Victor Forge
The human body is an intricate system, with over 600 muscles supporting almost every part of it. These muscles are soft tissues that help us move, breathe, swallow, and stay alive. One of the most vital organs in the body is the heart, a muscular organ that pumps blood throughout our system. The heart is made up of four muscular sections or chambers, and its primary function is to generate sufficient force to pump blood into circulation. This is achieved through the contraction of cardiac muscle cells, also known as cardiomyocytes, which are striated and under involuntary control. These cardiac muscles are unique to the heart and make up the middle layer of its walls, known as the myocardium.
| Characteristics | Values |
|---|---|
| Definition | Muscles are pieces of soft tissue throughout your body that help you move, breathe, swallow and stay alive. |
| Number of muscles in the body | More than 600 |
| Types of muscle tissue | Cardiac, smooth, and skeletal |
| Heart muscle tissue | Cardiac muscle |
| Heart muscle cells | Striated, branched, contain many mitochondria, and are under involuntary control |
| Heart chambers | Four |
| Heart function | To pump blood to the body |
| Heart weight | On average, an adult's heart weighs about 10 ounces |
| Heart diseases | Arrhythmia, Cardiomyopathy, Congestive heart failure, Heart attack, Heart valve disease, High blood pressure, High cholesterol, Pericarditis |
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What You'll Learn
The heart is a muscular organ
The heart is about the size of a person's fist and weighs around 10 ounces. It is made up of muscle and tissue, with the middle layer, called the myocardium, largely composed of cardiac muscle. This is the thickest of the three layers. Cardiac muscle is a special type of muscle tissue that is only found in the heart. It is striated, branched, and made up of cardiac muscle cells or cardiomyocytes. These cells are under involuntary control and contract together to enable the heart to work as a pump.
The primary function of the cardiac muscle is to pump blood into circulation by generating sufficient force. The contractile functions of the heart are determined by the contractile forces of the cardiac muscle and the frequency at which they are activated. The heart beats in response to electrical impulses, which cause the cardiac muscle to contract and relax, pumping blood through the body. This process is known as the cardiac cycle and consists of two periods: diastole, when the heart muscle relaxes and refills with blood, and systole, when the heart contracts and pumps blood.
Cardiac muscle is one of three types of muscle tissues, the others being skeletal muscle and smooth muscle. Smooth muscle lines the inside of some organs and performs essential jobs like moving waste through the intestines and helping the lungs expand during breathing. Skeletal muscle, on the other hand, is attached to the skeleton and is under voluntary control.
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Cardiac muscle makes up the heart
The heart is a muscular organ that pumps blood throughout the body. It is the main organ of the cardiovascular system, a network of blood vessels that supplies blood and oxygen to the body. The heart is made up of three layers: the pericardium, myocardium, and endocardium.
Cardiac muscle, also called heart muscle or myocardium, is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the heart wall. The cardiac muscle forms a thick middle layer between the outer layer of the heart wall (the pericardium) and the inner layer (the endocardium). The endocardium is not cardiac muscle and is comprised of simple squamous epithelial cells that form the inner lining of the heart chambers and valves. The pericardium is a fibrous sac surrounding the heart, consisting of the epicardium, pericardial space, parietal pericardium, and fibrous pericardium.
Cardiac muscle cells (cardiomyocytes) are the contractile myocytes of the cardiac muscle. They are surrounded by an extracellular matrix produced by supporting fibroblast cells. The sheets of muscle that wrap around the left ventricle closest to the endocardium are oriented perpendicularly to those closest to the epicardium. When these sheets contract in a coordinated manner, they allow the ventricle to squeeze in several directions simultaneously, maximising the amount of blood squeezed out of the heart with each heartbeat.
The primary function of cardiac muscle is to pump blood into circulation by generating sufficient force. The contractile functions of the heart require ATP, which can be obtained through various substrates, including fatty acids, carbohydrates, proteins, and ketones. The contractile functions of the heart are also dependent on electrical impulses. The rhythmic contractions of the cardiac muscle are regulated by the sinoatrial node of the heart and are not under voluntary control.
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The heart is part of the circulatory system
The heart is a muscular organ that pumps blood to the body. It is the main organ of the circulatory system, also known as the cardiovascular system, which is a network of blood vessels that pumps blood throughout the body. The heart is made up of four muscular sections or chambers that briefly hold blood before moving it. These chambers are created through the growth of various septa, with the muscular ventricular septum originating from the bottom of the ventricle.
The heart is about the size of a person's fist and weighs around 10 ounces in an adult. It has a shape similar to an upside-down pyramid with rounded edges. The heart contains large blood vessels that bring blood in and out, connecting it to the rest of the body.
The heart is composed of cardiac muscle, also known as myocardium, which forms the thick middle layer of the three-layered heart wall. This cardiac muscle is unique to the heart and does not exist anywhere else in the body. It contracts and relaxes to pump blood through the cardiovascular system. The heart's beating is caused by electrical impulses, with pacemaker cells sending electrical activity throughout the heart.
The cardiac muscle is made up of cardiac muscle cells or cardiomyocytes, which are striated, branched, and under involuntary control. These cells contain a high number of mitochondria and are connected by intercalated discs, allowing them to contract together synchronously. The contractile forces of the cardiac muscle, along with the frequency of activation, determine the cardiac output, which is the heart rate multiplied by the stroke volume.
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Heart muscle cells are called cardiomyocytes
The heart is a muscular organ that pumps blood throughout the body. It is the main organ of the cardiovascular system, a network of blood vessels that supply blood and oxygen to the body. The heart is made up of three layers: the pericardium, myocardium, and endocardium.
The myocardium, or cardiac muscle, forms the middle layer of the heart. It is composed of cardiac muscle cells, also known as cardiomyocytes. These cells are the contractile myocytes of the cardiac muscle, allowing the heart to pump. Each cardiomyocyte needs to contract in coordination with its neighbouring cells to efficiently pump blood from the heart. If this coordination breaks down, the heart may not pump at all, which can occur during abnormal heart rhythms such as ventricular fibrillation.
Cardiomyocytes are striated, branched, contain many mitochondria, and are under involuntary control. Each cardiomyocyte contains a single, centrally located nucleus surrounded by a cell membrane called the sarcolemma. The sarcolemma contains voltage-gated calcium channels, which are specialized ion channels that skeletal muscle does not possess. The calcium channels play a role in the excitation-contraction coupling process, where a rise in calcium causes the cell's myofilaments to slide past each other.
Cardiomyocytes are linked to the basement membrane by specialized glycoproteins called integrins. Humans are born with a set number of cardiomyocytes, which increase in size as the heart grows during childhood development. These cells can also grow in response to extensive exercise, heart disease, or heart muscle injury. During heart pressure overload, cardiomyocytes grow through concentric hypertrophy, resulting in a thicker heart wall.
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Heart muscle injuries and conditions
The heart is a muscular organ that pumps blood to the body. It is the main organ of the cardiovascular system, a network of blood vessels that pumps blood throughout the body. The heart is made up of four muscular sections or chambers that briefly hold blood before moving it. The heart's muscular ventricular septum originates from the bottom of the ventricle, with a membranous septum forming shortly after.
The cardiac muscle, or myocardium, makes up the middle layers of the heart. This muscle is responsible for the heart's contractile functions, which are determined by the contractile forces of the cardiac muscle and the frequency at which they are activated. The primary function of the cardiac muscle is to pump blood into circulation by generating sufficient force. The heart's contractile functions require ATP, which can be obtained through various substrates including fatty acids, carbohydrates, proteins, and ketones.
The pathophysiology of cardiac muscle is based on damage to cardiac muscle cells, leading to inappropriate contractility. Cardiomyopathy, for example, is a genetic or acquired disorder of the myocardium associated with cardiac dysfunction. It can lead to unusual thickening, enlargement, or stiffening of the heart muscle, resulting in congestive heart failure. Myocarditis, or inflammation of the heart muscle, is another condition that can contribute to heart disease and, in some cases, lead to dilated cardiomyopathy and heart failure.
Heart attacks, or myocardial infarctions, occur when blood flow to the heart muscle is reduced or blocked, causing oxygen deprivation to the heart. This can lead to damage or scarring of the heart muscle, impacting its ability to pump blood effectively. In some cases, cardiac contusions or bruises on the heart muscle can occur due to trauma or accidents, potentially affecting the heart's function.
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Frequently asked questions
Yes, the heart is a muscular organ. It is made up of a type of muscle tissue called cardiac muscle, which is only found in the heart.
The heart's main function is to pump blood throughout the body. It is the main organ of the cardiovascular system, which delivers oxygen and nutrients to all the organs and tissues of the body.
The heart has three layers: the outer layer (pericardium or epicardium), the thick middle layer (myocardium), and the inner layer (endocardium). The heart also has four chambers: two atria and two ventricles.
Some common heart conditions include arrhythmia, cardiomyopathy, congestive heart failure, heart attack, and high blood pressure. Heart conditions are among the most common types of disorders, and heart disease is the leading cause of death in the United States.
