Cardiovascular system Flashcards
1
Q
What is the cardiovascular system?
A
organ system responsible for transporting oxygen, carbon dioxide and nutrients etc.
2
Q
Where does gas exchange occur in the CVS?
A
capillaries
3
Q
Components of the CVS
A
heart, blood vessels, blood, (lymphatic system works in conjunction with CVS)
4
Q
Components of blood
A
erythrocytes, leucocytes, platelets, plasma
5
Q
What is the lymphatic system?
A
Organ system that transports excess interstitial fluid as lymph before returning it to venous circulation. Key part of immune system.
6
Q
Description of capillary microcirculation
A
The high HP at the arteriole end of the capillary forces out blood plasma to form interstitial fluid. As the volume of blood plasma has decreased in the venous end, this causes a lower HP but increases the osmotic pressure. This draws interstitial fluid back into capillaries.
7
Q
What are the two loops of circulation?
A
pulmonary and systemic circulation
8
Q
Outline of pulmonary circulation
A
deoxygenated blood is transported out of the RV via the pulmonary trunk which bifurcates into the left and right pulmonary arteries. Gas exchange occurs in lungs. 4 pulmonary veins (2 each side) transport oxygenated blood from lungs to the LA.
9
Q
Outline of systemic circulation
A
Oxygenated blood is transported from the LV to the body via the aorta. Deoxygenated blood returns to the RA via the SVC and IVC.
10
Q
What is the mediastinum?
A
anatomical region in middle of thorax bordered by pleural cavities (contain lungs)
11
Q
How is the mediastinum divided?
A
Into the superior and inferior mediastinum. The inferior mediastinum is further divided into the anterior, middle and posterior mediastinum.
12
Q
Borders of the superior mediastinum
A
Bordered superiorly by T1 posteriorly and the superior aspect of the manubrium anteriorly. Bordered inferiorly by the sternal angle anteriorly and T4/5 posteriorly.
13
Q
What structures are found in the superior mediastinum?
A
Aortic arch and its branches (SCCS), trachea, oesophagus, thymus gland.
14
Q
Function of thymus gland
A
Immune system development in childhood after which it atrophies.
15
Q
Borders of inferior mediastinum
A
anteriorly extends from sternal angle to diaphragm, posteriorly extends from T5 to T12
16
Q
Structures found in anterior mediastinum
A
remnants of thymus, fat
17
Q
Structures found in middle mediastinum
A
heart
18
Q
Contents found in posterior mediastinum
A
oesophagus and descending aorta
19
Q
What is the pericardium?
A
Double-layered membrane that surrounds the heart
20
Q
Structure of the pericardium
A
made of 2 layers - outer fibrous layer and inner serous layer (divided into parietal and visceral layers with pericardial cavity between)
21
Q
Function of fibrous layer of pericardium
A
dense CT that protects the heart and anchors it to the diaphragm (and prevents over-expansion, can restrict in case of pericardial effusion)
22
Q
What is pericardial effusion?
A
Abnormal accumulation of serous fluid in pericardial cavity/space
23
Q
Structure of serous pericardium
A
made of a parietal layer that lines inner surface of fibrous pericardium and a visceral layer that adheres to the heart surface. Separated by pericardial space/cavity
24
Q
Function of pericardial space/cavity
A
contains lubricating serous fluid that reduces friction during heart beats
25
Function of superior vena cava
transports deoxygenated blood from head, neck and upper limbs to RA
26
Function of inferior vena cava
transports deoxygenated blood from below the level of the heart to the RA
27
Function of pulmonary trunk
carries deoxygenated blood from RV towards lungs and bifurcates into left and right pulmonary arteries
28
Order of branches from the aortic arch (R->L)
Brachiocephalic trunk (branched into right subclavian and right common carotid artery), left common carotid artery, left subclavian artery. (SCCS)
29
Which arteries branch from brachiocephalic trunk
Right subclavian artery, right common carotid artery.
30
What is an auricle?
A muscular pouch that can increase atrial capacity and relieve high atrial pressure during times of stress.
31
Alternative name for auricle
atrial appendage
32
Where are auricles found?
Anterior surface of each atria
33
Which blood vessel transports oxygen rich blood from the mother to the foetus?
Umbilical vein
34
What happens at the placenta?
Exchange of oxygen and nutrients between foetal and maternal blood
35
Name of structure used to bypass liver in foetal circulation?
Ductus venosus
36
Where does 30% of the blood in the umbilical vein enter foetal circulation?
IVC (to RA) as the blood bypasses the liver via the ductus venosus
37
What is the remnant of the ductus venosus
ligamentum venosum
38
Where is the ligamentum venosum found?
passes superiorly from porta hepatis to IVC (near caudate lobe)
39
How does blood bypass the lungs in foetal circulation?
Foramen ovale allows blood to flow from RA to LA (then to LV and systemic circulation. Ductus arteriosus links pulmonary trunk to aorta (for any blood that doesn't pass though foramen ovale)
40
What is the foramen ovale?
Opening between the right and left atria that allows oxygenated blood to bypass lungs and enter the systemic circulation (RA -> LA -> LV -> aorta)
41
What is the remnant of the foramen ovale?
fossa ovalis
42
What is the ductus arteriosus?
A vessel connecting the pulmonary trunk to the aorta, allowing blood to bypass the lungs and enter systemic circulation.
43
Why are the lungs bypassed in foetal circulation?
They are not yet fully developed - filled with fluid and not yet involved in gas exchange.
44
Function of umbilical artery
carry deoxygenated blood and waste products away from the foetus to the placenta for exchange with mother's blood.
45
After birth, which structures from foetal circulation are sealed?
Ductus venosus, foramen ovale, ductus arteriosus.
46
Name of thick, muscular layer of heart wall
myocardium
47
Function of myocardium
thick, muscular layer that contracts and relaxes to pump and receive blood
48
What is the myocardium composed of?
cardiac muscle cells (cardiomyocytes)
49
Name of innermost layer of heart wall
endocardium
50
What is the endocardium?
the innermost layer of the heart wall. It is thin (single layer of endothelial cells) and has a smooth lining.
51
Function of endocardium
reduces friction and prevents blood clot formation
52
Name of irregular muscular projections on the inner surface of ventricles
trabeculae carnae
53
Where are trabeculae carnae found?
Inner surface of ventricles
54
What layer of the heart contains coronary arteries and veins?
epicardium (visceral layer of serous pericardium) - outermost layer of heart wall before cavity
55
Which heart layer makes up the epicardium?
Visceral layer of serous pericardium - outermost layer of heart wall
56
Function of coronary arteries
supply oxygenated blood to the heart muscle from the aortic sinus.
57
Function of coronary veins
transport deoxygenated blood from the heart muscles into the RA (mainly via coronary sinus)
58
What are the aortic sinuses?
3 widenings/dilations of the blood vessel wall above the aortic valve
59
Where to the left and right coronary arteries arise from?
the left and right aortic sinuses (2/3)
60
Where an external pacemaker typically placed?
Right auricle / appendage (close to SAN)
61
Name of muscle in inner atrial wall
Pectinate muscles / musculi pectinate
62
Function of pectinate muscles
Allows the atria to stretch and increase its volume when filling with blood
63
Function of coronary sinus
drains deoxygenated blood from the coronary veins into the RA
64
Location of pulmonary valve
base of pulmonary trunk between the RV and the pulmonary trunk. Anterior portion of heart
65
How many cusps/leaflets does the pulmonary valve have?
3
66
Where is the aortic valve located?
Between the LV and aorta (middle/anterior of heart)
67
How many cusps/leaflets does the aortic valve have?
3
68
Function of pulmonary valve
prevents backflow into RV
69
What is the infundibulum of the RV?
(aka conus arteriosus) is a smooth walled funnel shaped part of the RV leading towards the pulmonary valve (no trabeculae)
70
Name of the AV valve between the RA and RV
tricuspid valve (3 leaflets)
71
Name of the AV valve between the LA and LV
Mitral / bicuspid valve (2 leaflets/cusps)
72
Where are the AV valves positioned in the heart in comparison to the SL (semilunar valves)?
AV valves are more posteriorly situated in comparison to the SL valves which are more anterior in the heart.
73
What are the chordae tendineae?
String-like structures that anchor the cusps of the tricuspid and bicuspid valves to papillary muscles in the ventricular wall
74
Function of chordae tendineae
Help valve closure and prevent the inversion of the valve cusps into the atria during ventricular systole.
75
What are papillary muscles?
Cone-like muscles found in the ventricles that anchor chordae tendineae to the ventricular walls.
76
Function of papillary muscles
contract to tighten chordae tendineae inorder to stabilise AV valves during ventricular systole.
77
Branches of the left coronary artery
Anterior interventricular artery / left anterior descending (LAD) artery and the circumflex artery.
78
What is the name of the groove in which the anterior interventricular artery / left anterior descending artery runs along?
Anterior interventricular groove (anterior part of interventricular sulcus)
79
Function of the anterior interventricular / left anterior descending artery
Supplies oxygenated blood to the anterior walls of both ventricles and most of the interventricular septum
80
What is the pulmonary sinus?
Widening / dilation of wall at the base of the pulmonary trunk near the pulmonary valve
81
Function of the pulmonary sinus
Prevents the cusps of the pulmonary valve adhering to the wall of the pulmonary trunk.
82
Function of circumflex artery
Supplies blood to the LA and lateral and posterior walls of LV
83
Name of the venous structure that empties deoxygenated blood from the heart into the RA
Coronary sinus
84
Where is the coronary sinus found?
In the posterior heart entering at the RA
85
Which ventricular wall is thicker?
LV wall about 3 times thicker than RV wall
86
What is the interventricular septum?
Thick muscular wall separating the RV and LV
87
Branches of the right coronary artery
marginal artery and posterior interventricular artery
88
Function of the marginal artery
Supplies oxygenated blood to the RV wall
89
Function of posterior interventricular artery
supplies the posterior of the heart
90
Function of the right coronary artery
Supplies oxygenated blood to the RA, RV, conducting system (SAN and AVN), and part of the interventricular septum.
91
Along which sulcus does the posterior interventricular artery run?
Posterior interventricular sulcus
92
What are septal defects?
Abnormal openings / holes in the interatrial and/or interventricular septum.
93
Name of condition where there is a hole in the interatrial septum
atrial septal defects
94
Name of condition where there is a hole in the interventricular septum
ventricular septal defect
95
Name of condition in which there is a hole both in the interatrial and interventricular septum?
Atrioventricular septal defect
96
Consequence of atrial / ventricular septal defects
Smaller hole may close themselves. Larger holes can compromise the heart and lungs due to an increased BP
97
Why is an atrioventricular septal defect a more serious condition?
Blood continually shunts between the atria and ventricles leading to inefficient pumping of blood to the body. Requires surgery
98
Symptoms of an atrioventricular septal defect
breathing difficulty, racing heart, weak pulse, cyanosed, tire easily
99
Cause of atrial septal defect (ASD)
incomplete closure of the foramen ovale (used to bypass pulmonary circulation in foetus)
100
Effect of larger ASD
Hypertrophy of the RA and RV as blood flows from the LA into the RA down the pressure gradient. This increases the blood volume in the right side of the heart so the RA and RV must work harder to accommodate extra blood. .
101
Which direction does blood flow in an atrial septal defect (ASD) / ventricular septal defect (VSD)?
From the left side to the right (left side is at a higher pressure)
102
Effect of ventricular septal defect (VSD)
Blood flows from the LV into the RV causing hypertrophy of the RV and pulmonary hypertension as there is an increased blood flow to the lungs.
103
Name of the 4 heart valves
tricuspid, pulmonary, bicuspid/mitral and aortic valve
104
What is the cause of the "lub" sound of the heart beat?
The closure of the AV valves during ventricular systole (forcing blood against AV valve cusps)
105
What is the cause of the "dub" sound of the heart beat?
Closure of SL valves during ventricular diastole
106
Which is louder, the "lub" or the "dub"?
Lub is louder than dub
107
Which structures assist in AV valve closure and prevent inversion of the cusps into the atria?
papillary muscles contracting and chordae tendineae tightening (not present in SL valves)
108
How do SL valves close?
During ventricular diastole, there is a slight backflow of blood in the arteries which fills the half-moon shaped cusps of the SL valves, forcing them to close.
109
How are coronary arteries filled?
The slight backflow of blood in the aorta during ventricular systole fills the aortic sinuses where the coronary arteries arise from.
110
Clinical condition that can affect hear valves
infective endocarditis
111
What is infective endocarditis?
An infection of the endocardium (inner lining of heart) which typically involves heart valves.
112
Most common form of infective endocarditis
subacute bacterial endocarditis (SBE)
113
Which valves are most commonly affected by infective endocarditis?
Rheumatic valves, congenitally abnormal valves, prosthetic valves.
114
What is rheumatic heart disease?
Condition where heart valves are permanently damaged by rhematic fever
115
What is rheumatic fever?
inflammatory disease that can affect many CTS especially in the heart (can lead to rheumatic heart disease)
116
Examples of organisms that can cause infective endocarditis
streptococcus viridans / staphylococcus aureus
117
Oral infection that can cause infective endocarditis
dental abscess (or any procedure that allows bacteria to enter bloodstream)
118
Symptoms of infective endocarditis
heart murmur, fever, fatigue, weight loss or more severe complications like an embolism (blood clot) or heart failure.
119
What would cause a heart murmur in infective endocarditis?
Valvular vegetations (growth of infected material on valves) which can cause stenosis or regurgitation.
120
Stenosis definition
narrowing of valve
121
Regurgitation definition
backward flow of blood due to valve dysfunction
122
Which coronary arteries anastomose?
posterior interventricular artery (from R coronary artery) anastomoses with anterior interventricular (LAD) artery.
123
Tributaries of the coronary sinus
great cardiac vein, middle cardiac vein and small cardiac vein
124
Which coronary vein bypasses the coronary sinus and drains directly into the RA?
Anterior cardiac veins
125
Function of great cardiac vein
drains areas supplied by the left coronary artery
126
Function of middle cardiac vein
drains posterior interventricular region into coronary sinus
127
Function of small cardiac vein
Drains deoxygenated blood from the right side of the heart into the coronary sinus
128
What are end arteries?
Arteries that only supply oxygenated blood to a specific portion of tissue
129
Example of end arteries
coronary arteries
130
What is coronary artery disease (CAD)?
Condition where coronary arteries are narrowed due to the build up of plaque. This creates a reduced blood flow (ischaemia) to the heart.
131
What is ischaemia?
Reduced blood supply to part of the body.
132
What can ischaemia of the heart / coronary artery disease result in?
development of collateral circulation and angina pectoris
133
What is collateral circulation?
The growth of new blood vessels to pass around an area of reduced blood supply e.g. coronary artery disease. These vessels can rupture.
134
What is angina pectoris?
chest pain related to CAD
135
What may result if coronary artery disease is left untreated?
Myocardial infarction (death of heart cells due to lack of blood supply)
136
What percentage of heart attacks are due to blockages in the anterior interventricular branch (LAD)?
40-50%
137
What percentage of heart attacks are due to blockages of the right coronary artery?
30-40%
138
What percentage of heart attacks are due to blockages of the circumflex branch of the LCA?
15-20%
139
What percentage of heart attacks are due to blockages in the left side of the heart?
up to 70% - worrying because the LCA supplies majority of heart
140
Why is the anterior interventricular / LAD artery called the widowmaker?
LAD supplies large portion of heart's blood so a blockage in this artery can lead to a fatal heart attack (MI)
141
What is a coronary artery bypass?
Surgical procedure involving attachment of healthy blood vessels (grafts) from elsewhere in the body to beyond a coronary artery blockage which restores blood flow to the heart.
142
Examples of blood vessels used as grafts in coronary artery bypass
saphenous vein (longest vein, in leg), internal mammary/ thoracic artery, radial artery
143
Why may the internal mammary/thoracic artery be preferred over the saphenous vein in a coronary artery bypass?
Because it is an artery doing an artery's job.
144
Function of the heart's conducting system
ensures synchronised contraction of atria and ventricles for efficient pumping of blood
145
Where is the sinoatrial node (SAN) located?
right atrium
146
Function of SAN
generates electrical signals to initiate the heart beat. Acts as the pacemaker (controls heart rate)
147
Where is the atrioventricular node (AVN) located?
near the interatrial septum
148
Sequence of the heart conducting system
1. SAN generates electrical signals that travel across the atria causing atrial systole.
2. The electrical signals gather in the AVN where they transmitted to the bundle of His which splits.
3. The signals travel through the left and right bundles in the interventricular septum towards the ventricle walls.
4. Purkinje fibres conduct the impulse from the bundles to the ventricular muscle, causing synchronised ventricular systole.
149
What is the septomarginal trabecula / moderator band?
A thick, muscular structure extending from the interventricular septum to the anterior papillary muscle in the RV.
150
Function of the septomarginal trabecula / moderator band
Allows a shorter route for electrical impulses to pass from the right interventricular bundle directly to the anterior papillary muscle so it contracts to close the tricuspid valve.
151
What is atrial fibrillation (AF)?
rapid irregular contraction (quiver) of different parts of the atria
152
Effect of atrial fibrillation
less efficient blood flow from atria into ventricles. Not immediately life threatening
153
What is ventricular fibrillation (VF)?
rapid, irregular contraction (quiver) of ventricles
154
Effect of ventricular fibrillation
blood not pumped through systemic or cardiac circulation. Leads to cardiac arrest
155
What is the most disorganised form of dysrhythmia?
Ventricular fibrillation (leads to cardiac arrest)
156
Cardiac arrest vs heart attack
Cardiac arrest due to electrical issue in heart causing loss of consciousness, no breathing, no pulse. Heart attack due to blocked coronary artery (conscious).
157
What to do if someone has a cardiac arrest?
immediate CPR and defibrillator
158
Function of arterial system
distribute oxygenated blood from the heart to tissues while maintaining BP
159
What happens to the arterial walls during systole?
As ventricles pump blood into the arteries, the elastic walls expand.
160
What happens to the arterial walls during diastole?
Elastic walls recoil to maintain arterial blood pressure for continuous blood flow.
161
How is blood flow to tissues regulated?
By varying capillary diameter (using precapillary sphincters and arteriole constriction/dilation)
162
3 histological layers of arterial walls
tunica intima, tunica media, tunica adventitia
163
What is the tunica intima?
Innermost layer of arterial walls made of endothelium and CT.
164
Function of tunica intima
has a smooth surface to reduce resistance against blood flow.
165
What is the tunica media?
Middle layer of arterial walls composed of smooth muscle and elastic fibres.
166
Function of tunica media
Responsible for vasoconstriction/dilation which regulates blood flow
167
What is the tunica adventitia?
Outermost layer of the arterial wall composed of CT with collagen an elastic fibres.
168
Function of tunica adventitia?
structural support and anchors arteries to surrounding tissues
169
Examples of elastic arteries
aorta, common carotid, subclavian and pulmonary arteries
170
Examples of muscular arteries
radial, femoral, coronary and cerebral arteries.
171
What are arterioles?
Terminal branches of arteries supplying the capillary bed
172
Structural adaptation of elastic arteries
contain abundant elastic fibres in the tunica media
173
Function of elastic arteries
maintain BP and smooth blood flow (despite pulsatile output from the heart) by expanding and recoiling (lots of elastic fibres)
174
Function of muscular arteries
Distribute blood to specific organs/regions. Control blood flow by vasoconstriction / vasodilation (SM)
175
Structural adaptation of muscular arteries
thick tunica media rich in smooth muscle (for vasoconstriction and vasodilation)
176
Function of arterioles
Regulate blood flow to tissues and systemic BP via their ability to constrict and dilate which alters the resistance to blood flow.
