Biology Exam 3 Cardiovascular System What are the functions of the cardiovascular system 1 Generate blood pressure 2 Transport blood 3 Exchange of nutrients and wastes at the capillaries 4 Regulate blood flow as needed Anatomy of the heart myocardium A large muscular organ consisting of mostly cardiac tissue called the Consists of two sides right and left separated by a septum Consists of 4 chambers 2 atria and 2 ventricles 2 sets of valves semilunar valves and atrioventricular valves AV valves The valves give the resulting lub and dup sound of the heart How does blood flow through the heart Inferior and superior vena cava 1 dump blood into the right atrium 2 Right ventricle 3 2 pulmonary arteries 4 that lead to the lungs 5 where blood becomes oxygenated Pulmonary veins 6 bring blood from the lungs back the left atrium 7 Left ventricle 8 is large and muscular to pump blood into the aorta 9 and to the rest of the body 10 Eventually blood will be pumped back to each vena cava 1 What are the two cardiovascular pathways in the body Pulmonary circulation blood leaves the right ventricle travels to the lungs to become oxygenated and returns to the left atrium Systemic circulation the left ventricle pumps oxygen rich blood to the entire body which then returns to the right atrium Arteries and arterioles Arteries carry blood away from the heart Have highest blood pressure Thick muscular elastic walls Oxygen rich Arterioles are small arteries that regulate blood pressure Capillaries Microscopic vessels between arterioles and venules Only one cell thick Form beds of vessels where gas and nutrient exchange occurs Veins and venules Venules are small veins that drain blood from the capillaries Veins and venules carry blood toward the heart Oxygen poor Low blood pressure the heart Veins that carry blood against gravity have valves to keep blood flowing toward How does blood in the lower extremities return to the heart 1 Skeletal muscle contraction 2 Valves The Cardiac Cycle The cardiac cycle is one heartbeat lub dub on average occurs 70 times minute Lub closing of the AV valves upon ventricular contraction systole Dub closing of the SLvalves as the ventricles relax diastole Regulation of Heart Rate Internal control The SA node in the right atrium initiates the heartbeat and signals 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 from cell to cell via intercalated disks External control heartbeat is also controlled by a cardiac center in the brain and hormones such as epinephrine and Norepinephrine What is an electrocardiogram ECG A record of the electrical changes in the heart muscle during a cardiac cycle P wave current travels through the atria QRS complex current travels through the ventricles and atrial diastole T wave ventricular diastole Looking at these electrical changes allows doctors to detect abnormalities What is blood pressure The pressure against a blood vessel wall usually measured in an artery in the arm The highest pressure is during blood ejection from the heart called the systolic pressure The lowest pressure is the diastolic pressure when the ventricles relax Average blood pressure is recorded at about 120 80 mmHg systolic diastolic Reminder this is controlled by the arterioles Cardiovascular disease CVD is the most common cause of death in the western Cardiovascular Disease world Hypertension high blood pressure Atherosclerosis Stroke Heart attack Aneurysm Hypertension 140 90 mmHg is considered hypertension A silent killer because there are few symptoms Can lead to a heart attack stroke or kidney failure Causes Stress diet smoking atherosclerosis Atherosclerosis A build up of plaque in blood vessels Plaque that is stationary is called a thrombus Once it detaches and moves it is referred to as an embolus Associated with a stroke heart attack and aneurysm Stroke Also known as a cerebrovascular accident CVA Usually occurs when a cranial artery is blocked or bursts Part of the brain dies dues to lack of oxygen Symptoms may occur including numbness of hands or face difficulty speaking and inability to see in one eye Heart attack Also known as a myocardial infarction MI Part of the heart muscle dies due to lack of oxygen Can begin with angina pectoris a pain that radiates down the left arm due to a blockage of a coronary artery Aneurysm A ballooning of a blood vessel due to a weak spot Atherosclerosis and hypertension can weaken a vessel and cause ballooning The most commonly affected is the abdominal artery or the arteries leading to the brain How are disorders of the blood vessels treated Dissolving blood clots t PA is a drug that dissolves clots Treating clogged arteries Bypass surgery usually a vein from the leg is taken and used to bypass a clogged artery Stents wire mesh cylinder inserted into a clogged artery to hold it open Angioplasty a tube with a balloon is inserted into the clogged area and the balloon is then inflated to open the vessel A stent and angioplasty may be used in combination The muscular system 3 types of muscle tissue Smooth involuntary muscle found lining hollow organs and vessels Cardiac involuntary muscle found in the heart Skeletal voluntary muscle that is attached to the skeleton Functions of the skeletal muscles Support the body by allowing us to stay upright Allow for movement by attaching to the skeleton Help maintain a constant body temp Protect internal organs and stabilize joints Muscle fibers cells Cell structure sarco myo muscle The plasma membrane is called the sarcolemma The cytoplasm is called the sarcoplasm The SER of a muscle cell is called the sarcoplasmic reticulum and stores calcium Transverse tubules are deep invaginations of the sarcolemma that spread electrical excitation Structure within the whole muscle Muscle fibers are arranged in bundles called fascicles Myofibrils are bundles of myofliaments that run the length of a fiber Myofilaments are proteins actin and myosin that are arranged in repeating units Sacomeres are the repeating units of actin and myosin found along in myofibrils The sacromere The sarcomere is basic functional unit of skeletal muscle contraction Composed of myofilaments Z line defines the sarcomere Actin the thin filaments Attach to the z line Myosin the thick filaments Pulls actin towards the m line The sliding filament model Myosin heads pull actin towards the
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