Properties of cardiac muscle

[ "article:topic", "pacemaker", "T wave", "spontaneous depolarizationv", "sinus rhythm", "sinoatrial (SA) node", "QRS complex", "Purkinje fibers", "prepotential depolarization", "P wave", "myocardial contractile cells", "myocardial conducting cells", "internodal pathways", "intercalated disc", "interatrial band", "heart block", "electrocardiogram (ECG)", "bundle of His", "Bachmann\u2019s bundle", "autorhythmicity", "atrioventricular (AV) node", "atrioventricular bundle branches", "atrioventricular bundle", "artificial pacemaker", "license:ccby", "showtoc:no", "source[1]-med-755", "source[2]-med-755", "program:oeri", "authorname:humananatomyoeri" ] \( \newcommand\) • • • • • • • • • • • • • By the end of this section, you will be able to: • Describe the structure of cardiac muscle tissue and cells • Identify and describe the components of the conducting system that distributes electrical impulses through the heart Recall that cardiac muscle shares a few characteristics with both skeletal muscle and smooth muscle, but it has some unique properties of its own. Not the least of these exceptional properties is its ability to initiate an electrical potential at a fixed rate that spreads rapidly from cell to cell to trigger the contractile mechanism. This property is known as autorhythmicity. Skeletal muscle can not do this. Even though cardiac muscle has autorhythmicity, heart rate is modulated by the endocrine and nervous systems. Structure of Cardiac Muscle Tissue and Cells Co...

ADVERTISEMENTS: The physiological properties of the cardiac muscle are: 1. Rhythmicity 2. Excitability 3. Contractility 4. Conductivity. Property # 1. Rhythmicity/Automaticity/Chronotropism: In the myocardium, automaticity is the ability of the cardiac muscles to depolarize spontaneously, without external electrical stimulation from the nervous system. i. Primary Pacemaker: ADVERTISEMENTS: The sinoatrial node (SA node) is a group of cells positioned on the wall of the right atrium, near the entrance of the superior vena cava. These cells are modified cardiac myocytes. They possess some contractile filaments, though they only contract relatively weakly. Cells in the SA node spontaneously depolarize, resulting in contraction, approximately 100 times per minute. This native rate is constantly modified by the activity of sympathetic and parasympathetic nerve fibers, so that the average resting cardiac rate in adult humans is about 70 beats per minute. Because the sinoatrial node is responsible for the rest of the heart’s electrical activity, it is sometimes called the primary pacemaker. ii. Secondary Pacemaker: If the SA node does not function, a group of cells further down the heart will become the heart’s pacemaker, this is known as an ectopic pacemaker. These cells form the atrioventricular node (AV node), which is situated beneath the endocardium at the lower right posterior portion of the interatrial septum near the opening of the coronary sinus above the tricuspid valve....

Synonyms: Striated skeletal muscle, Textus muscularis striatus skeletalis Muscle is defined as a tissue primarily composed of specialized Depending on the type, the primary function of muscle is to move the bones of the skeleton. However, muscles also enable the heart to beat and can be found in the walls of hollow organs, such as the intestines, uterus and stomach. In this article, we will explore the many functions of muscle in the Key facts about muscle tissue Types Striated muscle (skeletal, visceral striated, cardiac) Non striated (smooth) muscle Skeletal muscle Striated muscle; formed of long, multinucleate, unbranched myocytes Attached at one or either ends to a bony attachment point Cardiac muscle Striated muscle; formed of short, uninucleate, branching myocytes which connected at intercalated discs Specialized muscle of the heart → myocardium Smooth muscle Non striated muscle; formed of short, uninucleate, spindle shaped myocytes Located in the walls of internal organs, blood vessels etc. Connective tissues Endomysium: loose connective tissue surrounding muscle cells/fibers Perimysium: Fibrous sheath which divides muscle tissue into fascicles Epimysium: Fibrous sheath which surrounds entire skeletal muscles Overview Muscle tissue has four main properties: • Excitability: an ability to respond to stimuli • Contractibility: an ability to contract • Extensibility: an ability to be stretched without tearing • Elasticity: an ability to return to its normal shape...

1 An Introduction to the Human Body • Introduction • 1.1 Overview of Anatomy and Physiology • 1.2 Structural Organization of the Human Body • 1.3 Functions of Human Life • 1.4 Requirements for Human Life • 1.5 Homeostasis • 1.6 Anatomical Terminology • 1.7 Medical Imaging • Key Terms • Chapter Review • Interactive Link Questions • Review Questions • Critical Thinking Questions • 2 The Chemical Level of Organization • Introduction • 2.1 Elements and Atoms: The Building Blocks of Matter • 2.2 Chemical Bonds • 2.3 Chemical Reactions • 2.4 Inorganic Compounds Essential to Human Functioning • 2.5 Organic Compounds Essential to Human Functioning • Key Terms • Chapter Review • Interactive Link Questions • Review Questions • Critical Thinking Questions • 3 The Cellular Level of Organization • Introduction • 3.1 The Cell Membrane • 3.2 The Cytoplasm and Cellular Organelles • 3.3 The Nucleus and DNA Replication • 3.4 Protein Synthesis • 3.5 Cell Growth and Division • 3.6 Cellular Differentiation • Key Terms • Chapter Review • Interactive Link Questions • Review Questions • Critical Thinking Questions • 4 The Tissue Level of Organization • Introduction • 4.1 Types of Tissues • 4.2 Epithelial Tissue • 4.3 Connective Tissue Supports and Protects • 4.4 Muscle Tissue and Motion • 4.5 Nervous Tissue Mediates Perception and Response • 4.6 Tissue Injury and Aging • Key Terms • Chapter Review • Interactive Link Questions • Review Questions • Critical Thinking Questions • 5 The Integumentary ...