CARDIAC PHYSIOLOGY Flashcards
(94 cards)
1
Q
what does ANP do
A
released from atria in response to increased ECV
promotes water excretion:
-> increases NA excretion
-> inhibits excretion of renin and ADH
2
Q
what responses to baroreceptors initiate following a drop in BP
A
- increased HR
- increase strength of contraction
- increased constriction of arterioles (except in brain)
- increased constriction of veins
this improve CO and raises VR
3
Q
where are the cardiac centres in the brain
A
medulla
4
Q
what is dracy’s law
A
Q=(P1-P2)/R
5
Q
what is resistance dependant on in blood vessels
A
steepness of velocity gradient between the layers of fluid (NO SLIP CONDITION)
VISCOSITY of fluid
described in
POISEULLE”S LAW
6
Q
what is the Fahraeus lindqvist effect
A
blood viscosity changes with diameter of vessels
minimal in micro vessels (bolus flow)
axial streaming in larger vessels
7
Q
3 things which alter blood viscosity
A
fahraeus lindqvist effect
shear thinning
haematocrit
8
Q
how do you measure mean arterial blood pressure
A
MABP=CO.TPR
9
Q
three methods of measuring blood flow
A
- Kety’s clearance
- Venous occlusion plethymegraphy
- Fick’s principle
10
Q
what are the main resistance vessels in the body
A
systemic arterioles
11
Q
2 mechanisms of radius regulation in arteriolses under intrinsic control
A
autoregulation (myogenic/vasodilator washout)
active hyperaemia (metabolic vasodilators)
12
Q
what happens during venous pooling in the lower extremities
A
- veins expand –> greater capacity (unto 600ml)
2. hydrostatic pressure forces fluid out
13
Q
how much water is in the average adult male
A
64% (42L)
14
Q
20:40:60 rule
A
20% ECF
40% ICF
60% TBW is water
15
Q
what is the osmolarity of blood
A
300-310 mOsm/L
16
Q
what is the osmolarity of 0.9% NaCl
A
308 mOsm/L
17
Q
what is the osmolarity of intracellular fluid
A
290mOsm/L
18
Q
what percentage of a unit of 5% dextrose would stay in the plasma after equilibration
A
7%
it has an osmolarity of 252mOsm/l
19
Q
2 systems which regulate body fluid compartments
A
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
Q
what is starling’s hypothesis
A
capillary filtration rate is proportional to hydraulic drive minus osmotic suction
21
Q
what is starling’s law of the heart
A
stroke volume increases in response to increased volumes of blood filling the heart
22
Q
how long is the normal PR interval
A
120-200ms (3-5 small squares)
23
Q
how long is the normal QRS
A
120ms (3 small squares)
24
Q
how long should the QT interval be
A
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.
