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A&P exam practice
Terms in this set (20)
atrial systole: atria contraction forces small amount of additional blood into the relaxed ventricles
atrial systole ends, atrial diastole begins
ventricular systole - 1st phase: as ventricles contract, they exert enough pressure to close the AV valves, but not enough to open the semilunar valves
ventricular systole - 2nd phase: as the pressure in the ventricles rise, the semilunar valves are forced open & blood is ejected
ventricular diastole - early: as ventricles relax, blood forces back against the cusps of the semilunar valves forcing them closed. blood flows into the relaxed atria
Ventricular diastole - ate: all chambers are relaxed, ventricles fill passively
how to increase CO (cardiac output) (5)
- exercise --> increases N, NE --> increases HR --> increases CO
- increase SV --> decreasing ESV --> increasing contractility
how to decrease CO (3)
- decrease HR --> parasympathetic drugs like ACH
- decrease SV --> decreasing EDV --> laying down
decreasing SV (5)
- decrease venous return --> decreases EDV --> decreases SV
- decrease contractility --> with parasympathetic stimulation --> increases ESV --> decreases SV
increasing SV (5)
- increase venous return --> increases EDV --> increases SV
- increases contractility -> with E, NE, T3 --> decreases ESV --> increases SV
increase heart rate (2)
- exercise --> increases N, NE --> increases HR
- increase venous return --> stretches pacemaker cells --> increases HR
decrease heart rate
- change permeability of channels (less sodium
- decrease venous return
flow of blood from the heart starting with the right atria and ending with the aortic arch
- The right atrium receives blood from the systemic circuit through the two great veins: superior & inferior vena cava
- The superior vena cava delivers blood (deoxygenated) to the right atrium from the head, neck, upper limbs & chest. The inferior vena cava delivers blood (deoxygenated) to the right atrium from the rest of the trunk, the viscera & lower limbs
- Blood travels from the right atrium into the right ventricle through the tricuspid valve.
From the right ventricle, blood flows through the pulmonary valve into the pulmonary trunk.
- From the pulmonary trunk, blood flows into the left & right pulmonary arteries. These vessels branch repeatedly within the lungs before supplying the capillaries, where gas exchange occurs.
- From the respiratory capillaries, blood collects into small veins that ultimately unite to form the four pulmonary veins.
- The posterior wall of the left atrium receives blood from the two left & the two right pulmonary veins.
- Blood flows from the left atrium into the left ventricle via the mitral valve.
- Blood leaves the left ventricle through the aortic valve and enters the ascending aorta.
- From the ascending aorta, blood flows through the aortic arch and into the descending aorta.
right v left side of the heart
receives deoxygenated blood from the right atrium
comprises a thin wall
pumps the received blood to the lungs through the pulmonary trunk
develops a lower pressure to the lungs through pulmonary trunk
develops a lower pressure than the left ventricle while pumping blood
receives oxygen-rich blood from the left atrium
comprises a thick wall
pumps the received blood to whole body through the aorta
develops higher pressure while pumping
how autorhythmic cells generate their own action potential (5 steps)
1. Get the message from SA node
2. SA node sends message all around the atria and comes back to converge on the AV node (sends message for atria to contract)
3. AV node holds action potential (100 m-sec delay) while atrias contact
4. the impulse is now sent to the AV bundle, left and right bundle branches
5. impulse is now distributed by purkinje fibers. atrial contraction is completed & ventricular contraction begins.
autorhythmic cell graph explained (4 steps)
1. have special channels called IF channels (leaky channels for NA+ & K+)
2. once enough sodium is in, reaches threshold, calcium channel open & calcium rushes in
3. K+ goes out, we repolarize
4. process repeats
what actives voltage-gated sodium channels? and then what do those channels activate?
- 20 mV passes through gap junction which activate voltage-gated sodium channels which activate contractile cells
how do contractile cells get their action potential
action potential enters through gap junctions through the intercalated discs
process of contractile cells during refractory period
sends message to muscle cells to shorten sarcomeres, myosin heads grabs actin & shortens the muscle tissue
contractile cells graph explained (5 steps)
1. action potential enters --> voltage gated sodium channels
2. voltage-gated potassium (K+) channels open
3. calcium channels open & calcium rushes in
4. creates a plateu bc the calcium entering balances out the potassium leaving
5. calcium channels close --> slows potassium channels open --> begin repolarizing and go back to the start
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