Mediastinum - answerHallow muscular organ that lies between the lungs
What is the base (posterior surface) of the heart formed by? - answerleft atrium, small
portion of the RA, and proximal portions of the superior and inferior vena cava, as well
as the pulmonary veins.
Where does the front (anterior) of the heart lie? - answerLies behind the sternum and
costal cartilages. Formed by part of the RA, left and right ventricles.
What is the lower(apex) portion of the heart formed by? - answerThe tip of the left
ventricle at about the 5th intercostal space midclavicular.
What is the pericardium? - answerdouble-walled sac that encloses the heart
What are the three tissue layers that make up the walls of the heart? -
answerendocardium, myocardium, epicardium
What and where is the endocardium? - answerThe heart's innermost layer. Made up of
smooth muscle that lines the hearts inner chambers.
What is the myocardium? - answermiddle layer, mostly cardiac muscle. Responsible for
the pumping action of the heart.
What is the hearts outermost layer? - answerThe epicardium and is continuous with the
inner lining of the pericardium at the hearts apex. Holds coronary arteries blood
capillaries, nerve fibers, and fat.
What is ischemia? - answerlack of blood flow
What do cardiac muscle fibers do? - answerMake up walls of the heart
What is the sarcolemma? - answermuscle cell membrane
What are myofibrils? - answerany of the elongated contractile threads found in striated
muscle cells.
What are sarcomeres? - answerThe functional units of myofibrils (they actually do the
contracting). They are the basic protein unit responsible for contraction.
, What is the sarcoplasmic reticulum? - answerThe sarcoplasmic reticulum is a modified
endoplasmic reticulum that stores calcium ions (in a muscle cell)
What is the sarcoplasm? - answercytoplasm of a muscle cell
What happens if the the muscle cells do not have calcium available? - answerThe
muscles will stay relaxed and contraction is inhibited.
What does the force of cardiac contraction largely depend on? - answerOn the
concentration of calcium ions in the extracellular fluid.
How many chambers does the heart have? - answer4 (2 atria, 2 ventricles)
What seperates the atria from the ventricles? - answercoronary sulcus
What are the two upper chambers of the heart called? - answerRight and Left Atria
What is the purpose of the atrium? - answerTo receive the blood
Where does the right atrium receive blood from? - answersuperior vena cava, inferior
vena cava, coronary sinus (carries blood from the head and upper extremities)
Where does the left atrium receive blood from? - answerReceives Oxygenated blood
from the lungs via the four pulmonary veins.
How is blood pumped through the atria? - answerThrough the atrioventricular valve
What are the hearts two lower chambers? - answerRight and Left Ventricle
What is the purpose of the ventricles? - answerpump blood out of the heart
What does the right ventricle do? - answerpumps blood to the lungs
What does the left ventricle do? - answerpumps oxygen-rich blood to the body
How many one way valves are in the heart? - answerfou; two av valves and two SL
(semilunar) valves
What do the four one way valves in the heart do? - answerassist in producig the
pressure gradient needed between chambers to ensure a smooth flow of blood through
the heart and prevent backflow of blood.
atrioventricular valves - answerValves located between the atrial and ventricular
chambers on each side of the heart, prevent backflow into the atria when the ventricles
are contracting.
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