Cardiovascular Flashcards
1
Q
overview of conducting system; describe route of AP
A
- SA node (atria)
- AV node
- Bundle of His
- Purkinje fibres (wall of ventricles)
2
Q
where is the AV node?
A
anterior to coronary sinus (R atrium)
3
Q
where is the SA node?
A
wall of R atrium; inf. to opening of sup vena cava
4
Q
name of cells which form the pacemaker?
A
autorhythmic cells
5
Q
which has a higher Na+ concentration; intracellular or extracellular?
A
extracellular
6
Q
what is a funny current, and what effect on the resting membrane potential?
A
- leakage of Na+ into the cell
- inhibits K+ from leaving
- causes increase in RMP = -40mM
- triggers AP
7
Q
what ion channel is opened in response to an AP?
A
slow L-type Ca2+
8
Q
3 steps in cardiac myocyte AP
A
- depolarisation
- plataeu phase
- repolarisation
9
Q
what is a refractory period?
A
time where another AP cannot be fired
10
Q
2 advantages of the refractory period?
A
- non-return valve; prevent AP from backflowing
2. prevents 2nd contraction before 1st contraction has ended (tetanic contraction)
11
Q
disadvantage to a tetanic contraction
A
produces long, slow muscular contractions - dont allow heart to pump sufficiently.
12
Q
what is hyperpolarisation?
A
overshoot in repolarisation - more negative than -90mV
13
Q
P wave:
A
depolarisation of atria
14
Q
QRS complex
A
depolarisation of ventricles
15
Q
T wave
A
repolarisation of ventricles
16
Q
PQ segment
A
conduction time between SA node + ventricular depolarisation
17
Q
where is the plateau phase
A
ST segment
18
Q
ECG: ventricular systole
A
QT wave
19
Q
where on ECG is the ventricular diastole
A
after T wave
20
Q
why is there a delay at the AV node?
A
allows ventricles to fill
21
Q
2 points on ECG where ventricular pressure increases?
A
- P wave = as atria pump blood into ventricles
2. QRS = as AV valves shut
22
Q
what occurs during isovolumetric contraction?
A
AV valves shut; pressure in V increases
23
Q
what occurs during isovolumetric relaxation?
A
AV valves open - due to pressure in aorta exceeding ventricles
24
Q
when does ventricular volume decrease?
A
during ventricular ejection - ST segment
25
when does ventricular volume increase?
ventricular relaxation - after t wave
26
what does a lup sound indicate?
closing of AV valves
27
what does a dup sound indicate?
closing of semi-lunar valves
28
2 major contractile filaments in myofibrils?
actin + myosin
29
what makes up I band
thin actin
30
what makes up A band
thick myosin
31
describe the chains in myosin filament
2 heavy chains - each of which is attached to a light chain
32
which 2 proteins are coupled to actin? and how frequently
troponin & tropomyosin - every 7th molecule
33
which troponin complex binds to actin and which binds to tropomyosin?
```
T= tropomyosin
I = actin
```
34
what occurs when Troponin C is added to actin?
1. becomes Ca2+ sensitive
2. 4 Ca2+ attach
3. tropomyosin undergoes a conformational change in shape
4. allows myosin to attach
35
how does heart muscle produce its own ATP?
Creatin kinase moves phosphate from creatin phosphate to ADP.
36
explain properties of elastic arteries
stretchy to propel blood
37
3 segments of tunica intima
1. endothelium
2. basement membrane
3. internal elastic lamina
38
structure at the end of arterioles to capillary
metarterioles
39
what monitors the blood flow into the capillary?
precapillary sphincter
40
name for distal end of metarteriole?
thoroughfare channel
41
what is vasomotion?
contraction of SMC allowing pulsatile flow of blood from metarterioles
42
which blood vessels have thin walls and large lumens?
venules
43
what are the greatest capacitance vessels?
veins
44
2 factors for filtration
blood hydrostatic pressure
| interstitial fliud osmotic pressure
45
2 factors for absorption
intersitital hydrostatic pressure
| blood colloid pressure
46
what condition occurs when filtration > reabsorption?
oedema
47
what does the right lymphatic duct drain into?
internal jugular vein
48
what does the thoracic duct drain into?
subclavian vein
49
6 major vasodialators
```
NO,
lactic acid,
histamine,
increased temp,
low pH = low CO2
low O2
```
50
mechanism of vasodilators
relax precapillary sphincters
51
2 vasodialators
thromboxanes and endothelins
52
when are thromboxanes released?
by platelets at a wound site
53
when are endothelins released?
by damaged endothelial cells
54
how do vasoconstrictors work?
by contracting precapillary sphincters
55
what is normal BP
120/80 mmHg
56
what 3 things does vascular resistance depend on
lumen diameter
blood viscosity
vessel length
57
what is the force driving venous return?
greater pressure in veins than right atrium
58
where is the cardiovascular centre?
medulla oblongata
59
input: from higher brain centres such as?
hypothalamus
limbic system
cerebral cortex
60
input; from sensory receptors?
propoiceptors
chemoreceptors
baroreceptors
61
sympathetic nerves out to the heart from CV centre
cardiac accelerator nerves
62
parasympathetic nerves out to heart from CV centre
vagus nerve
63
how does the CV centre increase of decrease HR?
increase/decrease depolarisation of AV & SA nodes
64
where are the baroreceptors which detect BP directly?
aortic & carotid bodies
65
which hormones increase BP?
epinephrine + norepinephrine
66
which system controls BP long term?
RAAS
67
what in the RAAS increases blood volume and how?
Aldosterone - increases renal reabsorption of Na+, therefore water follows
68
what in the RAAS causes vasoconstriction?
angiotensin II
69
how do parasympathetic neurones slow down heart rate?
1. parasymp neurones secrete ACh
2. causes K+ channels to open
3. K+ influx
4. Inhibits depolarisation
5. Less action potentials
70
what does the atrial reflex respond to
increase in venous return
71
3 homeostatic mechanisms to regulate cardiovascular system
1. autoregulation
2. neural
3. endocrine
72
what is autoregulation control?
vasodilation & vasoconstriction with chemicals
73
what innervation is used by neural regulatory mechanism?
sympathetic
74
which centre controls neural regulatory mechanism?
vasomotive centre
75
in the neural mechanism, describe the process of vasoconstriction
1. nerves are adrenergic - secrete noradrenaline
| 2. stimulates alpha1- adrenoreceptors; causes contraction of SMC in precapillary sphincters
76
in the neural mechanism, describe the process of vasodilation
1. nerves are cholinergic - secrete ACh - triggers NO releases
2. nerves are nitroxidergic - release NO
3. NO is a vasodialtor; causes relaxation of SMC in precapillary sphincter
77
when there is an increase in BP, what centres are inhibited & which are stimulated?
```
stim = cardio-inhibitory
inhib = cardio-accel & vasomotive
```
78
when there is an decrease in BP, what centres are inhibited & which are stimulated?
```
stim = cardio-accel & vasomotive
inhib= cardio- inhib
```
79
what does stimulation of the vasomotive centre cause?
vasoconstriction
80
which hormones work to increase BP?
ADH, angiotensin II, erythropoiten
81
which hormones work to decrease BP?
Anti-natriuteric peptide
82
where is ADH released from?
posterior lobe of pituitary gland
83
what stimulates production of ANP?
stretching of atrial wall
84
what cells produce ANP?
atrial myocytes
85
during exercise, where is more blood distributed to?
skeletal muscles, skin, heart
86
during exercise, where is less blood distributed to?
GI tract, kidneys
87
what is the anticipatory response
before exercise, the sympathetic NS increases HR, increasing CO, vasoconstriction of splanchnic arterioles
88
3 changes during light exercise
- increased vasodilation
- increased CO
- increased venous return
89
5 changes during heavy exercise
- Max CO
- peripheral blood changes
- vasomotive centre; direct blood to essential organs
- cardio-accelertory centre activated
- increased skin perfusion - due to increased body temp
90
during haemorrhaging, what are the short term responses? what do all of them do?
cause vasoconstriction
1. sympathetic response detected by low BP
2. neural - noradrenaline
3. endocrine - ADH
91
during haemorrhaging, what are the long term responses?
1. RAAS
2. ADH
3. EPO
92
what level of blood loss defines ischaemia?
<30%
93
what do lipoproteins consists of?
lipids + proteins
94
why are the different lipoproteins transported in differemt ways?
due to different apoproteins on their surface
95
function of lipoprotein lipase
converts triglycerides into fatty acds + monoacylglycerol
96
what is a characteristic of true congestive heart failure?
pulmonary oedema
97
what is arteioscleorisis?
thickening of arterole wall - causing reduction in elasticity
98
what is atheroscleosis?
plaque building up
99
narrowing of a blood vessel
stenosis
100
what is more anterior-pulm trunk or aorta?
pulm trunk/artery
101
what is afterload
pressure of heart to eject after atrial systole
102
what is preload
end-diastolic vol that stretches V to greastest dimension
103
pO2- hypoxia to hyperoxia
10-13
104
PCO2 - hypocapnia to hypercapnia
4.5-6
105
HCO3- high and low
22-26
106
what is type 1 respiratory failure characterised by, and what causes it?
hypoxia - ventilation exceeds perfusion
107
whatis type 2 respiratory failure characterised by, and what causes it?
hypoxia + hypercapnia; reduced lung SA
108
in embryology - what do the cardiogenic cords develop into?
endocardial tubes
109
what does the fusing of the endocardial tubes form?
primitive heart tube
110
what fuses to form the atrial septum?
sinoatrial orifice
111
what is the hole called which the septum primum close, and in what chamber?
ostium primum- atria
112
what prevents the complete closure of atria
ostrium secundum
113
what forms the foramen ovalis?
septum primum
114
remnant name for foramen ovals
fossa ovalis
115
what forms the AV valves?
mesenchymal extensions
