Cardiovascular System Flashcards
(130 cards)
1
Q
What is the daily output of blood from the muscular pumps?
A
7000L/day each
2
Q
What is the function of the aorta?
A
It is the main artery originating from the left ventricle that carries oxygenated blood away from the heart
3
Q
What is the function of the left atrium?
A
Receives blood from the lungs and pumps into the ventricles
4
Q
What is the function of the right atrium?
A
Receives blood from the venous circulation and pumps it into the ventricles
5
Q
What is the function of the superior vena cava?
A
Returns deoxygenated blood from the systemic circulation to the right atrium of the heart
6
Q
What is the function of the interior vena cava?
A
Carries deoxygenated blood from the lower and middle body into the right atrium
7
Q
What is the function of the auricles?
A
They are a thin pouch if heart wall that helps the atrium to hold more blood by holding blood and contracting to pump
8
Q
What is the peak pressure of the right ventricle?
A
27mmHg
9
Q
What is the peak pressure of the left ventricle?
A
120mmHg
10
Q
What is the peak pressure of the right atrium?
A
5mmHg
11
Q
What is the peak pressure of the left atrium:
A
8mmHg
12
Q
What are the 2 types of atrioventricular valves?
A
Bicuspid/mitral valve: left side
Tricuspid: right side
13
Q
Describe the atrioventricular valves:
A
They are found between the atrium and the ventricles on the left (mitral) and right (tricuspid) sides of the heart. One edge is attatched to the wall of the heart and the other side is free so it is tethered by tendinous chords to prevent it from bursting upwards.
14
Q
What is the purpose of chrodae tendine and papillary muscles?
A
To prevent the atrioventricular valves from going back up when the blood pushes against the valves after coming into the ventricles.
15
Q
The 2 inlet valves (mitral and bicuspid) - atrioventricular are much larger than the outlet valves (aortic and pulmonary) - semilunar valves, why is this?
A
The inlets must be bigger because they are letting in the blood at a lower pressure so they need a larger diameter whereas in the outlet ones they are leaving at high pressure so they don’t need a large diameter.
16
Q
What are the 2 types of outlet valves - semilunar valves?
A
Aortic valve
Pulmonary valve
17
Q
Describe how ventricular outlet valves/ semilunar work?
A
When blood leaves during ventricular ejection, it leaves the ventricle and flows up into the artery. The pressure of the blood trying to reenter the ventricles forces the free edges of the cusps together
18
Q
Do semilunar/ventricular outlet valves need papillary muscles and tendinous chords, why/why not?
A
No because they are smaller so they don’t need them
19
Q
Where is the apex of the heart?
A
It is at the bottom and it points inferiorly, anteriorly and to the left.
20
Q
What is the right border of the heart formed by?
A
The right atrium
21
Q
What is the left border of the heart formed by?
A
The left ventricle
22
Q
Describe the superior border of the heart:
A
It is the base border as it only attachment point of the heart and is tethered by blood vessels
23
Q
Describe the pericardium:
A
It encloses the heart in a double walled bag. There is an inner layer (visceral pericardium) and outer layer (parietal pericardium) and they are both made by a single layer of squamous mesothelial cells. In the middle there is the pericardial space which is filled with serous fluid
24
Q
What does the outer wall of the pericardium line?
A
The fibrous pericardium which is made up of collagen and is a tough fibrous sac.
25
Going from the blood to the outer pericardial sac, name all of the layers in between:
Blood, endocardium, myocardium (cardiac muscle), epicardium/visceral, pericardial space, parietal, fibrous, outer
26
What is cardiac temponade?
When the pericardial space has filled with blood
27
Describe how the valves of the heart are all connected to form the fibrous skeleton:
The fibres forming the tricuspid ring are incomplete and the pulmonary ring is absent. Both of these are associated with low pressure in the pulmonary pump. Fatty connective tissue is still present where the fibrous skeleton is incomplete.
28
Does the heart have nerves why/why not?
No it just has modified muscle that acts essentially as nerves.
29
Where is the AV node found?
Sitting in a hole in the fibrous skeleton
30
What is the function of the fibrous skeleton?
Conduction
31
Where is the SA node?
It is found at the junction between the superior vena cava and the right atrium
32
Where are the pacemaker cells that are influenced by hormones and peripheral nerves?
The SA node
33
What is the point of the 100m/s delay?
We don't want the atrium and ventricles contracting at the same time
34
Describe the first stage of how an action potential is conducted down the heart:
The SA node can spontaneously depolarise and repolarise so the action potential travels out of the SA node and out to the atrial muscle. It is very slow 0.5m/s and results in atrial contraction. It ensures that the atrial contraction is even and coordinated.
35
Describe the second stage of how an action potential is conducted down the heart:
It begins at the AV node which can also spontaneously depolarise and repolarise on its own but much slower than the SA node. The speed o f contraction is very slow about 0.05m/s which results in a 100ms delay
36
Describe the third stage of how an action potential is conducted down the heart:
The action potential goes down the AV bundle and out to the purkinje fibres. The speed is very fast about 5m/s and results in even ventricular contraction (systole)
37
About how long is one cardiac cycle?
1s
38
List the order of one cardiac cycle:
Ventricular filling (diastole), atrial contraction, isovolumetric ventricular contraction (systole), ventricular ejection (systole), isovolumetric ventricular relaxation
39
Describe the stage of the cardiac cycle: ventricular filling
This is the stage of diastole where the phase commences as pressure in the ventricles drops below that of the atrium. The mitral valve opens quietly and blood begins to enter the ventricle.
40
When exercising, which phase shortens the most?
Ventricular filling
41
Describe the phase of the cardiac cycle: atrial contraction:
The left atrium contracts to complete filling of the ventricles. The rise in atrial pressure is small because firstly the muscle layer of the atrium is thin and secondly because there are no valves where the pulmonary veins enter the atrium so there is nothing to prevent backflow back into the veins.
42
Describe the phase of the cardiac cycle: isovolumetric ventricular contraction
This is the beginning of systole. This is where the 1st heart sound is heard as the ventricle begins to contract. Blood within the ventricle lifts backwards towards the atrium and the mitral valve closes (first heart sound). Ventricular pressure is still lower than aortic pressure so the aortic valve remains closed. For this brief moment of rising pressure both its inlet and outlet valves are closed.
43
Describe the phase of the cardiac cycle: Ventricular ejection
Systole continues but now ventricular pressure exceeds aortic pressure and the aortic valves open. Blood leaves the ventricle. Because blood is ejected into the aorta faster than it can run off into the distributing arteries, the pressure in the ventricle and the aorta continues to rise rapidly, however later in this phase the rate of ejection falls below the rate of run off and aortic and ventricular pressures level off and then begin to decrease.
44
Describe the phase of the cardiac cycle: Isovolumetric ventricular relaxation
The ventricle relaxes and as it does so ventricular pressure drops suddenly, flow reverses in the aorta and the aortic valve closes (second heart sound), as blood tries to re-enter the ventricle. The mitral valve is closed because ventricular pressure although falling, is still higher than atrial pressure.
45
At what stage of the cardiac cycle does the mitral valve open?
Ventricular filling (diastole)
46
At what stage of the cardiac cycle does the mitral valve close?
Isovolumetric ventricular contraction.
47
At what stage of the cardiac cycle does the aortic valve open?
Ventricular ejection
48
At what stage of the cardiac cycle does the aortic valve close?
Isovolumetric ventricular relaxation
49
Why is the first heart sound louder than the second?
Because the inlet valves are bigger than the outlet valves.
50
What does systolic pressure represent?
Maximum pressure inside the systemic artery.
51
What does diastolic pressure represent?
Lowest pressure inside systemic artery.
52
What are the six types of blood vessels in the order of how blood leaving the heart sees them?
Elastic artery, muscular artery, arterioles, capillary, venule, vein.
53
How big are elastic arteries?
Size of finger.
54
How big are muscular arteries?
Pencil to pin
55
How big are arterioles?
Size of a human hair
56
How big are capillaries?
8 microns (the size of one red blood cell)
57
How big are veins?
Pencil to pin
58
Describe the function of elastic arteries:
During systole they expand to store blood leaving the ventricle then during diastole they push blood out of the atrial tree by elastic recoil. It smooths out the pulsatile nature of blood flow.
59
Describe the function of muscular arteries:
They distribute blood around the body at high pressure and the lungs at medium pressure. The rate of blood flow is adjusted by using smooth muscle to vary the radius of the vessel.
60
Describe the function of arterioles:
To control blood flow into capillary beds. They have a thicker muscular wall relative to their size than any other vessel. These are the vessels in circulation where the greatest pressure drop occurs and where there is greatest resistance to flow. The degree of constriction of arterioles in the body determines total peripheral resistance which in turn affects mean arteriole blood pressure.
61
At what vessel does the greatest pressure drop and the greatest resistance occur at?
Arterioles
62
Describe the function of capillaries:
They are tiny vessels which are thin walled to allow for the exchange of gases, nutrients and wastes between the blood and surrounding body tissues. Blood flow is slow to allow time for exchange
63
The capillaries are leaky, how do they recover the lost plasma?
By an osmotic gradient
64
Describe the function of venules:
Low pressure vessels which drain capillary beds. During infection and inflammation venules are the site at which white blood cells leave the blood circulation to attack bacteria in tissue alongside.
65
Describe the function of veins:
Thin walled, low pressure vessels that drain blood back to the atria (accept portal veins which drain blood to another capillary bed). Their walls are thin, soft and can stretch easily. A small change in venous pressure causes a large change in venous volume. Veins act as a resovoir to store blood.
66
Describe the structure of the blood vessel: Elastic artery
Large arteries near the heart with elastic walls. They consist of many thin sheets of elastin in the middle tunic.
67
Describe the structure of the blood vessel: Muscular arteries
Many layers of circular smooth muscle wrapped around the vessel in the middle tunic.
68
Describe the structure of the blood vessel: Arterioles
Between one and three layers of circular smooth muscle wrapped around the vessel in the middle tunic.
69
Describe the structure of the blood vessel: Capillary
Their diameter is just wide enough to fit one red blood cell. The capillary wall is one single layer of endothelium. No smooth muscle is present within the the wall and therefore no ability to adjust the diameter and no connective tissue.
70
Describe the structure of the blood vessel: Venule
Small venules have endothelial cells and a little bit of connective tissue whereas larger ones may have a single layer of muscle.
71
Describe the structure of the blood vessel: Veins
They are similar to a muscular artery but have much thinner walls for their size. Larger veins have valves to prevent back flow.
72
Where are the coronary arteries found?
They arise from the aorta just below the aortic valves
73
What type of blood vessels are coronary arteries?
Muscular arteries
74
What is the function of muscular arteries?
To supply the muscle of the heart (myocardium) with oxygenated blood
75
What is the consequence if a coronary artery is narrowed by about 20%?
Significant blood flow obstruction occurs. During exercise, the myocardium supplied by the diseased artery runs low on oxygen (ischemia) which causes chest pains (angina). Severe ichemia may result in death (infarction) of a local area of myocardium.
76
How do artery to artery junctions work to assist the heart when there is an ischemia?
Sometimes the junctions (anastomosis) between small penetrating branches of the main coronary arteries widen slowly so that the ischemic area of muscle can be supported by a distant artery.
77
What is dilated cardiomyopathy?
Disease of the heart muscle that causes the ventricles to dilate.
78
Describe how mitral regurgitation occurs?
It is idiopathic meaning that it could be started by an infection. After the viral infection, the surviving cells lengthen. The left ventricle is most affected because of the high pressure. Its walls stay the same thickness but the chamber has increased. This means that the fibrous ring surrounding the mitral valve stretches and the mitral flaps can no longer meet during systole which causes mitral regurgitation. There is more blood to pump with weaker walls.
79
Describe what happens to the pressures etc during mitral regurgitation and how it affects the lungs:
During systole, as much as half of the blood ejected by the LV is regurgitated into the LA. During the next diastole, the regurgitated blood returns to the ventricle along with fresh blood from the pulmonary veins. Then to maintain cardiac output, LV must pump more volume, in order to fill the ventricle to LA works harder, the LA pressure increases, so the pulmonary venous pressure increases and the pulmonary capillary pressure increases causing the lungs to be heavier and wetter, more rigid and harder to breathe.
80
CO = ?
CO = SV x HR
81
What is the stroke volume?
The amount of blood pumped out during each heart beat e.g 70ml.
82
What is the max and min volume of the LV?
120, 60
83
What is the average resting cardiac output and what can it be up to when exercising?
Resting - 5L/min
| Exercise - 20l/min
84
What is the cardiac reserve?
The difference between the resting and exercising CO. Athletes have big ones
85
How is the stroke volume regulated?
1. Preload - pressure of blood returning to the heart (venous return) mmHg
2. Afterload - pressure the heart has to work against to push blood out of the heart (arterial pressure).
3. Contractility - forcefullness of the contraction = inotropy
86
What is frank-starlings law of the heart?
More in = more heart
87
What is the ejection fraction?
The amount of blood pumped out/total amount of blood in ventricle
About 80/120
66%
88
Describe the intrinsic heart rate:
Is about 90bpm. Resting HR is about 60bpm - this is because the SA node is firing 90 action potentials each min so the intrinsic HR is the rate at which the heart beats when all of the neural and hormonal inputs are removed.
89
What happens if the SA node is damaged?
The AV node can take over as the pacemaker
90
Describe an ECG:
Electrocardiograms are when electrodes are placed around the body to get different views of the heart and
91
What is the refractory period?
The time before another action potential can be conducted down the heart. The max HR is about 185-200bpm
92
In one heart beat, what does the starting bit before the P wave represent?
Action potential in the SA node
93
In one heart beat, what does the P wave represent:
Depolarisation of the atrial contractile fibres then atrial systole (contraction)
94
In one heart beat, what does the Q represent:
Depolarisation of the ventricular contractile fibres
95
In one heart beat, what does the S to T represent?
Ventricular systole (contraction)
96
In one heart beat, what does the T wave represent?
Repolarisation of the ventricular contractile fibres
97
In one heart beat, what does the bit after the T wave represent?
Ventricular relaxation (diastole)
98
Afferent info:
Nerves to CNS
99
Efferent info:
CNS to nerves
100
What is inotropy?
Changes in stroke volume
101
What is chronotropy?
Changes in heart rate
102
What are the 2 types of input to the cardiovascular center in the brain?
1. From higher brain centers
2. From receptors e.g proprioreceptors (monitor movement), chemoreceptors (monitor blood chemistry), baroreceptors (monitor blood pressure)
103
Which of the nerves - parasympathetic or sympathetic goes through the spinal chord and which is a cranial nerve?
Parasympathetic: cranial
Sympathetic: spinal
104
For the following nerve, describe the function, the speed at which it conducts and how it affects the heart rate: parasympathetic:
Decreases the rate of spontaneous depolarisation by the SA node. It can happen very quickly i.e within 1 heart beat. Increased parasympathetic nerve activity means decreased heart rate.
105
For the following nerve, describe the function, the speed at which it conducts and how it affects the heart rate and stroke volume: sympathetic
They increase the rate at which the spontaneous depolarisation of the AV node. It also increases contractility of the atria and ventricles which increases stroke volume. It increases the release of norepinephrine which acts on the B1 receptors to increase HR and SV. It is much slower than parasympathetic nerves and takes about 4-5 seconds to occur.
106
What is hypertension?
High blood pressure that is sustained at a bp of 140/90
107
What is hypotension
Low blood pressure
108
What is the mean blood pressure?
About 100mmHg
109
What is the main reason as to why we need to keep the blood pressure stable?
For driving of capillary exchange.
110
BP = ?
BP = CO x TPR
111
What is total peripheral resistance and what type of blood vessel affects it the most?
Arterioles have a vascular tone/resistance so they are under a constant degree of tension. There is always a slight degree of resistance. Arterioles give rise to the greatest resistance as they change their diameter so much and have the largest pressure drop.
112
What are the 3 things that affect resistance?
1. Nerves e.g sympathetic
2. Intrinsic factors
3. Hormones e.g noreadreneline
113
Is the vagus nerve parasympathetic or sympathetic?
Parasympathetic
114
Is the cardiac accelerator nerves parasympathetic or sympathetic?
Sympathetic
115
What is the blood distribution in the following cardiovascular system: systemic veins and venules (reserves), pulmonary vessels, heart, systemic arteries and arterioles, systemic capillaries
```
systemic veins and venules (reserves) - 64%
pulmonary vessels - 9%
heart - 7%
systemic arteries and arterioles - 13%
systemic capillaries - 7%
```
116
Why is the cardiovascular system conduced in parallel not series?
So that blood flow stays the same throughout and each organ gets the same amount of blood
117
In the sympathetic nerves what does an increase in norepinephrine cause?
Vasoconstriction
118
In the sympathetic nerves what does an decrease in norepinephrine cause?
Vasodilation
119
Describe how the baroreceptors can sense a change in blood pressure?
It is sensed by the arterial baroreceptors that are stretch sensitive nerves that sit in the arteries leaving the heart. As the blood pressure decreases, so does the firing of the nerves to the cardiovascular system in the brain, which will increase in the activity of the sympathetic nerves to try and bring the BP up.
120
What is blood hydrostatic pressure?
The fluid pressure exerted on the capillary wall from the inside by the fluid component of blood. It is high on the arterial end and low on the venous end.
121
What is the interstitial fluid hydrostatic pressure?
The fluid pressure exerted on the capillary wall from the outside by interstitial fluid - 0 mmHg
122
What is the blood osmotic colloid pressure?
Proteins in the blood plasma are too large to diffuse/pass through the capillary walls so they exert osmotic pressure to oppose the interstitial fluid osmotic pressure.
123
What is interstitial fluid osmotic pressure?
The potential for movement of water out of capillaries and into the interstitial fluid space due to a difference in osmolarity caused by the presence of tiny amounts of proteins in the interstitial fluid - 1mmHg
124
What is the net filtration/reabsorption of capillaries eqn?
(BHP + IFOP) - (BCOP + IFHP)
125
What is tachycardia?
HR over 100bpm
126
What is bradycardia?
HR under 60 bpm
127
What is pousvilles law?
The relationship between the velocity of the blood to total cross sectional area of the vessels. The higher the cross sectional area of the vessels, the slower the blood flows
128
What is angiotesin?
An active hormone that raises the blood pressure by vasoconstricton and secondary kidney action.
129
What is a haemorrhage?
An escape of blood from a ruptured blood vessel.
130
What is sterlings law of the capillaries?
States that the movement of fluid between the capillaries and intersitial fluid is due to the balance of all 4 pressures: BHP, IHOP, BCOP, IFHP. Overall the amount of absorption should be equal to the amount of filtration.
