The Cardiac Cycle Flashcards

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1
Q

what is the cardiac cycle?

A

series of events that occur when the heart beats, circulates blood through pulmonary & systemic circuits that make up double circulatory system.

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2
Q

why is the double circulatory system more efficient?

A

keeps the oxygenated & deoxygenated blood separate.

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3
Q

where does the pulmonary circuit carry the blood?

A

to the lungs to be oxygenated & back to the heart.

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4
Q

what happens in the lungs?

A

CO2 is removed from the blood & O2 taken up by haemoglobin in RBC

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5
Q

where does the systemic circuit carry the blood?

A

around the body to deliver O2 & returns deoxygenated blood to the heart

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6
Q

what is the cardiac cycle broken down into?

A

the sequence of mechanical & electrical events that are repeated every heartbeat. 2 phases - diastole, systole.

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7
Q

whats diastole?

A

relaxation phase, during this stage blood pressure is at lowest.

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8
Q

whats systole?

A

contraction phase, this is when the blood pressure rises.

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9
Q

how do we monitor the frequency of the cardiac cycle?

A

heart rate - number of beats per minute.

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10
Q

how does the cardiac cycle start in the left side of the heart? CC in LSoH

A

blood drains into the left atrium from the lungs along the pulmonary vein.

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11
Q

what happens after the blood enters the left atrium? CC in LSoH

A

raise of BP in left atrium forces the left bicuspid valve open.

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12
Q

what happens when the left bicuspid valve is forced open? CC in LSoH

A

contraction of the left atrial muscle forces more blood through the valve.

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13
Q

what happens after the left atrial muscle is done contracting? CC in LSoH

A

the left ventricular muscles start to contract.

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14
Q

what happens after left ventricular systole is done?

A

forces the left bicuspid valve to close & opens the aortic valve causing blood to leave left ventricle via aorta.

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15
Q

whats cardiac diastole?

A

when heart refills with blood

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16
Q

whats ventricular diastole?

A

when the ventricles are refilling & relaxed

17
Q

what does the heart need to beat?

A

electrical signals to trigger the muscles to contract & relax.

18
Q

what are the components of the specific pathway for the heartbeat?

A

sinoatrial node, atrioventricular node, bundle of his, purkinje fibres.

19
Q

describe the sinoatrial node.

A

known as natural pacemaker - causes impulse to travel through the atria causing them to contract & forces blood into ventricles. It also sets hearts rhythm & rate.

20
Q

describe the atrioventricular node.

A

detects impulse travelling through the atria & redirects it to bundle of his - causes a delay , slowing the spread of electrical impulse across the heart & allowing atria to contract before ventricles.

21
Q

describe the bundle of his (atrioventricular bundle)

A

group of fibres in the septum which the impulse travels through to base of ventricles

22
Q

describe the purkinje fibres.

A

act as neurons & are found in the walls of the ventricles. the impulse from bundle of his reach here which cause ventricles to contract.

23
Q

what are baroreceptors?

A

the detect changes in pressure of blood filling the atria, they send signals to the CNS which triggers vasodilation which reduces pressure in the blood.