Chapter 20 - The Heart Lecture PDF

Part 1: Intro to Circulation, Blood Vessels, and the Heart’s Location within the Body. Part 2: The External Anatomy of the Heart and Cardiac Muscle Cell Comparison to Skeletal Muscle Consider: How does our body circulate all the various ingredients throughout our body? Part #1:  Describe the heart’...

Part 1: Intro to Circulation, Blood Vessels, and the Heart’s Location within the Body. Part 2: The External Anatomy of the Heart and Cardiac Muscle Cell Comparison to Skeletal Muscle Consider: How does our body circulate all the various ingredients throughout our body? Part #1:  Describe the heart’s role, and differentiate between the pulmonary, systemic, and coronary circuits.  Differentiate between the 3 blood vessel functions.  Describe the various anatomical terms to describe where the heart is located.  Identify the 3 layers of the heart. Part #2:  Use fig 20-3 to identify the anatomy of the heart.  Describe the main characteristics of cardiac muscle and compare them to skeletal muscle.   pump/circulate blood; 2 main circuits + 1 minor? 1) Pulmonary vs 2) Systemic, take blood where? ◦ 1) Heart ➔ Lungs (exchange w/environment) ➔ heart  CO2 out of blood; O2 saturation of blood (20.1) ◦ 2) Heart ➔ entire body (exchange w/tissues) ➔ heart  CO2 out of tissue (waste) + into blood; O2 removal from blood to supply tissues  Minor circuit? ◦ Not shown!  Coronary Circuit? ◦ Blood to/from myocardium (cardiac muscle cells)  Beats 100k/day + pumps 8 kLs of blood   1) Arteries, 2) Veins,, 3) Capillaries which? Carry mostly O2 rich blood away from heart ◦ During pulmonary circuit, blood is O2 poor  Carry mostly O2 poor blood back to heart ◦ During pulmonary circuit, blood is O2 rich  Thin exchange vessels ◦ gases, nutrients, wastes;   Bridge between arterial & venous structures. form “beds” (networks) w/in tissues; ◦ Exchange b/n blood and tissues(cells)/interstitial fluid  Mediastinum of thoracic cavity b/n lungs. (20.4) ◦ Just behind sternum/between pleural cavities ◦ Specific cavity for heart w/in lower mediastinum?   Pericardial cavity – open space. What membrane? Pericardium – serous membrane = lining cavity. ◦ Epicardium = visceral pericardium = covers heart. ◦ Parietal pericardium = outer layer = lines cavity  Pericardial fluid – between layers function to?  1) Epicardium? = ◦ visceral pericardium = outer surface/covering.  2) Myocardium = middle layer containing? ◦ Concentric layers of cardiac muscle tissue. ◦ Wrap and spiral producing “squeezing” contraction.  3) Endocardium ◦ internal lining of simple squamous. ◦ lines chambers & valves Pleural cavity Pericardial cavity Epicardium Pericardial sac 1. 2. 3. 4. 5. 6. How do the pulmonary, coronary, and systemic circuits differ? What vessels carry blood away from the heart? to the heart? allow for waste exchange? Which are mainly oxygenated? deoxygenated? Exceptions to being oxygenated/deoxygenated? What is the mediastinum? Pericardial cavity? What does parietal pericardium refer to? What are the bottom chambers of the heart called? Which side of the heart has oxygenated blood? Which vessels carry blood out of the heart? What chamber receives blood from the body? What is the ligamentum arteriosum? What are the 3 major vessels off the aortic arch, and what parts of the body do each supply? What characteristics do cardiac & skeletal muscle have in common and how do they differ? Part 1: Intro to Circulation, Blood Vessels, and the Heart’s Location within the Body. Part 2: The External Anatomy of the Heart and Cardiac Muscle Cell Comparison to Skeletal Muscle Part #1:  Describe the heart’s role, and differentiate between the pulmonary, systemic, and coronary circuits.  Differentiate between the 3 blood vessel functions.  Describe the various anatomical terms to describe where the heart is located.  Identify the 3 layers of the heart. Part #2:  Use fig 20-3 to identify the anatomy of the heart.  Describe the main characteristics of cardiac muscle and compare them to skeletal muscle.   Fig. 20-3 MUST REVIEW!!! Chambers that receive blood @ top of heart? ◦ Atria (left [oxygenated] and right [deoxygenated])   Coronary sulcus–runs laterally, separates atria from ventricles – inferior chambers of the heart. Interventricular sulcus – runs vertically, separating left and right “ventricles.”     Cell size compared to skeletal muscle? SMALLER 1 nuclei; striated = organized into sarcomeres High or Low amount of mitochondria? HIGH Special gap junction + desmosome linkage that joins cells + ensures efficient smooth contraction. ◦ Intercalated discs (fig. 20.14)  Voluntary or involuntary? INVOLUNTARY   Wider, yet shorter t-tubules and simpler SR. Function of intercalated discs? ◦ Synchronizes contraction (contracts as one);  Stimulus for contraction? ◦ Pacemaker cells vs motor neurons 1. 2. 3. 4. 5. 6. How do the pulmonary, coronary, and systemic circuits differ? What vessels carry blood away from the heart? to the heart? allow for waste exchange? Which are mainly oxygenated? deoxygenated? Exceptions to being oxygenated/deoxygenated? What is the mediastinum? Pericardial cavity? What does parietal pericardium refer to? What are the bottom chambers of the heart called? Which side of the heart has oxygenated blood? Which vessels carry blood out of the heart? What chamber receives blood from the body? What is the ligamentum arteriosum? What are the 3 major vessels off the aortic arch, and what parts of the body do each supply? What characteristics do cardiac & skeletal muscle have in common and how do they differ? Part 1: Breaking Down the Internal Anatomy of the Heart and Blood Flow Part 2: Tracing Blood Through the Heart, Coronary Vessel Identification, and CAD? Consider: How does the heart’s internal anatomy allow it to generate pressure? Part #1:  Use fig 20.6 to identify more parts of the heart, know where oxy/deoxygenated blood would be located.  Identify and differentiate among the 4 valves of the heart, and describe their function.  Completely explain and differentiate each of the 4 chambers of the heart. (oxy/deoxy, muscle size, circuits, receiving blood locations, sending blood) Part #2:  List the order in which blood flows through chambers + valves + circuits + first arteries + last veins blood flows.  Identify major blood vessels of coronary circ.  MUST IDENTIFY ALL PARTS & MUST KNOW WHICH ARTERIES/VIENS ARE OXY-/DE-OXYGENATED  Interatrial septum vs interventricular septum ◦ separates atria vs separates ventricles ◦ Septum = separates right and left sides!  Valves that separate atria from ventricles = ? ◦ Atrioventricular (AV) valves = links R. atrium to R. ventricle & L. atrium to L. ventricle. ◦ Folds of fibrous tissue that function to? ◦ Permit flow in 1 direction; prevent backflow from ventricle to atria.   AV Valve on the right vs AV Valve on the left? Tricuspid Valve; Bicuspid Valve   the system circuit via 1) Superior vena cava (VC), 2)Inferior VC, & 3)Coronary Sinus;each collect blood from 1) head, neck, upper limbs, and chest.  2) trunk, viscera, lower limbs  3) cardiac veins that blend into coronary sinus.  Is blood oxygenated or deoxygenated?  Deoxygenated;  More/Less muscle than ventricles?  Less, pumps blood to which part of heart?      Right atrium passing through what valve? Tricuspid valve – separates right atria + ventricle. Chordae tendineae = CT fibers that pull on valves. Papillary Mus.= muscular ridges that pull of fibers.  What circuit does this deoxy. blood go to? Pulmonary circuit (PC) via pulmonary trunk - has pulmonary semi-lunar valves.  Prevent backflow to ventricles.  Pulmonary art. & veins unique, why?  Deoxy. arteries; oxy. veins.   Pulmonary circuit via pulmonary veins Blood is: Oxy. or deoxy? OXYGENATED  From LA, blood flows through what AV valve?  Bicuspid OR mitral valve. ◦ Prevents backflow to LA.     Blood enters? Left Ventricle (LV). ◦ Holds same volume as RV. Muscle is larger than RV, Y? Blood leaves LV via aortic semi-lunar valve to systemic circuit ◦ ascending aorta ➔ aortic arch ➔ descending aorta    Left ventricle = thicker than RV = LV has to push blood to entire body. AV valves separating atria and ventricles. Semi-lunar valves = prevent backflow from pulmonary + systemic circuits. ◦ composed of 3 cusps    Start at left ventricle (1 minute); be sure to include valves and circuits and deoxy vs oxygenated! LV ➔ aortic semi-lunar valve ➔ aorta ➔ systemic circuit (oxy) ➔ Vena Cavas + coronary sinus ➔ RA (deoxy) ➔ tricuspid valve ➔ RV ➔ pulmonary semi-lunar valve ➔ pulmonary trunk ➔ pulmonary arteries ➔ LUNGS (pulmonary circuit) ➔ pulmonary veins (oxy) ➔ LA ➔ bicuspid valve ➔ LV Purpose of CT of heart? ◦ ◦ ◦ ◦ 1) 2) 3) 4) support cardiac muscle fibers distribute force of contraction evenly add strength/prevent overexpansion of heart Provide elasticity (heart return to normal shape after contraction) Part 1: Breaking Down the Internal Anatomy of the Heart and Blood Flow Part 2: Tracing Blood Through the Heart, Coronary Vessel Identification, and CAD? Consider: How does the heart’s internal anatomy allow it to generate pressure? Part #1:  Use fig 20.6 to identify more parts of the heart, know where oxy/deoxygenated blood would be located.  Identify and differentiate among the 4 valves of the heart, and describe their function.  Completely explain and differentiate each of the 4 chambers of the heart. (oxy/deoxy, muscle size, circuits, receiving blood locations, sending blood) Part #2:  List the order in which blood flows through chambers + valves + circuits + first arteries + last veins blood flows.  Identify major blood vessels of coronary circ.    Start at left ventricle (1 minute); be sure to include valves and circuits and deoxy vs oxygenated! LV ➔ aortic semi-lunar valve ➔ aorta ➔ systemic circuit (oxy) ➔ Vena Cavas + coronary sinus ➔ RA (deoxy) ➔ tricuspid valve ➔ RV ➔ pulmonary semi-lunar valve ➔ pulmonary trunk ➔ pulmonary arteries ➔ LUNGS (pulmonary circuit) ➔ pulmonary veins (oxy) ➔ LA ➔ bicuspid valve ➔ LV Purpose of CT of heart? ◦ ◦ ◦ ◦ 1) 2) 3) 4) support cardiac muscle fibers distribute force of contraction evenly add strength/prevent overexpansion of heart Provide elasticity (heart return to normal shape after contraction)  Blood to the heart (muscle tissue)(20-8) ◦ Coronary arteries (CA) + cardiac veins  Arise from aortic sinus + run transverse w/sulci. ◦ Left CAs ➔ 1) Ant. interventricular artery (downward) OR ➔ 2) circumflex artery ➔ L. marginal artery. ◦ Right CA ➔ R. marginal A. ➔ Post. intervent. artery.  Drain to coronary sinus. ◦ Great + middle + small cardiac veins + Post. Cardiac vein ➔ all drain to CORONARY SINUS ➔ RA  Blockage of coronary circulation decreasing O2 flow ◦ Leads to reduction of cardiac performance.  Caused by atherosclerotic plaque in coronary vessel, which is? (20.9) ◦ fatty deposit or clot that reduces blood flow due to narrowing of vessel.  Early sign of CAD = angina pectoris =? ◦ Chest pain during physical exertion (at rest no pain)  Can include pain of sternum, arms, neck + back    Heart attack developed from severe CAD. Death of cardiac muscle cells due to lack of O2. Death of affected tissue resulting in nonfunctional tissue =? ◦ Infarct or Infarction  Severity depends on artery location. ◦ Smaller arterial branches = complication but survival ◦ Coronary artery blockage = major issues, even death. 1. Identify if each has oxy/deoxy blood AND where would the next adjacent location be?  Pulmonary trunk? Left atrium? Aorta? Right atrium? Pulmonary veins? Vena Cava? Coronary Artery? Coronary Sinus 2. 3. 4. What is the difference between AV valves & semilunar valves? What are the specific names of each valve & which side of the heart are they located? What is the tip of the heart called vs the top where vessels come out? Which chamber of heart has the greatest muscle and why? Starting at the left atria, describe how blood moves throughout the heart and circuits.  Include chambers, valves, circuits, first arteries, last veins before blood flows back to heart. 5. 6. What is the coronary circuit, what are the main vessels and describe their locations? What is coronary artery disease, the signs of it, & what can it result in if left untreated? Part 1: Breaking Down the Internal Anatomy of the Heart and Blood Flow Part 2: Tracing Blood Through the Heart, Coronary Vessel Identification, and CAD? Consider: How does the heart’s internal anatomy allow it to generate pressure? he heart to contract? tion of cardiac muscle similar but ared to skeletal muscle?       Describe the conducting system, define automaticity, and differentiate between conducting and contractile cells. Define the cardiac cycle, and differentiate between the SA node and AV node and 3. Explain the steps of the conducting cycle and explain the role of Purkinje fibers. Identify the thresholds of atria, ventricles, and skeletal muscle, and explain the action potential of the ventricle. Define refractory period and know the 2 types. Compare and contrast skeletal vs cardiac muscle contractions.    Autorhythmic fibers that initiate & distribute the contractile stimulus; “specialized cardiac cells.” 2 main components (20-10): 1)Pacemaker cells–cells that set normal heart rate. ◦ Aka nodal cells = a cluster of cells  2)Conducting cells–cells that interconnect 2 nodes, & distribute contractile stimulus to myocardium.  The CS exerts control over heartbeat without neural or hormonal control – property known as autorhythmicity.  Contractile cells? ◦ Receive signals & contract ◦ Make up 99% of heart cells  All the events that produce a SINGLE heartbeat. ◦ Relies on the “conducting system”  1) SA (sinoatrial) node – wall of right atrium, which? ◦ Contain pacemaker cells that establish heart rate!  (1- rapid depolar; 2 – plateau; 3-repolar)  2) AV (atrioventricular) node – floor of atrium; ◦ receives impulse from SA node via internodal pathw. ◦ Links SA node to AV and triggers contraction of pectinate muscles.   Nodal cells initiate rate of contraction! 3) Final Conducting cells distribute impulse to myocardium. ◦ AV bundle ➔ right + left bundle branches ➔ Purkinje fibers   Contraction begin with? 1) SA Node activation! ◦ Generates electrical impulse   What occurs next? 2) Impulse passed to AV node via internodal cells; ◦ Spreads over atrial surface  Initiates contraction slowly. ◦ ~50 msec to reach AV  3) Impulse passes through AV node taking ~100 msec. ◦ Creates a delay, why?  Allows atria to finish contraction before ventricles.  Slowed impulse at AV node due to nodal cells being smaller in diameter than conducting cells  Impulse after AV node?  4) impulse travels w/in interventricular septum via AV bundle ➔ bundle branches ➔ Purkinje fibers. ◦ Moderator band ➔ impulse for papillary muscle contract ◦ ~25 msec; Final Stop?  5) Impulse distributed via Purkinje fibers = distribute impulse to ventricular myocardium causes ventricular contraction. ◦ ~50 – 75 msec.      1) SA Node activation 2) Impulse spreads across atria towards AV node & atria contract along way. 3) Impulse delayed at AV node to allow for complete atrial contraction. 4) Impulse moves through AV bundle, bundle branches, and Purkinje fibers. 5) Purkinje fibers distribute impulse to ventricular myocardium, & ventricles & papillary muscles (via moderator band) to contract.   Threshold (minimal voltage) reached on membrane near intercalated disc (ID). Leads to? 1) Rapid depolarization; which channels open? ◦ Fast voltage gated Na+ open; sodium rushes in briefly  2) Plateau occurs @ +30 mV = sodium channels close, what opens? ◦ Slow voltage-gated Ca2+ channels open & Ca2+ rushes INTO cell keeping it at ~0 mV. ◦ Major difference compared to skeletal muscle.  FYI: small # of K+ channels open = small repolarization  3) repolarization – calcium channels close, then? ◦ Slow K+ channels open; K+ rushes out   Resting potential = -80 mV atria; -90 mV ventricle; -85 mV skeletal.  Recovery time where membrane does not respond normally to second stimulus.  Membrane can’t ◦ Absolute RP vs relative RP? respond; Na+ channels are inactive until -60 mV ◦ Channels incapable of responding.  Membrane CAN respond (@ -60 mV), but requires stronger stimuli. ◦ Think sympathetic stimulation! ◦ Channels are closed, but can be activated.   Similar=1) Stimuli leads to Ca2+ release, 2) binding Ca2+ to troponin = contraction, 3) myofibril arrang. Differences: 1) stimuli - NTs vs nodal cells, 2) Steps of APs. 3) Contraction and AP duration ◦ s = faster; c = 30x slower = takes 250-300 msec Table 10-3 What are the various blood types, and which types can give and receive blood from which?   Identify & describe the 4 blood types + know which is the universal donor and receiver and why. This extension relates to Lab Concepts from Chapter 19 in the lab book. The pages to complete are as follows: ◦ P/533 [complete table 19.7 – IN-CLASS ACTIVITY] P/534 [complete table 19.8 – IN-CLASS ACTIVITY and continued to be completed as homework]   A, B, AB, and O AND Rhesus factor +/Blood type based off antigens found on RBCs. ◦ Surface proteins that allow body to recognize “self.” ◦ Aka agglutinogens  Type A has what antigen? produces which antibody? ◦ Circulating protein that recognizes foreign substances  Causes agglutination (clumping) of “bad” cells. ◦ Has antigen A, produces B antibody.    Antigens = A, B, AB, and Rh (+/-). What about O? No antigens BUT both antibodies! Rhesus = + (has antigens; not Abs) OR – (no antigens, produces Abs after initial exposure)       O-; no antigens on surface; Abs can’t detect them! Universal Receiver? Why? AB+; does not produce antibodies. What are cross-reactions? When Antibodies interact with RBC antigen causing agglutination leading to hemolyzes. Requires RBC compatibility = correct transfusions.  Image shows cross-reaction agglutination. 1. 2. 3. 4. 5. 6. What is the conducting system, and what are the 2 main cells involved in generating the heart’s contractual signal and explain their functions? What are the 2 nodes & how do they differ, what are conducting cells, and list the order in which signals travel through these parts? What are the steps of the cardiac cycle in correct order and the role of Purkinje fibers? What events occur during ventricular AP, what occurs during each stage & how does it differ compared to skeletal muscle AP? How do relative & absolute refractory period differ, and explain why each occurs? Is the following skeletal, cardiac, or both? ◦ very long cells? Single nucleus per cell? Striated in appearance? Calcium release via sarcomere reticulum? Calcium diffuses in via extracellular fluid (hint: intercalated disks)? fast contraction time? Can generate large tension? ◦ What are antigens? What are the 4 main blood types (excluding + or -), and how does this relate to antigens? What are the main parts of an EKG? What events occur during a full heartbeat? How is heart rate and blood pressure regulated?       Explain the role of an EKG, describe the 3 waves, define arrhythmias, and be able to identify whether it is atrial or ventricular related OR which waves (14). Define cardiac cycle and differentiate systole vs diastole. Describe the 4 main steps/events and 8 detailed steps/events of the cardiac cycle. Identify the 2 stages at which heart sounds are produced and explain why that occurs. Define stroke volume, end diastolic volume, end systolic volume, and relate to cardiac output. Be able to calculate CO, identify factors that impact CO, and explain what autonomic innervation is.     ECG or EKG = Electrocardiogram – detects the electrical events of cardiac muscle. 3 Key “waves” (points) to know. The first wave? P Wave = atrial depolarization or atrial contraction QRS complex = ventricles depolarize = Contraction shortly after “r wave”, remaining?  T waves = ventricles repolarize (relaxation)  EKG is good for detecting what?  Arrhythmias – abnormal patterns of cardiac electrical activity      LEFT = Atrial issues; RIGHT = Ventricular Tachycardia – heart rate over 100 beats/min (bpm) Bradycardia – heart rate under 60 BPM Atrial Fibrillation (Afib) – No P-wave, normal QRS complex; irregular timing Ventricular Fibrillation – No QRS-complex, no rhythmic contraction of myocardium.    Time spans between waves (3 MAIN intervals). P-Q Interval = beginning of P wave to QRS complex = time b/n atrial excitation to ventricular excitat. Q-T Interval = start of QRS to end of T wave = start @ ventricular depolarization to end of vent. Repolarization.  S-T Interval – end of S  to start of T wave = ventricular contractile fiber repolarization plateau phase. R-R – easy peaks to measure 1 complete cycle.    Events occurring in a single heartbeat. Involves periods of contraction? and relaxation? of different chambers. Systole; can be atrial systole OR ventricular systole ◦ volume shrinkage ➔ pressure increase ◦ What happens to blood in chamber? Blood is ejected  Diastole; can be atrial OR ventricular diastole. ◦ What happens to pressure and blood flow? ◦ Pressure is low, volume increases, blood passively fills chamber.   Blood moves from high pressure to areas of low. When would pressure be highest? (Dia or Systole) ◦ Systole = largest blood volume before contr., & decreasing chamber volume as contraction occurs.     4 Main Events: 1) Atrial Systole; 2) Atrial Diastole 3) Ventricular Systole (first phase + second phase) 4) Ventricular Diastole (early + late phase); Starts with ALL chamber relaxed, and ventricles are partially filled w/blood (~70% full)     1) Atrial systole = ventricles 70% full from passive filling, contraction begins (volume shrink), pressure builds Atria eject blood into ventricles via open AV valves; add ~30% to ventricles. 2) Atrial Diastole begins, overlapping w/3rd step. Chamber volume goes up, pressure drops, AV VALVES CLOSE, produces “lubb” sound (S1)  Ventricles are filled w/max blood = enddiastolic volume (EDV)       3) Ventricular systole – 1st phase - ventricles contract (decrease volume & increase pressure). All valves remain close; Contraction w/o blood flow? Isovolumetric contraction 2nd phase - Pressure increase continues causing semilunar valves open; Blood is ejected from the high pressure ventricles and flows towards the low pressure atria! The amount of blood ejected is the?    Volume ejected out of ventricle = 60% of EDV. Ventricles contain 40% of EDV = end-systolic volume (ESV). As blood leaves heart, what happens to pressure? Pres. drops = 4) Early Ventricular diastole = semilunar valves close producing “dubb” sound. (S2)  Isovolumetric relaxation occurs; no blood flow to ventricles happens ◦ Ventricular pressure higher than atrial (all valves are closed) but pressure is dropping   Pressure in atria builds as blood fills chamber. Higher pressure of atria causes AV valve to open; ◦ Ventricles fill passively – slowly, w/o contraction. ◦ Fill to ~70% before SA node activation and contraction!  Repeat with constant volume and pressure changes    1) Atrial Systole 2) Atrial Diastole 3) Ventricular Systole ◦ 1st phase & 2nd phase   4) Ventricular diastole. (early + late) Normal cycle takes ~800 msecs = 75 bpm ➔ 60 sec/.8 = 75 beat/min.     Atrial Systole – contraction of atria the results in decreased volume + increased pressure resulting in ejection of blood to ventricle. Atrial Diastole – relaxation of atria results in increased volume + decreased pressure; AV valves close preventing backflow to atria. Ventricular Systole = contraction of ventricle. 1st phase builds pressure (isovolumetric contraction), 2nd phase ejection of stroke volume out of heart. Ventricular Diastole – relaxation of ventricles & passive blood flow. Early phase = isovolumetric relaxation (all valves closed) – blood fills atria. Late phase – AV valves open, blood passively fills ventricles. Be sure to know when sounds are produced. S1 “lubb” = AV valves S2 “dupp” = semilunar valves Heart murmur caused by regurgitation through valves  4 Key locations to hear specific valves.  Semilunar valves – L. & R. sides of upper sternum  AV valves – R. AV – L. side of lower sternum L. AV – middle of ribs, middle region.     Movements + forces generated by cardiac contractions. EDV = max ventricular volume before systole. ESV = blood in ventricular after contraction (~40%). SV = blood ejected from heart after one “stroke.” ◦ SV = EDV (100%) – ESV (40%) = 60% of blood in heart is circulated.  With SV, one can calculated Cardiac Output (CO)? ◦ Volume of blood pumped per 1 minute ◦ CO = SV x HR (heart rate = beats per minute).  CO = indicator of blood flowing through tissues aka perfusion.  If HR = 75 bpm and SV 80 mL/beat, what is CO? ◦ 75 x 80 = 6000 mL/min or 6L/min. ◦ Given 2 of any variable = calculate the other.  An increase in CO = increase in perfusion ◦ highly regulated process.  Changes in HR or SV increases CO ◦ Can reach up to 30 L/min!    2 ways to increase CO = adjusting HR or SV, how is HR adjusted? SV adjustment? HR = autonomic nervous system OR hormones. SV = changing EDV or ESV = adjusting stroke volume (not covered in detail). ◦ depends on 1) preload (stretch of heart), 2) contractility (force), & 3) afterload (pressure)     Pacemakers cells are autonomous but can be modified via dual innervation of medulla oblong via cardiovascular centers. Which fibers increase heart rate? Decrease HR? Sympathetic neuron via cardioacceleratory centers. Parasymp. neurons via cardioinhibitory centers.  MPs: The autonomic NS regulates HR via sympathetic (increase) and parasymp. (decrease) even though neural stimuli is NOT required for heart.   Fig. 20.21 shows dual innervation. Additionally, cardiac reflexes (sensors that cause autonomic adjustments) exist in the heart. ◦ Blood pressure sensed via baroreceptors = stretch receptors.  O2 + CO2 levels detect via    chemoreceptors. HR increase due to E, NE, and thyroid hormone via sympathetic stimulation. HR decreases due to acetylcholine via parasympathetic. Finally, hormonal adjustments (TBD) 1. 2. 3. 4. 5. 6. What happens during the QRS waves? T wave? What would an irregular P wave indicate on EKG? When events occur during atrial diastole? Ventricular systole, atrial systole, & ventricular diastole? When is the S1 & S2 sound of the heart produced and what happens that produces the sound? Where are these sounds heard via stethoscope? The amount of blood ejected out of the heart is known as? How do EDV and ESV differ? How would you calculated SV using those numbers? Person has HB of 90 bpm and has a SV of 90 mL/beat, what is the CO? What allows the heart to “sense” current conditions? Which division speeds up the heart using what neurotransmitter? Which slows it down?