The Heart Flashcards

1
Q

Definition of the cardiac cycle

A

The sequence of events required in one successful heart beat (0.8 seconds)

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2
Q

Diastole:

A

Relaxing

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3
Q

Systole:

A

Contracting

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4
Q

What is atrial systole:

A

Atria contracts which forces blood into the ventricles

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5
Q

Definition of myogenic:

A

Ability to generate its own electrical impulse, causes cardiac muscle to contract

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6
Q

What is the aim of the cardiac conduction system?

A

Pass the electrical impulses through the cardiac muscle, forcing the atria and ventricles to contract

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7
Q

What are the 5 structures involved in the Cardiac Conduction Cycle?

A
SA Node
AV Node
Bundle of His
Bundle Branches
Purkinje Fibres
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8
Q

Describe the role of the SA (Sino-Atrial) Node and where it is located

A

Generates the electrical impulse, causes atria walls to contract
Known as the ‘pacemaker’
Located in the wall of the Right Atrium

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9
Q

Describe the role of the AV (Atrio-Ventricular) Node

A

Collects the impulse from the SA Node and delays it by 0.1 second to allow the atrium to finish contracting before sending it to the Bundle of His

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10
Q

Describe the role of the Bundle of His

A

Splits the impulse in two in order to distribute it to the ventricles
Located in the septum (separates left and right of heart)

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11
Q

Describe the role of the Bundle branches

A

Carry the the impulse around the walls and to the base of each of the ventricles

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12
Q

Describe the role of the Purkinje Fibres

A

Distribute impulses through the ventricle walls, causing them to contract

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13
Q

Name each stage (6) on the path of blood from the body to the lungs

A

Deoxygenated blood

Vena Cava -> Right Atrium -> (Tricuspid Valve) -> Right Ventricle -> (Semi-lunar valve) -> Pulmonary Artery

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14
Q

Name each stage (6) on the path of blood from the lungs back to the body

A

Oxygenated blood

Pulmonary Vein -> Left Atrium -> (Bicuspid Valve) -> Left Ventricle -> (Semi-lunar valve) -> Aorta

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15
Q

Define stroke volume (with units)

A

The volume of blood leaving the left ventricle during each cardiac cycle (ml)

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16
Q

Define venous return

A

The volume of blood that returns to the heart (right atrium) between cardiac cycles

17
Q

Define cardiac output (with units)

A

The volume of blood leaving the left ventricle per minute (HR x SV = CO) ml/min

18
Q

Define cardiac hypertrophy

A

The heart muscle getting bigger and stronger leading to greater contraction force

19
Q

Define bradycardia

A

A low resting heart rate (below 60 bpm)

20
Q

Define Starling’s Law

A

The more blood that returns to the heart (venous return), the more blood leaves the heart (stroke volume), caused by the stretch of the ventricular walls leading to greater contraction force

21
Q

CCC: (Name, location, function)

A

Cardiac Control Centre
Located in the medulla oblongata
Responsible for heart rate regulation

22
Q

What are the 3 channels that the CCC receives information via?

A

Neural (3)
Intrinsic (2)
Hormonal (1)

23
Q

What are the 3 neural receptors?

A

Chemoreceptors
Proprioreceptors
Barorecpetors

24
Q

What is the role of the Chemoreceptors and where are they located?

A

Detects chemical changes in the blood (pH) (e.g. inc in CO2, inc in lactic acid)
Located in the main wall of the blood vessels (aorta)

25
Q

What is the role of the Proprioreceptors and where are they located?

A

Inform the CCC that movement has increased

Located i muscles, tendons, joints

26
Q

What is the role of the Baroreceptors and where are they located?

A

Inform the CCC of changes (inc) in blood pressure by monitoring the stretch of blood vessels
Located in blood vessel walls

27
Q

What are the 2 methods of intrinsic control?

A

Temperature and Starling’s Law

28
Q

What is the role of temperature regarding intrinsic control?

A

Monitor blood viscosity (inc) and speed of nerve impulse transmission

29
Q

What is the role of Starling’s Law regarding intrinsic control?

A

Inc in VR -> Inc EDV which stretches the heart wall, results in greater SA firing rate

30
Q

What is the hormonal control method?

A

Adrenaline/Noradrenaline

31
Q

What is the role of adrenaline?

A

Increases contraction force which results in a stronger heart beat

32
Q

What is the role of noradrenaline?

A

Detect an inc or dec in HR

33
Q

What is the role of the Sympathetic/Parasympathetic Nervous System?

A

Symp: Increases HR by stimulating the SA node (increases firing rate) via the Cardiac Nerve Accelerator
Para: Vice versa -> dec HR using vagus nerve