16: Heart Flashcards
What space is the heart located in?
Mediastinum
Is the inferior tip of the heart the base or the apex?
Apex. Base is formed by the left atrium and pulmonary veins
What two circuits are in the human circulatory system?
Pulmonary and systemic
What is the name for the dense connective tissue that forms the four rings around the valves of the heart?
Cardiac skeleton
What is meant by the “autorhythmicity” of the heart?
The heart can initiate its own electrical signal to trigger the contractile mechanism
What are the two major types of cardiac cells? Which is more prevalent?
Myocardial contractile cells and Myocardial conducting cells
Myocardial contractile cells form 99% of the heart
What two intercellular connections are common at intercalated discs?
Desmosomes (for strength) and gap junctions (for ion passage)
Where is the SA node and what does it do?
The sinoatrial node is a specialized clump of myocardial conducting cells located in the superior and posterior walls of the right atrium in close proximity to the orifice of the superior vena cava that establishes a normal cardiac rythm
Impulses from the SA node travel throughout the atria via what?
Internodal pathways
What is the AV node and what does it do?
The atrioventricular node is a second clump of specialized myocardial conductive cells, located in the inferior portion of the right atrium within the atrioventricular septum. This node allows for a small pause in impulse (allowing the atria to contract) before the ventricles contract
What structure arises from the AV node and becomes the two atrioventricular bundle branches?
Atrioventricular bundle or Bundle of His
The left and right bundle branches connect to what structures?
Purkinje fibers
Through what structure does the body exercise neural control over the heart?
Cardiac plexus near the base of the heart
Through what nerve does the parasympathetic nervous system act on the heart?
Vagus nerve
The sympathetic nerves acting on the heart emerge from where?
Thoracic spinal cord
