The Heart + Cardiac Cycle Flashcards

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1
Q

The Human Heart’s Make Up

A

Consists of cardiac muscle - like smooth muscle but contracts involuntarily

=> made up of cells that are connected by cytoplasmic bridges
=> enables electrical impulses that pass through the tissue
=> has a lot of myoglobic (carries o2) + mitochondria (for energy)

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2
Q

Cardiac Cycle

A

The coordinated cycle of systole (contracting) and diastole (relaxation) that pumps blood away from the heart

=> sequence of events that take place during 1 heartbeat

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3
Q

Key Points to Remember

A

=> Blood flows from high pressure to low pressure
=> Contraction increases pressure

=> Valves (semi-lunar + A-V) are unidirectional
=> Valves open + close according to pressure gradients

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4
Q

(1) Diastole

A

=> Cardiac muscle relaxes
=> Atria fill w/ blood, increasing pressure + allowing blood to pass in to ventricles via A-V valves

=> A-V open - draining blood from atria into ventricles
=> Pressure in ventricles < aorta + pulmonary artery so semi lunar valves closes

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5
Q

(2) Atrial Systole

A

=> Cardiac muscles in atria contract, increasing pressure
=> Force blood into ventricles
=> Pressure in atria > ventricle, A-V valves open

=> Pressure in ventricles < aorta + pulmonary artery so semi-lunar valves remain open

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6
Q

(3) Ventricular systole

A

=> Atria relax + ventricles contract
=> A-V valves shut as pressure in ventricles > than atria

=> Semi-lunar valves open + blood is pushed in the aorta + pulmonary artery
=> Pressure in ventricle higher than artery

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7
Q

Step 1 in Cardiac Cycle

A

Wave of depolarisation spreads over the SAN over atria

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8
Q

Step 2 in Cardiac Cycle

A

Atria depolarizes, contracts and pump blood to ventricles

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9
Q

Step 3 in Cardiac Cycle

A

Wave reaches A/N and transmitted down the bundle of His

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10
Q

Step 4 of Cardiac Cycle

A

Wave transmitted along Purkinje fibres into ventricles

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11
Q

Step 5 of Cardiac Cycle

A

Ventricles depolarizes contract + pump blood into arteries

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12
Q

Step 6 of Cardiac Cycle

A

Atria + ventricles depolarizes and relax

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13
Q

Step 7 of Cardiac Cycle

A

Atria fill blood from vena cava + pulmonary vein

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