Cardiovascular System

Pulmonary Circulation Systemic Circulation Delivers blood to all body cells and carries away waste Pulmonary Circulation Eliminates carbon dioxide and oxygenates blood (lung pathwy)

Arteries and Veins Arteries Veins Carry blood AWAY from the heart Carry blood TO the heart

Structure of the Heart Heart Size: about 14 cm x 9 cm (the size of a fist)

Structure of the Heart Coverings: Pericardium: encloses the heart like a bag Pericardial cavity: contains fluid for the heart to float in reducing friction

Structure of the Heart Wall of the Heart: Epicardium: outer layer, reduces friction Myocardium: middle layer, mostly cardiac muscle Endocardium: inner layer, blood vessels

Structure of the Heart

Pathway of blood through the heart Label the major chambers, valves and blood vessels and draw the pathway of blood through the heart…

Heart Chambers and Valves Atria: top chambers Ventricles: bottom chambers Septum: divides left and right sides Atrioventricular Valve (AV) valves located between the atrium and the ventricle Tricuspid: right side AV Bicuspid: left side AV (Mitral valve)

Heart Chambers and Valves Superior vena cava: vessel that returns blood from the heart from the upper body Inferior vena cava: vessel that returns blood to the heart from the lower body

Heart Chambers and Valves Coronary sinus: a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium). It delivers deoxygenated blood to the right atrium

Heart Chambers and Valves Chordae tendinae/papillary muscles: muscles and tendons that hold the heart valves in place

Heart Chambers and Valves Pulmonary Trunk/Arteries: large vessel that splits into the left and right pulmonary arteries (the only arteries that carry deoxygenated blood) Pulmonary Valve: controls flow of blood into the pulmonary trunk Pulmonary Veins: returns oxygenated blood from the lungs Aorta: large vessel that delivers blood to the body Aortic Valve: controls the flow of blood into the aorta

Branches of the aorta Ascending and Descending Aorta Aortic arch Right and Left Coronary Arteries: supply blood to the heart itself Brachiocephalic Artery: branches into the right subclavian and right common carotid Right subclavian: supplies blood to the right arm Left subclavian: supplies blood to the left arm Common carotid: branches into left and right carotid, which supply blood to the head

Note that blood vessels are not symmetrical**

Blood vessels: arteries, veins, capillaries Arteries: strong elastic vessels which carry blood moving away from the heart Smallest ones are arterioles which connect to capillaries Veins: Thinner, less muscular vessels carrying blood toward the heart Smallest ones are called venules which connect to capillaries Contain valves Capillaries: penetrate nearly all tissues Walls composed of a single layer of squamous cells Allows exchange of materials between blood and tissues

Arteries, veins and capillaries

Control of Blood Flow Precapillary sphincters: circular, valve-like muscle at arteriole-capillary junction

Control of Blood Flow Vasoconstriction: narrowing blood vessel’s lumen (passageway) Vasodilation: expanding blood vessel’s lumen

Control of Blood Flow Blood flow through the veins is not very efficient Important factors: Sympathetic Nervous Pump Skeletal Muscle Pump Respiratory pump

Don’t be Nervous! Sympathetic Nervous Pump: Sympathetic input causes vasoconstriction, which increases pressure, which drives blood back to the heart. When the body needs to mobilize more blood for physical activity, the sympathetic nervous system induces vasoconstriction of veins.

Move your muscles! Skeletal Muscle Pump: Veins pass between skeletal muscles. The contraction of skeletal muscle squeezes the vein, thus increasing blood pressure in that section of the vein. Pressure causes the upstream valve (furthest from the heart) to close and the downstream valve (the one closest to the heart) to open. Repeated cycles of contraction and relaxation, as occurs in the leg muscles while walking, effectively pumps blood back to the heart.

Veins Pass Between Skeletal Muscles

Breathe In! Respiratory pump: the act of breathing helps to drive venous blood out of the abdominal cavity. As air is inspired, the diaphragm descends and abdominal pressure increases. The increasing pressure squeezes veins and moves blood back toward the heart. The rhythmic movement of venous blood causes by the act of breathing is called the respiratory pump.

Atherosclerosis Atherosclerosis is the major cause of coronary artery disease and stroke. Blood flow is diminished and could become blocked Due to development of fatty plaque

Risk Factors for Atherosclerosis genetic predisposition obesity age smoking hypertension diabetes high cholesterol

Disorders of the Circulatory System MVP: mitral valve prolapse The mitral valve does not close all the way Creates a clicking sound at the end of a contraction https://www.youtube.com/watch?v=HP7nIeQAEGM Heart Murmurs: valves do not close completely Causes an (often) harmless murmur sound Sometimes holes can occur in the septum of the heart which can also cause a murmur Normal: https://www.youtube.com/watch?v=dDg7GDpR1RE Murmurs: https://www.youtube.com/watch?v=6YY3OOPmUDA

Disorders of the Circulatory System Myocardial Infarction (MI): a blood clot obstructs a coronary artery Commonly called a heart attack Atherosclerosis: deposits of fatty materials form a “plaque” in arteries which reduces blood flow Treatment: angioplasty, where a catheter is inserted into the artery and a balloon is used to stretch the walls Stent and Angioplasty: https://www.youtube.com/watch?v=S9AqBd4RExk Heart Bypass: https://www.youtube.com/watch?v=DpyqtPjuPIw

Disorders of the Circulatory System Hypertension: high blood pressure The force within the arteries is too high A sphygmomanometer can diagnose hypertension

Blood Pressure Systolic occurs when blood is forced out of the left ventricle, and the aortic valve OPENS This is the high number Diastolic occurs when the aortic valve closes and the ventricle relaxes This is the lower number Average blood pressure: 120/80 Average heart rate 72

Blood Pressure The cusps (flaps) of the bicuspid and tricuspid valves are anchored to the ventricle wall by chordae tendinae This prevents valves from being pushed up into the atria during ventricular systole SPHYGMOMANOMETER: device used to measure blood pressure

Blood Pressure Factors affecting blood pressure: Cardiac output Blood volume (5Liters for avg adult) Blood Viscosity Peripheral Resistance