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14-2 Blood and Blood Vessels

14-2 Blood and Blood Vessels. BLOOD VESSELS. Blood circulates through the body through a series of vessels. 1. Arteries: blood vessels that carry blood away from the heart. Except for the pulmonary arteries, all arteries carry oxygenated blood

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14-2 Blood and Blood Vessels

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  1. 14-2 Blood and Blood Vessels

  2. BLOOD VESSELS • Blood circulates through the body through a series of vessels

  3. 1. Arteries: blood vessels that carry blood away from the heart • Except for the pulmonary arteries, all arteries carry oxygenated blood • With each contraction the heart forcefully ejects blood into arteries • The artery’s wall expands and then returns to its original size • Blood passes from the arteries into a network of smaller arteries called arterioles

  4. 2. Capillaries • blood vessels in which gases, nutrients, hormones and other molecules are transferred from the blood to the body’s cells • No cell in your body is more than a few cell diameters away from a capillary • Capillary walls are only one cell thick—gas and nutrient molecules easily pass through their thin walls • **INTERESTING FACT: If all the capillaries of your body were laid end to end, they would extend all the way across the US!!!!

  5. 3. Veins • blood vessels that return the blood to the heart • The walls of veins consists of a much thinner layer of smooth muscle than the walls of the arteries • They are farther away from the heart pump so therefore are exposed to less pressure

  6. The flow of blood in veins is helps by contractions of skeletal muscles • when muscles contract they squeeze against veins and help force blood toward the heart

  7. B) BLOOD PRESSURE • Blood moves through our system because it is under pressure • This pressure is caused by the contraction of the heart and by muscles that surround blood vessels • Blood pressure: a measure of force that blood exerts against the walls of a blood vessel

  8. Blood pressure is always highest in the two main arteries that leave the heart • Both high and low blood pressure can cause problems to our health • High blood pressure is very common in Americans—hypertension

  9. Blood pressure is measured with two numbers • 1—systolic: the pressure of the blood when the heart contracts • 2—diastolic: the pressure of the blood when the heart relaxes • blood pressure is given as the systolic number over the diastolic number

  10. C) BLOOD • “River of Life” • blood: type of connective tissue containing various substances and cells

  11. Blood serves many functions: • collects oxygen from the lungs • collects nutrients from the digestive tract • collects waste products from tissues • helps to regulate body temperature • helps fight infections • helps repair damaged blood vessels

  12. Blood is made up of various components: 1. Blood Plasma • Accounts for 60% of the blood • Liquid portion of the blood—90% water and 10% solutes • The other solutes include nutrients, gases, enzymes, hormones and waste products

  13. Cells that carry oxygen Each mL of blood contains 5 million RBCs RBCs have a biconcave shape—this means that they are narrower in the center than along the edges 2. Red Blood Cells

  14. Also known as ERYTHROCYTES • Carry hemoglobin—iron-containing protein that enables RBCs to carry oxygen—it also gives RBCs their color • Since mature RBCs carry so much hemoglobin, they do not have nuclei or organelles

  15. 3) White Blood Cells • “army” of the body • Also known as LEUKOCYTES • The main function of the WBCs is to protect the body against invasion by foreign cells or substances

  16. Outnumbered by RBCs almost 500 to 1 • larger than RBCs—do contain nuclei—almost colorless • there are different types of WBCs with different functions

  17. 4) Platelets • Platelets are not cells—they are tiny fragments of cells • Play an important role in blood clotting—they clump together and form a plug at the site of the wound

  18. D) BLOOD TYPES • Blood type is determined by the type of antigen present on the surface of RBCs • Antigen: a protein or carbohydrate that acts as a signal which cause antibodies to be made

  19. If a person has A antigens—they are type A • if a person has B antigens—they are type B • if a person has both antigens—they are AB • if a person has neither A nor B—they are type O

  20. Type AB is known as the universal receiver—they can receive any type of blood • Type O is known as the universal Donor, meaning they can donate blood to anyone

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