Cardiology Physiology Flashcards Preview

Year 1 Body Systems > Cardiology Physiology > Flashcards

Flashcards in Cardiology Physiology Deck (70)
1

Action potential in the T tubules of cardiac myocytes triggers calcium entry in which 2 ways?

1) L type channels - voltage sensitive Ca2+ channels
2) Calcium induced calcium release - Calcium released from SR

2

What protein does calcium interact with to induce contraction?

Troponin

3

What is the resting potential and threshold potential of pacemaker cells?

Resting = -60mV
Threshold = -40mV

4

What is the resting potential and threshold potential of cardiac myocytes?

Resting = -90mV
Threshold = -65mV

5

What is the TFR of a cardiac myocyte?

ARP (absolute refractory period) + RRP (relative refractory period)

6

In an ECG what direction does the depolarisation go in a +ve and -ve deflection?

Towards an electrode = +ve deflection
Away from an electrode = -ve deflection

7

What are Einthoven's 6 leads?

RA, LA, LA
Lead I - LA -RA
Lead II - LL-RA
Lead III - LL-LA
Augmented limb leads (recorded with respect to 0)
aVR = RA
aVL = LA
aVF = LL

8

What are Virchows leads?

Chest leads (V1-V6) Unipolar leads recorded with respect to 0

9

What leads is the electrical axis of the heart to do with?

Einthovens's leads

10

What is the electrical axis of the heart?

Max current produced by an ECG - normally lead II (60 degrees) but can be anywhere between -30 and 90 degrees (einthoven's leads)

11

What would left deviation (-150 - -30) and right deviation (+90 - -150) tell you?

Left deviation - left ventricular hypertrophy
Right deviation - right ventricular hypertrophy

12

What is the left ventricular axis and which leads is it to do with?

To do with Virchows leads
Max current generated by ECG - towards V6

13

What are the 4 phases of the heart beat?

1) Diastolic ventricular filling (passive phase followed by active phase when atria contract)
2) Isovolumic contraction (semilunar valves closed by ventricles contracting)
3) Systolic ejection ( 2nd phase of ventricular systole - ventricles contracting and blood ejecting - during this phase atria relax and fill with blood)
4) Isovolumic relaxation (ventricles relax, semilunar valves close, atria continue to fill)

14

What is cardiac power and how is it calculated?

Rate of work done by the heart
Cardiac power = pressure x flow rate

15

What is EDV?

End diastolic volume

16

What is ESV?

End systolic volume

17

How is stroke volume calculated?

EDV - ESV

18

How is ejection fraction (LVEF) calculated?

SV/EDV

19

What is the main source of ATP for the heart?

Free fatty acids

20

What does the difference between LV and aortic pressure tell us?

The extent of aortic stenosis

21

What is V (blood velocity)?

Distance travelled per particle per unit of time

22

What is the equation linking pressure, blood flow and resistance?

Pressure = blood flow x resistance

23

What is the difference between the action potential in cardiac and skeletal muscle and what is the purpose of this difference?

Presence of plateau caused by Ca2+ ions in the cardiac myocyte action potential
Maintains contractile period during depolarisation

24

What happens to the troponin tropmyosin complex during systole?

Calcium binds to troponin, troponin-tropomyosin complex moves and myosin can now dock onto the exposed binding sites

25

What happens to the longitudinal and horizontal and circumferential filaments during systole?

Longitudinal filament shortening
Horizontal and circumferential filament thickening

26

In which 2 ways can heart rate be increased?

1) Sympathetic innervation
2) Adrenaline - beta 1 agonism

27

In which 2 ways can stroke volume be increased?

1) Increase pre load
2) Sympathetic input - prolonged opening of Ca2+ channels, enhances calcium action in excitation/contraction coupling mechanisms

28

What happens to the LVEF of a failing heart?

Decreases

29

What is the physiological LVEF and the LVEF in exercise?

Physiological LVEF - 50-75%
LVEF in exercise - can reach 90%

30

Why would ischaemia and viral infection/alcohol lead to a heart which contracts with less force?

Ischaemia - scarred myocardium
Viral infection/alcohol - wall thinning

31

In heart failure how does you body try to compensate for the weaker contraction of the heart and what does this lead to?

1) SNS overactivates
2) RAAS kicks in
Both these measures increase the pre load and the LV stretch exceeds physiological levels - go onto descending limb of the curve

32

What 3 treatments would be given to a patient with heart failure and pulmonary oedema?

1) High flow O2
2) Morphine - relax pulmonary vessels to reduce preload and relieving pain
3) Furosemide - diuretic

33

How is preload measured?

End diastolic volume using an echocardiogram

34

What 6 ways can stroke volume be increased?

1) Increased central venous pressure - increased by increased circulatory volume
2) Decreased venous compliance
3) Increased atrial filling or contraction
4) Decreased heart rate - prolongs diastole and filling
5) Increased ventricular compliance - more can get in
6) Increased aortic or pulmonary pressure - need more blood to generate enough pressure to open valves

35

What is the bowditch effect?

Another curve, up to a point, increased heart rate = increased force of contraction

36

What organs does the parasympathetic nervous system have no effect on?

Adrenal glands and kidneys

37

What are the 4 effects of SNS on heart?

1) positive chonotropy - SA node
2) positive dromotropy - AV node
3) positive inotropy - atria and ventricles
4) positive lusitropy - atria and ventricles

38

What are the actions of RAAS (ie. angiotensin II, aldosterone and vasopressin)?

ANGIOTENSIN II
Vasoconstriction
Increased Na+ and H2O retention
Vasopressin release
Aldosterone release
ALDOSTERONE
Increased Na+ and H2O retention
VASOPRESSIN
Increased water retention

39

What are the PNS actions on the heart?

1) negative chonotropy - SA node
2) negative dromotropy - AV node
3) negative inotropy - Only ATRIA - no effect on ventricles

40

Epinephrine is released into the blood from the adrenal medulla in response to sympathetic innervation what 3 effects does it have in terms of the cardiovascular system?

1) Causes kidneys to release renin
2) Causes vasoconstriction
3) Acts directly on the heart to increase heart rate and stroke volume

41

How does the renal juxtaglomerular system work?

Macula densa cells in the distal convaluted tubule located next to the glomerulus sense a drop in NA concentration (lower transglomerular pressure - less filtered out - indicates BP) and signals to granular cells to secrete renin

42

Where are baroceptors located and how do they control BP?

Carotid sinuses and aortic arch
Decreased arterial pressure - decreased firing - increase in sympathetic tone and decrease in parasympathetic tone
Increased arterial pressure - increased firing - decrease in sympathetic tone and increase in parasympathetic tone

43

What is the anaerobic threshold in cardiopulmonary exercise testing?

Time when anaerobic respiration begins

44

What does cardiopulmonary exercise testing measure?

O2 consumption at rest and during exercise

45

What are the 6 consequences of uncontrolled hypertension?

1) Stroke - hameorrhagic/ischaemic
2) LV hypertrophy - diastolic dysfunction, AF, heart failure
3) Hastened atherosclerosis
4) Vascular disease - coronary, peripheral, arterial
5) Retinopathy
6) Renal failure

46

Where the cardiovascular center located in the brain?

Medulla oblongata of the brain stem - region known as the tractus solitarius

47

What are the 4 inputs to the cardiovascular center in the brain?

1) Higher brain centers
2) Proprioreceptors - monitor joint movements
3) Baroreceptors - monitor blood pressure
4) Chemoreceptors - monitor blood acidity

48

What are the outputs from the CV center in the brain?

1) Vagus nerves - heart (decreased rate)
2) Sympathetic nerves - heart (increased rate and contractility) and blood vessels (vasoconstriction)

49

What is orthostatic or postural hypotension?

Decreased BP on standing

50

Which 2 hormones lead to increased BP through increasing cardiac rate and contractility?

Epinephrine
Norepinephrine

51

What 4 hormones lead to increased BP through vasoconstriction?

1) Angiotensin 2
2) Vasopressin
3) Norepinephrine
4) Epinephrine

52

What 2 hormones lead to increased circulatory volume and thus increase in BP?

1) Vasopressin
2) Aldosterone

53

What hormone leads to decreased circulatory volume and thus a decrease in BP?

1) Atrial natiuretic peptide

54

What structures can pass through fenestrated capillaries and where are they found?

Small, lipophillic molecules
Intestinal villi, endocrine glands, kidney glomeruli

55

What substances can pass through sinusoidal capillaries and where are they found?

Red blood cells and large hydrophillic molecules
Liver, bone marrow and spleen

56

What is Starling's law of the capillaries?

Hydrostatic pressure out and osmotic pressure in
At arterial end net pressure is out
At venous end net pressure is in

57

What are the 3 types of blood flow?

1) laminar flow
2) Turbulent flow
3) Single file flow

58

What is the flow in the aorta?

Pulsating laminar flow during early systole
Turbulence during peak velocity of flow

59

Why is velocity of blood lowest in capillaries?

Velocity = Flow rate/cross sectional area
Flow rate must be the same throughout circulation
Capillaries have the largest cross sectional area and thus the lowest velocity

60

What 3 parameters determine resistance?

1) Length of blood vessel
2) Radius of the vessel
3) Viscocity of blood

61

The levels of what 4 substances rise in the blood during exercise and cause local vasodilation by relaxation of vascular smooth muscle?

1) H+
2) CO2
3) K+
4) Adenosine (ATP-ADP-AMP-Adenosine)

62

Why does NO have a protective effect against thrombosis?

Causes relaxation of vascular smooth muscle and thus vasodilation reducing blood pressure
It makes the blood less prone to clotting

63

By what process is increased NO formed in endothelial cells during exercise?

1) Increased blood flow through capillaries
2) Ca2+ moves into endothelial cell
3) Ca2+ causes the conversion of Larginine to NO
4) NO moves into vascular smooth muscle and causes relaxation

64

Why is NO given in GTN spray to relieve angina?

Causes vascular smooth muscle relaxation and thus vasodilation

65

Why does atheroma formation occur frequently at arterial junctions?

These are stress points
They have high flow rates and more turbulent flow in these regions

66

What are the 3 main stages of atheroma formation?

1) Endothelial damage
2) Uptake of LDL particles, adhesion and infiltration of macrophages
3) Smooth muscle proliferation and formation of a fibrous cap

67

What 4 factors promote atheroma formation?

1) Sheer stress - hypertension
2) Toxic damage, chemicals - cigarette smoke
3) High levels lipids - familial hypercholesterolaemia, diabetes
4) Viral or bacterial infection - chlamydia pneumoniae

68

What causes proliferation of smooth muscle and deposition of collagen in a atheromatous plaque?

Growth factors are released by the damaged endothelium which cause proliferation of smooth muscl and deposition of collagen

69

What forms a fibrous cap over an atheromatous plaque and why is the fragility increased?

Collagen forms a fibrous cap
Fragility is increased because of calcification of the plaque

70

What triggers the formation of a thrombus in atheroscelrosis?

Rupture of fibrous cap exposes collagen and TF to the blood which triggers the formation of a thrombus