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2 Answers Anonymous answered Unlike skeletal muscle cells that must be stimulated by nerve impulses before they contract, Cardiac muscle cells can and do contract spontaneously and independently, even if all nerve connections are severed. Anonymous answered The muscles of the heart contract and relax simultaneously (operate at the same time) focusNode Didn't know it? Knew it? Embed Code - If you would like this activity on your web page, copy the script below and paste it into
your web page. Cardiovascular system
Understanding how your heart functionsYour heart is roughly the size of a fist and sits in the middle of your chest, slightly to the left. It’s the muscle at the centre of your circulation system, pumping blood around your body as your heart beats. This blood sends oxygen and nutrients to all parts of your body, and carries away unwanted carbon dioxide and waste products. Structure of your heartYour heart is made up of three layers of tissue:
These layers are surrounded by the pericardium, a thin outer lining protecting your heart. There are four chambers that make up the heart – two on the left side and two on the right. The two small upper chambers are the atria. The two larger lower chambers are the ventricles. These left and right sides of the heart are separated by a wall of muscle called the septum. Circulatory systemYour heart pumps blood around the body all the time - about five litres (eight pints) of it - and this is called circulation. Your heart, blood and blood vessels together make up your cardiovascular system (or heart and circulatory system). The right side of the heart receives blood that is low in oxygen because most has been used up by the brain and body. It pumps this to your lungs, where it picks up a fresh supply of oxygen. The blood then returns to the left side of the heart, ready to be pumped back out to the brain and the rest of your body. Blood vesselsYour blood is pumped around your body through a network of blood vessels:
Blood vessels are able to widen or narrow depending on how much blood each part of your body requires. This action is partly controlled by hormones. ValvesYour heart has four valves. They act like gates, keeping the blood moving in the right direction:
Electrical systemFor your heart to keep pumping regularly, it needs electrical signals which are sent to the heart muscle telling it when to contract and relax. The electrical signal starts in the right atrium where your heart’s natural pacemaker - the sino–atrial node - is situated. This signal crosses the atria, making them contract. Blood is pumped through the valves into the ventricles. Where the atria meet the ventricles, there is an area of special cells - called the atrio-ventricular node - which pass the electrical signals throughout your heart muscle by a system of electrical pathways, known as the conducting system. The muscles of the ventricles then contract, and blood is pumped through the pulmonary and aortic valves into the main arteries. The heart’s natural ‘pacemaker’ - the sino-atrial node - produces another electrical signal, and the cycle starts again. Blood pressureThis is the measurement of the pressure within the arteries. It plays a vital role in the way your heart delivers fresh blood to all your blood vessels. For blood to travel throughout your body quickly enough, it has to be under pressure. This is created by the relationship between three things:
One heartbeat is a single cycle in which your heart contracts and relaxes to pump blood. At rest, the normal heart beats approximately 60 to 100 times every minute, and it increases when you exercise. To ensure an adequate blood supply around your body, the four chambers of your heart have to pump regularly and in the right sequence. There are two phases to your heart’s pumping cycle:
How does a healthy heart work? (https://www.youtube.com/watch?v=ep4cQrYFL0w)Read more from Chest Heart & Stroke Scotland on how the heart works. What can go wrong?StructureSome people are born with a heart that has not developed properly in the womb before birth - this is called congenital heart disease. Sometimes you can inherit a heart condition from your family. Cardiovascular systemProblems with your heart and circulation system include:
Heart disease can happen when your coronary arteries become narrowed by a gradual build-up of fatty material - called atheroma. If your coronary arteries are narrowed or blocked, the blood supply to your heart will be impaired. This is the most common form of heart disease, known as coronary heart disease (sometimes called coronary artery disease or ischaemic heart disease). Eventually, your arteries may become so narrow they can’t deliver enough blood to your heart. This can cause angina - a pain or discomfort in your chest, arm, neck, stomach or jaw. If the fatty material breaks off or ruptures, a blood clot will form, which can cause heart attack (or stroke, if the artery affected is carrying blood to your brain). Electrical systemNormally your heart will beat between 60 to 100 times per minute. This regular rhythmic beating is dependent upon electrical signals being conducted throughout your heart. If the electrical signals within your heart are interrupted, your heart can beat too quickly (tachycardia), too slowly (bradycardia) and/or in an irregular way. This is called an arrhythmia - see Chest Heart & Stroke Scotland. Conditions affecting the pumping of your heart There are some conditions which can damage your heart muscle, making it weak and unable to pump as efficiently as before:
There are also conditions - like high blood pressure (hypertension) - which mean your heart has to work harder. When your heart muscle can’t meet your body’s demands for blood and oxygen, you can develop various symptoms, like breathlessness, extreme tiredness and ankle swelling. This is called heart failure because of the failure of your heart to pump blood around the body and work efficiently. ValvesYour heart can’t function normally if the heart valves aren't working properly, as it can affect the flow of blood through the heart. There are two main ways that the valves can be affected:
Last updated: How does the heart's ability to contract differ from other muscles of the body?Cardiac muscle, like skeletal muscle, is made up of sarcomeres that allow for contractility. However, unlike skeletal muscle, cardiac muscle is under involuntary control. The cardiac muscle is responsible for the contractility of the heart and, therefore, the pumping action.
How is the heart able to contract on its own?For your heart to keep pumping regularly, it needs electrical signals which are sent to the heart muscle telling it when to contract and relax. The electrical signal starts in the right atrium where your heart's natural pacemaker - the sino–atrial node - is situated. This signal crosses the atria, making them contract.
How is cardiac muscle contraction different from skeletal muscle contraction quizlet?how do cardiac muscles differ from skeletal muscle cells? Cardiac muscle is involuntary and found only in the heart. Cardiac muscle is striated, but the bundles are connected at branching, irregular angles called intercalated discs. Skeletal muscle is striated in regular, parallel bundles of sarcomeres.
What is the contract of the heart muscle?Cardiac muscle tissue, or myocardium, contains cells that expand and contract in response to electrical impulses from the nervous system. These cardiac cells work together to produce the rhythmic, wave-like contractions that is the heartbeat.
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How does the hearts ability to contract differ from that of other muscles of the body
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