Blood

Blood

Physical characteristics and volume
1.  Blood is a sticky, opaque fluid with a metallic taste  Colour varies from scarlet (oxygen rich) to dark red (oxygen poor)  Temperature is 38 C slightly higher than normal body temperature  Blood accounts for approximately 8% of body weight
Circulating volume
1. In a typical adult the circulating volume is equivalent to the cardiac output per minute
  1. Cardiac Output = heart rate x stroke volume
Normal blood pH
1. 7.35-7.45
Normal blood glucose
1. 4-7mmol (FIVE)
Normal Blood Plasma Potassium
1. 3.5-5.5 mEq/L (FIVE)
Normal blood plasma sodium
1. 135 to 145 (mEq/L)
Normal carbon dioxide
1. 4.7-6.0 Kpa (FIVE)
Full blood count
1. Haemoglobin is the coloured pigment inside red blood cells that carries oxygen round the body. Haemoglobin levels in the blood are measured in grammes per 100 millilitres, which is abbreviated to g/dl. The normal range of haemoglobin for a man is 13.5 to 17.5 g/dl and for a woman is 11.5 to 15.5 g/dl. Anything less than these numbers is called anaemia.
2. Haematocrit is the volume percentage (%) of red blood cells in blood. Relative volume of blood occupied by erythrocytes (normal 45% for men 40 for women)
3. Platelets
  1. A platelet count is a diagnostic test that determines the number of platelets in the patient's blood. Platelets, which are also called thrombocytes, are small disk-shaped blood cells produced in the bone marrow and involved in the process of blood clotting. There are normally between 150,000-450,000 platelets in each microliter of blood. Low platelet counts or abnormally shaped platelets are associated with bleeding disorders. High platelet counts sometimes indicate disorders of the bone marrow.
4. Prothrombin time
  1. The prothrombin time test belongs to a group of blood tests that assess the clotting ability of blood. The test is also known as the pro time or PT test. The PT test is used to monitor patients taking certain medications (e.g. WARFARIN) as well as to help diagnose clotting disorders. The PT test is used in combination with the partial thromboplastin time (PTT) test to screen for hemophilia and other hereditary clotting disorders. The normal prothrombin time is 11-15 seconds
5. Partial Thromboplastin time
  1. The partial thromboplastin time (PTT) test is a blood test that is done to investigate bleeding disorders and to monitor patients taking an anticlotting drug (heparin). Liver disease decreases the production of clotting factors increasing the PTT Heparin therapy increases the PTT Normal PTT results are between 35-45 seconds
BLOOD CELLS
1. Plasma
  1. Functions
    1. 1.Water: transport medium
      1. ◦carries heat ◦ nutrients, wastes, gases, hormones
    2. 2.Electrolytes
      1. ◦membrane excitability ◦ osmotic distribution of fluid b/t ECF & ICF ◦ buffering of pH
  2. Components
    1. electrolytes= (Na+ & Cl-) 1%
    2. water= 90%
    3. Plasma Proteins 6-8 %
      1. Plasma Proteins: (albumins, globulins, fibrinogen)
        1. Maintaining colloid osmotic balance (albumins) 2. Buffering pH changes 3. Transport of materials through blood (such as water & hormones) 4. Antibodies (e.g. gamma globulins, immunoglobulins) 5. Clotting factors (e.g. fibrinogen)
    4. Other components:
      1. • Nutrients (e.g. Glucose and amino acids) • Hormones (e.g. Cortisol, thyroxine) • Wastes (e.g. Urea) • Blood gases (e.g. CO2, O2)
2. 2. Leukocytes (White Blood Cells)
  1. Form the body’s defense system against micro-organisms. Seek and destroy functions: destroy invading microorganisms destroy abnormal cells (ie: cancer ). Clean up cellular debris (phagocytosis) assist in injury repair
    1. Types of WBC’s
      1. Agranulocytes
        Monocytes
        • Exit blood (diapedesis) to become macrophages •2-6 % of the WBC's •Phagocytic = defend against viruses and bacteria
        Lymphocytes (B and T cells)
        * B-lymphocytes: produce antibodies * T-lymphocytes: directly destroy micro- organisms * 25-33 % of the WBC's
      2. Granulocytes
        neutrophils= 50-70% of all leukocytes (most abundant of WBC’s) Important in inflammatory responses Phagocytic (engulfs and absorbs waste material, harmful microorganisms, or other foreign bodies in the bloodstream and tissues.)
        Eosinophils= * 1-4% of the WBC's * Attack parasitic worms * Important in allergic reactions
        Basophils= * Release histamine * 0.5% of the WBC's * Contribute to allergic reactions
3. 1. Erythrocytes (Red Blood Cells)
  1. Shape - a biconcave disc with large surface area
  2. No Nucleus
  3. Contains hemoglobin
    1. Structure of haemoglobin
      1. 4 Haem molecules = carry gases. Oxygenated haemoglobin : bright Red (systemic) *Deoxygenated Hemoglobin: Blue (venous circulation)
  4. Approximately 250 ml of oxygen are used every minute by a conscious resting person (oxygen consumption) and therefore about 25% of the arterial oxygen is used every minute.
  5. Primary Function = Transport oxygen from the lungs to the cells of the body & assist with CO2 removal from cells to lungs
  6. Short Life Span (~120 days) ◦Fragile - prone to rupture. Ruptured RBCs: ◦are destroyed in spleen ◦phagocytic WBC’s “clear the debris” up. Ruptured cells must be replaced by new cells by: eythropoietin-from kidneys by process called erythropoiesis in bone marrow
4. 3. Thrombocytes (Platelets)
  1. Stop bleeding from a damaged vessel through: ◦Haemostasis by 3 steps: vascular Spasm formation of a platelet plug blood coagulation (clotting)
Total Blood Volume
1. 8 % of body weight. ◦2.75 / 5.5 liters of blood is plasma ◦(remaining is the cellular portion)
FUNCTION OF BLOOD
1. Defense:  Foreign organisms  Injury/infection  Clotting process  Body temperature
  1. Transports:  Nutrients  O2 & CO2  Waste Products  Hormones  Electrolytes. Oxygen, Carbon Dioxide Food Heat Waste Hormones Disease Clotting
    1. Both defense and transports maintain Homeostasis
The ABO Blood Groups System
1. Discovered in 1901 by Dr. Karl Landsteiner 4 Main Phenotypes (A, B, AB, O) ABO gene located on long arm of chromosome 9
2. Antigens & Antibodies
  1. Universal Donor and Recipient
    1. Universal Donor Group O ◦Carries no A or B antigens ◦Packed and processed units have little antibody
    2. Universal Recipient Group AB ◦Patient has no anti-A or anti-B present ◦Cannot lyse any transfused cells ◦Beware: other ◦antibodies may be present
  2. The Rh(D) Antigen
    1. Rh is the most complex system, with over 45 antigens Discovered in 1940 after work on Rhesus monkeys
      1. Significance of Rh(D)
        80% of Rh(D) –ve persons exposed to Rh(D) +ve blood will develop anti-D Anti-D can also be stimulated by pregnancy with an Rh(D) +ve baby Rh(D) -ve women of childbearing potential should never be given Rh(D) +ve blood products

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	Created by reader89 about 11 years ago