Blood

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Blood

• Al Mina, M.D.
• Erskine College

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What does blood do?

• Transports nutrients
• Removes waste products
• Helps maintain body temperature
• Provides mechanism for healing wounds
• Important part of immune system
• Transports hormones

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Composition of blood

• 45 cells
• 55 fluid plasma
• Typical adult blood volume 5L

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Cells

• 3 major categories
• In adults, blood cells come from bone marrow
• Precursor cells constantly form new cells which
  move into bloodstream

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Erythrocytes

• Red blood cells
• 99 of all blood cells
• Approx. 5 million RBCs/microliter of blood
• Primary function is oxygen delivery

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RBC contd

• Shape of biconcave disc
• Gives flexibility to fit through capillaries
• Minimizes diffusion distance for oxygen
• Mature cells have no nucleus cannot divide
• Contains hemoglobin
• Average lifespan 120 days removed by spleen and
  liver

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Figure 14.8
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Hemoglobin

• Large molecule
• Composed of four chains of proteins combined with
  iron (heme) groups
• Gives blood its red color
• Brighter red when carrying oxygen

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Leukocytes

• White blood cells
• Approximately 6-8000 cells/microliter
• Primary function is defense
• Several types each work differently
• Can leave bloodstream

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Granulocytes
Figure 14.9
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Methods of defense

• Phagocytosis
• Leukocyte surrounds invader, brings it inside
  cell, and destroys it with enzymes
• Production of antibodies

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Antibodies

• Each cell/organism has compounds that can trigger
  an immune response (antigens)
• The immune system identifies self and nonself
  compounds
• Antibodies are formed to bind to nonself
  antigens, helping identify and destroy unwanted
  invaders

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Antibodies contd

• Bacteria
• Viruses
• Allergens
• Cancerous cells

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Contd

• Once identified, body stores info on antigen
• Can quickly respond if re-exposed
• Basis for vaccines

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Platelets

• Small particles released from bone marrow
• 150,000 platelets/microliter
• Play major role in blood clotting/wound healing

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Platelets
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Anemia

• Low erythrocyte count
• Major causes
• Symptoms
• Treat based on cause

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Leukemia

• Cancer involving white cells
• Very high number of WBCs, but immunity is
  actually less than normal.
• Many types some with high cure rate
• Treatment chemotherapy to destroy cancerous
  cells followed by bone marrow transplant

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Deep venous thrombosis

• Disorder of abnormal clot in large veins
• Most common in legs
• Symptoms
• Complications pulmonary embolus

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Risk factors DVT

• Age
• Smoking
• Obesity
• Sedentary/travel
• Medications (birth control pills)
• After surgery
• Injury
• Genetic disorders

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Treatments

• Blood thinners - anticoagulants
• Filter in vena cava
• Evaluate risk factors