Cardiovascular System Flashcards
1
Q
Vessels which carry blood from the body to the heart are called…
A
Veins
2
Q
Vessels which carry blood from the heart to the tissues are called…
A
Arteries
3
Q
What is the sequence of blood leaving the heart?
A
Arteries > arterioles > capillaries > venules > veins
4
Q
Which blood vessel has the simplest structure?
A
Capillaries - a single layer of epithelial cells
5
Q
What are the three layers of arteries and veins?
A
- Tunica Intima/Interna - mainly epithelia
- Tunica Media - mainly smooth muscle.
- Tunica Adventitia/ Externia - mainly connective tissue
6
Q
Fill in the blanks
A
7
Q
What are arteries?
A
Thick-walled vessels
Blood at high pressure
Mostly oxygenated blood
8
Q
What tissue does elastic arteries have?
A
Elastic tissue
9
Q
What type of muscle does muscular arteries have?
A
Smooth muscle
10
Q
What is the function of elastic arteries?
A
Maintain the forward flow of the blood during relaxation phase of the cardiac cycle (diastole)
As blood is pumped out of the heart, the large elastic arteries are stretched.
Later they recoil and push the blood forwards
11
Q
What are arterioles?
A
Small arteries
They have a well defined smooth muscle layer
12
Q
What does contraction of the arterioles result in?
A
Vasoconstriction
13
Q
What does relaxation of the arterioles result in?
A
Vasodilation
14
Q
What are the main functions of the arterioles?
A
- Controls blood flow to the capillaries.
- Major influence on blood pressure.
15
Q
What happens at the capillaries?
A
- Site of exchange of oxygen and nutrients between blood and tissues.
- Pre-capillary sphincters can limit blood flow in the capillaries.
16
Q
What is the blood flow like in capillary?
A
Slow and low pressure
17
Q
What are venules and veins?
A
Thin walled vessels
Blood at low pressure
Large volume of blood ~ 60% of blood volume
Valves are present in large veins
18
Q
What can hinder blood flow in the lower limbs?
A
Gravity
19
Q
What is the role of the skeletal muscle pump?
A
The skeletal muscle pump aids blood flow black back to the heart
20
Q
What four factors affect Venous return?
A
- Muscle activity (lower limbs) - increases
- Gravity - decreases
- Breathing - increases.
- Blood pressure gradient (small) - increases
21
Q
What are the two functional halves of the heart?
A
- Atrium.
- Ventricle.
22
Q
What muscle is the heart composed of?
A
Cardiac
23
Q
What system does the heart work alongside?
A
The autonomic nervous system
24
Q
What is the average size of the heart?
A
12 cm long (small)
25
The heart has its own blood supply. Where does it come from?
The coronary artery
26
27
What are the AV valves?
1. Mitral valve or bicuspid valve - LHS
2. Tricuspid valve - RHS
28
What are the semi lunar valves?
1. Aortic semilunar valve. - LHS
2. Pulmonary semilunar valve - RHS
29
What is the root of blood through the circulatory system?
Left atrium > left ventricle > aorta > body tissues > back from body > right atrium > right ventricle > pulmonary artery > lungs > pulmonary veins > left atrium
30
What are the features of cardiac muscle?
1. Myocardium forms of the thick wall of the heart.
2. Muscle cells are short and branched.
3. They are joined at intercalated discs which contain gap junctions allowing action potentials to spread.
4. Many mitochondria - relies on aerobic production of ATP.
31
What are the coronary arteries function?
It is the heart blood supply
The arteries are extensively branched and most areas will receive blood from more than one coronary artery which reduces the risk of a lack of oxygen
32
What does the autonomic innovation of the heart mean?
1. The heart is supplied by both the sympathetic and parasympathetic nervous system.
2. Both affect heart rate.
3. The sympathetic nervous system can also alter the strength of cardiac muscle contraction. - increased contractility
33
The cardiac muscle must be __________ by an ______________ before it can conduct
Depolarised
Action potential
34
What is the pacemaker cell?
The sino atrial node
35
What is the membrane potential of the pacemaker cells?
It is constantly changing and action potentials are rhythmically produced - they can be sped up or slow down
36
The atria and ventricles contract in what way?
Coordinated way
37
The coordinated atria and ventricle contraction is produced by
The conducting system
38
What is the layout of the conducting system of the heart?
Sino atrial node > AV node > bundle of his > left and right bundle branches > purkinje fibres
39
What does a P wave on an ECG show?
Electrical activity produced by arterial depolarisation
40
What does the QRS complex on an ECG show?
Depolarisation of the ventricles
41
What does the T wave on an ECG show?
Repolarisation of the ventricles
42
When does the atria repolarise?
At the time of the QRS wave
43
On an ECG, what counts as one cardiac cycle?
P. Wave to P. wave.
44
What happens when the heart is in diastole?
Blood fills the atria and the pressure in the atria increases
45
What does an increase in atria pressure cause?
This opens the AV valves and blood flows into the ventricles
46
What happens after blood flows into the ventricles?
The atria contract moving blood still in the atria into the ventricles
47
When do the AV valves close?
When the ventricles contract the AV valves close and the blood can’t leave the ventricles. This causes an increase of pressure in the ventricles - Iso volumetric contractions
48
What happens when there is an increased pressure in the ventricles?
The increased pressure pushes open the semilunar valves
49
What happens when the semilunar valves are open?
Blood leaves the ventricles:
1. Aorta - LHS.
2. Pulmonary artery - RHS.
50
What happens after blood leaves the ventricles?
The semilunar valves shut preventing blood backflow from the arteries. The heart relaxes and begins diastole.
51
What is the average heart rate at rest?
~70 beats per minute
52
How long is the average cardiac cycle?
0.8 sec
53
How long does ventricular systole and diastole take
Ventricular systole - 0.3 sec
Ventricular diastole - 0.5 sec
54
How long does atrial systole and diastole take?
Atrial systole - 0.1 sec
Atrial diastole - 0.7 sec
55
What two factors does the amount of blood pumped by the heart over a period of time depend on?
1. Heart rate - number of cardiac cycles
2. Stroke volume - volume of blood ejected by one ventricle each time it contracts
56
What is the cardiac output formula?
CARDIAC OUTPUT (l/min) = heart rate (beats/min) X stroke volume (l/beat)
57
Is the proportion of cardiac output of a particular organ fixed?
No
58
What causes an increase in heart rate?
Increase in sympathetic activity
Decrease in parasympathetic activity
59
What causes an increase in stroke volume?
Increase in contractility
Increased filling
Increased Venous return
60
What happens if there’s an increase in mean arterial blood pressure?
Both systolic blood pressure and diastolic blood pressure will increase
61
What causes an increase in blood flow to active muscle?
Intrinsic and extrinsic control mechanisms
62
What is the blood flow to the brain like?
Blood flow must remain constant. As a percentage of cardiac output it may decrease as the cardiac output increases.
63
How would an athletes cardiovascular system differ at rest to a sedentary individual?
Lower heart rate
Higher stroke volume
64
How would an athletes cardiovascular system differ during exercise to a sedentary individual?
Take longer to achieve maximum heart rate
The maximum stroke volume is larger
65
If there is an increase in cardiac output, what must also happen?
A redistribution of blood.
From the GI tract
Skeletal muscle , coronary circulation and skin
66
What produces the redistribution of blood?
Vasodialation
Vasoconstriction
This is achieved intrinsically - local - and extrinsically - ANS and hormones
67
What does blood pressure normally refer to?
Arterial blood pressure
68
Is arterial blood pressure constant?
No, it is pulsatile
69
70
How do you calculate the mean arterial blood pressure?
Mean arterial BP = diastolic BP + 1/3 (systolic BP - diastolic BP)
71
What is systolic BP - diastolic BP also called?
Pulse pressure
72
How does cardiac output affect blood pressure?
The amount of blood pumped by the left or right ventricle into the aorta or pulmonary arteries each minute
73
What affects the total peripheral resistance (TPR)?
Blood vessel length
Blood viscosity
Blood vessel radius
74
How do you calculate mean arterial blood pressure?
Mean arterial blood pressure = cardiac output x total peripheral resistance
75
What blood vessel causes most of the resistance within the cardiovascular system?
The arterioles
76
During exercise, is there an increase or decrease in cardiac output?
Increase
77
During exercise, is there an increase or decrease in total peripheral resistance?
Decrease - this is due due to increased skeletal muscle blood flow
78
What can the diameter of arterioles influence?
1. Total peripheral resistance which affects blood pressure.
2. Blood flow to the capillaries which affect perfusion of tissues.
79
How does local or intrinsic control determine the diameter of arterioles?
1. Increases activity of tissue.
2. Increases accumulation of metabolites.
3. Arterioles dilate.
4. Increased blood flow.
80
How does extrinsic control determine the diameter of arterioles?
1. Increased sympathetic activity.
2. Increased nor adrenaline released - produces vasoconstriction
3. Increase in TPR.
81
What hormones causes vasoconstriction?
1. Plasma adrenaline
2. Angiotensin II
3. ADH
82
What hormone causes vasodilation in skeletal muscle?
Adrenaline
83
What monitors blood pressure?
Baroreceptors
84
Where are baroreceptors found?
Within the arteries located in aortic arch and the carotid sinus.
85
What can cause a fall in blood pressure?
Haemorrhage
86
What are the compensatory mechanisms in the heart?
1. Vasoconstriction of veins., arterioles in skin (cold and Pale), GI tract, muscles and kidneys
2. Coronary and cerebral blood flow stays constant.
3. Increased heart rate - tachycardia
4. Shift or redistribution of extra cellular fluid.
87
How does the distribution of extra cellular fluid occur after haemorrhage?
1. Decreased capillary pressure.
2. Increased fluid reabsorption from interstitial fluid.
3. Increased plasma volume.
4. Increased blood pressure towards normal.
88
What happens if blood loss continues?
1. There is an increase of water reabsorption by the kidneys.
2. Decrease urine output.
Through the actions of renin, ADH and aldosterone
3. EPO stimulates red blood cell production
89
What happens if blood flow to the brain stem is reduced?
Less vasoconstriction occurs
90
What does hypoxia lead to?
1. Increase capillary permeability.
2. Decreased blood volume causing decreased blood pressure.
91
What can cause shock?
1. Loss of blood.
2. Loss of fluid.
3. Heart failure.
4. Widespread vasodilation
92
What is septic shock?
Toxins released by infections
93
What is anaphylaxis?
An allergic reaction producing histamine release
94
What happens in the P-Q interval
P-Q interval – the cardiac action potential arising in the SA node spreads over the atria depolarising them and causing atrial systole.
95
What happens in the Q-T interval
Q-T interval – QRS indicates ventricular depolarisation leading to ventricular systole, AV valves close, Semi-lunar valves open & blood is ejected from the ventricles
96
What happens in the T-P interval
T-P interval – ventricles are repolarised & relax. The pressure within them drops, AV valves open & heart fills with blood - diastole
