BIO30S 4_4 Structure Function Vessels
- 1. Entry slip: What is the function of leukocytes? Lesson 4.4- Compare the structure and function of blood vessels. (pp306-307) of Biology-McGraw-Hill Ryerson) I. Terms: a.Arteries: blood vessels that carry blood away from the heart i. Arterioles are smaller arteries (like bronchioles are smaller bronchii) b.Veins: blood vessels that carry blood back towards the heart i. Venules are smaller veins c. Smooth muscle: muscle in your body that is involuntarily controlled (you have no control over it) such as the muscle in your intestines that helps push food along II. Arteries (3 layers): a. Outter layer(structure): connective tissue and some elastic fibres
- 2. i. Function(f): holds the artery’s shape (like pleura in lungs) b. Middle layer(s): thick layer of elastic fibres combined with smooth muscle i. ***Elastic fibres (f): allows the arteries to expand a little as a wave of blood rushes by (this expansion is what we feel as a “pulse”) A. Palpate pulses: radial, brachial, temporal, doraslis pedus, femoral ii. ***Smooth muscle (f): constricts to control blood pressure (the more they constrict the greater the blood pressure) c. Inner layer(s): endothelial cells: special cells that are very slippery i. (f): reduces friction to allow blood to flow by easily d. Notes on arteries: arteries have a smaller inner space than veins to increase blood pressure
- 3. III.Veins (3 layers and valve): a. Outter layer(s): connective tissue and some elastic fibres i. (f): holds the vein’s shape b. Middle layer(s): very thin layer of elastic fibres and smooth muscle i. (f) does very poor job of expanding or constricting c. Inner layer(s): endothelial cells: special cells that are very slippery i. (f): reduces friction to allow blood to flow by easily d.Valves: special structures along veins that prevent blood from flowing backwards i. (f): keeps blood flowing in the right direction towards the heart A. Once blood has reached the capillaries and has to return to the heart, it is moving very slowly. The heart cannot “pump”
- 4. blood in the veins at all at this point. Blood higher than your heart (in your head, neck and shoulders) easily flows down to the heart. Blood lower than your heart however needs something to prevent gravity from pulling it down. When the big muscles in your legs contract because you are moving them, blood in the veins is squeezed up, and once it passes by a valve, it cannot flow back. This continues until the blood has reached your heart. B. Valves that do not work properly anymore become “varicose” IV.Capillaries (One layer- only one cell thick) a.Single layer of endothelial cells- i. (f): allows blood to flow by easily ii. (f): capillary walls are extremely thin (one cell thick) to allow the diffusion of nutrients and wastes across the
- 5. capillary wall to and from all of the body’s cells b. Notes on capillaries: capillaries are microscopic: you cannot see them. They are only as wide as a white blood cell (the largest particle size of all blood components) so as to just allow them by. V. Youtube search: a. “Mechanism of Vein” - kosasihiskandarsjah b.“Varicose Vein 1” I. Homework Assignment: a.Based on information about the valves in veins, describe why human tend to sleep lying down. As well, describe one time that you were forced to sleep in a sitting position (like on an airplane, bus or on a long car ride) and how enjoyable this sleep was. Go into detail. 100 words minimum. b. Due next class.