Lab Exercise 29: Composition of Blood - Detailed Notes

Blood Composition

• Circulating blood is viscous.
• Oxygen-rich blood is bright red.
• Average blood volume:
  • Male: 5-6L
  • Female: 4-5L
• Blood is a connective tissue: consists of cells within a non-living matrix (plasma).

Blood Components

• Formed elements (45%)
• Plasma (55%)
• 100+ different substances in plasma:
  • 90% water
  • 10% nutrients, gases, hormones, waste metabolites, proteins, electrolytes

Formed Elements

• Erythrocytes (RBCs)
  • Hemoglobin molecule transports bulk of $O_2$ carried in blood.
• Leukocytes (WBCs)
  • Body's nonspecific defenses; immune system.
• Platelets
  • Function in hemostasis (blood clotting formation).

Erythrocytes (RBCs)

• Biconcave, anucleated disc.
• Function: Transporting $O_2$ and carbon dioxide.

Leukocytes (WBCs)

• Spherical, nucleated cells.

Classes of WBCs

Granulocytes

• Neutrophil
  • Nucleus multilobed, pale red/blue cytoplasmic granules.
  • Function: Phagocytize pathogens or debris.
• Eosinophil
  • RARE.
  • Nucleus bilobed, red cytoplasmic granules.
  • Function: Killing parasitic worms, slightly phagocytic, complex role in allergies/asthma.
• Basophil
  • Large blue-purple cytoplasmic granules.
  • Function: Releasing histamine and other mediators of inflammation; containing heparin.

Agranulocytes

• Lymphocyte
  • Nucleus spherical or indented, pale blue cytoplasm.
  • Function: Mount immune response by direct cell attack or via antibody production.
• Monocyte
  • Nucleus U- or kidney-shaped, gray-blue cytoplasm.
  • Function: In tissues, develop into macrophages that phagocytize pathogens or debris.

Platelets

• Cytoplasmic fragments containing granules, staining deep purple.
• Function: Sealing off small tears in blood vessels; helpful in blood clotting.

Leukocytes (WBCs) Details

• Nucleated cells.
• Formed in red bone marrow.
• Less than RBCs.
• Lifespan varies (minutes to decades).
• Protective pathogen-destroying cells.
• Transported throughout blood and lymph.
• Important protective function: ability to move in/out of blood vessels (diapedesis).
• Wonder by Amoeboid motion to reach sites of inflammation/tissue destruction.

Two Groups

• Granulocytes
  • Peculiarly lobed nuclei; stain with Wright's stain.
  • Neutrophils, Eosinophils, Basophils.
• Agranulocytes
  • No visible cytoplasmic granules.
  • Much more in Lymphoid tissues.
  • Lymphocytes, Monocytes.

Abundance of Leukocytes

• Most abundant to least abundant: Neutrophils, Lymphocytes, monocytes, Eosinophils, basophils

Platelets Details

• Cell fragments of large multinucleate cells (Megakaryocytes) formed in red bone marrow.
• Essential in blood clotting process.

Hematologic Tests

• Total WBC count
• Total RBC count
• Determining total number of that cell type per unit volume of blood.
• Routine test.

Total WBC Count

• Leukocytosis: WBC over 11,000 cells; may indicate bacterial/viral infection, metabolic disease, hemorrhage, or drugs/chemicals.
• Leukopenia: WBC below 4,000 cells; due to exposure to certain chemicals or toxins, including anticancer agents.
• Leukemia: Malignant disorder of lymphoid tissues by uncontrolled proliferation of abnormal WBCs, accompanied by a reduction in # of RBCs + platelets.

Total RBC Count

• Increase in RBC (polycythemia) may result where less $O_2$ is available or from living in High Altitudes.
• Decrease number in RBC = Anemia.

Anemia

• Decrease oxygen carrying capacity
• May result from bone marrow cancer.
• From decreased RBC number or size or decreased hemoglobin content of RBC.
• Decrease also result from Sudden hemorrhage

Differential White Blood Cell Count

• 100 WBCs are counted and classified according to type.

Hematocrit

• Determined when anemia is suspected.
• Hematocrit is generally considered equivalent to the RBC volume.

Hemoglobin Concentration

• Hb is the RBC protein responsible for $O_2$ transport.
• $O_2$ combines with heme (iron-containing portion) of hemoglobin molecule and is picked up by blood cells in the lungs and unloaded in the tissues.
• More hemoglobin = more $O_2$ will be transported.
• Normal blood contains 12-18g per 100mL.
• Higher in men.

Coagulation Time

• Hemostasis is a protective mechanism that is set into motion when blood vessel breaks.
• Responsible for stopping bleeding.

3 Events Occur

• Vascular Spasm
• Platelet plug formation
• Coagulation
  • Blood clotting/coagulation is a process & it requires plasma + some platelets & injured tissue +
  • Platelets release tissue factor (TF) + phosphatidylserine & it triggers the clotting mechanism or cascade.
  • Tissue factor and phosphatidylserine interacting w/ other blood protein clotting factors & Calcium ions to form prothrombin activator
  • Prothrombin activator → prothrombin → thrombin.
  • Thrombin then acts enzymatically to polymerize the soluble fibrinogen proteins into fibrin.
  • Fibrin forms meshwork of strands that traps the RBC, & forms basis Of the Clot

Blood Typing

• Antigens/Agglutinogens + are genetically determined.
• ABO groups and are accompanied by Antibodies/Agglutinis.
• Antibodies act against RBCs carrying antigens that are not normally present.
• Individuals whose RBC carry antigen are Rh positive & those w/o are Rh-Negative.
• Neither Rh+/Rn- have Anti-Rh antibodies.

ABO Blood Type

Cholesterol Concentration in Plasma

Atherosclerosis

• Disease process in which the body's blood vessels become increasingly occluded of Blocked by plagues
• Narrowing arteries, plaque.
• Contributes to HTN ♥ disease
• Starting point for blood clots
• Cholesterol major component of Smooth muscle plaques formed during Atherosclerosis.
• HDL = good cholesterol
• LDL = Bad cholesterol

Antigens and Antibodies

• Antigens: generators of anything)
• Antibodies: made by our own Immune System (immune cells ready to attack) pended in plasma (Plasma 55%

Constituents of Plasma

Constituents and Major Functions

• Water: Solvent for dissolving and carrying other substances, absorbs heat.
• Salts (electrolytes):
  • Sodium, Potassium, Calcium, Chloride
  • Osmotic balance, pH buffering
• Proteins:
  • Albumin: Osmotic balance
  • Fibrinogen: Clotting of blood
  • Globulins: Defense (antibodies) and lipid transport
• Substances transported by blood:
  • Nutrients (glucose, fatty acids, amino acids)
  • Waste products of metabolism (urea, uric acid)
  • Respiratory gases ($O<em>2$ and $CO</em>2$)
  • Hormones

Formed Elements Number and Function

• Erythrocytes (red blood cells): 4-6 million (per $mm^3$ of blood); transport oxygen and help transport carbon dioxide.
• Leukocytes (white blood cells): 4800-10,000; defense and immunity.
  • Basophil
  • Eosinophil
  • Lymphocyte
  • Monocyte
  • Neutrophil
• Platelets: 150,000-400,000; blood clotting.