Chapter 5 Cardiovascular System Heart and Blood vessels Cardiovascular system It includes the heart and blood vessels It brings nutrients oxygen irons vitamins to cells and helps get rid of wastes Blood is refreshed in the lung kidneys intestine and liver Lymphatic vessels help this system by collecting excess fluid surrounding tissues waste and returning it to cardiovascular system It has 2 cardiovascular pathways in the body Pulmonary circuit the right side of the heart that brings blood from the body to the heart and the lungs Systemic circuit the left side of the heart that brings blood to the entire body to deliver nutrients and rid it of wastes Coronary circulation is the heart s blood supply They are small coronary arteries right left that supply the heart They are separate from systemic pulmonary pathways of body Functions Generate blood pressure Transport blood Exchange of nutrients and wastes at the capillaries Regulate blood flow as needed How it works 1 Arteries carry blood away from the heart to the arterioles Their walls have 3 layers Thin inner epithelium Thick smooth muscle layer Outer connective tissue 2 Arterioles small arteries that regulate blood pressure 3 Capillaries microscopic vessels where body cells exchange Made of one layer of epithelial tissue Are located between the arterioles and venules Form beds of vessels where exchange with body cells occurs Combined large surface area 4 Venules small veins that receive blood from the capillaries Venule and vein walls have 3 layers Thin inner epithelium Thick smooth muscle layer Outer connective tissue 5 Veins carry blood toward the heart Veins that carry blood against gravity have valves to keep blood flowing toward the heart excessively Anatomy of the heart Heart large muscular organ consisting of mostly cardiac tissue called the myocardium Surrounded by a sac called the pericardium for protection Consists of 2 sides right and left separated by a septum Gap junctions make the heart beat at once Consists of 4 chambers 2 atria and 2 ventricles Valves produce the lub and dub sounds of the heartbeat 2 sets of valves semilunar valves and atrioventricular valves AV valves External Internal How does the blood flow in the heart Inferior and superior vena cava dump deoxygenated blood into the 1 2 Right atrium then into the 3 Right ventricle then goes to the 4 2 pulmonary arteries EXCEPTION carry deoxygenated blood to the 5 Lungs where blood becomes oxygenated and goes to the 6 Pulmonary veins EXCEPTION that bring oxygenated blood from the lungs back to the 7 Left atrium then to the 8 Left ventricle thicker and more muscular than the right one to pump blood to the rest of the body through the 9 Aorta then to the 10 Rest of the body and eventually blood will be pumped back to each vena cava 1 How do the structure of the vessels and heart match their functions The left ventricle is much more muscular and thicker than the right ventricle because it must pump blood to the entire body The arteries are more muscular than veins to withstand the higher pressure exerted on them The veins have a thinner wall and a larger center to contain blood Heartbeat Process Control process Internal control During systole the atria contract together followed by the ventricles contracting together This is followed by diastole a rest phase when the chambers relax This cardiac cycle or heartbeat occurs 70 times minute on average The SA node in the right atrium initiates the heartbeat and causes the atria to contract This impulse reaches the AV node also in the right atrium to send a signal down the AV bundle and Purkinje fibers that causes ventricular contraction These impulses travel between gap junctions at intercalated disks External control Heartbeat is also controlled by a cardiac center in the brain and hormones such as epinephrine and norepinephrine adrenaline rush Cardiac Cycle a heartbeat Visualizing the heartbeat Electrocardiogram ECG It is a record of the electrical changes in the heart muscle during a cardiac cycle Electrodes connected to a machine can detect stimuli and represent it The atria produce an electrical current called the P wave when stimulated by the SA node The contraction of the ventricles is the QRS complex The recovery of the ventricles is called the T wave Looking at these electrical changes allows doctors to detect abnormalities What is blood pressure It is the pressure against a blood vessel wall usually measured in an artery of the arm with a sphygmomanometer pressure force applied per unit area The highest pressure called the systolic pressure is during blood ejection from heart The lowest pressure the diastolic pressure occurs when the ventricles relax Average blood pressure is recorded at about 120 80 mmHg systolic diastolic Reminder this is controlled by the arterioles 3 facts that make blood flow important Blood flow is under the highest pressure in the arteries but remember the thick muscular walls Blood flow is slower in the capillaries which is important to allow time for exchange between cells Blood pressure is minimal in the veins and venules but blood flow increases because they have help 1 Skeletal muscle contraction 2 Breathing 3 Valves Cardiovascular disease CVD is the most common cause of death in the Western world Types of cardiovascular diseases all may lead to heart attack Hypertension high blood pressure High blood pressure results when blood moves through vessels at a rate higher than normal often due to arterial plaque fatty acids or other toxins in blood vessels 140 90 mmHg is considered hypertension normal blood pressure 128 80 It is a silent killer because there are few symptoms Can lead to heart attack stroke or kidney failure Atherosclerosis It is a buildup of plaque in blood vessels Plaque that is stationary is called a thrombus when it detaches and can move to distant sites it s called embolus It is associated with a stroke heart attack etc Stroke Heart attack It usually occurs when a cranial artery is blocked or bursts Also known as a cerebrovascular accident CVA Part of the brain dies dues to lack of oxygen Symptoms numbness of hands or face difficulty speaking or inability to see in one eye A heart attack is also known as a myocardial infarction MI Part of the heart dies due to lack of oxygen It can begin with angina pectoris a pain that radiates down the left arm due to a blockage of a coronary artery How are disorders of the blood vessels treated Dissolving blood clots t PA is a
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