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Blood and Lymphatic System
Functions of Blood
• Carries oxygen from lungs to body cells
• Carries carbon dioxide from body cells to
lungs
• Carries waste products from cells to kidneys
• Transport nutrients to cells
• Fights infections and heal wounds
Parts of blood
• Plasma liquid part of blood
– mostly water
– Nutrients, minerals, oxygen dissolved in plasma
– Carries waste from cells
• Red blood cells supply body with oxygen
– Contain hemoglobin, a chemical that carries
oxygen and carbon dioxide
– Life span is 120 days (rapidly replaced)
Parts of Blood
• White blood cells  fight bacteria and viruses
– Body reacts to invaders by increasing WBC
– WBC enter infected tissue, destroy bacterial/viral
invaders, absorb dead cells
– Life span a few days to many months
• Platelets irregularly shaped cell fragments
that help clot blood
– Release chemicals that form filaments of fibrin
– Life span 5-9 days
Blood Clotting
• Platelets and clotting factors plug up wound
– Platelets stick to wound and release chemicals
– Clotting factors carry out chemical reactions
– Threadlike fibers called fibrin form sticky net
• Net traps blood cells and plasma, forming clot
– Skin cells begin repair process
Blood Types
• A, B, AB, O
• Based on antigens
– Chemical ID tags on blood
– Type O has no antigens so can donate to everyone
• Based on antibodies
– Proteins identify substances that don’t belong in body and
destroy them
– AB has no antibodies so can receive from anyone
• Based on Rh factor
– People who lack Rh factor (negative type),
– Have Rh factor are positive (like being O+)
– If lack Rh but receive Rh positive blood, body will produce
antibodies against blood which can cause blood clots.
Blood Disease
• Anemia affects red blood cells
– Body tissues don’t get enough oxygen and are
unable to carry on usual activities
– Causes include loss of large amount of blood, diet
lacking iron, or heredity
• Leukemia affects white blood cells
– WBC made in excessive numbers, but are
immature and don’t fight infection well
– Immature cells fill up bone marrow and crowd out
normal cells
Lymphatic System
• Collects tissue fluid and returns it to blood
• Lymph tissue fluid that has diffused into
lymphatic capillaries
– Contains water and dissolved substances
– Contains lymphocytes, a type of WBC that helps body
defend itself
– Carried through lymphatic capillaries and vessels to
large veins near heart
– Moved by muscle contractions
– Has valves to keep lymph from flowing backward
Lymphatic Organs
• Lymph nodes bean shaped
organs of varying size found
throughout body that filter
microorganisms and foreign
material from lymphocytes
• Tonsils protect body from
harmful microorganisms
entering from mouth/throat
• Thymus makes lymphocytes
• Spleen filters blood by
removing damaged red blood
cells from blood, takes up and
destroys bacteria and other
invaders of body
Lymphocytes
• The HIV virus attacks lymphocytes called
helper T-cells