LAB 3: THE HEART Flashcards
(18 cards)
WHERE IS THE HEART LOCATED
mediastinum
WHAT IS THE MEMBRANE COVERING THE HEART, WHAT ARE ALL OF ITS LAYERS?
1) fibrous pericardium: is the outer layer contianing dense connective tissue
2)serous pericardium: contains 2 layers
–> parietal pericardium: adheres to the fibrous layer
–> viseral pericardium: is also called the epicardium, is tighly adhered to heart muscle
between the viseral and pareital pericardium is the pericardial cavity, which contains serous fluid to prevent friction
NAME THE LAYERS OF THE HEARTS WALL
1) epicardium: is also the visceral layer of the serous pericardium is the most superficial
2) myocardium: is the middle layer that is composed of cardiac muscle thats aranged in circular and spiral formation which allows the muscle to be connected. also contains the cardiac skeleton
3) endocardium: is the thin innermost layer that lines the walls of the heart
WHAT ARE THE 2 CIRCUITS OF BLOOD FLOW IN THE HUMAN BODY
1) Pulmonary circuit: delivers blood from to and from the lungs
2) systemic circuit: delivers oxygenated blood to the body tissues and returns deoxygenated blood back to the heart to enter the pulmonary circulation
EXPLAIN THE CORONARY CIRCULATION
provides oxygen and nutrient rich blood to the heart muscles.
right coronary artery: delivers blood to right atrium and both ventricles
left coronary artery: delivers blood to the left atrium, left ventricle, and interventricular septum
coronary veins drain blood from the heart and send it to the right atrium, all of the coronary veins will drain blood into the coronary sinus
EXPLAIN THE MICROSCOPIC ANATOMY OF THE HEART
cardiac muscle is striated, branched, and joined together by intercalated disks, these disks contain gap junctions that allow ion cbannels to communicate between cells. this allows for the muscles to contract as a unit for efficent blood pumping.
WHAT ARE PACEMAKER CELLS
they initiate the instrinsic conduction system which establishes the basic rhythm of the heart
WHAT ARE THE PHASES OF THE INTRINSIC CONDUCTION SYSTEM
sinoatrial node (SA node), atrioventricular node (AV node), atrioventricular bundles (AV bundles), right and left bundle branches, subendocarial conduction network (purkinje fibers)
EXPLAIN THE SINOATRIAL NODE PHASE
this is the pacemaker of the heart. the pacemaker cells depolarize more rapidly then the other cells in the ICS, this produces the sinus rhythm, which is around 75 beats/min. the depolarization from the SA node spread via gap junctions, to the AV node.
EXPLAIN THE ATRIOVENTRICULAR NODE PHASE
the authohythmic cells here depolarize slower than the ones in the AV node at around 50 times per minute. impulses are delayed by around 0.1 seconds, this allows for the contraction of the atria to be complete before contraction of the ventricles.
EXPLAIN THE ATRIOVENTRICULAR BUNDLES PHASE
is the only route by which the impulses from the SA node are passed to the ventricular myocardium. (only electrical connection between atria and ventricles)
EXPLAIN THE LEFT AND RIGHT BUNDLE BRANCHES PHASE
carry the electrical signal through the interventricular spetum towards the apex of the heart
EXPLAIN THE SUBENDOCARDIAL CONDUCTING NETWORK
carry impulses from the bundle branches, to the apex, and turn back upward towards the ventricular walls into the papillary muscles and ventricular myocardium. cell to cell transmission via gap junctions completes tehe sprrad of the impulse through the myocardium.
EXPLAIN WHAT EACH LETTER MEANS ON THE ECG WAVE
P-wave: when the atria depolarizes
QRS complex: when the ventricles depolarize. has the greatest amount of electrical activity
T-wave: is when the ventricles repolarize
EXPLAIN THE VENTRICULAR FILLING PHASE OF THE CARDIAC CYCLE (MID-LATE DIASTOLE)
- atria and ventricles both in diastole
- pressure in the heart is low so blood passivle flows into the ventricles from thr atria
- around 70-80% of ventricular filling happens this way
- the AV valves are open and the SL valves are closed
The atria depolarizes (P-wave), leading to atrial systole, atrial pressure forces the remaining 20% of blood out of the atria. the atrias then relax and then the ventricles contract (QRS complex). the ventricles now have max volume of blood, this is the end diastolic volume
EXPLAIN THE ISOVOLUMETRIC CONTRACTION PHASE OF THE CARDIAC CYCLE
ventricular systole occurs which increases pressure in the ventricles. this causes the AV valves to close to prevent backflow into the atria. the volume of blood in the ventricles remain unchanged since the semilunar valves are also still closed.
EXPLAIN THE VENTRICULAR EJECTION PHASE OF THE CARDIAC CYCLE
pressure continues to rise in the ventricles, once it exceeds the pressure of its associated large artery (aorta or pulmonary trunk), the semilunar valves open and blood is ejected into the aorta and pulmonary trunk. this is stroke volume
EXPLAIN THE ISOVOLUMETRIC RELAXATION PHASE OF CARDIAC CYCLE (EARLY DIASTOLE)
After the T-wave, the ventricles are in diastole. the amount of blood remaining in the ventricles during this phase is called end systolic volume. pressure rapidly falls in the ventricles which causes backflow from the major arteries, to prevent this the semilunar valves close, the blood rebounding off h=of the valves causes the dicrotic notch
