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Human Circulation

Human Circulation. The Need for Circulation. All living things must be able to supply their cells with materials from the surrounding environment (Ex. Oxygen, nutrients, enzymes ,etc.). Special Circulatory Systems. In this case materials are absorbed across the cell membrane by diffusion.

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Human Circulation

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  1. Human Circulation

  2. The Need for Circulation • All living things must be able to supply their cells with materials from the surrounding environment (Ex. Oxygen, nutrients, enzymes ,etc.)

  3. Special Circulatory Systems • In this case materials are absorbed across the cell membrane by diffusion. • For larger organisms,where some cells may be located far away from the outside, a special circulatory system is required. • These systems may be open or closed.

  4. Closed and Open Systems • A closedsystem, is one in which the blood is always confined in vessels (Ex. Earthworm). • An open system, is one in which the blood is not always enclosed in vessels, but flows into open spaces where it bathes the tissues of the body directly(Ex. Grasshopper). • Assignment: Write a detailed summary of open and closed circulation in the earthworm and grasshopper (pages 146-147). Also complete the coloring sheet-Correlative Circulatory Patterns.

  5. Components Involved • Three components: • 1. A fluid to transport dissolved materials (Blood) See handout-Components and Function. • 2. A network of tubes (or body spaces) to carry fluid (Blood vessels). • A means of pumping the fluid (Heart).

  6. Blood • Blood is a special type of connective tissue. • Two components; Formed Elements (the blood cells) and Plasma (fluid).

  7. Blood-Erythrocytes-Red Blood Cells • Make up 44% of blood. • Biconcave • no nucleus • contain the respiratory pigment hemoglobin (carries oxygen) • life span of 100-120 days

  8. Blood-Erythrocytes-Red Blood Cells continued • Lost cells are replaced by new cells produced in the red bone marrow. • The rate of RBC production is called hemopoiesis, and is controlled by the hormone erythropoietin (released by the kidneys in response to decreasing oxygen levels in the blood).

  9. Blood- White Blood Cells • More like body cells. • Make up 1% of blood. • Have nuclei. • Produced by lymphatic tissue. • Serve as a “movable army”-protect the body from bacteria, viruses and tumor cells.

  10. Blood - Platelets • Believed to be fragments of other blood cells formed in red bone marrow. • Small, irregular shapes. • Needed for clotting.

  11. Blood Clots • A whole series of reactions called the blood clotting cascade creates the clot. • Reduces blood loss. • Clotting process involves a number of substances.called the clotting factors.

  12. Plasma • Liquid portion • Make up 55% of blood. • Contains water, salts, proteins, nutrients, • waste products and hormones.

  13. The Blood Vessels • There are three main types of blood vessels: • 1. Arteries • 2. Veins • 3. Capillaries

  14. Arteries • Carry blood away from the heart. • Thick muscular walls. • No valves. • Form arterioles that join with capillaries in the capillary network. • Blood pressure higher than in veins.

  15. Artery Structure Connective tissue Smooth muscle Elastic fibers Endothelium

  16. Veins • Veins are the vessels that carry the blood to the heart. • Thin muscular walls. • Valves to prevent back flow. • Venules that join capillaries in the capillary network. • Blood pressure tends to be lower than in arteries.

  17. Veins Structure Connective Tissue Smooth muscle Elastic Fibers Valve Endothelium

  18. Capillaries • Capillaries connect arterioles and venules. • The wall of a capillary is made up of a single layer of endothelial cells. • Thin walls allow for nutrients and gases to diffuse quickly between the blood and body cells. Single layer of endothelium.

  19. Blood Flow in the Heart • Deoxygenated blood from the body enters the right atrium and is pumped to the lungs by the right ventricle. • Oxygenated blood returns to the left ventricle under high pressure and is pumped to the body tissues. • Note the thicker walls in the left ventricle that serve to handle the higher pressure.

  20. Blood Flow in the Heart • This animation shows the flow of blood in the heart.

  21. The Heart Beat Cycle (HBC) • The HBC refers to the periods of contraction and relaxation of the atria and ventricles in the heart. • Relaxation is known as diastole and contraction is called systole. • The accompanying blood pressure changes are called diastolic and systolic. • See the handout called The Heart Beat Cycle.

  22. Pulmonary Circulation • Blood travels through pulmonary arteries to the lungs. • Gas exchange occurs at the capillary level in the alveoli. • Veins pick up the oxygenated blood and bring it back to the left atrium via the pulmonary vein. Alveoli Capillary Network Gas Exchange

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