Week 5 Cardiac Anatomy & Physiology Study Guide Flashcards
What are intercalated discs?
The cells of cardiac muscle (cardiomyocytes) attach to one another with specialized cell junctions called intercalated discs.
These discs:
Transfer force of contraction between muscle fibers. (Make sure that all the muscle cells & fibers contract when they are supposed to at the same time to give us the maximum heartbeat.)
Characteristics of the heart
-Located in mediastinum with slight prevalence to the left.
-About 300g in the adult
-Wide superior border with an inferior border that comes to an apex.
Heart Coverings
-Fibrous pericardium (pericardial sac)-outermost covering of the heart
-Pericardium (made up of two layers:
1)Visceral pericardium (epicardium)-innermost covering surrounding the heart muscle (closest to the heart)
2)Parietal pericardium-inner lining of fibrous pericardium.
-Paricardial cavity filled with serous fluid
-Pericarditis
-Cardiac Tamponade-when bleeding from the heart seeps into the pericardial sac into serous fluid in pericardial cavity.
Heart wall structure
Epicardium
-Visceral percardium (aka epicardium)
-Its a serous membrane
-Epi-means on top of
Myocardium
-Muscle of the heart(muscle layer)
-cardiac muscle tissue
-Forms atria and ventricles
-largest portion of the heart
-Myo-means muscle
Endocardium
-Inner lining of the heart
-Endocarditis- inflammation of the inner lining of the heart
-Endo-means inside
Be able to Identify these anatomical parts of the heart.
-Atria
-Ventricles
-Interatrial Septum
-Interventricular Septum
-Tricuspid Valve
-Bicuspid Valve
-Papillary Muscle
-Chordae Tendinae
-Trabeculae Carnea
-Pulmonary Semilunar
Valve
Know the vessels that enter and which chambers they enter.
Superior vena cava, inferior vena cava, and coronary sinus all enter the heart through the right atrium.
Know the vessels that leave the heart and which chambers they exit.
Blood leaves the right ventricle through the pulmonary semilunar valve (PSL).
Blood leaves the left ventricle through the aortic semilunar valve (ASL).
Trace a drop of blood starting with the right atrium and ending with the Aorta through a pulmonary circuit.
- Right Atrium-A drop of blood enters the heart from the superior vena cava, inferior vena cava, and coronary sinus through the right atrium.
2.Triscuspid valve-That drop of blood will the go through the tricuspid valve.
- Right Ventricle-From the tricuspid valve into the right ventricle.
- Pulmonary Semilunar Valve-The right ventricle will send that drop of blood to the pulmonary semilunar valve.
- Pulmonary Trunk-then the pulmonary semilunar valve will send the drop of blood to the pulmonary trunk.
- Pulmonary Artery-then blood will be sent to the pulmonary artery.
- Alveolar Capillaries in the lung tissue-this is where the and carbon dioxide exchange will happen. (pulmonary circulation)
- Pulmonary Veins-the capillaries will merge together to form veins that we call pulmonary veins.
- Left Atrium-pulmonary veins will then enter the heart through the left atria.(Blood from veins will enter the heart.)
- Bicuspid (Mitral) Valve-then blood will leave left atria and enter bicuspid/mitral valve.
- Left Ventricle-(Then to left ventricle.
- Aortic Semilunar Valve-then to aortic semi-lunar valve.
- Aorta-then to the aorta and then out to the body tissues(systematic circulation)
Atrium receives veins, ventricles give rise to arteries. Arteries leave ventricles, veins enter the atria.
Right & Left Coronary Arteries
Right Coronary Artery-Supplies blood to the right atrium, portions of both ventricles and some of the cardiac conduction system. (SA node and AV node).
Left Coronary Artery-Supplies blood to the left ventricle, left atrium, and interventricular septum.
We get in the heart muscle of capillaries through the coronary arteries. We have blood in the heart, but that blood is useless unless it gets to the capillaries. Everything happens at the cellular level in our body. If the coronary artery gets blocked and blood can’t get to the muscular portion of the heart, it has to get to the capillary level of the heart so oxygen, carbon dioxide, nutrients to be exchanged.
Arteries will branch, branch and get smaller until they form arterial vessels (very small vessels) and capillaries. Capillaries merge together to form veins.
Arteries supply blood to areas. (oxygenated blood).
Veins drain blood from the areas. (Deoxygenated blood)
Cardiac Conduction System(depolarization, plateau, repolarization)
-Specialized autorhythmic tissue in the heart.
-Responsible for initiating and distributing electrical impulses throughout the myocardium.
Components-
-sinoatrial node
-atrioventricular node
-atrioventricular bundle
-Bundle branches
-Purkinje fibers
Cardiac Conduction System(depolarization, plateau, repolarization)
1)Depolarization
-When the threshold potential is reached, sodium channel open.
-Sodium ions rush into the contractile fibers and produce rapid depolarization
-Nerve impulses carried throughout cardiac muscle through the use of intercalated discs. (All cardiac muscles will contract at the same time.)
Cardiac Conduction System(depolarization, plateau, repolarization)
2) Plateau
-Calcium channels open and calcium enters the contractile fibers from the extra cellular fluid.
-Calcium also moves from the sarcoplasmic reticulum into the cytosol of the contractile fibers. Depolarization is maintained for 250ms. Calcium binds troponin and contraction of cardiac muscle begins. (Like a delay to allow the heart to do what it needs to do.)