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22 Cards in this Set
- Front
- Back
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Vascular System |
Blood vessels that carry blood through the body Deliver oxygen and nutrients to the body tissues Take away waste products like C02 |
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Two Types Of Circulation
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Pulmonary Systemic |
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Pulmonary Circulation |
Deoxygenated blood from the heart to the lungs and oxygenated blood back to the heart |
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Systemic Circulation |
Oxygenated blood from the heart to the body Return of deoxygenated blood from the body to the heart |
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Blood Vessels |
Arteries Arterioles Capillaries Venules Veins |
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Arteries |
Carry blood away from the heart Surges of pressure |
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Capillaries |
Single cell layer Only wide enough to let one red blood cell pass through Slows blood flow, allows the gaseous exchange |
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Veins |
Carry blood back towards the heart Under low pressure |
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Blood Vessel Layers |
Tunica externa Tunica media Tunica interna |
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Tunica Externa
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Outer layer Elastic, in order to stretch and withstand large fluctuations in blood volume |
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Tunica Media |
Middle layer Made up of elastic fibres and smooth muscle Elastic fibres strecth when blood is forced into the arteries during ventricular systole Smooth muscle in the walls to ensure the blood flow can vary depending on damand |
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Tunica Interna |
Thin epithelial cells Smooth, reduce friction between blood and vessel walls |
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Artery Features |
Tunica externa present Thick tunica media with many elastic fibres Tunica interna present Small lumen size |
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Capillary Features |
No tunica externa No tunica media Tunica interna present Microscopic sized lumen |
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Vein Features |
Tunica externa present Tunica media is thinner and less elastic than in an artery Tunica interna present Large sized lumen Valves to prevent backflow of blood |
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The Venous Return Mechanism |
Heart beat too low in the veins to push the blood back to the heart Large lumen in veins offers little resistance to blood flow Active mechanisms needed |
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Features Of The Venous Return Mechanism |
The skeletal muscle pump The respiratory pump Pocket valves Smooth muscle within the valves Suction pressure of the heart |
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The Skeletal Muscle Pump |
When muscles contract and relax they change shape Muscles press on the nearby veins and cause a pumping effect Squeeze blood towards the heart |
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The Respiratory Pump |
During inspiration and expiration pressure changes occur in the thoracic and abdominal cavities Pressure changes compress the nearby veins and assist blood return back to the heart |
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Pocket Valves |
Ensure that blood only flows in one direction Once the blood has passed through the valves close to prevent backflow |
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Smooth Muscle Within The Veins |
Very thin layer of smooth muscle in the walls of the veins Helps squeeze blood back towards the heart |
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Suction Pressure Of The Heart |
The heart acts as a pump, creating suction Suction pressure draws blood back towards the heart |
