Composition and Function of the Blood

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Chapter 6

• Composition and Function of the Blood

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Outline

• Composition and Function of Blood
• Plasma
• Red Blood Cells
• White Blood Cells
• Types of White Blood Cells
• Blood Clotting
• Capillary Exchange
• Blood Typing

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The Composition and Functions of Blood

• Blood is divided into two layers.
• Formed Elements.
• Red Blood Cells.
• White Blood Cells.
• Platelets.
• Plasma.

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Functions of Blood

• Transport of oxygen, hormones, and waste.
• Defense against pathogens.
• Regulation of body temperature.

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Plasma

• Water makes up about 92 of plasma, while the
  remaining 8 consists of various salts and
  organic molecules.
• Three major plasma proteins help to maintain
  homeostasis.
• Albumins.
• Globulins.
• Fibrinogen.

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Red Blood Cells

• Red blood cells (erythrocytes) contain hemoglobin
  that allows oxygen transport.
• All blood cells are formed from stem cells.
• Engulfed by macrophages in the liver and spleen
  after about 120 days.
• Releases hemoglobin.
• Insufficient number of red blood cells or
  hemoglobin leads to anemia.
• Hemolysis is rupturing of blood cells.

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White Blood Cells

• White Blood Cells (leukocytes) have a nucleus and
  lack hemoglobin.
• Fight infection and help maintain homeostasis.
• Derived from stem cells.
• Found in blood, tissue fluid, and lymph.

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Types of White Blood Cells

• Granular Leukocytes.
• Neutrophils.
• Eosinophils.
• Basophils.
• Angular Leukocytes.
• Monocytes.
• Lymphocytes.

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Blood Clotting

• Platelets (thrombocytes) result from
  fragmentation of megakaryocytes.
• Platelets clump at the site of a puncture in the
  skin and usually seal the break.
• Coagulation.
• At least twelve factors participate in the
  formulation of a blood clot.

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Blood Clotting
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Capillary Exchange

• Pumping of heart sends blood out via arteries to
  the capillaries where exchange takes place
  through capillary walls. Blood returns via veins.
• Arterial blood contains more oxygen and nutrients
  than venous blood.
• Venous blood contains more wastes, including
  carbon dioxide, than arterial blood.

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Capillary Exchange
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Blood Capillaries

• Processes at work during capillary exchange.
• Blood pressure.
• Diffusion.
• Osmotic pressure.

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Arterial End of Capillary

• When arterial blood enters tissue capillaries
• Bright red due to high oxygen levels.
• Rich in dissolved nutrients.
• Blood pressure is higher than osmotic pressure.
• Water and nutrients exit capillary.

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Venous End of Capillary

• Blood pressure is reduced because capillaries
  have a greater cross-section compared to blood
  vessels that enter and leave capillaries.
• No reduction of osmotic pressure.
• Water tends to enter capillary.

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Lymphatic Capillaries

• Lymphatic vessels are one-way system that carry
  lymph.
• Valves prevent backflow.
• Lymphatic capillaries absorb excess fluid at
  blood capillaries.

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Lymphatic Capillaries
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Blood Typing

• In the ABO system, the presence or absence of
  type A and type B antigens on red blood cells
  determines a persons blood type.
• Within the plasma are antibodies to the antigens
  that are not present on the persons red blood
  cells.

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Blood Typing
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Blood Typing

• Another important antigen is the Rh factor.
• Eighty-five percent of US population have Rh
  antigen on red blood cells and are Rh.
• Rh- individuals normally do not have antibodies
  to the Rh factor, but may make them when exposed.
• Hemolytic disease may exist in newborns when
  mother is Rh- and father is Rh.

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Hemolytic Disease
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Review

• Composition and Function of Blood
• Plasma
• Red Blood Cells
• White Blood Cells
• Types of White Blood Cells
• Blood Clotting
• Capillary Exchange
• Blood Typing

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