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Flashcards in CARDIAC PHYSIOLOGY Deck (94):
1

what does ANP do

released from atria in response to increased ECV
promotes water excretion:
-> increases NA excretion
-> inhibits excretion of renin and ADH

2

what responses to baroreceptors initiate following a drop in BP

1. increased HR
2. increase strength of contraction
3. increased constriction of arterioles (except in brain)
4. increased constriction of veins

this improve CO and raises VR

3

where are the cardiac centres in the brain

medulla

4

what is dracy's law

Q=(P1-P2)/R

5

what is resistance dependant on in blood vessels

steepness of velocity gradient between the layers of fluid (NO SLIP CONDITION)

VISCOSITY of fluid
described in
POISEULLE"S LAW

6

what is the Fahraeus lindqvist effect

blood viscosity changes with diameter of vessels
minimal in micro vessels (bolus flow)
axial streaming in larger vessels

7

3 things which alter blood viscosity

fahraeus lindqvist effect

shear thinning
haematocrit

8

how do you measure mean arterial blood pressure

MABP=CO.TPR

9

three methods of measuring blood flow

1. Kety's clearance
2. Venous occlusion plethymegraphy
3. Fick's principle

10

what are the main resistance vessels in the body

systemic arterioles

11

2 mechanisms of radius regulation in arteriolses under intrinsic control

autoregulation (myogenic/vasodilator washout)

active hyperaemia (metabolic vasodilators)

12

what happens during venous pooling in the lower extremities

1. veins expand --> greater capacity (unto 600ml)
2. hydrostatic pressure forces fluid out

13

how much water is in the average adult male

64% (42L)

14

20:40:60 rule

20% ECF
40% ICF
60% TBW is water

15

what is the osmolarity of blood

300-310 mOsm/L

16

what is the osmolarity of 0.9% NaCl

308 mOsm/L

17

what is the osmolarity of intracellular fluid

290mOsm/L

18

what percentage of a unit of 5% dextrose would stay in the plasma after equilibration

7%

it has an osmolarity of 252mOsm/l

19

2 systems which regulate body fluid compartments

1) osmoregulation (osmoreceptors in hypothalamus sense drop in osmolarity and stimulate pituitary to secrete ADH)
2) volume regulation sensed by blood vessels --> RAAS, SNS, ANP,ADH, pressure natriuresis

20

what is starling's hypothesis

capillary filtration rate is proportional to hydraulic drive minus osmotic suction

21

what is starling's law of the heart

stroke volume increases in response to increased volumes of blood filling the heart

22

how long is the normal PR interval

120-200ms (3-5 small squares)

23

how long is the normal QRS

120ms (3 small squares)

24

how long should the QT interval be

350ms (proportional to heart rate)

25

what is the duration of a ventricular action potential

400msec (4 in muscle)

26

what are the differences between atrial/nodal APs and ventricular APs

Atrial has shorter plateau phase, upstroke and a different NA channel in depolarisation

27

in a normal axis what would you expect to see on an ECG

+ve= I II aVL aVF
-ve= III aVR

28

what provides SHORT TERM control of BP

baroreceptor reflexes

29

what provides INTERMEDIATE control of BP

Transcapillary shift
Vascular stress relaxation (10-60mins)
Renin-angiotensin system (after 20mins)

30

what provides LONG TERM control of BP

KIDNEYS:
- aldosterone
- ADH

31

what is the difference between vasculogenesis and angiogenesis

vasculogenesis occurs in the early embryo

angiogenesis occurs during development, repair, tumour growth and in the endometrium

32

what is vasculogenesis

appearance of new blood cells and blood vessels

mesoderm --> haemangioblast

form dorsal aortae and cardinal veins

33

what is angiogenesis

formation of new blood vessels from existing ones

intussusception is the splitting of blood vessels into two

34

what happens in the initials stages of heart development in the embryo

vasculogenesis occurs in the caudal end of the flat embryo (blood islands around yolk sac and lateral mesoderm)

the embryo then folds laterally to form the early heart tube

35

describe the structure of the early

at this stage there are 3 pairs of veins at a sinus venosus
blood then goes through an early atrium, ventricle, bulbs cords and out through a truncus arteriorsus and into the paired dorsal aortae

36

how does folding occur in the heart

the heart is fixed at either pole by the blood vessels, growth in the middle means that folding occurs.

the ventricles grow anteriorly to cover the atrium and the great veins

37

what does the right ventricle differentiate from

the bulbus conus region

38

what does the truncus arteriosus become

bifurcation the pulmonary trunk and the aortic arches

39

endocardial cushions grow into what structures

split the atrioventricular canal into two

40

what forms the inter ventricular septum

proliferation from the muscular ridge at the base of the heart. This tissue is myocardium and forms the muscular inter ventricular septum
the membranous part forms from
the spiral conotruncal septum

41

how is the interatrial septum forms

septum premium forms as a wedge of endocardium

in the top of the septum there is the osmium primum
a second curved wedge of endocardium forms - the septum secundum but does not extend all the way down to the end cardinal cushions.

42

each aortic arch supplies what

a pharyngeal arch
each has its own cranial nerve

43

what does the first aortic arch become

it mostly disappears
some remains to make the maxillary artery

44

what does the second aortic arch become

most of it disappears

45

what does the 3rd aortic arch become

the common carotid artery and start of ICA and the ECA sprouts from it

46

what does the 4th aortic arch become

left --> arch of aorta
right --> start of right subclavian artery

47

what does the 6th aortic arch become

the pulmonary arteries

ductus arteriosus

48

the first heart sound is caused by what

closure of the AV valves when ventricular pressure> atrial pressure

49

what causes the second heart sound

closure of the aortic valve when aortic pressure is greater than ventricular pressure

50

what are the 5 stages of the cardiac cycle

atrial systole
isovolumetric contraction
ventricular ejection
isovolumetric relaxation
ventricular filling

51

what happens during atrial systole

atria contract
ventricle receives last 30% of blood

52

what happens during isovolumetric contrations

ventricles contract and pressure rises
volume is unchanged
AV valves shut

53

what happens during isovolumetric relaxation

venricle relaxes
outflow valves close

54

what happens during ventricular ejection

pressure in ventricle > aorta/pulmonary artery

55

what happens during ventricular filling

passive filling of ventricles and atria

56

what happens during the a wave of the CVP

atrial contraction

pathologies
no a wave --> AF
large A --> atrial hypertorphy
cannon wave --> complete heart block

57

what causes the c wave on the CVP

bulging of tricuspid into right atrium during ventricular contraction

58

what causes the x descent on the CVP

downward movement of the heart during ventricular systole and relaxation of the atrium

59

what causes the v wave of the CVP

atrial filling against closed tricuspid valve

pathology:
giant V wave --> tricuspid regurg

60

what causes the y descent of the CVP

passive ventricular filling after the opening of the tricuspid valves

61

which leads of an ECG look at the anterior surface (right ventricle and septum)

V1,2,3,4

62

which leads of an ECG look at the lateral surface of the heart (left ventricle)

V5,6, aVL, I

63

which leads of an ECG look at the inferior surface of the heart

II, III and aVF

64

which leads of an ECG look at the right atrium

aVR

65

what should the paper speed be on an ECG

25 mm per second

66

how do you calculate the ventricular rate

RR
300/large squares
1500/small squares

67

which three things must be present on an ECG for sinus rhythm

p wave before every QRS
P-R normal (3-5 small squares)
PR constant

68

what is sinus arrhythmia

normal variation
increased heart rate on inspiration

69

what would you see on an ECG in atrial fibrillation

erratic activity in the atria - no visible p waves
irregular QRS

70

what would you see on an ECG in atrial flutter

flutter waves give a saw-toothed appearance

can occur with a fixed degree of AV block - e.g. 3:1
or can be variable

71

what is present on an ECG in first degree heart block

prolonged PR (>5 small squares)
constant
p before every QRS

72

what is the Wenckebach phenomenon

Mobitz type I 2nd degree heart block
progressive lengthening of PR until non-conduction of p wave which resets the rhythm

73

what is the pathology is an ECG shows:
consistant PR interval
p waves with no associated QRS

Mobtiz type II 2nd degree heart block

74

which type of heart block has fixed degree of atrioventricular block

2 nd degree

75

which syndrome has shortened PR interval with delta waves on ECG

Wolff-Parkinson-White syndrome

76

what happens on an ECG in third degree heart block

dissociation between p waves and QRS

QRS are firing off intrinsic pacemaker

77

what describe tall peaked P waves (> 2.5 small squares) on an ECG

p pulmonale (enlarged right atria)

78

what describes bifid p waves on an ECG

p mitrale -->left atrial enlargement owing to mitral stenosis

79

what causes small QRS complexes

pericardial effusions
pericarditis
emphysematous lungs

80

what is the normal duration for a QRS

no more than 3 small square wide
wide QRS indicates abnormal conduction through the ventricles

81

what conclusions can you draw from an ECG in the presence of LBBB

none! it can distort the ECG therefore no inferences can be made about ST segments

however if it is new onset LBBB may be indicative of acute MI

82

what would an RSR in V6 indicate

LBBB

(WiiLLiamM)

83

what would an RSR in V1 indicate

RBBB
(MaRRoW)

84

what is a CONCAVE ST elevation associated with

pericarditis

85

what is a downwards sloping ST depression associated with

aka reverse tick
digoxin

86

how tall should a normal T wave be

no more than 2 large squares

87

in which leads are inverted T waves normal

aVR III (V1+/-V2)

not V2 alone

pathological inversion can be a sign of cardiac ischaemia

88

what are:
- tall tented T waves
- loss of p waves
- QRS broadening
- sine wave ECG

signs of

hyperkalaemia

89

what are :
- flat broad T waves
- ST depression
- long QT
- ventricular dysrhythmias

hypokalaemia

90

what are the shockable rhythms

VF
pulseless VT

non-shock
PEA
asystole

91

what is kissmauls sign

raised JVP on inspiration due to pericardial tamponade

92

What is Dressler's syndrome

a pericarditis which develops 2 to 10 weeks after a MI or heart surgery

Signs of this:
- low grade fever
- chest pain
- pericardial friction rub
(pericardial effusion)

93

A 65-year-old female presents six weeks after a myocardial infarction with deteriorating shortness of breath of relatively recent onset. On examination, there is a soft first heart sound followed by a mid-systolic murmur which is loudest at the apex and in expiration. What is the most likely diagnosis

This is likely to be mitral valve prolapse or dysfunction of the papillary muscles following MI, which has resulted in mitral regurgitation

94

A 72-year-old female presents with a deteriorating shortness of breath. On auscultation of the heart there is a loud first heart sound and a rumbling diastolic murmur. What is the most likely diagnosis

A classic description of mitral stenosis with the rumbling mid diastolic murmur and loud first heart sounds.

Other features include an opening snap (tapping apex beat is the palpable first heart sound) which signifies mobile leaflets, and in sinus rhythm a pre-systolic accentuation can be heard.