Structure of the Circulatory System Paul Buser, Courtney Green, Monica Roberts and Michelle Silver

Circulatory System a.k.a Cardiovascular  Main Function: Transport substances dissolved or suspended in the blood  O 2  CO 2  Nutrients - digested food molecules  Cells of immune and other defense systems  Hormones  Main Function: Transport substances dissolved or suspended in the blood  O 2  CO 2  Nutrients - digested food molecules  Cells of immune and other defense systems  Hormones

The Heart central pump for blood Right Atrium: receives de- oxygenated blood from veins (blood enters) Taken from body and sent to lungs to become rich in oxygen once more Left Atrium: Transfers oxygenated blood to the arteries (blood leaves) Taken from lungs, transferred to body Vena Cava Aorta Vena Cava

Types of Vessels in the body  Arteries/Arterioles - carry blood away from heart --> high pressure  Veins/Venules - carry blood back to the heart --> low pressure  Capillaries - provide the link between arterial and venous blood vessels, where diffusion occurs  Arteries/Arterioles - carry blood away from heart --> high pressure  Veins/Venules - carry blood back to the heart --> low pressure  Capillaries - provide the link between arterial and venous blood vessels, where diffusion occurs

Artery Arteriole Capillary Venule Vein

Arteries and Arterioles  Arteries (elastic and muscular) Muscular arteries are farther from heart, deliver blood to specific organ. Elastic arteries (aorta) hold more blood, take blood from the heart  Structure = large-diameter blood vessels, have smooth muscle  Function = efficiently transports oxygenated blood from the heart at high pressures, high pressure necessary to push blood, main force of blood to travel to tissues  Exception: pulmonary artery transports de-oxygenated blood to lungs  Arterioles  Structure = smaller-diameter than the arteries, connect to capillaries, have smooth muscle  Function = controls the volume of blood flow through organs  Arteries (elastic and muscular) Muscular arteries are farther from heart, deliver blood to specific organ. Elastic arteries (aorta) hold more blood, take blood from the heart  Structure = large-diameter blood vessels, have smooth muscle  Function = efficiently transports oxygenated blood from the heart at high pressures, high pressure necessary to push blood, main force of blood to travel to tissues  Exception: pulmonary artery transports de-oxygenated blood to lungs  Arterioles  Structure = smaller-diameter than the arteries, connect to capillaries, have smooth muscle  Function = controls the volume of blood flow through organs

Three Levels of the Artery 1. Tunica Intima: direct contact with blood, smooth/flat to minimize resistance of flow 2. Tunica Media: muscle level, holds artery in place, deals with high pressure-->contracts to adjust pressure 3. Tunica Adventitia: external layer, outer covering for protection

Veins and Venules  Veins- low resistant transport tubes to the heart  Structure = large in diameter, Valves + smooth muscles in the venous wall. Thinner than arteries because lower pressure  Function = valves prevent back flow of blood against gravity and smooth muscle controls venous pressure (low) and volume, thus allowing veins to serve as blood reservoirs. veins carry de-oxygenated blood to the heart  Exception: pulmonary vein carries oxygenated blood.  Low pressure of veins compliments high pressure of arteries  Venules (little veins) - Capillaries merge into venules venules then merge into the larger- diameter veins.  Veins- low resistant transport tubes to the heart  Structure = large in diameter, Valves + smooth muscles in the venous wall. Thinner than arteries because lower pressure  Function = valves prevent back flow of blood against gravity and smooth muscle controls venous pressure (low) and volume, thus allowing veins to serve as blood reservoirs. veins carry de-oxygenated blood to the heart  Exception: pulmonary vein carries oxygenated blood.  Low pressure of veins compliments high pressure of arteries  Venules (little veins) - Capillaries merge into venules venules then merge into the larger- diameter veins.

Vein: 3 Levels 1. Tunica Intima- has valves, direct contact with blood, smooth/flat to minimize resistance 2. Tunica Media- thinner smooth muscle than artery 3. Tunica Adventitia- outer covering

Capillaries  Structure: very thin, fragile tubes  Only one cell thick, not visible without microscope  Function: exchange of CO 2 and O 2 through thin walls, connects arterioles and venules  Structure: very thin, fragile tubes  Only one cell thick, not visible without microscope  Function: exchange of CO 2 and O 2 through thin walls, connects arterioles and venules

Types of Cells that Line Blood Vessels Endothelial Cells They are very flat with a central nucleus Function They play a major role in arterial diseases Flat/slick to allow blood to flow with less resistance in all vessels Act as a filter –they regulate the passage of gases, fluids, etc across their cell membranes. Most transports occur at capillary beds but a little bit occurs for muscles in arteries and veins Different organs have different types of endothelial cells that allow more or less passage of necessary nutrients or gasses

Subcategories of Circulatory System 1.Systemic Circulation 2.Pulmonary Circulation 3.Portal Circulation 1.Systemic Circulation 2.Pulmonary Circulation 3.Portal Circulation

Systemic Circulation supplies blood to all body tissues, exchange of nutrients and products of metabolism  Systemic arterial system- transfers oxygenated blood from heart to body tissues  Systemic venous system- returns de-oxygenated blood from tissues, rich in CO 2, back to the heart *This is the system that blood pressure is measured in  Systemic arterial system- transfers oxygenated blood from heart to body tissues  Systemic venous system- returns de-oxygenated blood from tissues, rich in CO 2, back to the heart *This is the system that blood pressure is measured in

Pulmonary Circulation movement of blood between the heart and lungs 1.De-oxygenated blood brought back to the heart Vena Cavae --> Right Atrium --> Right Ventricle --> Pulmonary Artery --> Lungs 2.In lung capillaries there’s an exchange between CO 2 and Fresh, oxygenated blood enters the heart Pulmonary Veins --> Left Atrium --> Left Ventricle --> Aorta --> body 1.De-oxygenated blood brought back to the heart Vena Cavae --> Right Atrium --> Right Ventricle --> Pulmonary Artery --> Lungs 2.In lung capillaries there’s an exchange between CO 2 and Fresh, oxygenated blood enters the heart Pulmonary Veins --> Left Atrium --> Left Ventricle --> Aorta --> body

Portal Circulation  The circulation of blood through larger vessels, from capillaries of one organ to capillaries of another organ *normally there is just one capillary bed for each branch of circuit, portal circulation has 2! EX: blood travels from the gastrointestinal tract and spleen to the liver: digested and absorbed substances from the gut go right to the liver to be synthesized/detoxify the blood  The circulation of blood through larger vessels, from capillaries of one organ to capillaries of another organ *normally there is just one capillary bed for each branch of circuit, portal circulation has 2! EX: blood travels from the gastrointestinal tract and spleen to the liver: digested and absorbed substances from the gut go right to the liver to be synthesized/detoxify the blood

Blood Pressure the force of the blood pushing against the walls of the arteries Factors affecting blood pressure - Gravity – pulls blood towards ground, heart pumping is needed to bring blood upwards. - Radius of the vessel – smooth muscle can change radius immediately if necessary. -Amount of blood: more viscous= higher pressure Types of Blood pressure - Systolic is the peak blood pressure-when blood pumped - Diastolic is the lowest pressure when the blood is moving through the vessels-remaining pressure after blood is pumped, enough flow to keep things moving

Highway Analogy

Sources  Healthwise Incorporated. “Normal Heart.” Healthwise Incorporated. Aug Nov  McGeachie, Professor John. "Blue Histology - more about Endothelial Cells." School of Anatomy & Human Biology - Teaching Website Index. N.p., n.d. Web. 11 Nov  Ross, John. “Structure and Function of Blood Vessels.” Fortune City. July Nov  Starr, Cecie and Ralph Taggart. Biology: The Unity and Diversity of Life 9th Edition. Pacific Grove, CA: Brooks/Cole, Print.  The Franklin Institute. “The Human Heart.” The Franklin Institute Nov  Healthwise Incorporated. “Normal Heart.” Healthwise Incorporated. Aug Nov  McGeachie, Professor John. "Blue Histology - more about Endothelial Cells." School of Anatomy & Human Biology - Teaching Website Index. N.p., n.d. Web. 11 Nov  Ross, John. “Structure and Function of Blood Vessels.” Fortune City. July Nov  Starr, Cecie and Ralph Taggart. Biology: The Unity and Diversity of Life 9th Edition. Pacific Grove, CA: Brooks/Cole, Print.  The Franklin Institute. “The Human Heart.” The Franklin Institute Nov