Heart Flashcards
What is the function of the pulmonary circuit?
Carries blood to and from lungs
What is the function of the systemic circuit?
Transports blood to and from the rest of the body
What do arteries do?
Carry blood AWAY from heart
What do veins do?
Carry blood TOWARDS heart
What is the fibrous pericardium?
Outer layer of parietal pericardium that anchors heart to sternum, vertebral column, and diaphragm
What is the parietal pericardium?
Attached to inside of fibrous pericardium; secretes serous fluid to decrease surface friction when heart beats
What is the visceral pericardium also known as?
Epicardium
What is the pericardial cavity?
Potential space between the parietal and visceral pericardia; contains serous fluid that decreases friction during contractions
Where is the base of the heart located?
Top of heart, between sternum and 2nd rib
Where is the apex of the heart located?
At the fifth intercostal space on left side tilted toward left hip
What are the three layers of the heart wall?
- Epicardium
- Myocardium
- Endocardium
What is the myocardium?
Thickest layer of the heart, comprised mainly of cardiac muscle tissue
What is the endocardium?
Thin smooth inner layer that lines the chambers of the heart
What does the right atrium do?
Receives deoxygenated blood from SVC and IVC as well as the coronary sinus
What is the role of the right ventricle?
Receives deoxygenated blood from right atrium and pumps it into pulmonary trunk leading to lungs
What does the left atrium do?
Receives oxygenated blood from pulmonary veins
What is the function of the left ventricle?
Receives blood from left atrium and pumps it to aorta to be carried to the rest of the body
What are the atrioventricular (AV) valves?
Valves found between atria and ventricles that prevent backflow
What are the two AV valves?
- Tricuspid valve
- Bicuspid (mitral) valve
What are the semilunar valves?
Valves found between ventricles and major blood vessels
What is the foramen ovale?
An opening between Right and Left Atria that allows blood to bypass trip through fetal lungs
What is the ductus arteriosus?
A bypass connecting pulmonary trunk and aorta in fetal circulation
What do coronary arteries supply?
Blood to muscle tissue of heart
What is coronary artery disease (CAD)?
Areas of partial or complete blockage of coronary circulation causing reduction of oxygen supply to muscle cells
What are symptoms of CAD?
- Angina pectoris
- Myocardial Infarction (MI)
What is myocardial infarction (MI)?
A heart attack where cardiac muscle cells die due to lack of oxygen from blocked blood vessels
What is the role of calcium in cardiac contractions?
Calcium must increase inside the cardiac muscle cell for contraction to occur
What is automaticity in the heart?
Inherent property of the heart to initiate contraction without neural or hormonal stimulation
What are the phases of action potential in cardiac myocytes?
- Depolarization
- Plateau
- Repolarization
What is depolarization?
Rapid change in electrical potential inside the cell, leading to contraction
What is repolarization?
Return to negative charge inside the cell, associated with relaxation
What is the conduction pathway of the heart?
- SA node initiates impulse
- Impulse spreads across both atria
- Converges at AV node
- Travels down AV Bundle
- Travels through Purkinje fibers
What does an electrocardiogram (ECG) record?
Electrical activity of the heart
What are the two phases of the cardiac cycle?
- Systole
- Diastole
What is bradycardia?
Condition of having a slow heart rate, less than 60 BPM
What is tachycardia?
Condition where heart beats excessively fast, greater than 100 BPM
What is the normal heart rate range for adults?
40-100 BPM
What characterizes tachycardia?
Condition where heart beats excessively fast, greater than 100 BPM
What is the role of the sinoatrial (SA) node?
It is the natural pacemaker of the heart, initiating electrical signals
What happens during tachycardia to blood flow?
Rapid heartbeat does not allow enough time for the heart to fill before it contracts, compromising blood flow
What are the sensitivities of the SA Node?
- Sensitive to sympathetic and parasympathetic stimulation
- Sensitive to changes in membrane potential
- Sensitive to the rate of spontaneous depolarization
What can abnormal patterns of electrical activity in the heart indicate?
- Decreased pump efficiency
- Damage to the myocardium
- Problems with the conduction system
- Electrolyte imbalances
- Drug exposure
What is a class of drugs that inhibits sympathetic stimulation?
α-blocker and β-blocker
What is the ejection fraction (EF)?
The % of the end-diastolic volume (EDV) that is ejected from the ventricle with each contraction
What is the typical stroke volume (SV) in adults?
70 mL
What is the formula for cardiac output (CO)?
CO = HR x SV
What does end-diastolic volume (EDV) represent?
Amount of blood in the ventricle at the end of ventricular diastole, about 130 mL in adults
What occurs during atrial systole?
Atria contract, AV valves open, and atria eject blood into the ventricle
What is the significance of stroke volume (SV)?
Amount of blood ejected from each ventricle with each cardiac contraction
What is the typical ejection fraction (EF) range?
55-85%
What is a heart murmur?
Swishing, gurgling sound heard when blood is regurgitating through valves or abnormal communications within the heart
What factors affect cardiac output (CO)?
- HR
- SV
- ANS and hormones
What is preload?
Degree of stretching during ventricular filling, depends on EDV
What is the Starling Principle?
Increase in EDV leads to an increase in SV
What is afterload?
Tension/pressure the ventricle must produce to open the semi-lunar valves and eject blood
What happens during ventricular diastole?
Ventricles relax, atrial pressure exceeds ventricular pressure, AV valves open, and ventricles fill passively
What is the normal heart rate (HR) range?
60-100 bpm
True or False: ESV is about 50 mL at rest.
True
What is cardiac reserve?
The difference between resting CO and maximum CO
What is the role of baroreceptors?
Respond to an increase in blood pressure
What is the Bainbridge reflex?
HR changes in response to venous return
