Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Semester 2: Physiology > cardiac cycle > Flashcards

cardiac cycle Flashcards

1
Q

What is convection?

A

Convection is the mass movement of fluid caused by pressure differences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the main function of the heart?

A

Driving force that creates large pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is the main function of the arteries?

A

Distribution that alters blood flow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the main function of the capillaries?

A

Allows gaseous exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the main function of the veins?

A

Reservoir (usually around 2/3 of the blood volume)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Describe the SAN and its functions

A

Sino atrial node (SAN) is a group of cells located in the walls of the right atrium
→ It has the ability to spontaneously produce action potentials that travel through the heart via the electrical conduction system
→ It sets the rhythm of the heart there aka the hearts natural pacemaker

However, the action potential frequency (heart rate) is affected by the nerves that supply it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the AVN and its functions

A

It electrically connects the right atrium and right ventricle, delaying impulses so that the atria have time to eject their blood into the ventricles before ventricular contraction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the interaction between the SAN and AVN

A

SAN initiates electrical impulse in the right atrium, the AVN delays this impulse from travelling from the right atrium to the right ventricle, therefore allowing the right atrium to fully eject all the blood into the ventricle. Once the atrium has fully ejected all the blood into the ventricle, the electrical impulse goes from the AVN and travels down the bundle of His; causing ventricular depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

SAN pacemaker potential

What is meant by If threshold?

A

If: Slow sodium channel
If threshold is the voltage required to activate these channels
If threshold is roughly -40mV/-50mV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What happens during phase 4 of the SAN pacemaker potential?

A

After the SAN action potential, the membrane hyperpolarises to below the If threshold. This hyperpolarisation activates the sodium channels to open, resulting in an influx of sodium and slow depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What happens during phase 0 of the SAN pacemaker potential?

A

Slow depolarisation due to sodium influx eventually reaches If threshold. This threshold opens the voltage gated calcium channels causing an influx of calcium ions; causing rapid depolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What happens during phase 3 of the SAN pacemaker potential?

A

Voltage gated calcium channels are switched off and voltage gated potassium channels open, causing an efflux of potassium ions; resulting in repolarisation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Describe the generation of atrial and ventricular muscle action potential

A

Phase 0: rapid depolarisation
Voltage gated sodium channels open, causing a sodium influx
Voltage gated calcium channels start to open slowly
Phase 1: early repolarisation
Sodium channels close
Phase 2: plateau phase
Voltage gated calcium channels are fully open= calcium influx
Voltage gated potassium channels slowly start to open
Phase 3: rapid repolarisation
Voltage gated calcium channels close
Potassium channels open fully = potassium efflux
Phase 4: resting phase
The sodium/potassium pump works to pump 3 sodium OUT and 2 potassium IN
Membrane is impermeable to sodium but NOT potassium; helping to establish equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Describe the plateau phase of atrial and ventricular contraction

A

During the plateau phase, the voltage gated channels are open, allowing an influx of calcium. This influx of calcium causes a calcium induced calcium release (CICR) response; allowing more contractions to occur. Voltage gated potassium channels slowly start to open.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Describe the electrical conduction through the heart

A
  1. Electrical activity generated in the SAN spreads out via gap junctions into the atria
    1. At the AV node, the electrical conduction is delayed; this allows the atria to fully empty all the blood out into the ventricle
    2. Conduction then occurs RAPIDLY through the bundle of His, into the ventricles
    3. Conduction occurs through the purkinje fibres and spreads quickly throughout the ventricles
      Ventricular contraction begins at the apex and travels upwards allowing the blood to flow out of the aorta
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is an ECG? Describe fully

A

P wave= atrial depolarisation
PR segment= AVN delay

QRS complex = ventricular depolarisation

ST segment = time during which the ventricles are contracting AND emptying

T wave = ventricular repolarisation

TP interval= time during which ventricles and relaxing and filling

17
Q

What are some general principles of the cardiac cycle regarding electrical conductivity, pressure and valves?

A
  • Electrical conductivity is generate at the SAN and conducted throughout the heart
    • Electrical activity is converted into myocardial contraction which creates pressure changes within chambers
    • Blood flows from an area of high pressure to an area of low pressure (UNLESS THE FLOW IS BLOCKED BY A VALVE)
    • Valves open and close depending on pressure changes in chambers
    • Events on the right and left sides of the heart are the same, but pressures are lower on the right side

This is because the left side of the heart requires more pressure to pump blood around the whole body, whereas the right side of the heart only pumps blood to the lungs to be re-oxygenated

18
Q

Describe the blood flow throughout the heart by listing all the structures it passed through in ORDER

A
  1. Right atrium via vena cava
    1. Tricuspid valve
    2. Right ventricle
    3. Pulmonary valve
    4. Pulmonary artery
      Lung circulation
    5. Pulmonary veins
    6. Left atrium
    7. Bicuspid valve
    8. Left ventricle
    9. Aortic valve
    10. Aorta
      Systemic circulation
19
Q

Describe the cardiac cycle by explaining the pressure and volume changes throughout

A
  1. Ventricular filling/atrial contraction
    The pressure in the atria > ventricle therefore opening the mitral/tricuspid valves
    Atrial contraction occurs
    High pressure and small volume = blood moves from atria —-> ventricles
  2. Isovolumetric contraction
    The pressure in the ventricle > atria = mitral/tricuspid valves close
    Ventricular contraction = pressure rises
  3. Ejection
    Pressure in ventricles > aorta
    Ventricular contraction = smaller volume
    Higher pressure and smaller volume = aorta/pulmonary valves open = blood enters aorta/pulmonary arteries
  4. Isometric relaxation
    Pressure in aorta/pulmonary arteries > ventricles
    Aorta/pulmonary valves close
    Closed ventricle relaxes
20
Q

what is the right AV valve called

A

tricuspid

21
Q

what is the left AV valve called

A

mitral

22
Q

What is EDV?

A

End diastolic volume = 120ml in ventricle

23
Q

What is ESV?

A

End systole volume = 40ml in ventricle

24
Q

What is meant by stroke volume?

A

EDV-ESV= stroke volume

120-40=80ml

25
Q

Describe the ventricular pressure-volume loop

A

A
• Mitral valve opens
• Ventricular pressure is low, volume is high during ventricular filling
B
• Mitral valve closes
• Ventricular systole (isovolumetric contraction)
• Ventricular pressure rises, volume remains the same (this is because all valves are shut at this point)
C
• Aortic valve opens
• Pressure in ventricles increases, allowing blood to be ejected into aorta at a high pressure
• Blood is ejected from ventricle to aorta; therefore volume of blood in ventricles decrease
D
• Ventricles have emptied
• Ventricular diastole (isovolumetric relaxation)
• Pressure decreases in ventricle
Mitral valve closes

26
Q

What is jugular venous pressure?

A

Reflects the right atrial pressure

27
Q

Name a mechanism which you can directly measure the right side of the heart’s activity

A

By directly looking at the jugular vein in the neck

28
Q

What happens during the right atrial cycle?

include descriptions of the A, X, V, Y waves and descent

A

A wave:
→ Atrium contracting (atrial systole)
→ Ventricular relaxation (ventricular diastole)
→ Blood moves out of atrium into the ventricle
→ Pressure drops in the atrium after emptying into the ventricle
X descent:
→ Tricuspid valves closed
→ Atrium relaxation (atrial diastole)
→ Ventricular contraction (ventricular systole)
V wave:
→ Refilling of atrium
→ Tricuspid valve closed
Y descent:
→ Atrium contracts (atrial systole)
→ Ventricular relaxation (ventricular diastole)
→ Tricuspid valve opened
→ Atrium starts emptying

29
Q

Describe the 4 heart sounds

A

S1: Lub
Closure of atrioventricular valves at the beginning of ventricular systole

S2: Dub
Closure of semi lunar valves at the end of ventricular systole

S3: Occasional (mostly in older people)
Turbulent blood flow into ventricles, detected near end of first 1/3 of diastole

S4: pathological in adults (LESS common in young people)
Forceful atrial contraction against a stiff ventricle

30
Q

Name the 2 atrioventricular valves and state where they are found

A
  1. Mitral valve found in the left side of the heart

2. Tricuspid valve found in the right side of the heart

31
Q

Name the 2 semilunar valves found in the heart and name where they are found

A
  1. Aortic valve found in the aorta on the left side of the heart
  2. Pulmonary artery valve found in the pulmonary artery on the right side of the heart

Semester 2: Physiology (35 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions