What is the purpose of the heart?
to pump blood either to the lungs through pulmonary circuit or through the body via the systemic circuit
Heart....
1. Size?
2. Weight?
3. begins beating how many days after conception?
4. Located where?
1. size of your fist2. weighs less than a pound3. 22 days4. thoracic cavity
What are the 4 points of the perimeter of the heart in order to distinguish a normal size heart from an enlarge heart?
superior left point-at costal cartilage of second rib about an inch lateral to sternum
inferior left point-fifth intercostals space at midclavicar line
superior right point-costal cartilage of third rib connects to sternum
inferior right point-costal cartilage of sixth rib about an inch lateral to sternum
What is the heart enclosed by?
a serous membrane that has 3 layers (fibrous, parietal, & visceral pericardium)
What is fibrous pericardium?
outer layer that adheres to the diaphragm & holds the heart in place
What is parietal pericardium?
adheres to the inner surface of fibrous pericardium & forms parietal cavity that is filled with serous fluid
What is visceral pericardium?
also called epicardium and lies just above myocardium
What are the 3 layers of the heart wall?
Epicardium -superficial, comes in contact with epicardium & holds fat
Myocardium - middle muscular layer that contracts to move blood
Endocardium - deepest layer composed of endothelial cells that line the chambers & make the valves
What are the heart chambers divided into left and right sides by interiorly?
interatrial septum or inventricular septum
1. Exteriorly, the seperation of atria of ventricles is indicated by what?
2. Ventricle seperation is indicated by what?
1. coronary sulcus (crown)2. anterior & posterior interventricular sulcus
What is the right atrium?
- top right chamber that has the right auricle- receives blood low in oxygen coming from upper & lower body via the superior & inferior vena cava & coronary sinus
What does the right atrium open into ventricle through?
the right atrioventricular valve (tricuspid)
What is fossa ovalis?
indicated the area at which the fetal heart had an opening
What is the right ventricle?
- a lower right chamber- receives blood from right atrium
When the ventricle contracts, what happens?
it sends blood out to the lungs, first through pulmonary semilunar valve then via the pulmonary artery
What is the left atrium?
- upper left chamber- receives oxygenated blood coming from the lungs via the pulmonary vein
What does the left atrium open into the ventricles through?
left atrioventricular valve (mitral/bicuspid valve)
What is the left ventricle?
- lower left chamber- receives blood from left atrium & forms the apex of the heart with the same cheracteristics as the right ventricle
What forms the apex of the heart?
left ventricle
When the left ventricle contracts, what happens?
blood flows through the aortic semilunar valve & then to system circulation via the aorta
What is the path that the blood takes as it travels through the pulmonary & systemic circulatory paths?
Blood empties into...right atriumthrough...SVC, IVC, Coronary Sinus
Right Atriumslightly contracts & blood moves past...Tricuspid valveinto...Right ventricle
right ventricle fills with blood & contracts sending blood out of the heart as it passes through....pulmonary semilunar valveto the....pulmonary trunkinto the...right and left pulmonary artery
pulmonary arteriescarry the blood into the...lungsand heads towards the heart via the...right and left pulmonary veins
blood empties into the...left atriumfilling the chamber slightly contracting as blood passes through the...mitral valveleaving the chamber
left ventriclefilles with blood & powerfully contracts to send blood past the...aortic semilunar valveinto the...aortic arch
aortabranches sending blood into all areas of the....body (systemic curculation)
then starts over again...back to the heart SVC, IVC, Coronary sinus
1. What is heart beat?
2. What is the resting heart rate?
1. sequence of atrial & ventricular contraction2. 60-80 beats per minute
What is systole and what is diastole?
Systole - when the heart contracts
Diastole - when the heart relaxes
What is the endocardium designed to do?
prevent back flow of blood into the chambers
Each valve has how many cusps?
two or three cusps
*RAV (tricuspid valve)-3 cusps*LAV (bicuspid/mitral valve)-2 cusps*Aortic semilunar valve-3 cuspids*Pulmonary semilunar valve-3 cuspids
What are the jobs of the atrioventricular valves?
prevent blood from flowing back into the atria when the ventricles contract
What is the job of the semilunar valves?
prevent blood from flowing back into the ventricles
What does closing of the valves cause?
vibrations that can be interpreted as sounds (lub-dub)
What is the lub and what is the dub?
lub - closing of AV valvesdub - produced by closing of semilunar valves
To listen to each valve, what is used to place at different locations when checking for heart beat?
stethoscope
Dense connective tissue lies throughout the heart and serves the following functions...
1. Anchors valves2. prevents over dialation of valves3. serves as insertion points for cardiac muscle4. prevents direct electrical impulse travel from atria to ventricles
1. How does the heart generates electrical impulse and conduct rhytmic contractions?
2. what are the components?
1. by the conduncting system:cardiac muscles generate impulses that signal rhythmic contractions independent of nervous control controlling the sequence at which the chambers contract-thus stablishing the basic heart rate
2. sinoatrial node, internodal fibers, atrioventricular node, atrioventricular bundle (bundle of his), bundle branches, purkinje fibers
What is the sinoatrial node?
starting point, pace maker, sends out 70-80 impulses per minute
What are internodal fibers?
fibers that transmit the impulse between SA and AV node
What is the atrioventricular (AV) node?
heart cells where signal is delayed so ventricles fill. When the SN stops working, AV node takes over.
What is the atrioventricular bundle (bundle of his)?
heart cells that carry an impulse to the interventricular septum
What are bundle branches?
heart cells that carry an impulse from interventricular septum & become pirkinje fibers
What are purkinje fibers?
long barrel like muscle cells specialized for conduction
What the innervation of the heart?
heart is altered by nervous system control where the nerve fibers that reach the heart are parasympathetic & sympathetic fibers
What is the heart blood supply?
heart muscles require its own set of blood vessels to nourish the cardiac tissue
What is coronary artery disease?
caused by atherosclerosis (accumulation of fatty deposits) with the arteries supplying the heart muscle becoming clogged causing chest pain
Howe does a heart attack occur?
when the cardiac cells die (myocardial infarction)
What is coronary bypass surgery?
restores blood supply to heart tissue
What is silent ischemia?
painless silent fatal heart attack
What is heart failure?
weakening of the heart because it cannot pump at a rate adequate enough to keep up with the body's oxygen demand resulting from a heart attack, improper filling of ventricles, or congestive heart failure
What is congestive heart failure?
enlargement of the heart causing pumping ineffiency with the right ventricle somtimes enarging due to hgih pressure in the pulmonary circuit
What are the disorders of the conduction system?
ventricular fibrillation - random firing of electrical impulses allow for improper filling of ventricles, can cause cardiac arrest
atrial fibrillation-random stimulation of AV node signals by multiple signals in atrial myocardium ventrals causing ventricles to contract quickly & irregurly potentially forming blood clots & the blood clots can cause strokes