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Heart
Anatomy & Physiology
Question | Answer |
---|---|
cardiovascular system | essential for life, composed of heart and blood vessels, and circulate blood continuously to maintain homeostasis |
transportation of blood through the body | allows for exchange of substances between capillaries and cells, adequate perfusion (sufficient blood delivered to maintain health of body cells), and requires continual pumping of the heart and open vessels |
perfusion | delivery of blood per time per gram of tissue |
if cardiovascular system fails (i.e. heart fails to pump blood or vessels are blocked) | cells will have inadequate amount of blood and will be deprived of oxygen and nutrients, waste will accumulate, and cell death is possible |
blood vessels | "soft pipes" of the cardiovascular system of which there are three types |
types of blood vessels | arteries, veins, and capillaries |
arteries | carry blood away from the heart, and most (but not all) carry oxygenated blood |
veins | carry blood back to the heart and most (but not all) carry deoxygenated blood |
capillaries | sites of gas exchange that occurs between blood and air in lungs and between blood and body cells |
heart | center of the cardiovascular system and is a hollow, four-chambered organ (atria and ventricles) with two pumps |
atria | receive blood from the pulmonary and systemic circuits |
ventricles | the pumping chambers of the heart |
two pumps of the heart | right sided pump and left sided pump |
right sided pump | receives deoxygenated blood from body and pumps it to the lungs |
left sided pump | receives oxygenated blood from lungs and pumps it to the body |
left atrium and right atrium | superior chambers for receiving blood |
left ventricle and right ventricle | receive blood from respective atria and are inferior chambers that are meant for pumping blood away |
great vessels of the heart | transport blood directly to and from chambers and are continuous with each chamber |
specific names of great vessels | pulmonary trunk, aorta, superior and inferior vena cava |
pulmonary trunk | splits into pulmonary arteries and receives deoxygenated blood from the right ventricle (only artery that caries deoxygenated blood) |
vessels entering the right atrium carrying deoxygenated blood are... | superior vena cava and inferior vena cava |
superior vena cava | bring blood back from the top part of the body |
inferior vena cava | brings blood back from the lower part of the body |
vessels entering the left atrium carrying oxygenated blood are... | right and left pulmonary veins (only veins that cary oxygenated blood) |
vessel leaving the right ventricle carrying deoxygenated blood | pulmonary trunk |
vessel leaving the left ventricle carrying oxygenated | aorta |
two sets of valves located within the heart | atrioventricular valves and semilunar valves |
atrioventricular valves | between the atrium and ventricle of each side and there are two |
two atrioventricular valves | right AV valve (tricuspid) and left AV valve (bicuspid or mitral) |
right AV valve or tricuspid | located between right atrium and right ventricle |
left AV valve or bicuspid or mitral | located between left atrium and left ventricle |
semilunar valves | boundary between the ventricle and arterial trunk and they open to allow blood to flow through the heart and close to prevent backflow and there are two |
two semilunar valves | pulmonary semilunar valve and aortic semilunar valve |
pulmonary semilunar valve | located between right ventricle and pulmonary trunk |
aortic semilunar valve | located between left ventricle and the aorta |
circulation routes | arranged in two circuits (pulmonary and systemic circulation) |
pulmonary circulation | carries deoxygenated blood from the right side of the heart, goes through blood vessels to the lungs, picks up oxygen and releases carbon dioxide, and brings blood back through vessels to the left side of the heart |
systemic circulation | moves oxygenated blood from the left side of the heart, moves through vessels to systemic cells, exchanges nutrients, gases, and wastes, and returns blood in vessels to right side of the heart |
pathway of blood through the heart | right atrium -> tricuspid valve -> right ventricle -> pulmonary semilunar valve -> pulmonary trunk -> pulmonary arteries -> lungs -> pulmonary veins -> left atrium -> bicuspid valve -> left ventricle -> aortic semilunar valve -> aorta -> systemic circ. |
heart location | posterior to sternum left of body midline, between the lungs in the mediastinum, enclosed in pericardium, a double-walled sac and is approximately the size of a fist |
pericardium | enclosed the heart and consists of three layers |
three layers of the pericardium | pericardial sac (outermost covering), visceral layer or serous pericardium (epicardium), and pericardial cavity |
pericardial sac | double-layered, fibroserous sac |
two layers of the periocardial sac | outer portion (tough connective tissue) and inner portion (thin serous membrane) |
outer portion of pericardial sac | attached to diaphragm and base of aorta and pulmonary trunk and restricts heart movement and prevents heart from overflowing |
visceral layer of serous pericardium (epicardium) | second serous membrane that tightly adheres to the heart and is continuous with parietal layer of the pericardium |
pericardial cavity | potential space between parietal and visceral layers |
varying wall heart thickness | ventricle walls are thicker than atrial walls because ventricles are the "pumping chambers" |
thickness of left ventricle | three times thicker than right ventricle because it must generate higher pressure to force blood through systemic circulation |
heart valves | ensure one way flow of blood, consist of endothelium-lined fibrous connective tissue flaps (called cups or leaflets), and the flexibility and elasticity of these decreases with age |
right atrioventricular (AV) valve | covers right atrioventricular opening and has three cusps |
left atrioventricular (AV) valve | covers left atrioventricular opening and has two cusps |
atrioventricular valves | when open, cusps extend into the ventricles (allow blood to move from atrium to ventricle), and close with ventricular contraction (forces blood superiorly) |
chordae tendinae | secured by papillary muscles and attach to the surface of the AV valves to prevent valve from being pushed open when closed |
pulmonary semilunar valves | located between right ventricle and pulmonary trunk |
aortic semilunar valve | located between left ventricle and the aorta |
semilunar valves | composed of three pocketlike semilunar cusps and do not have papillary muscles or chordae tendineae |
semilunar valves | open when ventricles contract and close when ventricles relax |
venticles contract causing | a force of blood that pushes valves open and blood enters arterial trunks |
ventricles relax causing | pressure in ventricle to be less than pressure in the arterial trunk, backward flow of blood toward ventricle, caught in cusps of valves, which close, and prevent blood flow back into ventricle |
two sounds associated with closing of heart valves (lub-dup) | first sound occurs as AV valves close and signifies beginning of systole and second sound occurs when SL valves close at the beginning of ventricular diastole |
heart murmurs | abnormal heart sounds most often indicative of valve problems |
conduction system | initiate and conduct electrical signals (sinoatrial (SA) node -> atrioventricular (AV) node -> atrioventricular (AV) bundle -> purkinje fibers) |
sinoatrial (SA) node | in posterior wall of right atrium, adjacent to superior vena cava, initiates heartbeat, and referred to as "pacemaker" of heart |
atrioventricular (AV) node | in floor of right atrium, between right AV valve and coronary sinus opening |
atrioventricular (AV) bundle | extends from AV node through interventricular septum, divides into left and right bundles |
purkinje fibers | extend from left and right bundles, from apex of heart through walls of ventricles |
electrocardiogram (ECG/EKG) | monitoring electrodes attached to skin (at wrist, ankles, and chest locations) that collect electrical signals and chart them to provide assessment of electrical changes of heart and composite tracing of all cardiac action potentials |
three deflections in waves and segments of ECG recording | P wave, QRS complex, T wave |
P wave | reflects electrical changes of atrial depolarization and originates in SA node |
QRS complex | electrical changes associated with ventricular depolarization and atria simultaneously repolarizing but masked by above |
T wave | electrical change associated with ventricular repolarization |
waves of ECG recording | associated with depolarization or repolarization |
flat lines of ECG recording | correspond to no electrical charge and are between cycles (heart resting between beats) |
systole | contraction of a heart chamber |
diastole | relaxation of the heart chamber |
cardiac cycle components... | changes within heart from one heartbeat to the next |
pressure changes in cardiac cycle | alternating contraction and relaxataion of atria and ventricles cause pressure increase during contraction and decrease during relaxation |
pressure changes in cardiac cycle are responsible for... | unidirectional movement of blood through chambers (blood moving along pressure gradient) and for opening and closing of heart valves (ensures blood moves in a "forward" direction |
ventricular contraction | causes ventricular pressure to rise, AV valves pushed and kept closed (preventing backflow), semilunar valves pushed open, and blood forced from ventricle into arterial trunk |
ventricular relaxation | causes ventricular pressure to decrease, closure of semilunar valves (pressure no longer pushing them open) and AV valves open (pressure no longer pushing them closed) |
as the cardiac cycle begins... | four chambers at rest, blood returning to right atrium and to left atrium, passive filling of ventricles, AV valves open, atrial pressure > ventricular pressure, SL valves closed, and pressure in ventricles < arterial trunk pressure |
atrial systole (1) | atria contracted and ventricles relaxed, moves remaining blood from atria to ventricles, ventricular pressure < atrial pressure and < arterial trunk pressure, AV valves open, SL valves closed, ventricles at maximum blood volume (EDV in ventricle) |
end-diastolic volume (EDV) | most amount of blood volume in ventricles |
early ventricular systole (2) | beginning of ventricular contraction (moves blood into arterial trunks), atria relaxed & ventricles contracted, ventricular pressure > atrial pressure & ventricular pressure < arterial trunk pressure, AV valves/SL valves closed, isovolumetric contraction |
isovolumetric contraction | no change in volume |
late ventricular systole (3) | atria relaxed and ventricles contracted, ventricular pressure > atrial pressure, ventricular pressure > arterial trunk pressure, AV valves closed, SL valves open |
late ventricular systole (3) continued | blood ejection term ventricular ejection, amount of blood (stroke volume) and some blood remaining in ventricle (end-systolic volume (ESV) |
ESV equals | EDV - SV |
stroke volume | amount of blood |
ventricular ejection | blood ejection |
end-systolic volume (ESV) | blood remaining in ventricle |
early ventricular diastole (4) | atria relaxed and ventricles relaxed, ventricular pressure > atrial pressure, ventricular pressure < arterial trunk pressure, AV valves closed, blood flowing backward slightly (caught in SL valves, which close) and prevent backflow into ventricles |
late ventricular diastole (5) | start of ventricular filling, atria relaxed and ventricles relaxed, ventricular pressure < atrial pressure (forces open AV valve), ventricular pressure < arterial trunk pressure, SL valves closed, and when most ventricular filling occurs |
cardiac output (CO) | amount of blood pumped by a single ventricle in one minutes, measure of effectiveness of cardiovascular system, increases in healthy individuals during exercise, may not increase in inds with impaired heart function, determined by heart rate & stroke vol. |
heart rate (HR) | number of beats per minute |
stroke volume (SV) | volume of blood ejected during one beat |
CO equals | HR x SV |
function of heart rate and stroke volume | smaller heart, smaller stroke volume and larger heart, larger stroke volume |
smaller heart, smaller stroke volume | resting heart rate higher to maintain normal resting cardiac output (why women's heart rate typically greater than men and why children and newborns have faster heart rate) |
larger heart, larger stroke volume | (i.e. athletes with larger and stronger heart) cardiac muscles hypertrophied, larger stroke volume, lower heart rate to maintain cardiac output (i.e. Lance Armstrong with HR of 33 bmp) |