20.2 heart valves and circulation of blood

what happens to blood as the ventricles contract?

as each of the ventricles contract it pushes blood into the ventricles or our into an artery

when do heart valves open and close?

walves open and close in response to pressure changes as the heart contracts and relaxes

valves ensure what?

valves ensure one way flow of blood

valves open to

let blood through

valves closes to prevent what?

valves close to prevent back flow

what are the names of the atrioventricular valves?

tricuspid (R), bicuspid (L)

what do the AV valves look like when they are open

ends of the cusps project into the ventricle

what do the components of the ventricles look like when the ventricles are relaxed?

papillary muscles relaxed

chordae tendineae slack

how does blood move from atria?

blood moves from higher pressure in the atria to lower pressure in the ventricles through open AV valves

what happens to parts of the ventricles when the ventricles contract?

blood pressure drives the cusps up until they are closed

papilary muscles contract, tightening chorade tendineae

what does the tightening of the chordae tendineae by the papillary muscles prevent?

back flow

if AV valves or chordae tendineae damaged what happens?

back flow during ventricular contraction

what do the semilunar valves do?

SL valves allow ejection of blood from the heart into the arteries

what do the SL valves prevent?

back flow into the ventricles

when do the SL valves open?

the SL valves openwhen pressure in the ventricles exceeds the pressure in the arteries

what happens to blood flow when ventricles relax?

blood flows back to the heart

what is stenosis?

the narrowing of a heart valve opening that restricts blood flow

what is insufficiency?

filure of a heart valve to close completely

what is mitral stenosis?

scar formation or a congenital defect causes narrowing of the mitral valve

what is a cause of mitral insufficiency? (backflow into l. atrium)

mitral valve prolapse

what is the most common valve disorder?

mitral valve prolapse

what is aortic stenosis?

aortic valve narrowing

what is aortic insufficiency?

backflow of blood from the aorta into the left ventricle

what is an example of an infectious disease that damage or destroy valves?

Rheumati fever: acute systemic inflammatory disease occurring after strep throat

what two circuits does the heart pump into with each beat?

systemic and pulmonary circuits

the left side of the heart pumps into what circuit?

systemic circuit - to receive oxygenate blood from the lungs

what do arteries give rise to in the systemic circuit?

arterioles leading to systemic capillaries

what happens in the walls of systemic capillaries?

exchange of nutrients and gases

blood unloads oxygen and takes CO2

what happens after blood flows through the capillaries?

blood enters systemic venules which carry deoxygenated blood away and merge to form systemic veins

what circuit does the right side of the heart pump through?

pulmonary circuit - receives all deoxygenated blood returning from the systemic circuit

what happens to CO2 in pulmonary capillaries?

in pulmonary capillaries blood unloads CO2, which is exhaled, they pick up O2 from inhale

what is coronary circulation?

the myocardium’s own network of blood vessels

the coronary arteries branch from?

the aorta and encircle the heart

where does blood go when the heart relaxes?

when the heart relaxes the high pressure of blood in the aorta propels blood through coronary arteries into c. veins

what do the left and right coronary artery do?

supply blood to the myocardium

what does the anterior interventricular branch (artery) do?

supplies blood to the walls of both ventricles

where does the right coronary artery supply blood to?

supplies atrial branches to the right atrium

where does the posterior interventricular branch (artery) supply blood?

supplies walls of the two ventricles with oxygenated blood

where does the marginal branch (artery) supply blood?

transports oxygenated blood to the wall of the right ventricle

what is anastomosis?

an end to end union or joining of blood vessels, lymphatic vessels, or nerves

what do anastomosis do when there is a block?

provide oxygen to the heart through a different route

what are the different routes of anastomosis called?

collateral circulation

does myocardium have any anastomoses?

myocardium has a lot of anastomoses

where does deoxygenated blood drain?

from the myocardium into the coronary sinus

where does blooc from the coronary sinus empty?

into the right atrium

what are the principal veins that carry blood into the coronary sinus?

great cardiac vein, middle cardiac vein, small cardiac vein, and anterior cardiac veins

great cardiac vein drains blood were?

L & R atrium and ventricles

where does the middle cardiac drain?

drains areas of the L & R ventricles

where does the small cardiac vein drain?

drains the right atrium and ventricles

where do the anterior cardiac veins drain?

drains the R ventricles and open directly to R atrium

what causes further damage to the heart with a coronary artery is blocked?

reperfusion

what is reperfusion?

reestablishment of blood flow, leading to further tissue damage

what causes the further tissue damage of reperfusion?

the un paired electron of free radicals forming in reintroduced oxygen

what enzymes does the body produce to make free radicals less reactive?

superoxide dismutase, catalase

what nutrients remove free radicals from circulation?

Vitamin E, C

zinc

beta -carbonate

selenium

what is a partial block in a coronary artery?

myocardial ischemia - lowers blood flow to the myocardium

what does myocardial ischemia cause?

hypoxia

what is angina pectoris?

“strangled chest” the pain associated with myocardial ischemia

what is silent myocardial ischemia?

an ischemia episode without pain

what is myocardial infraction?

complete obstruction in blood flow of the coronary artery

what happens as a result of MI?

tissue death of the area with block

depending on location of tissue death potential for sudden death b/c ventricular fibralation

treatments for MI are?

injection of thrombolytic agent (clot dissolving):

streptokinase

heparin

coronary angioplasty

coronary artery bypass grafting