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Flashcards in Cvs 5-9 Deck (61)
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0

Describe the relationship between velocity and surface area.

At a given flow, if surface area increases then velocity will decrease.

At a given pressure gradient then if surface area increases velocity will increase due to laminar flow - further from vessel walls then the faster the blood flow.

1

What is transmural pressure and what does it determine?

Pressure difference across vessel wall. Determines amount of stretch and recoil of a vessel wall.

2

What is the relationship between resistance and radius

Resistance decreases with 4th power of radius

3

What are the advantages of having distensible walls?

Unlike non distensible (linear relationship between flow and pressure) distensible walls have a much higher flow at a set pressure. The recoil may also give them a capacitance so they can store pressure.
Note at low pressures there may be no flow as the walls collapse

4

How does blood flow match tissue O2 demand

Vasodilatator metabolites relax sm increasing bF.

5

What is reactive hyperaemia?

Blood supply is cut off it then returns with an enormous increase due to vasodilator metabolites

6

What is the connection between tpr and demand for O2

More demand for O2 more dilation so lower tpr

7

What does central venous pressure depend on

Pumping of heart.
Return of blood from body.
Gravity and muscle action

8

What is the role of baroreceptors?

Sense arterial pressure and increase sympathetic - HR and contractility
Via medulla

9

How can high venous pressure increase CO?

Starlings curve
Bainbridge reflex - sensed high pressure in ra leading to reduced parasympathetic activity

10

Describe eating a meal

Increased O2 demand at gut
Increased blood flow there
Decreased arterial pressure/ increase venous pressure
Increased Co

11

Decribe effect of HR increasing alone

Arterial rises, venous falls, SV decrease, CO the same

12

Describe the effects of instant exercise

Fall in Arterial and rise in venous
Risk of PO/ fainting from low BP/ overfilling of heart on starlings curve.
HR quickens instantly to avoid this.

13

Describe sequence of events standing up

Blood pools in superficial veins of legs
CO falls, arterial pressure falls,
Baroreceptors increase TPR
Further reduces venous pressure
Solved with veins constricting.

14

Describe the sequence of events associated with haemorrhage.

Arterial pressure fall, venous pressure falls.
HR increases due to baroreceptors, SV falls die to starlings curve.
Fixed via constriction of veins and auto transfusion (volume increase)

15

Describe what a long term increase in BV can lead to.

Kidneys increase Bv
Increases VP, CO then AP
More flowing through tissues, but body only takes what it needs so constricts increasing TPR.
Increases AP further.

16

Describe the signal recorded by a probe near a myocardial cell during systole.

Positive signal (de) followed by a negative signal (re)

17

What causes the Q signal?

Depolarisation of ventricles away from probe.

18

How can signals be amplified in an ECG? What do all amplified signals e.g. I, II, III use?

Reverse negative electrode result/ use positive and add to another positive reading (vectors will be accounted for) so view point is in between.

When you reverse the negative electrode you then have the positive view from the other side of the heart.

They all use one posit I and one negative electrode.

19

Give positivism of all V leads

V1 4th intercostal space right side
V2 4th intercostal space left side
V3 in between V2 and V4
V4 5th intercostal space inline with clavicular midline
V5 5th intercostal space at beginning of axilla
V6 5th intercostal space directly beneath axilla.

20

Describe locations of avr avl, avf and N leads

Avr, right arm
Avl, left arm
Avf, left foot,
N right foot.

21

Describe the views of I, II and III and the electrodes they use

Lead I: LA-RA left side
Lead 2: LL - RA apex
Lead 3: LL - LA bottom

22

What does atrial fibrillation look like?

No P waves

23

Describe the 3 classes of heart block and their ECG appearance

1st, lengthened PR
2nd erratic relationship between P and R e.g. Lengthening time or skips QRS in regular pattern.
3rd degree, no relationship between P and R waves.

24

How can an ECG appear different in bundle branch block?

Lengthened QRS and changes it's shape.

25

What is ST depression indicative of and why?

Myocardial ischemia (often along with angina) due to depolarisation occurring after QRS as damage effects current flow.

26

What is ST elevation indicative of and why? What else would indicate this? Which of these things will remain me why?

MI as dying tissues produce injury currents.

Pathological q waves (deep and wide) and inverted T waves.

Q waves due to altered flow due to fibrous repair.

27

State the normal blood pressures in the pulmonary artery, vein and capillaries

Artery = 12-15
Capillaries= 9-12
Vein = 5

28

What is ventilation and perfusion and how does ventilation affect perfusion in the lungs.

Ventilation - amount of O2 to area
Perfusion - amount of blood to area.
If ventilation decreases to an area of lung e.g. Emphysema. Hypoxia occurs, triggering vasoconstriction and decreasing perfusion to that part of lung (therefore increasing to another part). Ventilation perfusion ratio is kept around 0.8 which is optimal.

29

Explain starlings forces and explain how this can lead to pulmonary oedema.

Forces= hydrostatic out and oncotic in.
So normally fluid out at arterial but back in at venous end.
If venous pressure increases e.g. Mitral valve stenosis/ left ventricular failure.