10.2: Heart Anatomy — Overview
- Page ID
- 100116
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)The heart is a muscular double pump within the thoracic cavity that drives blood through two circuits — pulmonary and systemic.
- Describe the heart’s location within the thoracic cavity.
- Describe the basic anatomy of the heart.
- Explain how the heart functions as a double pump.
You are about to explore the remarkable pump that propels the blood into and through the vessels. The heart functions as a “double pump,” since its contraction develops the pressure that ejects blood into the major vessels for two separate circuits of blood flow: blood from the left side of the heart flows into the aorta for the systemic circuit and blood from the right side of the heart flows into the pulmonary trunk for the pulmonary circuit. From these vessels, blood is distributed to the remainder of the body. Although the connotation of the term “pump” suggests a mechanical device made of steel and plastic, the anatomical structure is a living, sophisticated muscle. As you read on, try to keep these twin concepts in mind: pump and muscle.
Although the term “heart” is an English word, cardiac (heart-related) terminology can be traced back to the Latin term, “kardia.” Cardiology is the study of the heart, and cardiologists are the physicians who deal primarily with the heart.
Location of the Heart
The human heart is located within the thoracic cavity, medially between the lungs in the region known as the mediastinum. The mediastinum also includes the portions of the major blood vessels, the trachea, and the esophagus that are positioned between the lungs medially. Within the mediastinum, the heart is separated from the other mediastinal structures and is held in place by a tough wrapping known as the pericardium, or pericardial sac. The sac also limits the range of motion of the heart as it beats. The double layered pericardial sac creates a thin space surrounding the heart called the pericardial cavity that is filled with serous fluid to prevent friction as the heart beats.
The dorsal surface of the heart lies near the bodies of the vertebrae and its anterior surface sits deep to the sternum and costal cartilages. The great veins, the superior and inferior venae cavae, and the great arteries, the aorta and pulmonary trunk, are attached to the superior surface of the heart, called the base. The inferior tip of the heart, the apex, lies just to the left of the sternum between the junction of the fourth and fifth ribs.
The heart is also rotated slightly around its vertical axis such that more of the right side of the heart is visible in an anterior view while more of the left side is visible in a posterior view. There is a slight deviation of the apex to the left.
Basic Heart Anatomy
The heart is a muscular double pump made up of four chambers separated into two sides. Each side has an atrium, which receives blood returning to the heart, and a ventricle, which pumps blood out. Valves between the atria and ventricles prevent backflow, ensuring one-way movement of blood. A thick wall called the septum divides the right and left sides of the heart, keeping oxygen-poor and oxygen-rich blood separate.
The right side of the heart controls the pulmonary circulation — it receives deoxygenated blood from the body through the superior and inferior vena cavae and pumps it to the lungs through the pulmonary arteries.
The left side of the heart controls the systemic circulation — it receives oxygenated blood from the lungs through the pulmonary veins and pumps it to the rest of the body through the aorta. Valves at the exits of the ventricles (the pulmonary and aortic semilunar valves) prevent blood from flowing backward into the heart.
The heart has its own conduction system that coordinates each heartbeat. The sinoatrial (SA) node, located in the right atrium, acts as the natural pacemaker, sending electrical impulses that cause the atria to contract. The signal then passes to the atrioventricular (AV) node, which briefly delays the impulse before sending it down the bundle of His, bundle branches, and Purkinje fibers, triggering the ventricles to contract. Although the heart beats automatically, the autonomic nervous system can speed it up or slow it down as needed.
Finally, the heart has its own blood supply through the coronary arteries, which deliver oxygen and nutrients to the cardiac muscle itself—because the blood inside the chambers does not nourish the heart tissue directly.