Cardiac Muscle Contraction
The heart is a muscular organ which pumps blood through the blood vessels of the circulatory system. Blood provides the body with oxygen and nutrients, as well as assists in the removal of metabolic wastes. In humans, the heart is located between the lungs and divided into four chambers: upper left and right atria; and lower left and right ventricles. The heart is enclosed in a protective sac, the pericardium, which also contains a small amount of fluid. The wall of the heart is made up of three layers: epicardium, myocardium, and endocardium. The heart contains a unique tissue called cardiac muscle.
Cardiac muscle tissue is an involuntary, striated muscle that is only found in wall of the heart--myocardium. Myocardium
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Oxygen is provided by the lungs through respiration. The electrical stimulus (action potentials) does not come from the nervous system like skeletal muscle. The nervous system can not make heartbeats but can influence heartbeats to go fast or slow--heart rate. In the heart there are specialized myocytes called pacemaker cells that constitute the cardiac conduction system. Unlike in skeletal muscles which needs a motor neuron to initiate an action potential. The sinoatrial node, located in the wall of the right atrium of the heart, initiates all heartbeats and controls heart rate by producing action potential at regular intervals. If the sinoatrial node becomes damaged another part of the conduction system can take …show more content…
In the heart there are specialized myocytes called pacemaker cells that constitute the cardiac conduction system. The cardiac conduction system begins with contractile signal initiated by the sinoatrial node and travels through the muscle of the heart. The excitation contraction coupling is used to link the action potential generated in the sarcolemma to the start of a muscle contraction. Once calcium enters the myocyte the signal is amplified by the calcium-induced calcium release (CICR) mechanism. The calcium then binds to troponin complex causing a conformational change in the complex that exposes a site on the actin molecule that is able to bind to the myosin ATPase located on the myosin head; This creates a muscle contraction. All these processes come together to aid in the main function of the heart; pump blood throughout the
Throughout the heart, Cardiac Muscle cells are connected together to form a large network from one end to the other. These cells form a shape such that each individual cell always remains in-contact with 3 others cells at all times.
When a muscle contracts and relaxes without receiving signals from nerves it is known as myogenic. In the human body, the cardiac muscle is myogenic as this configuration of contractions controls the heartbeat. Within the wall of the right atrium is the sino-atrial node (SAN), which is where the process of the heartbeat begins. It directs consistent waves of electrical activity to the atrial walls, instigating the right and the left atria to contract at the same time. During this stage, the non conducting collagen tissue within the heart prevents the waves of electrical activity from being passed directly from the atria to the ventricles because if this were to happen, it would cause a backflow. Due to this barrier, The waves of electrical energy are directed from the SAN to the atrioventricular node (AVN) which is responsible for transferring the energy to the purkyne fibres in the right and left ventricle walls. Following this, there is a pause before the wave is passed on in order to assure the atria has emptied. After this delay, the walls of the right and left ventricles contract
This report will explore the structure and function of skeletal muscle within the human body. There are three muscle classifications: smooth (looks smooth), cardiac (looks striated) and skeletal (looks striated). Smooth muscle is found within blood vessels, the gut and the intestines; it assists the movement of substances by contracting and relaxing, this is an involuntary effort. The heart is composed of cardiac muscle, which contracts rhythmically nonstop for the entire duration of a person’s life and again is an involuntary movement of the body. The main focus of this report is on skeletal muscle and the movement produced which is inflicted by conscious thought unless there is a potentially harmful stimulus and then reaction is due to reflex, as the body naturally wants to protect itself. Skeletal muscle is found attached to bones and when they contract and relax they produce movement, there is a specific process that the muscle fibers go through to allow this to occur.
The blood circulates through coronary arteries and then to smaller vessels into cardiac muscle (myocardium). The blood flow is influenced by aortic pressure, which increases in systole, and the pumping activity of the ventricles. When the ventricle contracts, in systole, the coronary vessels are compressed by the contracted myocardium and partly blocked by the open aortic valve therefore the blood flow through the myocardium stops.
The cells of a cardiac muscle are shaped and wider and shorted than a skeletal muscle however they are stripped like skeletal
Cardiac muscle is a type of involuntary muscle found only in the walls of the heart, specifically the myocardium. Cardiac muscles contract automatically to tighten the walls of the heart in a rhythmic fashion. The heart beats nonstop about 100,000 times each day. Smooth muscle is a type of involuntary muscle found within the walls of blood vessels such as in small arteries and veins. Smooth muscle is also found in the urinary bladder, uterus, male and female reproductive tracts, gastrointestinal tract, and the respiratory tract. Skeletal muscles are voluntarily controlled and are attached to bones by tendons. Skeletal muscles also vary considerably in size and shape. They range from extremely tiny strands such as in the muscle of the middle ear as large like in the muscles of the thigh. The three individual muscle types also serve five main functions. The five basic functions are movement, organ protection, pumping blood, aiding digestion, and ensuring blood flow.
The heart is one of the most unique organs in the human body. Its capabilities and functions truly are amazing. The heart 's function is to pump blood throughout the body supplying oxygen and nutrients to tissues. The heart is the size of your fist and weighs roughly 8-12 ounces depending if you’re male or female. The heart pumps through 100 kilometers of blood vessels for blood that is 3 to 4 times thicker than water at 60 to 80 times minute for a total volume of 5 million liters a year at rest. A basic diagram of the heart includes, right coronary, superior vena cava, aorta, pulmonary artery, pulmonary vein, right atrium, right ventricle, left atrium, left ventricle. There are more in
is the biggest of all. Myocardial Infarction is a disease later read about in this report. The pericardium is a fibrous sac which is very smooth lining. In the space space between the pericardium and epicardium is a small amount of fluid. This fluid makes the movement of the heart muscles smooth. Myocardium is the heart muscle itself.
The cardiac cycle is composed of five stages. These stages are atrial systole, early ventricular systole, late ventricular systole, early ventricular diastole, and late ventricular diastole. In order for atrial systole to occur, the blood that has been flowing between the atrium and ventricle via the opened atrioventricular valves must be deposited into the ventricles. The SA node is responsible for the contraction of the atrial myocardium. Once the atrium contracts, blood cannot flow back into or enter the atria because the openings of the great veins has been narrowed by pressure. The ventricles are now filled with blood accomplishing end-diastolic volume which is another term for how much blood your ventricles can contain while your body is at rest. The next phase is early ventricular systole. Now that all the blood is in your ventricles, it must continue onward to the
The heart serves as a powerful function in the human body through two main jobs. It pumps oxygen-rich blood throughout the body and “blood vessels called coronary arteries that carry oxygenated blood straight into the heart muscle” (Katzenstein and Pinã, 2). There are four chambers and valves inside the heart that “help regulate the flow of blood as it travels through the heart’s chambers and out to the lungs and body” (Katzenstein Pinã, 2). Within the heart there is the upper chamber known as the atrium (atria) and the lower chamber known as the ventricles. “The atrium receive blood from the lu...
Everyone knows that the heart is a vital organ and we cannot live without it. It is complex and important; therefore it is critical to know how it works. With knowledge about the heart and what is good and bad for it, one can significantly decrease the risk for diseases. Now, the heart has three layers. Endocardium is the smooth inside lining, myocardium id is the middle layer of heart muscle, and it is surrounded by a fluid filled sac called the pericardium. The heart is split into four parts; some may call it chamber or rooms. These parts are the: right atrium, the left atrium, the right ventricle, and the left ventricle. The chambers are separated by partition walls known as the septum and each has a one-way valve that prevents blood from flowing backwards.
The heart is two sided and has four chambers and is mostly made up of muscle. The heart’s muscles are different from other muscles in the body because the heart’s muscles cannot become tired, so the muscle is always expanding and contacting. The heart usually beats between 60 and 100 beats per minute. In the right side of the heart, there is low pressure and its job is to send red blood cells. Blood enters the right heart through a chamber which is called right atrium. The right atrium is another word for entry room. Since the atrium is located above the right ventricle, a mixture of gravity and a squeeze pushes tricuspid valve into the right ventricle. The tricuspid is made up of three things that allow blood to travel from top to bottom in the heart but closes to prevent the blood from backing up in the right atrium.
It is about the size of a person's fist. The heart has four chambers. The upper two chambers are the right artium and left atrium, and the lower two are the right ventricle and left ventricle. Blood is pumped through the chambers, aided by four heart valves. The valves open and close to let the blood flow in only one direction.
The heart is a pump with four chambers made of their own special muscle called cardiac muscle. Its interwoven muscle fibers enable the heart to contract or squeeze together automatically (Colombo 7). It’s about the same size of a fist and weighs some where around two hundred fifty to three hundred fifty grams (Marieb 432). The size of the heart depends on a person’s height and size. The heart wall is enclosed in three layers: superficial epicardium, middle epicardium, and deep epicardium. It is then enclosed in a double-walled sac called the Pericardium. The terms Systole and Diastole refer respectively and literally to the contraction and relaxation periods of heart activity (Marieb 432). While the doctor is taking a patient’s blood pressure, he listens for the contractions and relaxations of the heart. He also listens for them to make sure that they are going in a single rhythm, to make sure that there are no arrhythmias or complications. The heart muscle does not depend on the nervous system. If the nervous s...
The human heart has two ventricles and two atria making up four chambers. The heart includes the atria and ventricles. The left atrium and the left ventricle make up the left side of the heart and the right atrium and right ventricle make up the right side of the heart. Each side is important but the left ventricle and left atrium is the most important, and I will tell you why. The left ventricle receives blood from the left atrium and pumps into the aorta. The aorta pumps oxygenated blood to the rest of the body. If someone shot you in your left ventricle, you would most certainly die. That is why it is the most important. It pumps blood to the rest of your body. The right ventricle is important too. The right ventricle receives blood from the right atrium and pumps blood to the pulmonary artery. The pulmonary artery ha...