1. Blood Vessels and Circulation Objectives: 1.Describe the structure and function of each of the three types of blood vessels 2.Compare and contrast each type of blood vessel 3.Explain the path that blood takes from the heart

2. Quiz 1.What is a Erythrocyte? 2.What is the function of leukocytes? 3.Type A blood has what antibodies? 4.Which blood type is the universal recipient? (Don’t forget the +/-) 5.What component of blood initiates blood clotting?

3. How Does Blood Get Around? Vessel A hallow tube that circulates blood An average adult has ~160 000 km of blood vessels

4. The need for a circulatory system Simple organisms don’t require a circulatory system…Unicellular organisms are in direct contact with their environment. Multicellular organisms like Sponges don’t need a circulatory system because their body has only two layers so all their cells are very close to their environment. Also their body cavity has water containing oxygen and nutrients constantly circulating through it.

5. Increasing Body Size Bigger organisms have cells that are not in contact with the external environment. Cells can’t move around to get oxygen and nutrients. Cells must be surrounded by fluid for gases, nutrients and wastes to be able to diffuse across. The cells of complex multicellular animals are surrounded by tissue fluid.

6. Types of circulatory systems Open circulatory system: blood and tissue fluid (hemolymph) is pumped into body cavities where it bathes all the cells. Closed circulatory system: blood flows through vessels. Blood and tissue fluid is kept separate.

7. Three types of blood vessels 1.Arteries 2.Capillaries 3.Veins

8. These blood vessels acting together are responsible for transporting or carrying blood to and from the heart, and to and from every cell in the body This network is a continuous and closed network Note: the arrow → represents the direction of blood flow through the blood vessels of the body

9. heart → arteries → arterioles → capillaries → venules → veins → heart ↓ ↑ O2 CO2 ↓ ↑ cell

10. Function to carry blood away from the heart to the cells of the body Structure thick, muscular walls can stretch slightly to accommodate the heart pumping blood

11. Gas content of Blood blood carried by most arteries is rich in oxygen (oxygenated) Colour of blood bright red Blood is pushed by blood in these vessels is pushed by the force of contraction of the left ventricle of the heart Blood Pressure these vessels are under high pressure due to the force of contraction of the left ventricle

12. Clinical Usage to measure a pulse that represents an estimation of heart rate to measure blood pressure Note: the pulmonary arteries are the only arteries that carry deoxygenated blood (blood being pumped from the heart to the lungs) Note: Blood pressure is greatest in the aorta, the largest artery of the body, and then decreases as it moves farther away from the heart

13. are ‘small’ arteries they link arteries with the capillaries

14. Function Allow for the exchange of gases and the transfer of nutrients and waste products between cells and the blood; and they allow for the continuation of blood flow as they connect arterioles with venules. every cell in the body is within 50 micromillimetres of a capillary but only certain capillaries are open at any given time.

15. Structure narrow – only one blood cell at a time can flow through this vessel numerous – placed end to end they represent 6,300 square metres thin walls – composed of only a single layer cells. The walls are only one cell thick, allowing for maximum diffusion of gases, nutrients and waste products

17. Gas content of Blood blood carried by capillaries will contain O 2 leaving the blood in the capillary and diffusing into the cells and CO 2 entering the blood from the cell. Colour of blood red in arterial end and maroon in venous end Blood is pushed by blood in these vessels is pushed by the residual or left-over pressure of the force of contraction of the left ventricle of the heart Blood Pressure is very low in these vessels due to the large surface area covered by capillaries, but not as low as the blood pressure in the veins

18. are ‘small’ veins they contain deoxygenated blood collected from capillaries they connect or link capillaries to veins

19. Function to carry or return blood back to the heart Structure the walls of the veins are thinner than those of the artery. Veins contain valves that allow for one-way flow of blood back to the heart. Valves prevent back flow of blood, counter balancing the affect of gravity

21. Gas content of Blood blood carried by most veins is rich in carbon dioxide (deoxygenated) Note: the pulmonary veins are the only veins that carry oxygenated blood (back to the heart from the lungs) Blood is pushed by blood in veins is squeezed back to the heart slowly, step by step, valve by valve. The return of blood is also aided by contraction of surrounding skeletal muscles

22. Blood Pressure is negligible Movement of blood blood moves slowly and steadily through veins. There are more veins than arteries and veins can expand more than arteries, thus they contain about 70% of total blood volume. Clinical Usage veins are used for injections, transfusions and withdrawing blood. The reason for this is the fact that the walls of veins are relatively thin and therefore easily punctured, and the blood pressure is negligible so that blood will not rush out of the puncture

25. Key Terms: –Arteries  Arterioles –Veins  Venules Valves –Capillaries What is the function of each of these structures?

26. The cardiovascular system is composed of two major components or organs, what are they? i) a network of vessels – arteries, capillaries and veins ii) a pump – the heart

27. transporting or carrying blood to and from the heart, and to and from every cell in the body

28. Q) What is a clinical usage of Arteries??? A) to measure a pulse that represents an estimation of heart rate A) to measure blood pressure Q) What is a clinical usage of Veins??? A) used for injections, transfusions and withdrawing blood. The walls of veins are relatively thin and therefore easily punctured, and the blood pressure is negligible so that blood will not rush out of the puncture

29. Varicose Veins

30. A)Venules B)Veins C)Capillaries D)Arteries E)Arterioles 1)Drain blood from capillaries 2)Smallest blood vessels 3)May contain valves 4)Take blood to the heart 5)Sites for exchange of substances between blood and tissue fluid 6)Rate of blood flow is the lowest Drain blood from capillaries Smallest blood vessels May contain valves Take blood to the heart Sites for exchange of substances between blood and tissue fluid Rate of blood flow is the lowest A)Venules B)Veins C)Capillaries

31. Your Task Fill in the table comparing the structure and function of each of the types of blood vessels we discussed today. H/W: Read through pages 250-254 Answer questions 2-4 on page 253 and 1, 5-9 on page 255. These are potential test questions and we can discuss them tomorrow if enough people complete them.

32. Plenary 1.What are the three types of blood vessels? 2.What is the function of veins, capillaries and arteries? 3.How are veins structured to help blood get back to the heart? 4.How are capillaries structured to do their job? 5.State the path that blood takes from the heart…what blood vessel does it pass through first?