Cardiovascular System Flashcards
(131 cards)
1
Q
What is the Mediastinum?
A
The mediastinum is the central compartment of the thoracic cavity, situated between the lungs.
2
Q
What does the mediastinum contain and consist of?
A
It contains all the thoracic structures except the lungs and is a highly mobile region in the living because it consists primarily of hollow visceral structures which are joined by loose connective tissue.
3
Q
Describe where the inferior mediastinum is situated.
A
The mediastinum extends from the superior thoracic aperture to the diaphragm and from the sternum and costal cartilages to the bodies of the thoracic vertebrae.
4
Q
Name the 3 parts of the inferior mediastinum.
A
- Anterior mediastinum
- Middle mediastinum
- Posterior mediastinum
5
Q
Describe where the superior mediastinum is situated.
A
Extends inferiorly from the superior thoracic aperture to the horizontal plane, which includes the sternal angle and passes approximately through the junction of T4 and T5 vertebrae posteriorly.
6
Q
What does the superior mediastinum contain?
A
Contains the roots of the great vessels and the trachea.
7
Q
Define the sternal angle.
A
The sternal angle is the joint between the manubrium (top part) and the body (middle part) of the sternum. It also marks the division of the superior and inferior mediastinum.
8
Q
At what vertebral level is the sternal angle found?
A
Between T4 and T5.
9
Q
Which part of the inferior mediastinum contains the heart?
A
The middle mediastinum.
10
Q
What lies within the fibrous pericardial sac?
A
The heart.
11
Q
The pericardial sack is fused superiorly with what?
A
The aorta and pulmonary trunk.
12
Q
The pericardial sac is blended inferiorly with what?
A
The central tendon of the diaphragm.
13
Q
The pericardial sac has a tough fibrous outer layer (the fibrous pericardium) which protects the heart against sudden over filling by doing what?
A
Physically preventing overexpansion.
14
Q
What is the internal surface of the fibrous pericardium lined with and what does it do?
A
A serous membrane which passes onto the surface of the heart to provide a continuous membrane surrounding the fluid filled pericardial cavity.
15
Q
What is the epicardium?
A
The visceral layer of the serous pericardium.
16
Q
What does the fluid in the pericardial cavity do?
A
The fluid in the pericardial cavity allows the heart to beat in an almost frictionless environment.
17
Q
Name the 2 circulatory systems.
A
Pulmonary and systemic systems.
18
Q
Name the 4 chambers of the heart and their relative positions.
A
Left & Right Atria. Left and Right ventricles. The atria are the upper chambers.
19
Q
What are the chambers of the heart made of?
A
Specialised cardiac muscle known as myocardium.
20
Q
True or false? Expulsion of blood from the hearts chambers is a passive process.
A
False. Contraction of the cardiac muscle pushes blood out of the chambers. The passive process of relaxation causes the chambers to refill.
21
Q
Define Systole.
A
Contraction of the ventricles.
22
Q
Define Diastole.
A
Relaxation of the ventricles.
23
Q
Pulmonary, derived from the Latin for lungs, is used to describe what?
A
Objects or systems that are related to the lungs.
24
Q
Is the pulmonary circulation pumped at a high or low pressure? Why?
A
The pulmonary circulation is pumped at a low pressure. Not much force is required to send blood the short distance through the lungs from the right to the left heart and high pressure in pulmonary capillaries would force fluid out of the blood, into the lung tissue and we would drown.
25
In pulmonary circulation, blood leaves the right ventricle through what?
The pulmonary arteries.
26
In pulmonary circulation, blood returns to the heart from the lungs through what vessels?
Pulmonary veins.
27
In pulmonary circulation, blood enters which chamber of the heart after returning from the lungs?
The left atrium.
28
In pulmonary circulation what does the pulmonary trunk divide into?
The right and left pulmonary arteries.
29
Define Systemic.
Affecting the whole body.
30
Which chamber of the heart is the origin of systemic circulation?
The left ventricle.
31
Which chamber of the heart is the end of systemic circulation?
The right atrium.
32
Why does the systemic circulation operate at a high pressure (compared to the pulmonary)?
Considerable force is required to adequately perfuse all the tissues in the human body and the blood has a much larger distance to travel.
33
Arteries carry _____ blood?
Oxygenated.
34
Veins carry _____ blood?
Deoxygenated.
35
From superficial to deep, name the 3 layers of the heart.
- Epicardium
- Myocardium
- Endocardium
36
What separates the atria?
The Interatrial (IA) septum.
37
What separates the ventricles?
The Interventricular (IV) septum.
38
Why is the left ventricle especially muscular?
As it has to push blood around the whole body.
39
The systemic circulation drains into the right atrium through what vessels?
The superior and inferior vena cava.
40
Describe the epicardium.
The epicardium consists of a layer of connective tissue and provides a protective layer over the heart.
41
Describe the myocardium.
This is the muscular component of the heart wall, it consists of myocytes or cardiac muscle cells.
42
Describe the endocardium.
This layer of epithelium and connective tissue lines the heart and covers the heart valves. The endocardium is continuous with the endothelial lining of blood vessels.
43
At rest when do the atria contract?
At the end of diastole.
44
During exercise, how does atrial contraction change?
During exercise, atrial contraction becomes essential to match the speed of ventricular filling to the increased rate of ventricular contraction.
45
Which have thicker walls, the atria or the ventricles? Why?
The ventricles. The atria only need to pump blood into the ventricles therefore have little muscle whilst the ventricles pump blood much further therefore have thicker, more muscular walls.
46
How are muscle fibres in the ventricles arranged?
Muscle fibres in the ventricles are arranged so that ventricular contraction progresses upwards in a spiral from the apex of the heart, towards the vessels leading out of the ventricles.
47
Where does the de-oxygenated blood carried by the superior vena cava come from?
The systemic circulation superior to the heart.
48
Where does the de-oxygenated blood carried by the inferior vena cava come from?
The systemic circulation inferior to the heart.
49
Name the 4 pulmonary veins.
Left superior and left inferior pulmonary veins and the right superior and right inferior pulmonary veins.
50
What do the valves of the heart separate?
Atria from ventricles, and ventricles from great vessels.
51
What would happen to the heart if it lacked valves?
If it were not for the valves of the heart, contraction of the wall surrounding the ventricles would send the blood both forwards, into the pulmonary artery and aorta, and backwards into the atria. Relaxation of the ventricles would also allow blood to re-enter the heart from the pulmonary artery and aorta.
52
What do atrioventricular valves do?
They prevent backflow of blood from the ventricles into the atria during systole.
53
Where is the tricuspid valve found and how many cusps does it have?
It is found between the right atrium and ventricle and has 3 cusps.
54
What ensures proper closure of the valves?
Papillary muscles and tendons attached to the cusps ensure proper closure and prevent inversion.
55
Where is the mitral valve found and how many cusps does it have?
The mitral valve is found between the left atrium and ventricle and is the only heart valve to consist of just two cusps.
56
What are the valves between the ventricles and great vessels called and what do they prevent?
The valves between the ventricles and great vessels are known as the semilunar valves, they prevent backflow of blood into the heart during diastole.
57
What valve is found between the left ventricle and the aorta?
The aortic valve.
58
Which valve separates the right ventricle from the pulmonary artery?
The pulmonary valve.
59
What are the spaces behind the aortic valves known as?
Aortic sinuses
60
What are the recognised sounds of the heart beat and what is each associated with?
Lub & Dub. Lub is associated with the closing of the atrioventricular valves and dub is associated with the closing of the semilunar valves.
61
What is a heart murmur caused by?
A heart murmur is caused by blood leaking through an incompletely closed or excessively narrowed (stenosed) valve.
62
How do aortic sinuses close the aortic valves?
Blood flow back towards the heart at the end of systole causes these sinuses to fill with blood, ballooning and closing the valve.
63
Name the AV valves.
Tricuspid and mitral valves.
64
Name the semilunar valves.
Aortic and pulmonary valve.
65
Name the 4 borders of the heart?
- Right border
- Inferior border
- Left border
- Superior border
66
True or false? The borders of the heart are visible in both anterior and posterior views.
True.
67
Describe the right border of the heart.
The right border of the heart is formed by the right atrium and extends from the superior vena cava to the inferior vena cava.
68
Describe the left border of the heart.
The left border is formed mostly from the left ventricle, a small portion is formed by the left atrium.
69
Describe the superior border of the heart.
The superior border is formed from the right and left atria. The superior vena cava enters the heart on the right of this border and the aorta and pulmonary trunk arise from this border.
70
Describe the inferior border of the heart.
The inferior border of the heart is roughly horizontal. Most of this border is formed from the right ventricle but a small contribution is made by the left ventricle.
71
Describe the left surface of the heart.
This surface is formed mostly by the left ventricle. It is related laterally with the left lung and occupies a depression in this lung know as the cardiac impression.
72
Where is the base of the heart anatomically situated?
The base is situated on the posterior aspect, directed towards the vertebrae T6-9.
73
What is the base of the heart formed from?
It is formed mostly from the left and partly from the right atrium and extends from the bifurcation of the pulmonary trunk superiorly to the atrioventricular groove inferiorly.
74
In what direction is the apex directed?
The apex of the heart is directed antero-inferiorly, forwards and down.
75
Where is the loudest part of the heartbeat found?
Directly superficial to the apex, on the surface of the thorax, is where the apex beat or loudest part of the heartbeat can be found on auscultation.
76
What are papillary muscles?
Papillary muscles are extensions of the muscle of the ventricular walls.
77
What and how are the papillary muscles attached to?
They are attached to the mitral and tricuspid valves via the inextensible papillary tendons.
78
At what vertebral level is the arch of the aorta?
The arch of the aorta is level with T4.
79
Describe the direction of the aortic arch.
The aorta ascends from the heart then loops posteriorly and to the left to pass behind the heart and descend through the thorax and abdomen.
80
Name the three branches of the aortic arch.
| Which parts of the body do they supply?
- Brachiocephalic trunk
- Left common carotid artery
- Left subclavian artery
They supply the head, neck and upper limbs.
81
What does the brachiocephalic trunk divide into?
The right subclavian artery and the right common carotid artery.
82
At what vertebrae level do the common carotid arteries divide into the internal and external carotid arteries?
C3.
83
The internal carotid artery is the major blood supply to the what?
Brain.
84
The external carotid artery is the major blood supply to the what?
Neck, face and scalp.
85
The subclavian arteries are the major blood supply to the what?
- Arm
- Thoracic wall
- Shoulder
- Neck
86
Which arteries supply the heart with the rich blood supply it requires?
Coronary arteries.
87
Where do the coronary arteries arise from?
These arteries arise immediately superior to the cusps of the aortic valve, from the aortic sinuses.
88
Name the 3 sinuses of the aortic valve.
- Left
- Right
- Posterior
89
The right coronary artery rises from the ____ sinus?
Right sinus.
90
The left coronary artery rises from the ____ sinus?
Left sinus.
91
Does a coronary artery arise from the posterior sinus?
No.
92
How is deoxygenated blood removed from the heart tissue?
A network of cardiac veins drains deoxygenated blood from the heart tissue and deposits it in the coronary sinus which drains into the right atrium.
93
What does the left coronary artery supply?
- Left atrium
- Most of left ventricle
- Some of right ventricle
- Anterior part of the IV septum
- The SA node
94
What does the left coronary artery divide into?
The anterior interventricular branch and the smaller circumflex branch.
95
Describe what the anterior interventricular artery supplies and where it travels.
The anterior interventricular branch travels down the anterior surface of the heart along the interventricular groove, supplying the anterior walls of both ventricles until it passes around the apex of the heart where it anastomoses with the posterior interventricular branch.
96
Describe what the circumflex branch supplies and where it travels.
The circumflex branch passes along the coronary (atrioventricular) groove on the left border of the heart to the posterior surface of the heart where it typically anastomoses with the posterior interventricular branch. It also gives off a left marginal artery which runs on the left border of the heart and supplies the left ventricle.
97
What does the right coronary artery supply?
- Right atrium
- Most of right ventricle
- Some of left ventricle
- Posterior IV septum
98
Which vessel supplies the SA node and where does it originate from?
Close to its origin the right coronary artery gives off an ascending sinoatrial node branch that supplies the SA node.
99
Describe what the right coronary artery supplies and where it travels.
It descends in the atrioventricular groove, giving off a marginal branch at the right margin of the heart that supplies the right border of the heart.
100
At the crus of the heart the right coronary artery gives off the large posterior interventricular branch that descends in the what?
Posterior interventricular groove.
101
The cardiac muscle is anchored to a supporting structure known as what?
Fibrous skeleton.
102
What is the support in the fibrous skeleton provided by?
Dense collagen.
103
How many fibrous rings surround the valve openings?
4.
104
How many fibrous trigones lie between the fibrous rings of the collagen support?
2.
105
List the purposes of the fibrous skeleton.
- Prevents the valve openings from collapsing or distending.
- Provides a base for attachment for the leaflets and cusps of valves.
- Most importantly, forms an electrical barrier between the atria and ventricles, preventing them from contracting together.
106
Describe cardiac muscle.
Cardiac muscle is found only in the heart, it is striated muscle but it is not under voluntary control.
107
True or false? Cardiac muscle cells form a highly branched, interconnecting network of fibres.
True.
108
The heart operates as a functional syncytium. What does this mean?
This means that an electrical stimulus to any one part of the heart can cause contraction of the whole myocardium.
109
The cardiac cells are physically divided by the _______ around the fibrils and _______ discs between the cells.
1. Sarcolemma
| 2. Intercalated
110
By what mechanism does contraction occur?
Cardiac muscle, like skeletal muscle, contracts by a sliding filament mechanism between thick and thin filaments of the sarcomeres.
111
Describe intercalated discs.
Intercalated discs separate the sarcoplasm of adjacent cardiac muscle cells.
112
Intercalated discs hold the cells firmly together through the action of what?
Desmosomes.
113
Although separating the cells, intercalated discs allow electrical excitation to pass between cells through what?
Gap junctions.
114
What is the technical name for the pacemaker?
Sinoatrial (SA) node.
115
Where is the SA node situated?
The posterior wall of the right atrium, close to the superior vena cava.
116
The rate at which the SA node fires is modified by what?
Autonomic input – sympathetic increasing heart rate, parasympathetic decreasing heart rate.
117
The heart’s electrical tissues consist of two nodal tissues. Name them.
SA and AV nodes.
118
Name the three different electrical tissues of the heart.
- Nodal tissue
- Conductive fibres
- Myocardium
119
Describe the function of the AV node.
The AV node acts as an electrical gateway between the atria and ventricles. It slows the passage of the electrical impulse initiated by the SA node before allowing it to continue to the ventricles. This allows the atria to contract fully before the ventricles contract.
120
Describe the function of the AV bundle.
The AV bundle conducts the electrical impulse from the atria to the ventricles.
121
Describe the function of the Purkinje fibres.
The Purkinje fibres are fast-conducting fibres in the subendocardium which spread the impulse through the myocardium. The distribution of the Purkinje fibres ensures that the ventricles contract upwards from the apex.
122
Except for capillaries all blood vessels have a three layered wall. The wall consists of what 3 parts?
- Tunica intima (inner most layer)
- Tunica media (middle layer)
- Tunica adventitia (outer layer)
123
Describe the tunica intima.
The intima consists of a single sheet of endothelial cells resting on a thin layer of connective tissue. This layer is mechanically weak however the endothelium is the main barrier to plasma proteins and also secretes many vasoactive products
124
In order list the vessels from the aorta and the pulmonary artery, to the pulmonary vein and the vena cava.
```
Aorta and pulmonary artery ---
Arteries ---
Arterioles ---
Capillaries ---
Venules ---
Veins ---
Vena cava and pulmonary vein ---
```
125
Describe the differences in the tunica media in elastic arteries, muscular arteries and in veins.
- Elastic arteries - The tunica media is rich in elastin
- Muscular arteries - The tunica media is relatively thicker than in elastic arteries and contains a higher proportion of smooth muscle to prevent blood vessel collapse.
- Veins - The tunica media consists of smooth muscle and collagen and hardly any elastin.
126
Name the 3 surfaces of the heart.
- Anterior (sternocostal) surface
- Inferior (diaphragmatic) surface
- Left (pulmonary) surface
127
Describe the anterior surface of the heart.
Formed mostly from the right ventricle, this surface is related anteriorly to the sternum and ribs.
128
Describe the tunica media.
The media consists of a layer of smooth muscle of varying thickness in a matrix of elastin and collagen. This layer supplies mechanical strength, elasticity and contractile power to the vessel.
129
Describe the tunica adventitia.
The adventitia is a connective tissue sheath with no distinct outer border. It’s main role is to tether vessels loosely in place. In large arteries it contains a small blood vessel network called the vasa vasorum which are responsible for nourishing the media. In larger arteries the vessels also penetrate the outer tunica media.
130
Describe the inferior surface of the heart.
This surface is formed mostly by the left and partly from the right ventricle. It is related inferiorly to the centre of the diaphragm.
131
The aorta and pulmonary artery divide into smaller arteries. These then branch progressively to form tiny arteries of diameter what?
0.1-0.5mm.
