Module 3.1 - Cardiovascular Anatomy Flashcards
1
Q
total blood volume
A
5L
2
Q
blood output from one pump (ventricle)
A
5L per min
3
Q
pulmonary circuit blood volume
A
9%
4
Q
pulmonary circuit pressure
A
medium pressure circuit due to proximity of lungs to heart (“low pressure” used for veins in tissues)
5
Q
systemic circuit blood volume
A
84%
6
Q
systemic circuit pressure
A
high pressure circuit as it encounters high systemic resistance
7
Q
systemic arteries pressure
A
120 - 80 mmHg
8
Q
pulmonary arteries/trunk pressure
A
~27 mmHg
9
Q
blood vessel function
A
expand/contract to direct blood to the target circuit/organ
10
Q
deoxygenated blood
A
never see purple/blue blood outside body since as soon as blood comes in contact with air, it picks up oxygen
11
Q
ventricular pumps blood volume
A
7% (most of the time in circulation)
12
Q
valves in filling phase
A
inlet: open
outlet: closed to prevent arterial blood from returning to the pump
13
Q
ventricles in filling phase
A
high volume
low pressure
14
Q
valves in ejection phase
A
inlet: closed to prevent high-pressure blood in pumping chamber from returning to veins
outlet: open
15
Q
ventricles in ejection phase
A
low volume
high pressure
16
Q
atrium
A
receiving chamber/reservoir
17
Q
atrium ejection phase
A
inlet valve closed => atrium accumulates venous blood
18
Q
atrium filling phase
A
accumulated blood enters ventricle quickly
19
Q
auricle
A
an appendage that increases capacity of atrium
20
Q
position of pump inlet/outlet
A
lie closer together on same side => walls of pumping chamber can shorten in length AND width
21
Q
blood flow through heart
A
right side = deoxygenated
left side = oxygenated
vertical orientation = systemic circuit
horizontal orientation = pulmonary circuit
22
Q
pressures
A
RA: 5 mmHg
RV: 27 mmHg
LA: 8 mmHg
LV: 120 mmHg
23
Q
trends in pressures
A
- pulmonary has lower return/receiving pressure than systemic as small circuit => pressure retained
- left pressure is 4 times right
24
Q
valve expansion
A
passive - rely on elastic recoil
25
chordae tendineae
prevent valves from inverting (flaps from bursting upwards into atrium during systole)
- in atrioventricular valves
26
types of valves
- atrioventricular
- semilunar
27
atrioventricular valves
INTO ventricle
28
semilunar valves
OUT OF ventricle
29
atrioventricular valves
- bicuspid / mitral (left)
- tricuspid (right)
30
semilunar valves
- aortic (left)
- pulmonary (right)
both have 3 cusps
no tendonous chords or papillary muscle
31
papillary muscles
apply enough tension to prevent valves from being pushed back
- not related to valve opening
- in atrioventricular valves
32
semilunar valves mechanism
pressure of blood trying to re-enter the ventricle forces the free edges of the cusps tightly together by filling up the pockets
- more force => pushed tighter together
33
ventricle pressure/wall thickness/volume
left:right
pressure - 5:1
wall thickness - 3:1
volume: 120 mL for both
34
inlet valve diameter
large diameter to admit blood at low pressure
35
outlet valve diameter
small diameter as blood leaves at high pressure (can be forced out)
36
orientation of heart
one third of heart's mass lies to the right of the midline of the body and two thirds to the left
37
right border
formed mainly by right atrium
38
superior border
= blood vessels = base
39
inferior border
formed mainly by right ventricle sitting on the diaphragm (+ apex)
40
left border
formed mainly by left ventricle as well as the left auricle/atrium
41
apex
points inferiorly, anteriorly and to the left
42
rheumatic fever
body produces antibodies that attack own tissue - vulnerable: collagenous leaflet of outlet (esp aortic) valve => cusps lose integrity => seams between cusps fuse => aortic stenosis (narrowing) => ventricles need to work harder to eject blood out => walls thicken => lumen shrinks => holds less volume => coronary arteries struggle to supply blood to the heart => ischemia => heart failure
43
pericardium (peritoneum, pleura)
universal way of body dealing with friction
- lubricating outside of organ by enclosing in a double-walled bag
44
visceral pericardium
- inner wall
- adheres to heart
- forms outer surface of heart
- aka epicardium
45
parietal pericardium
- outer wall
- lines a tough fibrous sac (fibrous pericardium)
46
both layers of pericardium are:
- single layer of squamous mesothelial cells
- continuous where great vessels enter/exit heart
47
order of layers of heart
lumen -> endocardium -> myocardium -> epicardium / visceral pericardium -> pericardial space (serous fluid) -> parietal pericardium -> fibrous pericardium -> outside pericardial sack
48
cardiac tamponade
if left ventricle punctured => blood goes into pericardial space and doesn't return => affect heart's ability to fill (passive process)
- can't be caught easily
- pericardial cavity filling up with fluid
49
fibrous skeleton of heart
- present in mitral / aortic
- absent in pulmonary and incomplete in tricuspid (associated with low-pressure pulmonary pump)
- made of dense connective tissue
50
where fibrous skeleton is incomplete....
there is fatty connective tissue
51
fibrous skeleton function
- provide structural support for high pressure valves of heart
- insulate ventricular myocardium from electrical activity of atria except at AV node
52
flow of electrical conduction through heart
SA node (initiate) -> atrial muscle -> atrial node -> atrioventricular bundle -> bundle of His -> right and left bundle branches -> Purkinje fibres
53
SA node
modified cardiac cells
- can depolarise/repolarise by themselves
- also influenced by nerves (sympathetic => speed up and parasympathetic => slow down)
- right atrial wall near opening of superior vena cava
54
purkinje cells
- not branched
- don't contract
- good at conducting AP
55
SA node -> atrial muscle speed
slow
0.5 m/s
56
SA node -> atrial muscle result
uniform atrial contraction
57
atrioventricular node speed
very slow
0.05 m/s
58
AV node result
100 ms delay
- needed as without this, atria contract at same rate as ventricle which can't keep up => want ventricle to contract after atria has had a chance to contract
59
AV bundle -> purkinje fibres speed
fast
5 m/s
60
AV bundle -> purkinje fibres result
complete/uniform ventricular contraction (systole)
61
nerves speed
50 m/s
62
five stages of the cardiac cycle
1) ventricular filling
2) atrial contraction
3) isovolumetric ventricular contraction
4) ventricular ejection
5) isovolumetric ventricular relaxation
63
cardiac cycle
includes all events associated with one heartbeat
- forcing blood from areas of high to low pressure
64
ventricular filling
- vent P < atrial P
- mitral valve opens
- blood enters ventricle
- ventricle fills 80% of its capacity (~105 mL)
- aorta P = 90 mm Hg
- LA P = 5 mm Hg
- LV P = < 5 mm Hg
65
atrial contraction
- atrial systole / ventricular diastole
- 0.1 sec
- natural depolarisation of SA node => LA contracts to complete filling (last 25 mL top up)
- only small rise in atrial pressure
- end diastolic volume = ~130 mL
66
why only small rise in atrial pressure during atrial contraction
1) atrial muscle layer is thin
2) no inlet valves for atria
=> nothing to prevent backflow into veins
67
isovolumetric ventricular contraction
- ventricular systole / atrial diastole
- 0.3 sec
- isometric ventricular muscle contraction
- all valves closed (mitral: closes due to backflow towards atrium, aortic: still closed due to insufficient ventricular pressure)
- first heart beat
- atrial P < increasing vent P < arterial P
- highest volume
- ends when vent P > arterial P
- mitral regurgitation likely
68
mitral regurgitation
blood regurgitation from LV to LA during ventricular systole due to failure of valves closing properly
- as soon as vent P > atrial P, regurgitation may occur
69
ventricular ejection
- ventricular systole continues
- 0.25 sec
- vent P > aortic P (both rise steeply as blood is ejected into aorta faster than it runs off into distributing arteries)
- aortic valve opens
- blood leaves ventricle
70
isovolumetric ventricular relaxation
- ventricle relaxes
- 0.4 sec (total diastole)
- atrial P < decreasing vent P < arterial P (vent P drops suddenly as its size increases - no contraction)
- all valves closed (aortic: closes due to backflow in aorta, mitral: still closed as vent P < atrial P)
- second heart beat
- ends when vent P > atrial P
71
ventricles in isovolumetric relaxation/contraction
vent P is isolated from the rest of the circulation
72
stroke volume
volume ejected per beat from each ventricle
- ~70 mL (130 - 60 mL) at rest
73
ejection fraction
indicator of how efficient ventricle is at emptying itself
= stroke volume / end diastolic volume
normally 60-70%
74
normal ranges of measured blood pressure
max. arterial (systolic) pressure/min. of arterial (diastolic) pressure
- young women: 115/75
- other: 120/80
75
min. arterial pressure
how good peripheral blood vessels are
76
why does ventricular pressure go up and down during ventricular ejection
up: more stretched => greater force => fill artery faster than it drains
max.: ventricle ejects blood into artery = blood flowing out of artery
down: blood flowing out of artery > blood flowing into artery from ventricle
77
ventricular volume ejected
ejects ~60-70 mL per cardiac cycle for both aortic (left) and pulmonary trunk (right)
78
rate of ventricular volume change during filling/ejection
- filling/ejection is fastest at the beginning (exponential)
=> phases can be shortened without affecting volume filled/ejected too much
79
why is the second heart beat split
second heart beat is due to backflow of blood that has left the ventricle back towards the ventricle closing the outlet valves
- aortic has higher pressure (120 mmHg) => blood returns faster => first split
- pulmonary (27 mmHg) has lower pressure => slightly slower beat
80
classes of blood vessels
1) elastic arteries
2) muscular arteries
3) arterioles
4) capillaries
5) venules
6) veins
81
elastic artery structure
- very large
- elastic walls
- middle tunic: many thin sheets of elastin
82
elastic artery function
- systole: expand to store bolus of blood leaving ventricle
- diastole: push blood out into arterial tree by elastic recoil
=> smooth pulsatile flow of blood leaving ventricles
- shock/pressure absorber
83
elastic artery examples
aorta, pulmonary trunk
84
muscular artery structure
- medium-sized
- middle tunic: many layers of circular smooth muscle wrapped around the vessel
85
muscular artery function
- distribute blood around body at high pressure, lungs at medium pressure
- rate of blood flow adjusted by smooth muscle to vary radius (flow directly proportional to radius^4 => small change in radius has large effect on flow rate)
86
arteriole structure
- thicker muscular wall relative to their size than any other blood vessel
- middle tunic: between 1 and 3 layers of circular smooth muscle wrapped around vessel
87
arteriole function
- control of blood flow into capillary beds (last chance to alter blood pressure)
- greatest pressure drop occurs/greatest resistance to flow
- degree of constriction of arterioles throughout body determines total peripheral resistance thus mean arterial blood pressure
88
capillary structure
- size of RBC
- thin-walled single layer endothelium with external basement membrane
- no smooth muscle in wall => can't adjust diameter
- no connective tissue
89
capillary function
- allow exchange of gases, nutrients, wastes between blood and surrounding tissue fluid
- slow blood flow to allow time for exchange to occur
- leaky vessels (more/less depending on location)
- most of lost plasma immediately recovered due to osmotic gradient
- net loss => lymphatic system
90
venule volume/pressure
high volume, low pressure
91
venule structure
- small venules: endothelium plus a little connective tissue
- larger venules: single layer of smooth muscle
92
venule function
- drain capillary beds
- during infection/inflammation, site where WBC leave blood circulation to attack bacteria in tissue alongside
93
vein pressure
low pressure
94
vein structure
- thin/soft walls that stretch easily
- similar to muscular artery but less muscle/connective tissue
- larger veins (esp in legs): valves to prevent backflow
95
vein function
- acts as venous pump that returns blood to right atrium (except portal veins: drain blood to another capillary bed)
- small change in venous blood pressure causes large change in venous blood volume
=> act as reservoir storing blood (64% in systemic veins/venules, 13% in systemic arteries/arterioles)
- vasoconstriction
96
vein reservoir function + taking blood out
when blood taken out, ~1 L of removal required for hypovolumetric shock (only need 4L out of the 5L to function)
97
coronary arteries
- normal muscular arteries but important due to the tissue that they supply (myocardium)
- run alongside cardiac veins in the interventricular sulci
98
coronary arteries lumen
approx. 2-4 mm in diameter
99
coronary arteries entrance
aorta just behind/downstream of aortic valve (leaflets)
- blood enters when ventricle relaxes and blood tries to flow back
=> greatest flow when heart relaxing (can't fill when contracting as muscles push)
100
atheroma
- plaques (fatty substances) that cause atherosclerosis
can cause coronary artery to narrow in which if ~20% of its normal cross-section is narrowed, significant obstruction to blood flow occurs (ischemia)
101
ischemia
- reduced blood flow / oxygen supply
- during exercise, the myocardium supplied by diseased artery gets low oxygen => chest pain (angina)
- severe => death (infarction) of local area of myocardium
102
body's way of supplying ischemic muscle
sometimes artery-to-artery junctions (anastomoses) between small penetrating branches of main coronary arteries widen slowly so ischemic muscle area can be supplied by distant artery
103
coronary arteries clinical significance
atherosclerosis (narrowing) => ischemia (low blood flow) => angina (chest pain) / severe cases: infarction (death of local area of myocardium)
- widening anastomoses allow supply by distant artery
104
atherosclerosis
type of arteriosclerosis (artery narrowing due to age)
105
cardiac veins
- return deoxygenated blood drained from myocardium to right atrium
- great cardiac vein, middle cardiac vein, small cardiac vein -> coronary sinus (opens into RA)
- anterior cardiac vein -> directly into RA
- no clinical importance
106
atrial fibrillation
irregular, often rapid heart rhythm (arrythmia) due to chaotic signals in the atria causing fluttering
107
arrythmia
irregular heartbeat
108
atrial fibrillation can cause
blood clots in heart => poor blood flow
109
causes of atrial fibrillation
coronary artery disease, heart attack, high BP etc.
110
blood vessel wall thickness
elastic>venacava>muscular>vein>precapillarysphincter>arteriole>venule>capillary
111
blood vessel internal radius size
venacava>aorta>muscular>arteriole=precapillary sphincter>venule>true capillary
112
fibrous skeleton is penetrated by
atrioventricular bundle (not AV node)
113
pectinate muscle
trabeculae carneae (in ventricles) for the auricles
114
atria/great veins are
more posterior than ventricles/great arteries
115
mediastinum
midline (central portion of thoracic cavity)
116
thrombosis
when blood clots block veins/arteries
117
ventricular/atrial septal defect
hole in ventricles/atria
118
midline incision =>
left atrium is the least likely to be seen
