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76 Cards in this Set
- Front
- Back
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Describe the location of the heart,
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Superior surface of diaphragm, left of midline, anterior to the vertebral column, posterior to sternum
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What's the pulmonary circuit?
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It's a short loop that oxygenates blood. Consists of left and right pulmonary artery, left and right pulmonary vein, and capillary bed of left and right lung.
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What's the systemic circuit?
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It's a long loop that carries blood to and from body tissues.
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What two valves lie between the atria and the ventricles, maintaining unidirectional blood flow?
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The "Atrioventricular valves," also known as the bicuspid valve (left side) and tricuspid valve (right side)
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What valves prevent backflow into the atria when ventricles contract?
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The atrioventricular valves (bicuspid on the left and tricuspid on the right)
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What tendons anchor the AV valves to papillary muscles?
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Chordae tendinae (singular chorda tendinea)
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Blood flows into the right ventricle through which valve?
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Tricuspid valve
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What is the tricuspid valve made up of?
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Three cusps composed of dense connective tissue (CT) covered by endocardium
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What is the bicuspid valve composed of?
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Two cusps composed of dense CT, anchored to the papillary muscles by the chordae tendineae
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Which valves prevent backflow of blood into the ventricles?
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Semilunar valves. The aortic semilunar valves prevent backflow from the aorta to the left ventricle, and the pulmonary semilunar valves prevent backflow from the pulmonary trunk into the right ventricle.
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What arteries leaving the heart provide arterial blood supply?
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right and left coronary (in atrioventricular groove), marginal, circumflex, anterior and posterior interventricular arteries.
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What vessels return blood to the heart?
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Superior and inferior vena cavae, right and left pulmonary veins, small cardiac, anterior, and great cardiac veins (into the coronary sinus -- these three constitute the "venous return."
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What is angina pectoris?
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The medical term for chest pain due to coronary heart disease.
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Of what condition is angina a symptom?
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myocardial ischemia
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When does angina pectoris occur?
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When the heart muscle (myocardium) doesn't receive enough blood, thus enough oxygen. It occurs when one or more of the heart's arteries is narrowed or blocked.
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What's insufficient blood supply called?
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ischemia
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What's ischemia?
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Insufficient blood supply
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What's the medical term for a heart attack?
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Myocardial infarction (MI). Also "Acute myocardial infarction" or AMI.
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What are the symptoms of a myocardial infarction?
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chest pain or discomfort, weakness, sweating, nausea, vomiting, and arrhythmias sometimes resulting in loss of consciousness
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Describe cardiac muscle fibers.
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Striated, short, quadrangular-shaped, branching fibers with a single centrally located nucleus. Cells are connected with intercalated discs with gap junctions.
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Cardiac muscle has a much greater concentration of ____ than skeletal muscle.
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Mitochondria --- reflecting the heart's dependence on cellular respiration for ATP.
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What are the two types of cardiac muscle cells?
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99% are contractile cardiac muscle cells (mitochondrial). The rest are autorhythmic cells of the heart, which lack the elaborate sarcomeres and other contractile machinery.
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Describe autorhythmic cells.
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Self excitable, able to initiate their own depolarization (action potentials), they have unstable resting potentials called pacemaker potentials.
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What two ions are required for cardiac contraction to occur?
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Sodium and calcium
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What ions initiate the action potential in cardiac muscle?
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Sodium
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Which ions cause depolarization for a greater duration after the action potential is initiated?
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Calcium ions
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What protein do calcium ions bind to, allowing myosin and actin to associate through cross-bridge formation?
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Troponin
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Where is the sinoatrial (SA) node located?
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Adjacent to the SVC opening in the right atrium --- and it generates impulses about 75 times per minute
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How frequently does the sinoatrial node generate impulses?
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75 times per minute, and it's located right next to the SVC (superior vena cava) opening in the right atrium.
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Where is the atrioventricular node and what does it do?
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It's located near the right atrioventricular (AV) valve at the bottom of the interatrial septum, it delays the impulses about 0.1 second.
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What bundle of modified heart muscle carries impulses from the atrioventricular node to the ventricles, causing them to contract?
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The atrioventricular bundle (Bundle of his)
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What's the atrioventricular bundle?
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A bundle of modified cardiac muscle that carries impulses from the atrioventricular node to the ventricles, causing them to contract.
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Where does the atrioventricular bundle split into two pathways?
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In the interventricular septum
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What's another word for the atrioventricular bundle?
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Bundle of His
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What's another name for the Bundle of His?
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Atrioventricular bundle
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Where are impulses directed from the AV bundle branches at the interventricular septum?
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Towards the apex of the heart
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What fibers throughout the ventricles carry impulses to the heart apex and ventricular walls?
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Purkinje fibers
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What do Purkinje fibers do?
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Carry impulses to the heart apex and ventricular walls.
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What "center" stimulates the heart?
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The sympathetic cardioacceleratory center
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What "center" inhibits the heart?
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The parasympathetic cardioinhibitory center
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What branch of the autonomic nervous system inhibits the heart?
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The parasympathetic
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What branch of the autonomic nervous system stimulates the heart?
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Sympathetic
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Parasympathetic fibers inhibiting the heart travel down which cranial nerve?
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Vagus nerve
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What device can measure electrical activity created by the heart?
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electrocardiogram (ECG or EKG) machine
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Which wave measured by an ECG machine corresponds to depolarization of the SA node?
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P wave
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What does the P wave as measured by an ECG machine correspond to?
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Depolarization of the SA node
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The QRS complex of an EKG signifies what?
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ventricular depolarization
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The T wave of an EKG corresponds to what?
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ventricular repolarization
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What portion of an EKG masks atrial repolarization?
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QRS complex
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Where can you see atrial repolarization on an EKG?
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Nowhere -- it's masked by the QRS complex
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What are the scientific terms for repetitive contraction and relaxation of the heart?
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Contraction = systole
Relaxation = diastole |
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What happens during diastole?
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The heart relaxes and blood fills the atria, then begins to fill the ventricles
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What stage of the cardiac cycle is characterized by relaxation of the heart and filling of the atria and ventricles?
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Diastole
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What happens during systole?
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First, both atria contract almost simultaneously, filling the ventricles with blood.
Then the ventricles contract several tenths of a second later and pump blood out to the body. |
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What event is the cause for the first heart sound (S1)?
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Closure of the atrioventricular valves as ventricular systole begins.
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What is the cause for the second heart sound (S2)?
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Closure of the aortic and pulmonary semilunar valves at the beginning of ventricular diastole.
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Occasionally you hear a third heart sound. What causes it?
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Turbulent bloodflow into the the ventricles during the first third of diastole
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Define cardiac output (CO)
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The amount of blood pumped by each ventricle in one minute.
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CO is the product of what other two measurements?
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Stroke volume (SV) and heart rate (HR)
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What is stroke volume?
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The amount of blood the heart pumps with each beat
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What is cardiac reserve?
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The difference between resting and maximal CO
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What term is defined as "the difference between resting and maximal CO?"
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Cardiac reserve
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What term is defined as "the amount of blood the heart pumps with each beat?"
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Stroke volume
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What is preload?
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Preload is the stretched condition of the heart after diastole
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What factors increase stroke volume?
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exercise, slow heartbeat
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What factors decrease stroke volume?
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extremely high HR, blood loss
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Define contractility as it relates to cardiac muscle
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Contractile force due to factors other than end diastolic volume
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What factors can increase contractility?
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Increased sympathetic stimuli, certain hormones, CA2+ and some drugs
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Define "afterload."
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Back pressure exerted by blood leaving the large arteries leaving the heart
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Which hormones increase heart rate?
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epiniphrene and thyroxine
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Define "tachycardia"
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HR above 100 BPM
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Define "bradycardia"
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HR below 60 BPM
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What's the average resting heart rate?
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70 BPM for males, 75 for women
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What term describes an HR above 100 BPM?
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Tachycardia
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What term describes an HR below 60 BPM?
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Bradycardia
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What causes congestive heart failues (CHF)?
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1) Coronary atherosclerosis
2) Persistent high blood pressure 3) Multiple myocardial infarcts 4) Dilated myocardiopathy (DCM) |
