Heart & Mediastinum Flashcards
What are the boundaries of the mediastinum?
superior: thoracic inlet
inferior: diaphragm
anterior: sternum and costal cartilages
posterior: thoracic vertebrae
lateral: pleura
What are the contents of the superior mediastinum?
great vessels of heart, thoracic duct (left), parts of azygos system, R&L vagus nerves, pulmonary plexus, esophageal plexus, cardiac plexus, thymus, parts of trachea & esophagus
What are the contents of the inferior, anterior mediastinum?
fat, lymph tissue, and vessels
What are the contents of the inferior, middle mediastinum?
the heart and its pericardial tissues
What are the contents of the inferior, posterior mediastinum?
thoracic aorta, esophagus, pulmonary arteries & veins, azygos system, thoracic duct, sympathetic trunk & thoracic splanchnic nerves
What side does the brachiocephalic trunk go to in the mediastinum?
right
What is special about the left recurrent laryngeal nerve in the mediastinum?
it wraps around the aortic arch and then ascends
Describe the thoracic sympathetic trunk in the mediastinum
bilateral; continuous with cervical and lumbar parts of sympathetic trunk; paravertebral ganglia along its course; it is lateral to the vertebral bodies
Describe the thoracic splanchnic nerves
bilateral; emerge from thoracic sympathetic trunks; there is a greater, lesser and least nerve; all three are part of the abdominopelvic sphlanchnic nerves and are all presynaptic fibers that will synapse with pre vertebral ganglia in abdomen
What type of innervation do the thoracic sphlanchnic nerves provide?
sympathetic innervation to viscera inferior to the diaphragm
What are the three locations in the mediastinum that are areas of constriction where swallowed foreign objects are most likely to lodge and where a stricture may develop after drinking caustic liquid
arch of aorta; left main bronchus; diaphragm
What is the esophageal hiatus?
location where the esophagus opens up and meets the stomach
What are the functions of the heart?
center of the cardiovascular system, connects to blood vessels that transports blood between the heart and other body tissues
What is the main difference between arteries and veins?
arteries carry blood away from the heart
veins carry blood back to the heart
True or False?
Arteries carry blood high in oxygen and veins carry blood low in oxygen.
True; except for the pulmonary arteries/veins
What are the arteries and veins entering and leaving the heart called?
the great vessels
What type of blood flow occurs through both the heart and blood vessels?
unidirectional flow
Backflow of blood is prevented by ___ within the heart
valves
True or False
The two side-by-side pumps of the heart work independently but at the same rate.
true
How is blood pressure in the heart developed?
through alternate cycles of heart wall contraction and relaxation
What does the pulmonary circuit consist of?
the right atrium and ventricle of the heart as well as the pulmonary arteries and veins
When blood returns to the left side of the heart it enters the ___ circuit
systemic
What does the systemic circuit consist of?
left atrium and left ventricle along with the other named blood vessels
Gas exchange in tissues occurs from what?
capillaries
Most veins merge and drain into the superior and inferior ____ _____, which drain blood into the right atrium
venae cave
How much does the heart weigh?
250 to 350 grams
Where in the chest is the heart located?
left of the body midline posterior to the sternum in the middle mediastinum
How is the heart rotated in the chest?
rotated such that its right side or border is located more anteriorly, while its left side or border is located more posteriorly
The posterosuperior surface of the heart, formed primarily by the left atrium, is called the ___
base
The inferior, conical end of the heart is called the ___
apex
The heart projects slightly anteroinferiorly toward the ___ side of the body
left
What is the pericardium?
fibrous, serous sac that contains the heart. It is held within the mediastinum by connective tissue that supports the great vessels’ external walls superior to the heart and the diaphragm inferior to it
True or False?
The pericardium restricts heart movements so that it doesn’t bounce and move about in the thoracic cavity, and prevents the heart from overfilling with blood
true
What is the outer portion of tough, dense connective tissue layer of the pericardium called?
fibrous pericardium
What two things is the fibrous pericardium attached to?
sternum and the diaphragm
What is the inner portion of the pericardium - thin, double-layered serous membrane called?
the serous pericardium
- parietal layer
- visceral layer
What are the three distinctive layers of the heart wall called?
external epicardium
middle myocardium
internal endocardium
What is the epicardium?
the outermost heart layer and is also known as the visceral layer of serous pericardium
What happens to the epicardium as we age?
this layer becomes thicker and more fatty
Are atria thin-walled or thick-walled?
thin-walled
What is the wrinkled, flaplike extension of the atria called?
auricle
Left atrium receives blood from what circuit?
pulmonary circuit
Right atrium receives blood from what circuit?
systemic circuit
What surface do the two large arteries (the pulmonary trunk and aorta) exit the heart?
basal surface
The pulmonary trunk carries blood from the ___ ___ into the ____ ___
right ventricle; pulmonary circuit
The aorta conducts blood from the ___ ___ into the ___ ___
left ventricle; systemic circuit
What separates the atria from the ventricles externally?
a deep coronary sulcus (atrioventricular sulcus) that extends around the circumference of the heart
The anterior interventricular sulcus and the posterior interventricular sulcus are located between what?
the left and right ventricles
The anterior interventricular sulcus and the posterior inter ventricular sulcus extend inferiorly from what?
extend inferiorly from the coronary sulcus toward the heart apex
The fibrous heart skeleton is located between what? And what is it formed from?
located between the atria and the ventricles; formed from dense irregular connective tissue
How does the fibrous skeleton of the heart anchor heart valves?
by forming supportive rings at their attachment points
What does the electrical insulation that the fibrous skeleton of the heart provides, ensure?
that muscle impulses are not spread randomly throughout the heart, and thus prevents all of the heart chambers from beating at the same time
The fibrous skeleton of the heart provides rigid framework for the attachment of what?
cardiac muscle tissue
The right atrium receives blood from the what?
the systemic circuit and the heart muscle itself
What three major vessels empty into the right atrium?
superior vena cava: drains blood from the head, upper limbs, and superior regions of the trunk
inferior vena cava: drains blood from the lower limbs and trunk
coronary sinus: drains blood from the heart wall
What muscle is located in the right atrium?
pectinate muscle
What does the right atrioventricular valve (AV) aka the tricuspid valve separate?
separates right atrium from the right ventricle
When is the tricuspid valve forced closed?
when the right ventricle begins to contract, preventing blood back flow into the right atrium
The right ventricle receives oxygenated or deoxygenated blood from the right atrium?
deoxygenated
The internal wall surface of each ventricle muscular projections called what?
papillary muscles
What do papillary muscles anchor?
chordae tendinae; attach to the cusp of the right AV valve and prevent everting and flipping into the atrium when contracting
The superior end of the pulmonary trunk narrows into a smooth-walled, conical region called what?
conus arteriosus
The pulmonary semilunar valve marks the end and beginning of what?
end of the right ventricle; entrance into the pulmonary trunk
The pulmonary trunk divides shortly into what?
right and left pulmonary arteries
Where are semilunar valves located?
within the walls of both ventricles immediately before the connection of the ventricle to the pulmonary trunk and aorta
Each of the semilunar valves is composed of three what?
thin, pocket-like semilunar cusps
As blood is pumped into the arterial trunks it pushes against the cusps of the semilunar valves which does what?
forces the valves open
When do the semilunar valves close?
when ventricular contraction ceases
The left AV valve separates what two chambers of the heart?
separates the left atrium from the left ventricle
Another name for the left AV valve is what?
the bicuspid valve
What is the largest of the four heart chambers?
left ventricle
The wall of the left ventricle is typically how much thicker than the right ventricular wall
3X thicker
Why does the left ventricle need thick walls?
in order to generate enough pressure to force the oxygenated blood from the lungs into the aorta and then through the entire systemic circuit
True or False?
trabeculae carnae in the left ventricle are more prominent
true
At the superior end of the ventricular cavity, the aortic semilunar valve marks the end of what?
end of left ventricle and the entrance into the aorta
True or False?
external nerves are responsible for causing the heart to beat
false; the heart itself exhibits autorhythmiticity
The heartbeat is initiated by the cardiac muscle fibers of which node?
Sinoatrial (SA) node
The SA node is nicknamed what?
the pacemaker
What is the normal amount of heartbeats per minute?
70-80
Impulse travels to both atria, stimulating what?
atrial systole
Where is the AV node located?
in the floor of the right atrium between the right AV valve and the coronary sinus
Cardiac impulse travels from the AV node to the what?
Atrioventricular bundle (bundle of His)
The bundle of His conducts the impulse to what?
purkinje fibers
True or False?
The heart is innervated by both sympathetic and parasympathetic components
true
Left and right coronary arteries travel where?
in the coronary sulcus of the heart to supply the heart wall
Where are openings for the coronary arteries?
immediately superior to the aortic semilunar valve
The right coronary artery typically branches into what?
marginal artery; posterior interventricular artery
The left coronary artery typically branches into what?
the anterior interventricular artery and the circumflex artery
What is cardiomyopathy?
condition where a ventricle has become enlarged, thickened, or stiffened. As a result the heart’s ability to pump is reduced.
What is angioplasty?
a procedure in which a catheter is inserted with a tiny balloon that presses the plaque blockage against the artery so that blood may flow more freely through the vessel. A stent is then inserted.
Where is the SA node found?
Posterior wall of the right atrium, adjacent to the entrance of the superior vena cava
