Components of Blood

Circulatory System

Circulation

Types of Blood Vessels• Arteries

– Carry blood away from the heart– Have thick, muscular walls– Branch out into arterioles– Largest artery = Aorta

• Veins (Contain valves – prevent backflow)– Carry blood back to the heart– Have thinner walls (less muscle)– Veins branch out into venules– Largest vein = Vena Cava

• Capillaries– Connect arterioles to venules– Extremely thin walls (allow oxygen & carbon

dioxide to pass through)

Components of Blood1. Red blood cells (RBC)2. White blood cells (WBC)3. Plasma4. Platelets (Thrombocytes)

• Plasma– Made of mostly water– Transports nutrients, hormones, proteins,

salts, & enzymes– Suspends solid components of blood

Types of Blood Cells• Erythrocytes

– RBCs– Carry oxygen to body cells / Return carbon

dioxide to the lungs– Contain hemoglobin

• Heme = Iron compound• Globin = Protein molecule

• Leukocytes– WBCs– Fight infection– 5 types of WBC

• Thrombocytes– Known as platelets– Purpose is to clot RBC together

– When a vessel is cut, platelets collect @ the site to form a sticky plug (then form scab)

Platelets

Types of WBC

Neutrophils• Most numerous• Destroy bacteria

(surround & consume = phagocytosis)

Eosinophils• Destroy parasites

(release toxin to kill)• Defends against allergic

reactions

Basophils• Produce histamine;

participates in body’s inflammatory response

Monocytes• Destroy bacteria &

foreign materials (dead cells)

• Largest type of WBC

Lymphocytes (Special type)• Can multiply in tissues of

tonsils, spleen, lymph nodes

• T-Cells (Helper T / Killer T) & B –Cells (create antibodies)

• T and B Cells fight viruses

• Protect against cancer cells

Circulation Facts• About 4 to 6 quarts of blood in the average

adult.• Heart circulates the body’s blood supply

about 1,000 times each day.• At age 70, the heart has beat about 2 ½

billion times.• Plasma is 90% water• RBC / WBC / Platelets are made in the

bone marrow