin – pH buffer and osmotic pressure

b. Globulins – binding proteins and antibodies

c. Clotting proteins – prothrombin and fibrinogen

d. Other proteins – enzymes, hormones, others

e. Nutrients – glucose, fatty acids, amino acids, cholesterol, vitamins

f. Electrolytes – Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, CI^–, phosphate, sulfate, bicarbonate, others.