30 Questions
What is the primary function of the heart?
To pump blood in sufficient amounts to meet the needs of the body's cells
Approximately how many times would a human heart contract in one year?
39 million times
In which cavity is the heart located?
Thoracic cavity
What is the name of the tough membrane that surrounds the heart?
Pericardial sac
How many chambers does the human heart have?
4
What is the function of the tricuspid valve?
To allow blood to flow from the atria to the ventricles
What is the primary function of the ventricles?
To pump blood to the lungs or the rest of the body
What is the purpose of the semilunar valves?
To prevent blood from flowing back into the ventricles from the pulmonary and aortic arteries
What are the two major types of cardiac muscle cells?
Myocardial contractile cells and myocardial conducting cells
How many atria and ventricles does the human heart have?
Two atria and two ventricles
What percentage of the cells in the atria and ventricles are contractile cells?
99%
What is the function of the coronary arteries?
To supply the heart with blood
What node has the highest inherent rate of depolarization?
Sinoatrial node
What prevents the impulse from spreading directly to the ventricles without passing through the AV node?
The atrioventricular septum
What is the first part of the aorta that emerges from the left ventricle of the heart?
Aortic root
Which artery supplies blood to the right atrium and right ventricle?
Right coronary artery
What is the function of the Purkinje fibers?
To conduct impulses to the cardiac muscle
What is the term for a complete heartbeat?
Cardiac cycle
Which layer of the heart wall is the innermost layer?
Endocardium
What is the function of the bundle of His?
To conduct impulses to the Purkinje fibers
What is the period of time that begins with contraction of the atria and ends with ventricular relaxation?
Cardiac cycle
Which valve is responsible for allowing blood to flow from the right ventricle to the pulmonary artery?
Pulmonary valve
What is the primary cause of coronary disease in industrialized countries?
Arteriosclerosis
What is the term for the death of heart muscle cells due to lack of oxygen?
Ischemia
Which of the following is NOT a type of heart disorder?
Hypertension
What is the term for the reception of unoxygenated blood from the body into the right atrium?
Venous return
Which laboratory test is used to diagnose myocardial infarction?
Troponin
What is the term for the contraction of the atria and ventricles?
Atrioventricular contraction
Which of the following is a type of lipid?
HDL
What is the term for the failure of the heart to pump sufficient blood to meet the body's needs?
Congestive heart failure
Study Notes
The Heart
- The heart pumps blood to meet the body's cellular needs, contracting approximately 108,000 times daily and 3 billion times in a 75-year lifespan.
- Located in the thoracic cavity, the heart is separated from other mediastinal structures by the pericardium, a tough membrane enclosing the pericardial cavity.
Heart Structure
- The heart consists of four chambers: the left and right atria and ventricles.
- The atria receive blood, while the ventricles pump blood to the lungs or the rest of the body.
- The heart valves (tricuspid, mitral, pulmonary, and aortic) allow blood to flow in one direction, preventing backflow.
Cardiac Muscle Cells
- There are two types of cardiac muscle cells: myocardial contractile cells (99%) and myocardial conducting cells (1%).
- Contractile cells conduct impulses and pump blood, while conducting cells form the conduction system.
Myocardium
- The myocardium is the cardiac muscle tissue, making up the bulk of the heart.
- The heart wall is a three-layered structure with the myocardium sandwiched between the endocardium and epicardium.
Coronary Arteries
- The coronary arteries supply the heart with blood, providing oxygen and nutrients to the heart muscles.
- The two coronary arteries (right and left) branch off the aorta and supply the atria and ventricles.
Electrical Conduction System
- The sinoatrial (SA) node, located in the right atrium, is the pacemaker of the heart, generating impulses.
- The atrioventricular (AV) node receives the impulse and transmits it to the atrioventricular bundle.
- The bundle of His and Purkinje fibers transmit electrical signals to the ventricles.
Cardiac Cycle
- The cardiac cycle is a complete heartbeat, consisting of systole (contraction) and diastole (relaxation).
- The atria contract simultaneously, followed by ventricular contraction and relaxation.
Heart Function
- The right side of the heart receives unoxygenated blood, pumps it to the lungs, and receives oxygenated blood.
- The left side of the heart receives oxygenated blood from the lungs and pumps it to the rest of the body.
Heart Disease
- Coronary disease is the most common type of heart disease, caused by arteriosclerosis (plaque buildup in coronary arteries).
- Myocardial infarction (heart attack) occurs when a blood clot blocks a coronary artery branch, depriving heart muscle cells of oxygen.
Laboratory Tests
- Troponin, cholesterol, triglyceride, HDL, LDL, and other tests are used to diagnose and monitor heart conditions.
- Microbiology cultures and potassium levels are also used in diagnosis.
Learn about the vital importance and functions of the human heart, including its location and contraction rate.
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