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CVS Flashcards

1
Q

Features of cardiac muscle

A 
Striated 
Involuntary 
Extensive branching
Intercalated disc 
Gap junctions
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2
Q

Role of intercalated disc in cardiac muscle

A

Present at Z line
Increases cell to cell cohesion
Heart is a mechanical synctium

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3
Q

Role of gap junctions in cardiac muscle

A

At z line

Heart is a functional synctium

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4
Q

Difference between skeletal muscle and cardiac muscle

A

Sk muscle - c muscle
T-tubule- at A-I junction- at Z line,wider
SR. - well developed- less developed
DHPR - voltage sensor- voltage gated ca Channel
Source of Ca- SR- SR+ ECF
Removal of SR Ca- SERCA - SERCA+ Na/K antiport
Phospholamban-absent-present

(See your notes)

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5
Q

Name the modified contractile cells that have pacemaker potential

A

SA node

AV node

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6
Q

Modified contractile cells (conducting tissue) that have plateau potential

A

Internodal tracts
Bundle of His
Bundle branches
Purkinje fibres

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7
Q

Fastest conducting tissue

A

Purkinje fibres 4 m/s

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8
Q

Which is the slowest conducting tissue and why

A

AV node 0.05 m/S
Small diameter
Very few gap junctions

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9
Q

What is the advantage of AV node delay

A

Atria contract ahead of ventricles

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10
Q

Advantages of having a plateau potential in cardiac muscle

A

Prolonged ARP

cardiac muscle cannot be tetanized

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11
Q

What happens during plateau phase in cardiac muscle

A

K efflux Ca influx (slow Ca channel/slow Na-Ca channel)

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12
Q

What happens in depolarisation in pacemaker potential cardiac muscle

A

Ca influx through CaL channels

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13
Q

What is pre-potential phase in pacemaker potential (cardiac muscle)

A

Slow and spontaneous depolarisation till firing level

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14
Q

What does pre-potential phase start with (cardiac muscle)

A

Decrease K efflux

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15
Q

What does opening of F channels do

A

F ‘funny’ channels permit movement of both Na and K but movement of Na predominates

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16
Q

Main reason for reaching the prepotential phase (level becoming positive)

A

Ca influx through CaT channels

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17
Q

Effect of sympathetic discharge on pacemaker potential

A

Increase heart rate (know how)

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18
Q

Effect of parasympathetic discharge on pacemaker potential

A

Dual action

Decreased heart rate

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19
Q

What is the intrinsic rate of discharge of SAN

A

100/min

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20
Q

What is the resting heart rate

A

70-80/min

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21
Q

What is the heart rate of transplanted heart

A

100/min

As there is no sympathetic or parasympathetic discharge

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22
Q

Why do athletes have bradycardia at rest and what is the advantage

A

Very high resting vagal tone
Adv-high cardiac reserve

Cardiac reserve = maximum CO- basal CO

23
Q

Sympathetic and parasympathetic effect on force of contraction do heart

A

Sympathetic-increases force

Parasympathetic-no effect (no vagus to ventricles)

24
Q

At what seconds does conduction reach AVN,leave AVN,leave bundle of his (not too sure of the question is right)

A

Reach AVN- 0.03s (duration 0.03s)
Leave AVN-0.12s (duration 0.09s)
Leave bundle of His 0.15s (duration 0.03s)

25
When does the conduction reach endocardium and epicardium in heart
Endo-0.18-0.19s | Epi-0.21-0.22s
26
Ventricular depolarisation direction
Septum-endo-epi
27
Ventricular repolarisation direction
Epi-endo
28
What are the types of blood vessels present in the heart and eg
``` Wind Kessel vessels-aorta,large arteries Resistance vessel-arterioles Exchange vessels -capillaries Capacitance vessels-venues,veins,vena Cava Shunt vessels -AV anastomoses ```
29
What’s re the determinants of DBP
Elastic recoil of aorta and large arteries | TPR
30
What is known as the seat of peripheral resistance
Arterioles
31
Which vessels respond to local metabolised
Exchange vessels
32
Decreased pO2 causes vasodilation by what mechanism
ATP dependent K channels
33
``` Decreases pO2 (hypoxia) causes vasodilation everywhere except? And what is the mechanism ```
Lungs (vasoconstriction) | Sensitive K channels
34
Increase sympathetic discharge in resistance vessels causes what
Increased resistance
35
Why does resting skeletal muscle blood flow increase during exercise
Due to release of local metabolised | Exchange vessels respond
36
Increases sympathetic discharge causes what in capacitance vessels
Increases venous return
37
Where are shunt vessels present (eg) and what is it’s function
Earlobes Fingertips Function- temperature regulation
38
What are the hemodynamics laws applicable to CVS
1.Flow=deltaP/R 2.velocity of flow ~ 1/cross section area V1A1=V2A2 3.Hagen poisuille law (know the formula in terms of resistance and flow) 4.laminar and turbulent flow (reynold’s number) 5.La place’s law
39
Resistance in woods unit is
R= deltaP(mm Hg)/flow (L/min)
40
Resistance in R units (PRU)
R= delta P (mm Hg)/flow (ml/sec)
41
Maximum velocity in a) aorta b) capillaries
Aorta Total surface area Aorta= 4.5 sq cm Capillaries= 4500 sq cm
42
In terms of hagen poisuille law what kind of circulation will anemia have
Anemia-viscosity low Flow ~ 1/eta Therefore hyper dynamic circulation
43
In terms of hagen poisuille law what kind of circulation will a vessel with larger radius have
Larger radius Flow ~ radius More flow
44
What is Reynolds number and what is it’s significance
Reynolds number = rhoDV/eta >3000- turbulent <2000-laminar 2000-3000-transitional flow
45
La place’s formula for cylinder and sphere
If wall thickness (W) is significant T= Cylinder = Pr/W (artery) Sphere = Pr/2W(ventricle) If wall thickness is not significant T= Cylinder=Pr (capillaries) Sphere=Pr/2(alveoli) P-pressure r-radius
46
Korotkoff sounds can be related to which hemodynamic rules of CVS
Reynolds number high (due to less radius during cuffing) | Turbulence therefore sound heard
47
Cardiac cycle time
0.8 s
48
Atrial systole and atrial diastole timings
Atrial systole 0.1s | Atrial diastole 0.8s
49
Ventricular systole and diastole timing
Ventricular systole - 0.3s | Ventricular diastole-0.5s
50
Phases of cardiac cycle
0.3s Isovolumetric contraction Rapid ejection Slow ejection ``` 0.5s Isovolumetric relaxation 1st Rapid filling Diastasis 2nd Rapid filling ``` KNOW THE WHOLE THING VERY IMPORTANT
51
What and when is S1 due to
Onset of ventricular systole | Closure of AV valve
52
What and when is S2 due to
End of ventricular systole | Closure of semilunar valves
53
What and when is S3 due to
Due to rapid flow of blood from atria to ventricle | During first rapid filling phase
54
What and when is S4 due to
Second rapid filling phase | Coincides with AS

Physiology (7 decks)

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