Cardiovascular - Anatomy + Physio Flashcards
(91 cards)
1
Q
Which coronary artery branches off the posterior aortic sinus?
A
Left coronary artery
2
Q
Which coronary artery branches off the anterior aortic sinus?
A
Right coronary artery
3
Q
What is the route of the left coronary artery?
A
LCA
1. Left Anterior Descending / Anterior Interventricular Artery (anterior)
–> Diagonal branches
2.** Left circumflex (posterior)**
—–> 3 Left Marginal Arteries
4
Q
What is the route of the right coronary artery?
A
RCA
1. RCA comes down anterior (anterior)
–> Right marginal artery
2. Posterior inter-ventricular artery (posterior)
5
Q
Where does the SAN artery branch off?
A
Right coronary artery
6
Q
Which 2 arteries meet at the apex of the heart?
A
- Left Anterior Descending
- Posterior Interventricular Artery
7
Q
Which artery supplies the inferior wall of the heart?
A
Left circumflex artery
8
Q
Which artery supplies the antero-lateral wall of the heart?
A
Left Anterior Descending Artery
Distal - V3 + V4
9
Q
Which artery supplies the antero-septal wall of the heart?
A
Left Anterior Descending Artery
Proximal - V1 + V2
10
Q
What is right dominance of the heart?
A
Posterior descending artery supplied by the RCA
Most common
11
Q
What is left dominance of the heart?
A
Posterior descending artery supplied by the LCA
Worst prognosis in MI - loss of anterior and posterior blood supply
12
Q
What is co-dominance?
A
Posterior descending artery supplied by both the RCA and LCA
Best prognosis but least common
13
Q
What is a myocardial bridge?
A
Myocardial muscle covering a major coronary artery
runs through the heart, only branches visible externally
14
Q
What are the 3 things in the carotid sheath?
A
- Common carotid artery
- Internal jugular vein
- Vagus nerve
15
Q
At what level of the spinal cord do the common carotids bifurcate into internal and external carotids?
A
C3-4
Level of the posterior hyoid bone
16
Q
What level of the spinal cord do the phrenic nerve branch off?
A
Phrenic nerve branches off at C3,4,5
Comes down mediastinum, contributes to cardiac plexus and innervates the diaphragm
17
Q
How does referred pain work in heart injury?
A
When heart injury - phrenic nerve sends afferent signals to CNS
Phrenic nerve originates at C3,4,5 - so CNS cannot localise the pain and instead gives response of pain in whole region
C3,4,5 also supplies shoulder, neck and jaw = referred pain in MI
18
Q
What structures lie in the superior mediastinum?
A
Trachea
Oesophagus
Arch of aorta
SVC
Vagus and phrenic nerves
Left recurrent laryngeal nerve
19
Q
At what point of the spinal cord is the mediastinum split into superior and inferior?
A
T4-5
Sternal Angle
20
Q
What lies in the anterior inferior mediastinum?
A
Thymus
21
Q
What structures lie in the middle inferior mediastinum?
A
Heart
Pericardium
Phrenic nerves
Ascending aorta
Pulmonary trunk
22
Q
What structures lie in the posterior inferior mediastinum?
A
Oesophagus
Sympathetic chain
Azygous vein
Descending aorta
Vagus nerve
Thoracic duct
23
Q
What is the relation of the left recurrent laryngeal nerve to the aortic branch?
A
LRLN heads behinds arch of aorta and loops around right sublavian artery to head back up to larynx
Left laryngeal nerve branches off the vagus nerve
LRLN provides motor innervation to the intrinsic muscles of the larynx
24
Q
What are the 3 functions of the pericardium?
A
- Anchor heart to surrounding structures
- Protect heart from trauma, damage etcccc
- Prevent heart from overfilling and stretching
25
What are the layers of the heart?
| From in to out
- Endocardium
- Myocardium
- Epicardium - Visceral layer of serous pericardium
- Pericardial cavity - Serous Fluid - prevent friction
- Parietal Layer of serous pericardium
- Fibrous pericardium - dense irregular connective tissue
26
Which vein is suitable for a central venous line to monitor central venous pressure and why?
Right Internal jugular vein
- Direct route to right atrium
- No valves
27
What vessel is best used for a autograft in a CABG?
Internal thoracic / internal mammory
28
Why is a thoracic artery better than a vein from the leg for autograft in a CABG?
Artery already adapted to carry high pressure blood so less likely to become dilated.
Can provide alternative source of blood supply - only have to change one side and leave the other intact
Do not have valves
29
Where is the coronary sinus located?
Posterior aspect of the heart
30
What does the coronary sinus drain into?
Right atrium
| 85% of venous drainage occurs via coronary sinus
31
What are the thesbian veins?
Smallest cardiac veins
Drain into the 4 chambers of the heart
32
Why is the blood in the left ventricle less saturated with oxygen than the blood it originally receives from the pulmonary veins?
Left ventricle receives blood from thesbian vein = mixing venous blood = physiological shunting
33
What is the vessel course of the arch of aorta?
**Brachiocephalic trunk**
- Right common carotid
- Right subclavian artery
**Left common carotid**
**Left subclavian artery**
34
Where does the azygous vein drain into?
Posteriorly in to inferior vena cava
35
What are aortic sinuses?
Small swelling in aortic artery
- Stops valves sticking to the aortic wall so they can still close
- Allows blood to pool in the sinuses after systole to allow valves to shut before flowing out arteries
36
What are the atrio-ventricular valves?
Left - Mitral/bicuspid
Right - Tricuspid
| Between atria + ventricle - Closed at start of ventricular contraction
37
What 3 strucutres help atrio-ventricular valves work?
**Chordae tendinae** reinforce valves by tethering to papillary muscle
Papillary muscle gets electrical signal from bundle branches via **moderator band** to contract when the ventricles will contract
**Papillary muscles** contract to prevent prolapse of valves to stop backflow of blood into atria during ventricular contraction
38
What are the semi-lunar valves?
Left - aortic valve
Right - pulmonary valve
| Between ventricles + arteries - close during ventricular relaxation
39
How many papillary muscles are there in the heart?
5 papillary muscles
3 in the right ventricule supporting tricuspid valve
2 in the left ventricle suppporting mitral valve
40
What is the AV valve structure within the heart?
Tricuspid - 3 cusps
Mitral - 2 cusps
Base of each cusp anchored to a fibrous ring that surrounds the orifice
41
How do the semi-lunar valves ensure they close and not leak open?
At the beginning of ventricular diastole - blood in artery falls back on to the valve via gravity = filling the sinuses and pushing valve cusps together
| No tethering muscles
42
How does blood enter the left and right coronary arteries?
LCA - fills from left aortic sinus in the left cusp of aorta
RCA - fills from right aortic sinus in the right cusp of aorta
| Blood recoils during ventricular diastole into aortic sinuses
43
What is the route of blood on the left side of the heart?
Pulmonary veins pump oxygenated blood from lungs into left atrium → left ventricle → aortic arch → supply whole body (except lungs)
| Left ventricle wall thicker to pump blood round whole body
44
What is the route of blood on the right side of the heart?
SVC pumps deoxygenated blood from upper limbs/head/neck/thorax and IVC pumps deoxygenated blood from below diaphragm into right atrium → right ventricle → pulmonary trunk → pulmonary arteries → 1 to each lung
45
Which valve is most likely to wear down over time?
Mitral Valve
Blood flows on both sides of the anterior/septal cusp during atrial and ventricular systole = more likely to wear down
46
What is the function of the moderator bands?
Conduct impulses from the interventricular bundle to the base of the anterior papillary muscle
Ensure the papillary muscles can contract to shut AV valves at the same time as ventricular systole to prevent backflow of blood
47
What part of the autonomic nervous system is predominantly responsibke for innervating SA node to generate an impulse
Sympathetic nervous sytem
48
What is cardiac output?
CO = the volume of blood ejected by left or right ventricle in 1 minute
CO = Heart Rate x Stroke Volume
CO = 70bpm x 75ml = 5L/min
49
How much can cardiac output increase in exercise?
x4-6 increase
50
What is stroke volume and what affects it?
SV = the volume of blood ejected from the ventricle from 1 contraction
SV = ESV - EDV
51
What has a positive correlative affect on stroke volume?
Preload
Contractility
52
What has a negative correlative affect on stroke volume?
Afterload
53
What is preload?
The amount of stretch of the cardiac myocytes in the ventricles at the end of diastole, prior to systole
54
How is preload measured?
**End diastolic volume or pressure **
Equivalent to atrial volume/pressure - which is the same as **venous return**
55
What affects preload?
Central venous pressure
Heart rate
Ventricular compliance
Atrial contractilty
Valvular disease
56
What factors affect central venous pressure?
- Circulating volume - haemorrhage, dehydration = decrease CVP
- Respiratory pump
- Skeletal muscle pump - pressure from muscles constricting on veins = increase CVP
- Gravity - blood pooling in peripheral vein = decrease CVP
- Sympathetic nerve - constriction of veins = increase CVP
57
How does the respiratory pump affect central venous pressure?
Negative pressure in throacic cavity compared to below diaphgram -
- pressure difference enhanced in inspiration (very negative in lungs and positive in abdomen)
Pressure gradient = blood pulled back to lungs with negative pressure to enhance venous return
58
How does compliance affect preload?
Increase compliance = more stretched = higher EDV but at lower EDP
Decreased compliance = less ability to stretch = lower EDV but at higher EDP
## Footnote
Increase compliance in dilated cardiomyopathy, regurgitation
Decrease compliance in HOCM, hypertrophy
59
What is the affect of heart rate on preload?
Low heart rate = more filling time of ventricles = increase in preload
60
What is the frank-starling law of the heart?
The more a ventricle is filled during diastole = greater stretch = greater force of contraction = greater stroke volume
61
What is contractility and what affects it?
Force of contraction that is independant on initial fibre length
Dependant on intraceullar free calcium during systole affected by positive and negative inotropic agents
62
What are inotropic agents and how do they work?
Agents that increase or decrease contractility of the heart by affecting free intracellular calcium levels or sensitivity of receptor proteins to calcium
63
What are positive inotropic agents?
Drugs
- Dopamine, atropine, dobutamine, digoxin, milrinone, epinephrine, norepinephrine, isoprenaline, caffeine
Ions
- High calcium
Hormones
- glucagon, insulin, T3 + T4
64
What are negative inotropic agents?
Drugs
- Verapimil, diltiazem, beta blockers, anti-arrhythmics
Parasympathetic stimulation
- Acetylcholine
Ions
- Low calcium, high potassium and sodium
65
What is afterload?
Reflects the resistance that the ventricle must overcome when ejecting blood
Increased after load = less blood able to be ejected = decreased stroke volume
| Law of Laplace - ventricular wall stress at start of systole
## Footnote
Hugely dependant on aortic pressure - ventricular pressure has to be greater than this to eject blood
66
What are factors decreasing afterload?
Ventricular hypertrophy - thicker wall means shared tension = less tension experienced by each sarcomere unit = less wall stress = reduced afterload
67
What increases afterload?
Aortic valve stenosis
Atherosclerosis in aorta and proximal arteries
Hypertension
Vasoconstriction
68
What are chronotropic agents?
Agents that affect the heart rate - by altering the electrical impulse at the SAN that regulate the heart's rhythm
69
What are physiological causes of low HR?
Endurance athletes
Sleeping
Sedatives
70
What are physiological causes of high HR?
Exercise
Stress
Caffeine
Female > Male
Age - babies and elderly
71
What are negative chronotopic agents?
Acetylcholine - parasympathetic
Digoxin
Beta blockers
Verapmil
Diltiazem
Hypothyroidism
Hypothermia
72
What are positive chronotropic agents?
Adrenaline, Noradrenaline - sympathetic
Atropine, isoprenaline
Hyperthyroidism - T3/4
73
When do the coronary arteries get their blood flow?
**Diastole**
Coronary arterial tree is intramural so get compressed during systole - 80% of blood flow occurs when ventricles are relaxed
74
What is the functional adaptation of the myocardium to meet high oxygen demand?
HIgh blood flow in coronary arteries
Myocardium extracts 75% of the oxygen it receives in the blood
The rest of the bosdy extracts 25% of the oxygen it receieves in the blood
75
What is a structural adaptation of the myocardium?
High myocardial capillary density
Distance that oxygen and nutrients travel from blood to the myocyte is shorter
76
What is metabolic hyperaemia?
Metabolites released in exercise have vasodilative effects on necessary muscles
Whilst systemic vasoconstriction in other organs to redirect their blood supply where needed
77
How is cardiac output increased during exercise?
| SV and HR
**Increase in stroke volume**
*Increased preload*
- Skeletal muscle pump
- Peripheral venoconstriction - in veins not being used
*Increased contractility*
- Increased sympathetic activity
**Increase in heart rate**
- Increase sympathetic activity - stimulate cardiac sympathetic fibres
- Decreased parasympathetic activity - normally inhibit SAN
78
What are the demands on the CVS during exercise?
- Increase oxygen and remove carbon dioxide
- Increase blood flow to active muscles
- Stabilise blood pressure
- Keep core temperature cool
79
How is cardiac output different in athletes?
Same cardiac output
- Lower HR
- Higher SV (heart muscle hypertrophy = reduce afterload, more responsive to catecholamines = increase contractility) (lower HR = increase filling time = increase preload)
80
How is cardiac output increased during exercise?
Increase in HR (main factor at high work loads)
Increase in SV (eventually plateus at high work loads)
## Footnote
Stroke volumes eventually plateaus and falls at very high work rates(less time for filling of ventricles) → increased heart rate becomes more important at high work loads to maintain increased CO
81
How does stroke volume response differ in a supine exercise like swimming vs upright exercise like cycling?
Swimming = high SV at beginning due to lack of gravity working on venous pressure = increased CVP --> so increase HR is main way of increasing CO
Cycling = sudden burts of exposive exercise - increase in preload from skeletal muscle pump - large increase in SV + along with increase in HR
82
Why can heavy weight lifting be dangerous in uncontrolled hypertension?
BP = CO X TPR
Massive increase in total peripheral resistance due to muscle contraction against vessels
Leads to large increase in blood pressure
| Also avoid in ischaemic heart disease
83
How does the total peripheral resistance affect the blood pressure in exercise?
Dilation in blood vessels in active muscles = lower vascular resistance - risk of hypotension
Vasoconstriction in inactive tissues - gut, kidneys, inactive muscles = increase vascular resistance = to compensate for risk of hypotension
Balance between the two to allow net fall in TPR to match rise in CO to maintain BP
| BP = CO X TPR
84
What is the difference between blood flow to the skin during light and moderate exercise?
Light exercise = vasoconstriction
Moderate exercise = vasodilation to allow heat loss through skin to reduce core temp (less blood back to heart = reduced preload ---> increase HR to maintain CO)
85
How can heavy exercise in hot weather lead to heat stroke?
Vasodilation for heat loss through skin but cannot increase heart rate to maintain CO → reduced CO detected by baroreceptors in heart → activates sympathetic nervous system = vasoconstriction to maintain blood pressure (at expense of cooling function) → elevation in core body temp
86
How long is 1 cardiac cycle and how is the time split?
0.8 seconds
0.3 - ventricular contraction
0.5 - ventricular relaxation
87
What occurs in the cardiac cycle during ventricular contraction?
**1. Isovolumetric contraction**
- Ventricle full of blood
- Ventricle Pressure > Atria Pressure = closure of AV valve = S1 sound LUB
- Ventricular contraction = massive increase in pressure but no movement of blood as all valves closed
- QRS complex
**2.Ventricular Ejection**
* Arterial pressure > Ventricular Pressure = SL valves open
* Ejection of bloof from ventricle
* Ventricular volume decreases
* ST complex
88
What occurs in the cardiac cycle during ventricular relaxation?
**1.Isovolumetric relaxation**
* Relaxation of ventricles
* Residual volume after ejection = ESV
* Ventricle repolarises = T wave
* Artery pressure > Ventricle pressure = SL valve shut = S2 sound DUB
* All valve shut so no movement of blood in ventricle
**2.Ventricular filling**
* Atria filling so atria pressure > ventricle pressure = AV valves open
* Passive filling of ventricles - 70/80% of blood volume
**3.Atrial contraction**
* SAN fires for contraction of atria
* Remaining blood pushed into ventricles 10/20%
* P wave
* EDV of ventricle
89
When and how is a S4 heart sound heard?
During Atrial Systole - just before S1 (closure of AV valve)
Active blood filling in ventricle against non-compliant, stiffened ventricle
Best heard in apex
Heard in HCM, ventricular hypertrophy
| Atrial Gallop
90
When and how is a S3 heart sound heard?
During ventricular filling, just after S2 (before atrial contraction)
Passive filling of blood in ventricle against a very compliant ventricle wall
Heard in congestive heart failure, dilated cardiomyopathy
May be normal in children,
| Ventricular Gallop
91
What are the 3 pressure changes in the atria and what waveforms represent these?
| Wigger's diagram
V wave - atria fill with blood
A wave - contraction of atria
C wave - bulging of AV valves into the atria during ventricular contraction
