Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Primary FRCA > Physiology > Flashcards

Physiology Flashcards

1
Q

During which phase of the cardiac cycle does ventricular filling occur?

A

Diastole

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

If a persons heart rate is 60 bpm, how long is systole and how long is diastole?

A

60 bpm = 1 beat/sec
In 1 second, 0.66 s is diastole, 0.34 s is systole

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

Which valves are
a) open
b) closed
during atrial systole?

A

During atrial systole;
a) Mitral and tricuspid valves are open
b) aortic and pulmonary valves are closed

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

Approximately what % of ventricular filling does atrial systole account for? How does this change when a patient is tachycardia and why?

A

At rest - approximately 20%.
Tachycardia - 40% - when patients are tachycardia due to reduced passive diastolic filling

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

on the cardiac cycle diagram, what is the a wave and x descent (with reference to atrial systolic pressures)

A

Atrial systole causes small increase in pressure (a wave). Once complete, the pressures fall (x descent), the AV valves float upwards and close .

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

Are the valves open or closed during isovolumeric contraction?

A

All valves are closed

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

What is isovolumetric contraction?

A

Time interval between the mitral and tricuspid (AV) valves closing and the semilunar (aortic and pulmonary) valves opening. These changes occur as during this phase, there is ventricular depolarisation and a rapid increase in ventricular pressure. During this phase, there is an increase in pressure but no increase in the volume of the heart.

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

What causes the first heart sound? Why is it split?

A

The closing of the mitral and tricuspid valves secondary to ventricular depolarisation and contraction. The increase in pressure forces the valves to close. It is split because the mitral valve closes slightly before the tricuspid.

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

Why does atrial pressure increase during isovolumetric contraction? What is the name of the wave in the cardiac cycle?

A

The closure of the AV valves increases atrial pressure during isovolumetric contraction. This is shown as the “c wave”

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

What is the name of the phase after isovolumetric contraction?

A

Rapid ejection

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

What happens to the atria’s blood flow and pressure during rapid ejection?

A

Blood flows into the atria during rapid ejection from both the lungs and systemic circulation.
The pressure will decrease as the AV valves get pulled downwards and the size of the atria increases.

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

Why does ventricular emptying continue during the reduced ejection phase of the cardiac cycle?

A

The kinetic energy generates continues to propel blood forward

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

What is the normal flow velocity of the aortic valve?

A

0.7 - 1.2 m/sec

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

This is a doppler ultrasound of blood flow across a stenosed aortic valve. What does the bright yellow area and dull yellow area represent?

A

the bright yellow area represents the low velocity/large area of the LVOT, and the peak of 4 m/s represents the large velocity/small area through a stenosed aortic valve.

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

Which equation can demonstrate the pressure gradient over an aortic valve from the flow velocity ?

A

Bernoulli equation ΔP ≃ 4 x V2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the valves doing during isometric relaxation?

A

They are all closed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What does the dicrotic notch represent?

A

Increased aortic and pulmonary pressure during isometric relaxation that occurs due to the closure of the semilunar valves, brief reversal of blood flow and the subsequent elastic recoil of the vessel walls e.g. the sinus of valsalva will bulge (sinus just above aortic root)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What makes the AV valves close during IMR?

A

Continued relaxation of the ventricles results in a continued decrease in intraventricular pressures which reverses the pressure gradient across the semilunar valves causing them to close.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is represented by the v wave in IMR?

A

The back flow of blood against the closed AV valves during IMR creates the v wave of the jugular pulse.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What creates the second heart sound? Why is it split?

A

The closure of the aortic and pulmonary valves. Split because the aortic valve closes slightly before the pulmonary valve.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Are the valves open or closed during the rapid filling phase of the cardiac cycle?

A

Mitral and tricuspid are open and the aortic and pulmonary valves are closed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What stage occurs after isovolumetric relaxation in the cardiac cycle? Why is it called this?

A

Rapid (ventricular) filling.
It’s called rapid filling because during IVR, the ventricular pressure falls. When the ventricular pressure is lower than atrial pressure, the AV valves open and there is rapid filling as the atrial are at maximal pressure (high volume) AND there is diastolic suction of the ventricles as it actively relaxes.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the name of the part of the jugular pulse waveform which represents the fall in atrial volume and pressure ?

A

y descent

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What causes a third heart sound?

A

Occurs at the end of diastole, after the rapid filling phase. Caused by the tensing of the chord tendinae and the atrioventricular ring supporting the valve leaflets - always pathological.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Why does ventricular filling have a reduced filling stage?
As the ventricles become more full, the pressure gradient between the atria and the ventricles decreases causing them to fill more slowly.
26
What happens in the a wave, c wave and x descent ?
a wave. Atrial contraction causes a reflux of blood into the venae cavae, which briefly increases the pressure to the maximun central venous pressure of 3-5 mmHg. No a wave is seen in atrial fibrillation c wave. Occurs as the cusps of the AV valves bulge back into the atria during isovolumetric contraction and the transmitted pulsation from carotid arteries forms the c wave x descent. Following the c wave, the atrial pressure drops rapidly as the atria relax and the atrioventricular ring and base of the ventricle are pulled down during the early rapid ejection phase
27
What happens during the v waves and y descent?
v wave. In ventricular systole, the pressure rises due to filling of the atria from the continued venous return of blood to the heart and closed AV valves y descent. This pressure drop represents the AV valves opening and blood rapidly leaving the atria into the relaxed ventricle in diastole
28
When can a 4th heart sound occur?
Atrial systole
29
What does the 4th heart sound represent?
Vibration of the ventricular walls during atrial contraction and occur in conditions associated with stiff ventricles.
30
When does the aortic valve open?
When the ventricular pressure exceeds the aortic pressure
31
What is systolic pressure? Why is this not reached immediately after rapid ejection?
The maximal aortic pressure. After rapid ejection, the volume of blood in the aorta exceeds the amount that can be distributed to the peripheral circulation causing bulging of the aorta as it reaches its maximal systolic pressure
32
Why does the aortic valve not close at the start of the rapid ejection?
Although the aortic pressure is higher than the ventricular pressure, the aortic valve stays open during rapid ejection due to the kinetic energy of blood flowing past the valve and propelling it open.
33
What causes the aortic valve to close? What phase does this occur in?
When approximately 5% of blood has flowed back into the left ventricle, the aortic valve closes. This occurs during the reduced (ventricular) ejection phase. There is back flow of blood during the rapid ejection phase as the valve remains open.
34
What does the dicrotic notch represent?
Increase in aorta pressure when the aortic valve closes and there is bulging at the aortic root (the sinus of valsalva).
35
Do heart sounds result from valves opening or closing?
Closing
36
What is stroke volume?
End diastolic volume (EDV) - End systolic volume (ESV)
37
What is a syncytium ?
A network of myocytes connected by gap junctions that allows coordinated contraction of the ventricles.
38
What is the definition of depolarisation?
depolarisation or hypopolarization is a change within a cell, during which the cell undergoes a shift in electric charge distribution, resulting in less negative charge inside the cell compared to the outside.
39
What phases are there is the cardiac conduction system action potential?
Phase 0, Phase 1, Phase 2, Phase 3 and Phase 4
40
Describe what happens in phase 0 of a cardiac myocyte's action potential?
Fast Influx of Na+ ions down a concentration gradient causing depolarisation of the myocyte's transmembrane.
41
At approximately what membrane potential (mV) does depolarisation occur?
- 90 mV
42
Describe what happens in phase 1 of a cardiac myocyte's action potential?
Depolarisation begins due to the sudden closure of Na+ channels, efflux of K+ ions through voltage gated channels.
43
Describe what happens in phase 2 of a cardiac myocyte's action potential?
Opening of slow L type Ca 2+ channels causing an influx of Ca 2+ ions. Balances the efflux of K+ ions and maintains depolarisation.
44
What is the name of Phase 2 of the myocyte's action potential?
Plateau absolute refractory period
45
What does the influx of calcium ions prevent from occurring during phase 2 of the myocyte's action potential?
The calcium ions prevent any further depolarisation from occurring so therefore tetany contraction is not possible.
46
Why is the plateau phase not completely flat?
The influx of calcium ions slows depolarisation but it is not halted altogether
47
Describe what happens in phase 3 of a cardiac myocyte's action potential? What is the name of this phase?
Relative refractory repolarisation. Closure of L type Ca channels with ongoing efflux of K+ channels.
48
What happens during phase 4 of the myocyte's action potential's ?
Resting membrane potential.
49
What maintains the myocyte's resting membrane potential?
Na/K ATPase pump
50
Why is the resting potential of a myocyte negative?
At rest, the membrane's Na/K+ ATPase pump pumps 3 Na+ OUT the cell in exchange for 2 K+. The overall effect is therefore the slow loss of positive ionic charge from within the cell
51
Which ECG leads are bipolar and unipolar?
Bipolar leads - lead 1, lead 2 and lead 3. Unipolar leads - aVR, aVL and aVF and all chest leads V1-V6.
52
What is the difference between unipolar and bipolar leads?
Bipolar leads measure the difference between two leads. Lead 1: LA-RA Lead 2: LL-RA Lead 3: LL-LA Unipolar leads measure the potential from one limb lead compared to a common neutral lead. aVF: LL - common aVR: RA- common aVL: LA-common
53
Which two leads can be used to estimate cardiac axis?
Lead 1 and aVF
54
What is normal cardiac axis?
Between -30 and +90 degrees
55
What is shown here?
Pacemaker action potential
56
Describe Phase 4 of the pacemaker action potential
-60mV Slow inward Na+ funny currents for gradual depolarisation -50 mV T-type Ca2+ channels open allowing Ca2+ influx for further depolarisation -40mV, L-type Ca2+ channels open, allow further influx till the threshold potential of approximately -35mV is reached.
57
What can influence phase 4 of a pacemaker's action potential?
Sympathetic or parasympathetic activity. Sympathetic activity will increase the gradient of depolarisation and vice versa. I.e. you reach the threshold potential quicker with increased sympathetic activity.
58
Describe phase 0 of a pacemaker's action potential
Phase 0 - L type Ca2+ channels creates a slow rise in action potential to depolarisation at +10mV
59
Describe Phase 3 of the pacemaker's action potential?
Closure of Ca2+ channels and efflux of K+ ions returns AP to resting potential of -60mV needed for reactivation of phase 4 ion channels
60
Why is the SAN the primary pacemaker?
Has the highest rate of spontaneous depolarisation than any other pacemaker cell
61
What is the name of the structures connecting the SAN to the AVN?
Internodal tracts - anterior, middle and posterior internal tracts.
62
What separates the atria from the ventricles? What property does this carry?
A band of fibrous tissue electrically insulating the atria and ventricles from each other
63
Where is the SAN and AVN located?
SAN is located in the posterolateral wall of the right atrium. The AVN lies in the right atrium behind the tricuspid valve.
64
Why is it important that there is a delay in conduction at the AVN? How is this achieved ?
There is a delay (PR interval) between atrial systole and ventricular systole to allow the ventricles to fill. This is achieved by a reduction in the number of gap junction between adjacent cells and a transmission in a unidirectional manner.
65
From the AVN, describe the cardiac conduction pathway?
AVN -> bundle of his -> L and R bundle branches -> Purkinje fibres. The LBB divides into anterior and posterior fascicles. The Purkinje fibres are very large and highly permeable to ions allowing for very fast transmissions of action potentials.
66
Why does the T waves have a lower peak and longer duration than the QRS?
Represents depolarisation which doesn't relay on the Purkinje fibres so it is slower.
67
What does the PR interval represent?
The action potential travelling from the SAN through the AVN to the bundle of His
68
Describes 3 features of cardiac myocytes
- Develop from splanchnic mesoderm which migrates and surrounds the primitive heart tube - 50-100 um long and 10-20 um in diameter - Have a single central nucleus - Depend entirely on aerobic respiration - Have numerous mitochondria (up to 25% in volume vs 2% in skeletal muscle) - Can be branched - Either specialised for mechanical work (>99%) or electrical conduction - connected end to end and laterally by intercalated discs.
69
This is a sarcomere i.e. a basic contractile unit of muscle. Note where the Z-disc is, surrounded by the I-band followed by the A-band, H-zone and thin M - disc.
ZIAHM
70
What is the sarcolemma?
Cardiomyocyte, bilipid membrane
71
What is the function of the cardiomyocyte's T tubules ?
Short and broad invaginations of the sarcolemma. Allow the depolarisation of the sarcolemma to rapidly penetrate the myocyte
72
What is sarcoplasmic reticulum? What is its role?
Specialised form of Endoplasmic Reticulum that takes, holds and releases the majority of calcium ions needed for muscle contraction.
73
What are 3 important proteins in the sarcoplasmic reticulum,?
- The ryanodine receptor (RyR2) - a type of intracellular calcium channel activated by calcium and inhibited by dantrolene and the plant alkaloid ryanodine. -The inositol triphosphate receptor (IP3R) - glycoprotein complex that functions as a calcium channel -Phospholamban (PLN) - pentameter. Inhibits SR Ca2+ ATPase. When it's phosphorylated by protein kinase C, PLN effect is reversed
74
Where are T tubules located on the cardiomyocyte?
At Z-lines and close to a terminal sarcoplasmic reticulum cisterns to form a diad
75
What are the two types of cell junction?
Desmosome junctional complexes Gap junctions
76
What does a desmosome junctional complex contain?
Intercellular adhesion plaques and cadherins. Cadherins are transmembrane glycoproteins spanning that gap between myocytes.
77
Where are gap junctions located?
In the sarcolemma
78
What do gap junctions consist of? What are their functions?
Connexons. Connexons located in the myocyte's sarcolemma unite in adjacent myocyte cells to allow the passage of small molecules and ions like calcium
79
6 connexINS form 1 connesON which forms a gap junction. What makes up a singular connexIN?
4 transmembrane domains (M1-M4) 2 extracellular loops (E1, E2) Cystoplastic loop (CL), cytoplasmic C-terminals and N terminals
80
What do thick filaments contain?
Myosin
81
In a thick filament, how is the myosin arranged?
In a helix 6 rows 2 regions (LMM and HMM) separated at a hinge.
82
What is the LMM region of a thick filament composed of?
Light meromysin (LMM) and heavy meromysin (HMM) arranged in an alpha helix with a flexible hinge region
83
What is the HMM region of myosin composed of
2 globular heads each with three segments. ›
84
What is the name of the structure where the adjacent, bare thick filaments join? How it this part of the filament stabilised?
M disc Stabilised with creatinine kinase, M-protein and myosin to form a stable lattice
85
Name two other proteins that stabilise the thick filaments
Titin - largest polypeptide, bound to M and Z lines. Contains an elastic amine that stabilises myosin and limits sarcomere stretching. Myosin binding proteins C and H - Holds thick filaments together and modulates actin-myosin interaction under influence of cyclic AMP
86
What are the three components of thin filaments?
Tropomyosin Actin Troponin
87
Where are thin filaments anchored? Which other proteins help this anchoring ?
Z-disc A-actinin Nebulette Filamin
88
What it the most abundant cytoplasmic polymer in mammalian cells?
Actin
89
What is the name of the type of actin that forms the classic helical pattern ?
Filamentous "F" actin polymer. 2 F actins wind together to form a helix pattern.
90
What is the name of the individual actin monomers that form the polymers? What important binding site do they contain?
G-actin. Globular actin monomer. Contain binding sites for myosin heads.
91
How many tropomyosins wind around the actin polyfilament? What is their function?
4. Block the myosin binding site.
92
Where are troponin found? What are the three types?
Found in clusters spaced out along the tropomyosin. TnI - inhibitory actin binding TnC - calcium binding TnT - tropomyosin binding
93
How many thin filaments surround each thick filament?
6
94
With reference to actin, myosin and troponin describe the stages of muscle contraction?
1. At rest, tropomyosin is bound to actin by TnI and TnT, blocking its binding sites. 2. Muscle contraction requires the release of calcium from the sarcoplasmic reticulum. Calcium ions bind to TnC which causes the unbinding of the myosin heads to actin. 3. Myosin binding to 1 actin subunit causes full displacement of tropomyosin and allows additional heads to bind. 4. Calcium is sequestered (separated) and tropomyosin rebinds to actin preventing further cross links
95
What is desmin?
52 kD intermediate filament protein that encircles the z-disc and connects to the z-disc of adjacent sarcomeres, intracellular surface of sarcolemma, nucleus, mitochondria and other organelles. Involved in force transmission and longitudinal load bearing. Plays an important role in the integrity of cardiac myocytes.
96
Name one benefit of cardiac muscle having a higher capillary density (3000cm2) compared with skeletal muscle (1000cm2)
5x greater endothelial surface area for gas exchange
97
What is meant by the helical ventricular band model?
Describes the pattern of muscle fibre bands found in cardiac muscle. They are arrange in multiple directions allowing the muscle to generate ascending, descending and rotational forces during ventricular systole.
98
What type of receptor is a beta adrenoceptor?
G protein coupled enzymatic receptors
99

Primary FRCA (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions