Cardiac Muscle In The“Heart” of Muscles

Introduction Take a look the instruments that are laid out before you These instruments are called stethoscopes They are used to allow a person to listen inside of the human body Since they are going to highly amplify sounds, please be careful when they are in your ears

Introduction Lets try to listen to the five major places a doctor will listen to a heart beat

Introduction What was the sound that you heard? Can anyone describe it? Was there one sound or two different sounds? Why was there multiple sounds? What is the purpose of these sounds?

Cardiac Muscle Cardiac muscle is located in the heart and is structurally different from skeletal muscle However it works on the same basic principals Contraction at pull on the Z line of each sarcomere making each sarcomere shorter This overall reduces the size of each muscle fiber cell

Cardiac Muscle Each cardiac muscle cell is small compared to a skeletal muscle cell Most also only contain one nucleus that powers each cell A few will have two or more nuclei Cardiac muscle cells are almost completely dependent on aerobic metabolism

Intercalated Discs Each cardiac muscle cell connects to several others at sites called intercalated discs These play a vital role in contraction between cardiac muscle cells They can be seen as dark lines between each muscle fiber

Intercalated Discs Intercalated discs are elaborate connections at the boundaries of each cell These allow the cell to move small molecules between the cells so they can share materials and information This also allows an action potential to travel from one cell to the next very rapidly

Intercalated Discs Since they are chemically, mechanically and electrically connected the heart muscle cells work like one large organ This allows the entire system of cells to beat at once, maximizing their potential This process is called functional syncytium (fused mass of cells)

The Heart The main organ that circulates blood around the body is the heart The heart is a four chambered organ that uses two chambers to force blood to the lungs and two chambers to force blood to the rest of the body

The Heart When looking at a heart you can tell that not all four chambers are the same Each side of the heart is divided to an upper and lower part The atriums are the blood collecting chambers in the heart The ventricles are the blood pumping chambers in the heart

The Heart The heart is divided by the septum This is a wall of muscle that separates the atriums and ventricles Valves are flaps of tissue that separate the sections of the heart These flaps prevent the different sections of blood from mixing

How the Heart Pumps The heart has to have a very systematic pattern for how it beats This keeps the blood flow to the body regular and constant There are a few steps to the heart pumping

How the Heart Pumps It is important to remember that when the heart pumps it has two different stages First the atriums contract together After they contract the ventricles contract together This gives a heart beat a distinct “lub – dup” sound

Path of Blood 1. Deoxygenated (DOX) blood enters the heart through the right atrium This is the main collecting chamber from the body 2. The DOX blood is forced into the right ventricle when the atriums contract

Path of Blood 3. The ventricles contract and send the blood to the lungs After the blood returns from the lungs it is oxygenated (OX) 4. The OX blood from the lungs then collects in the left atrium

Path of Blood 5. The atriums pump and send blood down to the left ventricle The left ventricle is the strongest part of the heart 6. The ventricles then pump. This sends blood to the various parts of the body

Electrical Systems The heartbeat is controlled by electrical systems The heart only beats when there is an electrical current that tells it how and why to beat When this electrical impulse is moving and regular, people have a normal heartbeat

Electrical Systems The SA node is a group of cells on the right atrium that initiate their own electrical signal This signal regulates the heartbeat It also tells the atriums to contract When this group of cells does not work correctly, a pacemaker is installed

Electrical Systems The AV node is located in the septum and collects signals from the SA node This tells the ventricles when to contract This grouping of cells is reactive and relies on the information that is passes on to it from the SA node

?v=H04d3rJCLCE ?v=H04d3rJCLCE

Reading a Heartbeat If the heart is not functioning properly, there can be changes to the oxygen levels of cells Because this can lead to several serious complications, machines called electrocardiograms (EKG or ECG) read the electrical signals that control the heart Reading these can help a medical professional understand what is wrong with a heart

Reading a Heartbeat The first reading on the EKG is the P Wave The P Wave indicates the atria are contracting and pumping blood to the ventricles The second reading, the QRS Waves, indicate the depolarization and contraction of the ventricles The T Wave represents ventricular repolarization

Any deviations in the EKG can show a medical professional if there are some abnormalities in the heart These simple charts can show a medical professional what condition the patient is in, how to treat the patient or how long the patient can go without care Reading a Heartbeat