front 1 Flow | back 1 Constant motion of a fluid |
front 2 Pressure | back 2 Physical force required to create flow through any tube |
front 3 Boyle's law | back 3 Pressure and force have an inverse relationship |
front 4 Resistance | back 4 Force which opposes flow |
front 5 Pressure gradient | back 5 Difference between area of high pressure and area of low pressure |
front 6 Valves | back 6 Prevent backflow and ensure one-directional flow of blood |
front 7 The heart is a ___ pump | back 7 Double |
front 8 Contraction | back 8 - Decreases chamber volume - Increases chamber pressure |
front 9 Relaxation | back 9 - Increases chamber volume - Decreases chamber pressure |
front 10 Pulmonary circuit | back 10 Lungs |
front 11 Systemic circuit | back 11 Tissues |
front 12 Coordination of the beating heart | back 12 - Pulmonary and systemic pumps work in parallel - They are connected to each other and highly coordinated - Contract and relax together - Pump roughly the same volume of blood |
front 13 The heart is located in the ___ ___, protected by the ___ | back 13 Thoracic cavity; pericardium |
front 14 Fibrous pericardium | back 14 Outer layer, made of dense regular connective tissue |
front 15 Serous pericardium | back 15 Double-layered, pericardial fluid-filled membrane |
front 16 Parietal layer | back 16 Outermost layer, in contact with fibrous pericardium |
front 17 Visceral layer | back 17 Surrounds and is continuous with surface of the heart |
front 18 The heart is a ___-layered organ | back 18 Multi |
front 19 Epicardium | back 19 - Outermost layer (superficial) - Made of loose areolar connective tissue and adipose tissue |
front 20 Myocardium | back 20 - Thickest later (middle later) - Contains cardiomyocytes and cardiac skeleton |
front 21 Endocardium | back 21 - Deepest layer - Made of simple squamous endothelial tissue |
front 22 Heart has four chambers | back 22 - Two upper chambers: atria - Two lower chambers: ventricles |
front 23 Left and right side are separated by ___ | back 23 Cardiac septum |
front 24 Systemic pump | back 24 - Left atrium + left ventricle - Pumps oxygenated blood |
front 25 Pulmonary pump | back 25 - Right atrium + right ventricle - Pumps deoxygenated blood |
front 26 Valves create ___ blood flow | back 26 One-directional |
front 27 Blood flow through the heart and major vessels | back 27 1. Deoxygenated blood enters right atrium from body through super and inferior vena cava 2. Pumped through tricuspid valve to right ventricle 3. Blood exits heart through pulmonary arteries into pulmonary circulation 4. Oxygen-rich blood returns through pulmonary veins into the left atrium 5. Pumped through mitral valve into left ventricle 6. Blood exits heart through aorta into systemic circulation |
front 28 Exceptions to blood flow during fetal development | back 28 Fetal shunts |
front 29 Foramen ovale | back 29 Small hole that allows blood to bypass the right ventricle, moving directly between right atrium and left atrium |
front 30 Ductus arteriosus | back 30 Connects pulmonary trunk to aorta |
front 31 Cardiac anastosomes | back 31 Create different pathways for blood |
front 32 Cardiomyocytes | back 32 - Have a single, centrally-located nucleus - Short and wide - Myofilaments are arranged into sarcomeres - Striations are less pronounced - Myofibrils are branched and variable in size - Have great abundance of mitochondria |
front 33 Features of cardiomyocytes | back 33 - Resist fatigue through anaerobic metabolism - Begin to die after a few minutes without O2 - Sarcoplasmic reticulum lacks cisternae - Membranes are fused together (intercalated discs) - Entire tissue functions together (syncytium) |
front 34 0. Resting membrane potential (action potential in contractile cardiomyocytes) | back 34 - Typically between -80 mV and -90 mV - Created from continuous efflux of K+ through inward rectifier potassium channels (Kir) - Also small amount of Ca2+ and Na+ permeability - Na/K/ATPase serves to maintain concentration gradients |
front 35 1. Depolarization (action potential in contractile cardiomyocytes) | back 35 - Similar to the process in skeletal muscle - Voltage-gated fast sodium channels (Naf) are activated, allowing influx of positively-charged sodium ions |
front 36 2. Transient repolarization (action potential in contractile cardiomyocytes) | back 36 - Voltage-gated sodium channels rapidly inactivate at the peak of the action potential - Sodium permeability decreases - Cardiomyocytes go into refractory period - Membrane potential begins to hyperpolarize due to transient outward current from potassium channels |
front 37 3. Plateau phase (action potential in contractile cardiomyocytes) | back 37 - Voltage-gated L-type calcium channels (CaL) open, bringing positively-charged Ca2+ ions into the cell - This is opposed by the efflux of K+ ions through delayed rectifier potassium channels (Kdr) - Two opposite electrical forces create plateau in membrane potential |
front 38 4. Rapid repolarization (action potential in contractile cardiomyocytes) | back 38 - L-type calcium channels close - Efflux of K+ continues through voltage-gated potassium channels - Membrane potential repolarizes to resting state |
front 39 1. Pacemaker potential (aka prepotential) (autorhythmicity is due to pacemaker cells) | back 39 - Delayed rectified channels (Kdr) allow constant efflux of K+, steadily increasing membrane potential - Hyperpolarization-activated cyclic nucleotide gated channels (HCN) begin to open, allowing Na+ influx - Results in "funny current": slow, incremental depolarization - T-type calcium channels are activated, allowing influx of Ca2+, further depolarization |
front 40 2. Rapid depolarization (autorhythmicity is due to pacemaker cells) | back 40 - Inward sodium (funny current) and transient calcium influx continue depolarization until the threshold of the voltage-gated L-type calcium channel is reached - T-type calcium and HCN channels close - Rapid depolarization of membrane potential due solely to calcium ions |
front 41 3. Repolarization (authorhythmicity is due to pacemaker cells) | back 41 - L-type calcium channels close at peak of action potential - Inward rectifying potassium channels (Kir) open - Increased permeability to K+ returns cell to hyperpolarized membrane potential |
front 42 SA node | back 42 - Where pacemaker cells are located - Generate action potentials faster than any other heart cell |
front 43 Internodal pathways | back 43 Conducts action potentials from SA node to the myocytes in the atria through gap junctions |
front 44 AV node | back 44 - Contains slower pacemaker cells - Slows action potential conduction to allow time for an atrial refractory period |
front 45 Bundle of his | back 45 Conducts action potential from AV node to interventricular septum, where it splits into left and right bundle branches |
front 46 Right and left bundle branches | back 46 Propagate action potential through interventicular septum to heart apex |
front 47 Purkinje fibers | back 47 Spread action potentials from apex to left and right ventricles rapidly due to their high proportion of intercalated discs |
front 48 Arrhythmias | back 48 Family of disorders characterized by abnormal electrical activity within the heart |
front 49 Causes of arrhythmias | back 49 Breakdown in coordination of the electrical conduction system |
front 50 Effects of arrhythmias | back 50 Changes in pumping activity, producing a variety of effects, from harmless to fatal - Atrial fibrillation - Ventricular fibrillation |
front 51 ECG | back 51 - Provides an electrical picture of heart function - Obtained through leads placed on the surface of the skin - Summary of electrical changes taking place within all cells of an entire organ - Not a direct measure of action potentials within individual cells |
front 52 Positive end of lead | back 52 - Depolarizing current: produces upward deflection - Repolarizing current: produces downward deflection |
front 53 Negative end of lead | back 53 - Depolarizing current: produces downward deflection - Repolarizing current: produces upward deflection |
front 54 P wave | back 54 Depolarization of atria |
front 55 QRS complex | back 55 Ventricular depolarization |
front 56 Q wave | back 56 Depolarization of septal region of ventricle |
front 57 R wave | back 57 Depolarization of anterior region of ventricle |
front 58 S wave | back 58 Depolarization of inferior portions of ventricle |
front 59 T wave | back 59 Ventricular repolarization |
front 60 P-Q interval | back 60 Time required for atrial depolarization and action potential to reach ventricles |
front 61 P-R interval | back 61 Time required for atrial depolarization to propagate through the ventricles |
front 62 S-T segment | back 62 Time course of ventricular depolarization |
front 63 Q-T interval | back 63 Combined time required for ventricular depolarization and repolarization |
front 64 The force of cardiac contraction is ___ to the amount of calcium released into the cytoplasm during excitation-contraction coupling | back 64 Proportionate |
front 65 1. Atrial systole (cardiac cycle) | back 65 - Corresponds with contraction of the atria - Atrial pressure: greater than ventricle - AV valves: open - Ventricles: blood volume increasing, eventually reaching the maximum they can hold (end diastolic volume, or EDV) |
front 66 2. Early ventricular systole (cardiac cycle) | back 66 - Corresponds with contraction of the ventricles - Ventricular pressure: greater than atria, less than great vessels - Blood volume: constant at EDV - AV valves: closed - SL valves: closed |
front 67 3. Late ventricular systole (cardiac cycle) | back 67 - Ventricular pressure: greater than atria, greater than great vessels - Blood volume: decreasing as stroke volume (SV) is ejected, until residual end systolic volume (ESV) is left - AV valves: closed - SL valves: open |
front 68 4. Early ventricular diastole (cardiac cycle) | back 68 - Corresponds to relaxation in ventricles - Ventricular pressure: greater than atria, less than great vessels - Blood volume: constant at ESV - AV valves: closed - SL valves: closed |
front 69 5. Atrial diastole (cardiac cycle) | back 69 - Atrial pressure: less than ventricles - Ventricular blood volume: decreasing - AV valves: open |
front 70 6. Late ventricular diastole (cardiac cycle) | back 70 - Ventricular pressure: less than atria, less than great vessels - Ventricular blood volume: increasing through passive filling - AV valves: open - SL valves: closed |
front 71 Cardiac output | back 71 Amount of blood pumped by a ventricle in a period of time |
front 72 Cardiac output (CO) | back 72 Stroke volume (SV) x heart rate (HR) |
front 73 Cardiac reserve | back 73 Difference between cardiac output at rest and during exercise |
front 74 The force of cardiac muscle contraction is proportional to the ___ of its fibers | back 74 Resting length |
front 75 During exercise ___ | back 75 Ventricles stretch to accommodate increasing amounts of passively-entering blood (preload) |
front 76 Extrinsic regulation of cardiac output through neural mechanisms | back 76 Innervated by both sympathetic and parasympathetic branches of the autonomic nervous system |
front 77 Sympathetic effects | back 77 Catecholamines are released onto B1-adrenergic receptors - Activation of PKA, phosphorylation of targets and production of cAMP |
front 78 Parasympathetic effects | back 78 Acetylcholine is released onto muscarininc receptors - Decreases cAMP and speed of cardiac contraction |
front 79 Phosphorylation of PKA ___ the strength of cardiac contraction | back 79 Increases |
front 80 PKA activation results in | back 80 - Phosphorylation of L-type Ca2+ channels: increase conductance - Phosphorylation of the ryanodine receptor: open - Phosphorylation of troponin C: increases Ca2+ sensitivity - Phosphorylation of regulatory protein PLB: increases SERCA activity |