The Blood: Composition, Volume, and Functions

The Blood

• Circulating blood helps to maintain homeostasis
• It brings nutrients and oxygen to cells and carries waste away
• The heart pumps blood continuously through a closed system of vessels
• Blood is classified as connective tissue because it consists of cells suspended in an intercellular background material, or matrix
• Blood cells share origination and development traits with other connective tissues
• Blood differs from other connective tissues because its cells are not fixed in position
• Blood cells move freely in plasma, which is the liquid part of the blood
• Whole blood is a viscous, thick fluid that changes color from bright scarlet to dark red, depending on how much oxygen it carries
• Blood volume accounts for approximately 8% of total body weight
• The average adult male, weighing 70 kg. (154 pounds) approximately has 5 liters (5.2 quarts) of blood

Functions of Blood

• Transportation
• Regulation
• Protection

Transportation

• Oxygen from inhaled air diffuses into the blood through thin membranes in the lungs and is carried by the circulation to all body tissues
• Carbon dioxide, a waste product of cell metabolism, is carried from the tissues to the lungs, where it is breathed out
• The blood transports nutrients and substances, like electrolytes (salts) and vitamins, to the cells
• These materials enter the blood from the digestive system or are released into the blood from body reserves
• The blood transports waste products from the cells to removal sites
• The kidney removes excess water, acid, electrolytes, and urea (a nitrogen-containing waste)
• The liver removes blood pigments, hormones, and drugs, and the lungs eliminate carbon dioxide
• The blood carries hormones from their sites of origin to the organs they affect

Regulation

• Buffers in the blood help keep the pH of body fluids steady at about 7.4 (a range of blood pH is 7.35 to 7.45)
• At an average pH of 7.4, blood is slightly alkaline (basic)
• Blood regulates the amount of fluid in the tissues by substances (mainly proteins) that maintain osmotic pressure, which is needed for fluid balance
• The blood transports heat generated in the muscles to other body parts, aiding in body temperature regulation

Protection

• Blood is important in defense against disease with cells and antibodies of the immune system that protect against pathogens
• Blood has factors to protect against blood loss from an injury
• Blood coagulation is needed to prevent blood loss

Blood Constituents

• Blood has two main components
• Liquid portion is the plasma
• Formed elements fall into types
• Erythrocytes, meaning red, are the red blood cells, that transport oxygen
• Leukocytes, meaning white, are the several types of white blood cells, which protect against infection
• Platelets also called thrombocytes are cell fragments, that participate in blood clotting

Types of Blood Samples

• Whole Blood is a sample drawn and mixed with an anticoagulant to maintain the integrity of the blood cells and prevent clotting, allowing whole blood analysis to be accurate
• Serum is the liquid portion allowed to clot where the clotting factors are bound in the clot
• Plasma is liquid portion that has not been allowed to clot, usually using anticoagulants with clotting factors present

Serum

• Blood collected in a tube with no additive will clot within 15-45 minutes
• One 10 ml tube of whole blood will yield 3-4 ml of serum
• Invert the serum tube

Plasma

• Formed when blood is mixed with anticoagulants
• This sample is mixed 6-8 times and immediately centrifuged and plasma is removed
• Plasma is 55% of the total blood volume and is 91% water
• Dissolved or suspended substances make up the other 9% by weight
• Content may vary somewhat because substances are removed and added as the blood circulates
• Body tends to maintain a constant level of substances (e.g., a constant level of about one-tenth of one percent (0.1%) level of glucose) After water, the next largest percentage (about 8%) of material in the plasma is protein

Plasma Proteins

• Albumin is the most abundant protein in plasma, which is important for maintaining the osmotic pressure of the blood, produced by the liver
• Clotting factors are also manufactured in the liver which are needed for blood coagulation
• Antibodies combat infection, which are made by certain white blood cells
• Complement consist of a group of enzymes that helps antibodies in their fight against pathogens

Order of Draw

• Blood collection tubes must be drawn in a specific order to avoid cross-contamination of additives between tubes
• First: blood culture tube (yellow-black stopper)
• Second: non-additive tube (red stopper or SST)
• Third: coagulation tube (light blue stopper)

Order of Draw Considerations

• If only ordering a routine coagulation assay, drawing a single light blue stopper tube may do
• If there is a concern regarding contamination by the tissue fluids or thromboplastins, then a first drawn of non-additive tube, followed by the light blue stopper tube may do

Last Draw - Additive Tubes

• SST (red-gray, or gold, stopper) that contain a gel separator and clot activator
• Sodium heparin (dark green stopper)
• PST (light green stopper) containing lithium heparin anticoagulant and a gel separator
• EDTA (lavender stopper)
• ACDA or ACDB (pale yellow stopper) containing acid citrate dextrose
• Oxalate/fluoride (light gray stopper)
• Tubes with additives must be mixed thoroughly
• Erroneous test results may be acquired when the blood is not completely mixed with the additive
• For plastic tubes, the order of draw goes in reverse for tubes 2 and 3

Multiple Tube Collection Order

• The chart below reflects the most current standard for order in blood samples
• It includes the change in which CLSI (formerly NCCLS) recommended
• Yellow: Blood Cultures-SPS
• Light Blue: Citrate Tube
• Gold or Red/Gray: SST Gel Separator Tube
• Red: Serum Tube
• Dark Green: Heparin Tube
• Light Green: PST Gel Separator Tube
• Purple/Lavender: EDTA Tube
• Gray: Fluoride (Glucose) Tube
• Follow your facilities protocol for order of draw

Collection set usages

• When using a winged blood collection set (a.k.a., Butterfly) for venipuncture and a coagulation (citrate) tube is the first sample to be drawn, a discard tube should be extracted first but does not need to be fully filled
• Use the discard tube to fill the blood collection sets tubing's "dead space" with blood
• This makes sure of both maintenance and blood-to-additive ratio
• The discard tube should be a nonadditive or coagulation tube

Collection Tubes

• SST - Serum Separator Tube

  • Gold/Red-Gray Marble
  • Polymer gel and powdered glass clot activator
  • Hemogard™
    • Gold top
    • Conventional Red-Gray Marble
  • Plastic tube 13 x 100/16 x 100
  • Serum type specimen
  • 5.0 ml/8.5 ml draw
  • Inversions: 5
  • Sterile SST® brand tube for serum clot activator determinations that require serum in chemistry or infectious testing
  • Gel separates serum from cells
  • Tube inversion ensures mixing of clot activator with blood and clotting within 30 minutes

• Mint Green Stopper- PST, Plasma Separator Tube: HOSPITAL PATIENTS ONLY

  • Lithium Heparin, Polymer gel plasma separator
  • Hemogard TM
  • Plastic tube 13 x 75
  • Whole Blood, Plasma
  • 3.0 ml
  • Inversions: 8
  • General chemistries and some therapeutic drugs (DO NOT USE FOR LITHIUM TESTING)
  • After the tube has been filled with blood, immediately invert the tube several times in order to prevent coagulation

• Green Stopper Tube

  • Dark Green/Clear Green
  • Additive
  • Hemogard TM
  • Plastic tube 13 x 75
  • Whole Blood, Plasma Specimen
  • 4.0 ml/2.0 ml
  • Inversions: 8
  • For plasma determinations in chemistry, tube inversion prevents clotting
  • Dark green 4.0 ml Sodium Heparin used for chromosome studies
  • After filled with blood, immediately invert the tube several times to prevent coagulation

• Lavender Stopper Tube

  • Two types consist of:
  • Dark Lavender/Clear Lavender
  • EDTA-K2
  • Hemogard TM
  • Plastic tube 13 x 75
  • Whole Blood, Plasma
  • 4.0 ml/2.0 ml draw
  • Inversions: 8
  • For whole hematology, ammonia, lead, HIV, RNA quantization determinations and for blood bank testing tube inversion prevents clotting
  • NOTE: After the tube has been filled with blood, immediately invert the tube several times in order to prevent coagulation

• Light Blue Stopper Tube

  • Two types:
    • Solid Light Blue/Clear Light Blue
  • Additive: Sodium Citrate
  • Hemogard TM
  • Glass 13 x 75
  • Whole Blood, Plasma Specimen
  • 2.7 ml/1.8 ml draw
  • 4 Inversions: 4 (gently)
  • For coagulation determinations of plasma specimens and tube inversion prevents clotting
  • Tubes require specific chilled specimens
  • NOTE: Tube is completely filled as the ratio of blood to anticoagulant is needed for results
    • Inverted tube: 6 to 10 times to activate anti-coagulant

• Gray Stopper Tube

  • Additive : Sodium fluoride/Potassium oxalate
  • Hemogard TM
  • Plastic- 13 x 75
  • Specimen: Whole Blood, Plasma
  • Draw: 4.0 ml
  • 8- Inversions
  • For glucose, toxicology determinations Antiglycolytic additives stabilizes glucose values for up to 24 hours at room temperature and ensures proper mixing of additive and blood
  • After filling and inverting, tubes should be inverted immediately

• Red Stopper Tube

  • Additive: Clot Activator (powdered glass)
  • Hemogard TM
  • Plastic: 13 x 75
  • Specimen: Serum
  • Draw: 6.0 ml
  • Inversions: 5
  • For serum determinations in chemistry, serology and blood bank testing and can be used as sterile transport tube

• Royal Blue Stopper Tube

  • Two types consist of:
    • No additive/EDTA
  • Two types of royal blue top Monoject® tubes - one with EDTA anticoagulant and other blank which are for trace metals analysis
  • Additive: None/EDTA
  • Hemogard TM
  • Glass: 13 x 100
  • Specimen: Whole Blood, Plasma
  • Draw: 7.0 ml
  • Inversions: None
  • For trace element, toxicology and nutrition determinations containing a special stopper formulation which offers low levels of trace elements available and referrals to each test for proper tube

• Yellow Stopper Tube

  • Two types consist of: (ACD)
    • Solution A
  • Additive: ACD, solution A Conventional
  • Glass: 16 x 100
  • Specimen: Whole Blood
  • Draw: 8.5 ml
  • Inversions: 8
  • Tissue typing and some Red Cross testing (Specific test for proper tube)
  • Additive: ACD, solution B Conventional
  • Glass: 16 x 100
  • Specimen: Whole Blood
  • Draw: 6.0 ml
  • Inversions: 8 and Tissue typing used for Specific test for proper tube

Specialized Collection Tubes

• Ascorbic Acid Tube Used exclusively for blood serotonin assay; contains EDTA in an anticoagulant and ascorbic acid as the preservative with a red and yellow marbled stopper
• (FDP) or (FSP) Tubes Special collection tubes are needed for fibrin with light blue or black stoppers, which must have approxiamtely 2 ml of blood and be inverted immediately for fibrin clot to occur within 30 seconds

Blood Typing Chart

Top Collection tubes for Phlebotomy

• Red is a top collection tube with no Additive, blood clots, the serum separate by centrifugation used for serum and blood bank testing
• Red-Gray is a top collection tube with Serum Separating Tube with clot activator designed to quickly seperate blood from serum
• Dark Green is a top collection tube with additive Sodium heparin used for lithium level examinations
• Purple is a top collection tube withadditive EDTA liquid that forms calcium, it used for hematology or crossmatches
• Light Green is a top collection tube with additive PST with Lithium that forms calcium, used to chemically separate plasma
• Light Blue is a top collection tube with additive Sodium citrate that forms calcium, it is copulated and full from what is required
• Yellow is a top collection with additive ACD is designed to inactive complement
• Yellow Black is a top collection tube with additive Broth mixture intended to keep viable microorganisms
• Brown is a top collection tube with additive Sodium, designed to inactive thrombin and thromboplastin
• Orange is a top collection tube with additive Thrombin designed to quickly clot blood
• Light Gray is a top collection tube with additive Sodium fluoride and potassium oxalate to preserve glucose for up to 5 days

Explore the composition of blood, its classification as connective tissue, and its vital role in maintaining homeostasis. Learn about blood volume, which accounts for approximately 8% of total body weight. Discover the crucial functions of blood, including transportation, regulation, and protection within the body.