The Cardiovascular System Flashcards
What two parts of the body make up the cardiovascular system? What makes up the circulatory system?
“Cardiovascular” refers to the heart and the blood vessels. “Circulatory” refers to these organs in addition to the blood as well as the lymphatic vessels.
What is the anatomical position of the heart? Describe what other features can be found here…
The heart is found between the lungs, within the mediastinum, tilting toward the left side of the body. The apex or lowermost portion of the heart is found lying just above the diaphragm.
The mediastinum also includes the esophagus, trachea, aorta, etc.
What surrounds the heart and how does this feature contribute to the heart’s function?
The heart is surrounded by a fibrous pericardial sac that enables the heart to have room for expansion while simultaneously preventing excess expansion. The sac secretes a lubricating substance called pericardial fluid which aids to minimize heart beat friction against the thoracic wall.
Describe the organization of the heart. Name the regions, divisions, and valves.
The two upper chambers are the right and left atrium separated from one another by the interatrial septum. The two lower chambers are the right and left ventricles, which are separated by the interventricular septum.
Between the right atrium and the right ventricle is the triscuspid valve - named for its consisting of three flaps or cusps. Between the right ventricle and the pulmonary artery is the pulmonary valve - which prevents backflow.
Between the left atrium and left ventricle is the bicuspid valve - named for its consisting of two flaps or cusps. Between the left ventricle and the aorta is the aortic valve which serves to prevent backflow
Pulmonary veins bring blood to the left atrium.
The vena cava (superior and inferior) bring blood into the right atrium.
Describe the direction of blood flow on the right side of the heart.
Blood flows into the right atrium through the superior vena cava.
The AV valve between the right atrium and ventricle is known as the tricuspid valve.
The right ventricle pumps blood into the pulmonary trunk, to the lungs.
The pulmonary valve regulates one-way blood flow out of the pulmonary trunk.
Describe the direction of blood flow on the left side of the heart.
The pulmonary veins bring blood into the left atrium.
The AV valve between the left atrium and ventricle is known as the bicuspid valve.
The left ventricle pumps blood into the aorta on its way to the body.
The aortic valve regulates one-way blood flow out of the aorta.
What layer of the heart is the most superficial? What cell type(s) is it made up of? Where is this layer the thickest?
Epicardium
Simple Squamous Epithelium aka Mesothelium overlying a layer of connective tissue and sometimes a thick deposit of adipose tissue.
*Various thickness
Thickest in the vicinity of the coronary sulcus, anterior interventricular sulcus, and posterior interventricular sulcus - the fat cushions the arteries and nerves running through the sulci.
What layer of the heart is the thickest? What cell types(s) is it made up of? What is this layer responsible for?
Myocardium
Composed of Cardiac Muscle Cells called Cardiocytes and Cardiomyocytes arranged in fascicles
Responsible for the rhythmic muscular contractions of the heart.
What layer of the heart is innermost? What cell type(s) is it made up of? What special structure is located here?
Endocardium
Similar histologically to the epicardium - simple squamous epithelium overlying a thin layer of areolar tissue (subendocardial layer).
contains nervelike “Purkinje fibers”
Describe the function and anatomy of the myocardial vortex.
Myocardial muscle fascicles are coiled around the heart in a spiraling pattern toward the apex - resulting in a twisting muscle contraction which is more effective for pumping blood.
Cardiocytes lack parallel orientation but rather are found in a variety of orientations.
Describe the cardiac skeleton.
a dense fibrous connective tissue forming the superior portion of the interventricular septum - separating the pathway of electrical signals into a specific order.
anuli fibrosi – encricle the bases of the aorta and pulmonary trunk
trigonum fibrosum – anchors valve cusps as patches
Describe the cells and orientation of cells that make up cardiac muscle.
Cardiocytes meet end to end at intercalated discs - featuring interdigitating folds that enhance surface area of cell-cell contact; fasciae adherentes and desmosomes that link cells together as well as gap junctions which allow for electrical communication between cells.
What is the function of specialized cardiocytes that generate and conduct electrical signals?
The cells define the “pacemaker” and the “cardiac conduction system” that coordinate heart movement.
Discuss the differences between the SA Node and the AV Node.
sinoatrial (SA) node - a small patch of cells just below the epicardium - located near the junction of the superior vena cava and the right atrium. this node spontaneously depolarizes and initiates cell - cell electrical stimulation resulting in atrial contraction.
atrioventrivular (AV) node - a small patch of cells just below the epicardium - located low in the right atrial wall above the interventricular spetum, close to the right AV valve. the route by which electrical signals of the SA node reach the ventricles (0.05 m/s, slowing down ventricular contraction to ensure the ventricles are completely full before contraction).
What is the function of the atrioventricular bundle or “bundle of His”?
a cord of cardiomyocytes arising in the AV sode running into the interventricular septum lying just below the endocardium to ensure rapid stimulation of the ventricular myocardium.
beginning in a solid bundle, it splits left right into branches giving rise to purkinje fibers.
What role do purkinje fibers play in electrical conduction?
located at the lower end of the septum, branches of the atrioventricular bundle give rise to these fine nerve-like extensions
these fibers conduct signals to the apex of the heart and upward in the ventricular walls.
as a result contraction starts in the apex of the heart, driving blood upward toward the pulmonary and aortic valves.
*fatter, more vacuolated than cardiomyocytes
What is the coronary sulcus?
a region between the atrium and ventricle that is filled with fat.
What are blood vessels?
tubular, muscular organs for the transport and distribution of blood.
What is the difference between the pulmonary and systemic circuit(s)?
Pulmonary - conducts blood from the heart to the lungs and back - only serving O2 and CO2 exchange
Systemic - conducts blood from the heart to all parts of the body and back again.
What are the three main classes of blood vessels? Describe the major differences.
Arteries, Veins, Capillaries
Arteries: Efferent - conduct blood away from the heart, subject to a great stress of blood pressure generated by the heart beat = most muscular vessel type resulting in circular cross sections where the tissue is strong. Smallest arteries = arterioles.
Veins: Afferent - conduct blood toward the heart, not as subject to blood pressure, thinner walls than arteries resulting in a collapsed shape when cross sectioned. Smallest veins = venules.
Capillaries: microscopic vessels that connect arteries and veins, not muscular at all.
