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39 Cards in this Set
- Front
- Back
Walls of the Heart |
Three layers: ** Epicardium (Outer layer): contains Visceral Pericardium, Fibroelastic and Adipose CT ** Myocardium (Middle layer): contain Cardiac muscle ** Endocardium (Inner layer): Contains Endothelium; simple squamous epithelium overlying CT |
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External Anatomy of Heart |
** Auricle: Increases capacity of Atrium ** Sulci: Contain coronary blood vessels and adipose CT |
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Right Ventricle |
** Receives blood from Right Atrium ** It pumps blood through Pulmonary Semilunar Valve into Pulmonary Trunk Pulmonary Trunk- divides into right and left Pulmonary Arteries to the Lungs |
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Left Ventricle |
** Thickest chamber** ** Pumps blood through Aortic Semilunar Valve into Ascending Aorta; blood flows to Coronary Arteries, Arch of Aorta, Descending Aorta |
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Four Valves of the Heart |
** Valves open and close in response to pressure change as Heart contracts and relaxes ** One way flow of Blood ** Atrioventricular: Right side of heart has Tricuspid valve; Left side of heart has Bicuspid valve aka Mitral valve ** Semilunar: Right side: Pulmonary valve Left side: Aortic valve |
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Atrioventricular Valves (AV) |
** When AV is open, rounded ends of cusps project into Ventricles ** Ventricles are Relaxed > Papillary Muscles are Relaxed > Chordae Tendineae are Loose > Blood moves from higher pressure in Atria to Lower pressure in Ventricles ** Once Ventricles contract > Pressure of blood pushes cusps upward > Cusps close ** Papillary Muscles contract > Chordae Tendineae are tight this prevents opening of Cusps into Atria |
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Semilunar Valves (SV) |
**When Ventricles contract > free borders of cusps project into Arteries Cusps open > Blood is pumped into Arteries ** When Ventricles relax > Back flowing blood fills Valve cusps then Valves close |
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Blood Flow through Ride side of Heart |
** Blood flow of deoxygenated: start at the Right Atrium from Superior Vena Cava, Inferior Vena Cava, and Coronary Sinus ** From right atrium to Tricuspid valve to Right Ventricle ** From right ventricle to Pulmonary Valve to Pulmonary Trunk ** From Pulmonary trunk to Pulmonary Arteries to Lungs |
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Blood Flow through Left side of Heart |
** Blood from Left Atrium flow from Pulmonary veins from Lungs ** From Left Atrium to Bicuspid valve to Left Ventricle ** From Left Ventricle to Aortic Valve to Aorta to Arteries through entire Body |
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Coronary Arteries |
** Branch from Ascending Aorta to supply the heart with Oxygenated blood Two main coronary arteries: Right and Left Coronary Artery |
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Left Coronary Artery branches: |
** Anterior interventricular: Supplies both ventricles; aka LAD: Left Anterior descending artery ** Circumflex: Supplies left atrium and ventricle |
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Role of Gap junction between Cardiac Muscle |
** Presence of gap junctions allow impulses to spread rapidly from cell to cell so the Myocardium contracts as a single unit |
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Physiology of the Heart |
** Electrical events: Generation and transmission of electrical impulses through Myocardium ** Mechanical events: Pressure changes, Volume changes, and Valve changes during Cardiac Cycle |
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Sequence of Electrical Events |
** Sinoatrial Node (SA) depolarizes, the wave of depolarization spreads through Atria ** Atrioventricular Node (AV) depolarizes, AV bundle transmits wave of depolarization to Bundle branches ** The bundle branches transmit depolarizing wave to Apex of Ventricles ** Purkinje Fibers transmit depolarizing wave to Ventricular Muscle cells |
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Phases of Cardiac Cycle |
** Systole: Muscular contraction and pumping of blood out of a chamber
** Diastole: Muscular relaxation and filling of blood into a chamber *** Note Atrial diastole occurs at same time as Ventricular Systole |
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Phases in Atria |
** Atrial Systole: contraction of the atrial walls and ejection of blood into ventricles - Right or Left Atrium to Right or Left Ventricle ** Atrial Diastole: Relaxation of atrial walls and filling of atrial chambers - SVC, IVC, and Coronary sinus to Right Atrium - 4 Pulmonary veins to Left Atrium |
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Phases in Ventricles |
** Ventricular Systole: contraction of Ventricular walls and ejection of blood into the outflow tracts - Right ventricle to Pulmonary Trunk - Left ventricle to Aorta ** Ventricular Diastole: relaxation of ventricular walls and filling of ventricular chambers - Right atrium to right ventricle - Left atrium to left ventricle |
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Pressure and Volume changes during Atrial Systole |
** When Atrial are contracting, ventricles are relaxed ** During Atrial systole, pressure increases in Atria ** At beginning of Atrial diastolic period, 130mL of blood in each ventricle (End-diastolic volume) |
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Pressure and Volume changes during Ventricular Systole
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** When Ventricles contract, Atria are relaxed ** During Ventricular systole, pressure increases in ventricles ** When left ventricular pressure rises more than 80mmHg, the Semilunar valve opens and ejection of blood begins; More contraction pressure rises to 120mmHg ** Left ventricle ejects 70mL of blood in Aorta; 60mL remain (End Systolic Volume) ** When right ventricle pressure rises more than 20mmHg the Semilunar valve open and ejection of blood begins; More contraction pressure rises to 25-30 mmHg ** Right ventricle ejects 70mL of blood into Pulmonary trunk; 60mL remain (End Systolic volume) |
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S1 and S2 |
** Two distinct sounds are heard ** S1 or Lubb: First heart sound heard when Atrioventricular valves close (Tricuspid and Bicuspid); it's the beginning of Ventricular Systole ** S2 or Dupp: Second heart sound heard when Semilunar valves close (Pulmonary and Aortic); it's the beginning of Ventricular Diastole |
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Pressure Changes during a Cardiac Cycle |
** Pressures increase during Systolic phase of a chamber ** Pressure decreases during diastolic phase of a chamber Pressure is measured in mmHg |
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Cardiac Output |
** Measurement of pumping effectiveness ** The volume of blood pumped by a ventricle per minute ** Measured in milliliters per minute ** Calculated: CO= SV x HR Cardiac output= Stroke volume x Heart rate ** To increase cardiac output: increase stroke volume or heart rate; or increase both |
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Stroke Volume |
** Volume of blood pumped during each ventricular contraction; Measured as milliliters per beat ** Calculated: SV= EDV-ESV; 130-60= 70 mL EDV: volume in ventricle at end of relaxation, After ventricle filling ESV: volume in ventricle at end of contraction, after ejection of blood |
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Heart Rate |
** Number of ventricular contractions per minute; measured as beats per minutes ** At rest, 75 beats per minute |
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Normal cardiac output |
** Stroke volume= 70mL per beat ** Heart rate= 75 beats per min ** CO= SV times HR Once you do the math divide by 1000 |
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Regulations of Cardiac Output |
** Cardiac output depends on Stroke volume and heart rate; and the factors that affect stroke volume or heart rate will affect cardiac output |
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Three factors that affect Stroke Volume |
1) Preload 2) Contractility 3) Afterload |
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Preload |
** Amount of stretch on Ventricular wall ** Greater of Preload, the more forceful muscle contraction then more blood is pumped out of ventricle ** Adding more blood to ventricular chamber, increases stretch in its wall, then more forceful contraction increases stroke volume then increase cardiac output |
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Preload and End-Diastolic Volume |
** Greater end-diastolic volume has increase preload then increase stroke volume then increase cardiac output ** Longer duration of ventricular diastole and more venous return increases EDV |
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Contractility |
** Forcefulness of ventricular contraction ** Increase in contraction increase in stroke volume ** Decrease in contraction decrease in stroke volume |
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Afterload |
** Pressure that should be overcome before a semilunar valve can open ** To open semilunar valves, pressure in ventricles should exceed pressure in aorta 80mmHg and Pulmonary trunk 20mmHg ** Higher afterload means lower stroke volume and more blood stays inside ventricles |
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Factors that affect Heart Rate |
1) Autonomic nervous system (ANS) 2) Hormones 3) Level of physical fitness 4) Age and Several other factors |
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Autonomic Regulation of Heart Rate |
** Cardiovascular center: collection of neurons in Medulla Oblongata; that receive input from various areas ** Output is via Sympathetic (Cardiac accelerator) and Parasympathetic (Vagus) nerves |
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Input into Cardiovascular Center |
** Higher brain centers: Cerebral cortex, Limbic system, Hypothalamus; Thoughts and feelings affect activity of Heart ** Baroreceptors: Located in walls of Aorta and internal carotid arteries; Detect pressure changes ** Chemoreceptors: Located in wall of Aorta and common carotid arteries; Detect chemical changes ** Proprioceptors: Located in joints; Detect joint movement |
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Output: Sympathetic Innervation of Heart |
** Increases activity of SA and AV nodes that increases heart rate ** Increases strength of muscle contraction that increase pumping effectiveness ** Norepinephrine is neurotransmitter which binds to Beta 1 adrenergic receptor |
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Output: Parasympathetic Innervation of Heart
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** Decreases activity of SA and AV nodes that decreases heart rate ** Has little effect on muscular contraction ** Acetylcholine is neurotransmitter which binds to Muscarinic receptors |
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Hormones |
** Epinephrine and Norepinephrine released from Adrenal glands mimic the effects of Sympathetic stimulation ** Hormones increase SA and AV nodes activity that increase heart rate and contractility |
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Level of Physical Fitness |
** Athletes develop physiological Cardiomegaly Increase contractility increase stroke volume ** Heart is lower and resting cardiac output is normal |
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Exercise |
** Muscle contractions activates proprioceptors in joints ** Then cardiovascular center is stimulated then activates sympathetic nerves ** Sympathetic stimulation increase contractility then increase stroke volume Increased heart rate and stroke volume increases cardiac output |