BIOL 320 1st EditionLecture 8Outline of Last Lecture I. Coronary Circulation- Clinical CorrelationsII. Heart: Microscopic AnatomyIII. Heart Physiology- Action Potentials of Auto-rhythmic CellsIV. Conduction System of the HeartV. Regulation of Heart RateVI. Electrocardiography- Normal and Abnormal ECG TracingsVII. Heart DysfunctionOutline of Current Lecture VIII. Cardiac CycleIX. Cardiac Output- Flow Chart to Increase Cardiac OutputX. Regulation of Stroke Volume (SV)- Three Factors that Regulate SV:XI. Effects of Calcium in Cardiac MuscleXII. Heart DevelopmentXIII. Congenital Heart DefectsXIV.Aging of the HeartI. Blood Vessels- StructureII. ArteriesIII. Capillary Beds: sites of gas exchange- Thoroughfare channel: bypass capillary bedCurrent LectureCardiac Cycle- As P wave is occurring…electrical stimuli activating the atria (the AV nodes open) get the blood into the ventricles- QRS complex: ventricles are contracting so the SL valve is open (gets open from the blood pressure/pushing up on it forcing it to open)…AV valve is closed (delay due to ECG reading depolarization)- First sound: is AV valve closing- T wave: ventricular repolarization- Second sound: SL valve closing- End Diastolic Volume: full- End Systolic Volume: empty- EDV – ESV = Stroke Volume- Systole: contracting- Diastole: relaxingCardiac Output- Cardiac Output (CO) = volume/minute blood pumped by ventricles- CO (ml/min) = HR (beats/min) x SV (ml/beat)o CO = Cardiac Outputo HR = Heart Rateo SV = Stroke Volume- SV = EDV – ESVo SV = Stroke Volumeo EDV = End Diastolic Volumeo ESV = End Systolic Volume- Extra Notes:o Average blood volume is being pumped throughout your body every minute.o Heart is fullest at diastole.o Heart is emptiest at systole.- Flow Chart to Increase Cardiac OutputRegulation of Stroke Volume (SV)- Three Factors that Regulate SV:o Preload: degree of stretch of cardiac muscles (Frank Starling Law of the Heart)o Contractility: intrinsic ability of tissue to contract (ex: greater calcium influx  greater contractility…anything that increases S-ANS input…glucagon…digitalis…epinephrine…thyroxin)o Afterload: pressure of aortic blood on SL valve (aortic valve)…weight of blood on cusps…(hypertensive patient heart will have to work harder because it puts strain on heart…not a problem if healthy)- Blood Loss/Rapid Heartbeat: when blood volume goes down blood pressure goes down…tachycardia will also decrease volume because less time to refill…both result in decreased SVEffects of Calcium in Cardiac MuscleHeart Development- Foramen ovale: bypass pulmonary circuit since gas exchange is occurring by the placenta (fossa ovale is the scar of this in the adult heart)Congenital Heart Defects- Ventricular Septal Defect: the superior part of the inter-venticular septum fails to form; thus, blood mixes between the two ventricles. More blood is shunted from left to right because the left ventricle is stronger.- Coarctation of the Aorta: a part of the aorta is narrowed, increasing the workload of the left ventricle.- Tetralogy of Fallot: multiple defects (tetra = four)o Pulmonary trunk too narrow and pulmonary valve stenosed, resulting ino Hypertrophied right ventricleo Ventricular septal defecto Aorta opens from both ventriclesAging of the Heart- Sclerosis & Thickening of Valve Flaps:o Most common site: mitral valveo Result: heart murmur (leaking of blood through valve)- Cardiac Reserve Decline:o Cardiac reserve = heart’s ability to respond to sudden & prolonged cardiac outputo Sympathetic control: less efficiento Heart rate: more variableo Example: cliché of older man with younger woman…[asystole = no pumping]- Fibrosis of Cardiac Muscle:o Stroke volume: decreaseso Fibrosis of nodes: increased incidence of arrhythmias- Atherosclerosis:o Contributing factors: inactivity, smoking, high cholesterol diet, stress, geneticso Consequences: hypertension, coronary arteries occludeo Risks: stroke and heart attackBlood Vessels- Structure: Tunicso Arteries vs. Veins Arteries: lumen is smaller…thickness is thicker Veins: lumen is larger…thickness is thinnero Tunica intima: innermost layer Endothelium: same as what is in hearto Tunica media: middle layer Smooth muscle and elastic fiberso Tunica externa: outermost layer Collagen fibersArteries- Physical characteristics serve to: decrease shock and even out flow- Muscular artery: supply organs/tissue with bloodo If “faucet” wide open?...pressure/flow decreaseso Blood is “time-shared” by tissues…vasoconstriction/vasodilationo Limit flow to inactive areas- Arteriole: connect arteries to capillarieso Can vasoconstrict to further limit flow to inactive areaCapillary Beds: sites of gas exchange…create a micro-circulation- Pre-capillary sphincters: if closed, blood doesn’t flow through…if open, it does.- True capillaries: vessels after pre-capillary sphincter- Thoroughfare channels: bypass capillary bed when pre-capillary sphincters are closed- Pericytes: smooth muscle like cells; stabilize capillary walls- Tissues without: tendons and ligaments; cartilage and epithelial tissue (none at all); cornea (eyeballs)- Function: exchange of gases, nutrients, hormones,