Cardiovascular System cont 2 17 2020 1 Electrocardiography i ii iii iv v Depolarization electrical event that leads to systole Repolarization electrical event that leads to diastole Systole mechanical event of contraction Diastole mechanical event of relaxation An EKG displays electrical events not mechanical ones 1 Electrical events cause mechanical events b Electrocardiogram P wave depolarization of sinoatrial node and atria QRS complex ventricular depolarization and atrial repolarization T wave ventricular repolarization i ii iii iv Waves can detect arrhythmias v P R interval beginning of atrial excitation to beginning of ventricular excitation S T segment entire ventricular myocardium Q t interval beginning of ventricular depolarization through ventricular repolarization vi vii 2 Heartbeat a Contraction of the heart b Cardiac cycle Each heartbeat 1 Systole 2 Diastole ii Consists of i i ii 1 Atrial systole and diastole 2 Entire cardiac cycle last about 850 milliseconds iii Heart rate number of cardiac cycles per minute c EKG can detect arrhythmias Normal 65 100 beats per minute 1 Average is 72 Tachycardia 100 bpm Bradycardia 60 bpm An ECG can help diagnose heart problems Fibrillation irregular firing of the heart a rapid and irregular rhythm d e Heart sounds due to the closing of valves Auscultation the act of listening to sounds of the heart Heart sounds lub dub 1 Atrioventricular valves closing lub 2 Semilunar valves closing dub iii iv i ii i ii iii iv v i ii 3 Blood vessels Form closed circulatory system begins ends at heart a b 5 types of vessels Arteries carry blood away from the heart arterioles small arteries Veins carry blood to the heart Venules small veins Capillaries are in between arteries and veins c 3 layers of vessels Tunica intima 1 Endothelium a Simple squamous epithelium 2 Basement membrane a Wraps around the lumen Tunica media Elastin 1 2 Smooth muscle a Vasoconstriction b Vasodilation 3 Wraps around the intima iii Tunica externa 1 Adventitia Fibrous tissue a b Elastin c Anchor to surrounding tissue 2 Wraps around the media 4 The arterial system a Receives blood from the heart b Elastic arteries Closest to heart Largest diameters Elastic protein elastin c Muscular arteries Branch from elastic arteries Tunica media full of smooth muscles Vasoconstriction dilation Branch from muscular arteries Smallest diameter of arterial system Vasoconstriction and vasodilation d Arterioles i ii iii 5 Capillaries a Connect arterial and venous system i Microcirculation b Form large beds i ii Between arterioles and venules Branching network c Exchange of materials i Mainly tissue ii Only 1 layer thick tunica intima Endothelium 1 2 Basement membrane Small diameter 8 10 or less 6 The venous system a Receive blood from capillaries Join to form postcapillary venules b Venules join to form veins Veins bring blood back to heart c 3 tunics in veins larger lumens i ii iii i ii iii iii i i Pronounced tunica externa 1 Overall thin walls 2 Collagenous and elastic fibers d Veins are the blood reservoir 60 e Bringing blood back to the heart Venous valves 1 Prevent backflow Skeletal muscles i i ii
View Full Document
Unlocking...