Cardiac Muscles – Class 11 | Chapter – 18 | Biology Short Notes Series PDF

Cardiac Muscles: Cardiac muscle, also known as heart muscle, is the layer of muscle tissue which lies between the endocardium and epicardium. These inner and outer layers of the heart, respectively, surround the cardiac muscle tissue and separate it from the blood and other organs. Cardiac muscle is made from sheets of cardiac muscle cells. These cells, unlike skeletal muscle cells, are typically unicellular and connect to one another through special intercalated discs. These specialized cell junction and the arrangement of muscle cells enables cardiac muscle to contract quickly and repeatedly, forcing blood throughout the body.

The chronic disease of the heart or blood vessels, including diseases of the heart muscle, valves, and arteries is called “cardiovascular disease.” This term includes coronary artery disease (CAD), congestive heart failure, hypertension and more.

Structure of Cardiac Muscles

Cardiac muscle is very different from skeletal muscle because it has a much more complex structure. Cardiac muscle is able to contract and relax, unlike skeletal muscles which only contract. This means that cardiac tissue will have far more irregular shapes than skeletal muscles. Cardiac muscle cells contain T tubules that connect to the sarcoplasmic reticulum which stores the calcium ions needed for the contraction of the cell.

The myocardium is a thin, yet strong membrane that surrounds and protects the heart and its associated structures. The heart wall has three layers: epicardium, myocardium, and endocardium.

The endocardium lines the inside of all four heart chambers and covers the heart valves. The epicardium forms a thin layer on top of the exterior surface of the heart and it also wraps around to cover areas of any openings in this layer.

Functions of Cardiac Muscles

The cardiac muscle is made up of cells that are specialized for contraction and pumping. They contract in intervals to pump blood through the heart and into the rest of the body.

Cardiac muscles also contain a specialized cell called Purkinje fibres – which help transmit electrical impulses to and from the heart muscle cells, making them an important component in the functioning of the heart

What is Cardiomyopathy?

Cardiomyopathy is one of the main conditions that can affect your cardiac muscle tissue. It’s a disease that makes it harder for your heart to pump blood.

There are several different types of cardiomyopathy:

  • Hypertrophic cardiomyopathy. The cardiac muscles enlarge and thicken for no apparent reason. It’s usually found in the lower chambers of the heart, called the ventricles.
  • Dilated cardiomyopathy. The ventricles become larger and weaker. This makes it hard for them to pump, which makes the rest of your heart work harder to pump blood.
  • Restrictive cardiomyopathy. The ventricles become stiff, which prevents them from filling to their full volume.
  • Arrhythmogenic right ventricular dysplasia. The cardiac muscle tissue of your right ventricle is replaced with fatty or fiber-rich tissue. This can lead to arrhythmia, which refers to an abnormal heart rate or rhythm.

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By Team Learning Mantras