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What is the function of the heart?
- Pumps blood
- creates blood pressure
- circulates oxygen, nutrients, and other substances
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Where is the heart located?
In the mediastinum, the area between the lungs in the thoracic cavity
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What are the three pericardial membranes that enclose the heart?
- Fibrous pericardium - outer
- Parietal pericardium
- visceral pericardium
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Function of of serous fluid
When located between the parietal and visceral membranes, the fluid prevents friction as the heart beats
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Fibrous Pericardium
- Made of fibrous connective tissue
- loose fitting sac
- surrounds the heart and extends over the diaphragm of the great vessels
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Myocardium
Cardiac muscle tissue, forms the walls of the four heart chambers
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Endocardium
- Lines the chambers and covers the heart valves
- Prevents abnormal clotting
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Atriums
Receive blood from the veins
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Ventricles
Pump blood into the arteries
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Interatrial Septum
Separate the left and right atriums
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Interventricular Septum
Separate the left and right ventricles
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Tricuspid Valve
Prevents backflow of blood from the right ventricle to the right atrium when the right ventricles contracts
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Right Atrium
Receives blood from the upper body by he superior vena cava lower from the lower body by the inferior vena cava
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Left Atrium
Receives blood from the lungs by the way of four pulmonary veins
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Mitral Valve (Bicuspid)
Prevents back flow of blood from the left ventricle to the left atrium when the left ventricle contracts
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Right Ventricle
- Pumps blood to the lungs through the pulmonary artery
- relatively thin walls
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Pulmonary Semilunar Valve
Prevents back flow of blood from the pulmonary artery to the right ventricle when the right ventricle relaxes
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Left Ventricle
- Thicker walls than right ventricle
- Pumps blood to the body via the aorta
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The right side of the heart receives _____ blood from the body and pumps it to the _______.
Deoxygenated, lungs
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The left side of the heart receives _____ blood from the _____ and pumps it to the _______.
Oxygenated, lungs, body
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"Lubb"
Created by the closure of the AV valves during ventricular systole
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"Dubb"
created by closure of the aortic and pulmonary semilunar valves
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Heart murmur
Created by an improper closure of the valves
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Electrocardiograph, (ECG)
Depicts the electrical activities of the heart
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SA Node
- Located in the wall of the right atrium
- initiates each heart beat
- More permeable to Na+ ions
- depolarize more rapidly than any other part of the myocardium
- action potential spreads rapidly throughout the myocardium because of the intercalated discs at adjacent cells
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Coronary Vessel Pathway
Ascending aorta to right and left coronary arteries to smaller arteries to capillaries to coronary veins to the coronary sinus to the right atrium
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Coronary circulation supplies _______ blood to the ______.
Oxygenated, myocardium
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Myocardial infarction
Death of an area of myocardium due to the lack of oxygen
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What does an obstruction of a coronary artery cause?
Myocardial infarction, heart attack
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Cardiac output
Amount of blood pumped by a ventricle in one minute
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Stroke volume
Amount of blood pumped by a ventricle in one beat; average 60-80
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Cardiac output equation
Stroke volume x pulse, 5 to 6 liters average
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Medulla
Contains the cardiac centers: the accelerator center and the inhibitory center
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Sympathetic vs Parasympathetic
Sympathetic - impulses to the heart increase rate and force contraction
parasympathetic - impulses vagus nerve to the heart decrease heart rate
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Pressoreceptors
- In the carotid and aortic sinuses
- Detect changes in the blood pressure
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Chemoreceptors
- In the carotid and aortic bodies
- detect changes in the oxygen level of the blood
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Ejection fraction
Percent of its total blood that a ventricle pumps per beat, average 60-70%
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Arrythmias
Irregular heart beats, can be harmless to life threatening
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What happens if part of the conduction pathway does not function properly?
The next part will initiate contraction but at a slower rate
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Right and left bundle branches
- In the interventricular septum
- transmit impulses to the purkinje fibers in the ventricular myocardium which complete ventricular systole
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AV bundle (bundle of his)
- In the interventricular septum
- first part of the ventricle to depolarize
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AV Node
- In the lower interatrial septum
- depolarization spreads to the AV node and to the atrial myocardium and brings about atrial systole
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What generates the heart beat?
The heart generates its own beat but the nervous system brings about changes due to reflexes
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Normal heart rate
60-80 BPM
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Bradycardia
heart rate less than 60
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Tachycardia
Heart rate greater than 100
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Ischemic
deprived of blood supply
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Cardiac cycle
The sequence of events in one heartbeat
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Which fluid prevents frictions of the layers of the heart?
Serous fluid
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Which part of the heart is responsible for pumping the blood?
Myocardium
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which area is the heart located?
Mediastinum
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What supports the flaps of the valves?
Papillary muscles and chordae tendineae
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how many valves of the heart are there?
Four
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What is the general function if valves?
Prevent backflow
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What is the hormone responsible for lowering blood volume which lowers blood pressure?
Atrial natriuretic peptide (ANP)
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The inferior vena cava returns blood from ___ to ____
The lower body to the right atrium
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What does diastole and systole mean?
- Relaxation - D
- contraction - S
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T or F: in the cardiac cycle, the flow from the atria to the ventricle flows actively
False: passively
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What is the definition of stroke volume?
- The amount of blood pumped by a ventricle in one beat
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Which nerves or impulses are used by the cardiac accelerator center?
Sympathetic
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T or F: the vagus nerve carries impulses from the medulla to increase heart rate
False: decrease
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Pain in the heart is caused by what?
Lack of oxygen
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the blood from the lungs goes through ___ to ___
Pulmonary vein to the left atrium
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T or F: during one cardiac cycle, the atrial contracts first followed by the ventricles contract together
False: both atriums contract followed by both ventricles contracting together
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T or F: the sequence of blood flow is from the right heart to the lungs to the right heart to the body
False
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What is the function if the SA node
Initiates the heart beat, "natural pacemaker"
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What is the name that is used for the percentage of blood that is in the ventricle that is pumped during systole
Ejection fraction
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What does the medulla regulate?
Heart rate and blood pressure
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cardiac conduction pathway
SA node , AV node, bundle of his, right and left bundle branches, purkinje fibers
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What chambers of the heart in the upper part?
Atriums
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When bp increases, atriums produce what hormone?
ANP
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The coronary sinus is the union of __ and returns blood to ____.
vein, atrium
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