Cardiac cycle Flashcards
(106 cards)
1
Q
What is the cardiac cycle? Name the two phases
A
- Systole (contraction)
- Diastole (relaxation)
2
Q
What is the primary function of the heart?
A
To pump blood throughout the body.
3
Q
True or False: The right atrium receives oxygenated blood.
A
False.
4
Q
Fill in the blank: Blood enters the right atrium from great veins called the …and … .
A
superior vena cava; inferior vena cava.
SVC carries blood from head. IVC drains lower body
5
Q
What valve separates the right atrium from the right ventricle?
A
Tricuspid valve.
6
Q
Which atrium recieves venous blood from the coronary circulation
A
Right
Via the coronary sinus
7
Q
What happens to blood in the right ventricle?
A
It is pumped to the lungs for oxygenation.
8
Q
True or False: The pulmonary valve is located between the right ventricle and the aorta.
A
False.
9
Q
What is the function of the pulmonary arteries?
A
To carry deoxygenated blood from the heart to the lungs.
10
Q
Fill in the blank: After oxygenation, blood returns to the heart via the which veins?
A
The Right and Left Pulmonary Veins
11
Q
What valve is located between the left atrium and left ventricle?
A
Mitral valve.
12
Q
What is the main role of the left ventricle?
A
To pump oxygenated blood to the rest of the body.
13
Q
True or False: The aortic valve prevents backflow into the left atrium.
A
False.
14
Q
What large artery carries blood from the left ventricle?
A
Aorta.
15
Q
What is the term for the cycle of blood flow through the heart?
A
Cardiac cycle.
16
Q
Which chamber of the heart has the thickest walls?
A
Left ventricle.
17
Q
What structure prevents backflow of blood in the heart?
A
Valves.
18
Q
What is the presure within the aorta at systole in a healthy person?
A
120 mmHg
19
Q
What is the pressure within the Aorta at Diastole in a healthy person?
A
70 mmHG
20
Q
True or False?
The pressure in the arterioles is higher than the arteries
A
False
The pressure gets lower the further away from the heart’s pumping action
21
Q
What three anatomical processes maintain adequate venous return
A
- Skeletal muscle massaging action
- Valvular prevention of backflow in the lower limbs
- Inhalation (the Respiratory Pump)
Veins pass between the pumping action of skeletal muscle
22
Q
What does the decrease in thoracic cavity pressure cause the thoracic veins to do?
A
Blood gets sucked from the abdominal to thoracic veins (then back to the heart)
23
Q
When are both aortic and pulmonary valves both closed at the same time?
A
Briefly, after blood is ejected into the systemic and pulmonary circulations
24
Q
When do the Atria fill with blood?
A
When the ventricles are relaxed
25
All the Blood flows from the atria to the ventricles with force. T or F?
False
## Footnote
The AV valves open and 80% of the blood flows into the ventricles passively (only 20% comes in under force)
26
True or False
Ventricular contraction starts from the base of the heart
False
## Footnote
Contraction starts at the Apex
27
Which valves are shutting when the pressure builds in the ventricles
Tricuspid and Mitral
28
What forces the pulmonary and aortic valves open
A build up of pressure in the left and right ventricles
## Footnote
The pressure exceeds that of the the pulmonary artery and aorta
29
Fill in the blank: The ______ system controls the heart's rhythm.
electrical conduction.
30
What is the role of the sinoatrial (SA) node?
To act as the natural pacemaker of the heart.
31
True or False: Blood flows from the aorta directly to the right atrium.
False.
32
What is the term for the phase when the heart muscle relaxes?
Diastole.
33
What is the term for the phase when the heart muscle contracts?
Systole.
34
Fill in the blank: The ______ is responsible for supplying the heart muscle with blood.
coronary arteries.
35
What is the average heart rate for adults at rest?
60 to 100 beats per minute.
## Footnote
Average is about 75
36
A cardiac cycle is how long?
0.8 seconds
## Footnote
Diastole = 0.5. Systole = 0.3 (never below 0.2)
37
True or False
Diastole increases if a patient is tachycardial?
False
## Footnote
Diastole is only 0.1 second if heart rate is 180 as cardiac cycle is only 0.33 seconds long and systole will never go below 0.2
38
What electrical heart process end in muscle contraction?
Depolarisation
39
Why is the sinoatrial node referred to as the heart's pacemaker
Because it generates the impulse for each heart beat
40
What is rate of heart beats known as?
Sinus Rhythum
41
True of False?
Cardia muscle is under voluntary control
False
## Footnote
Skeletal muscle is under voluntary control but heart muscle is automatic
42
How long does it take for the electrical signals to get from the sinoatrial to to sinoventricular node?
0.1 seconds
43
How does the heart react to the first electrical impulse at the SA node?
During the tiny pause between the impulse getting from SA to SV node, the atria contract and blood is forced into the ventricles
44
Where does the electrical impulse that controls ventricular contract travel?
Bundle of His, through the Left and Right Bundle Branches and Purkinje fibres to ventricular muscle fibres
45
What is meant by sinus rhythm?
Normal rhythm of the heart in which electrical activity is originated at the SA node
46
What is the refractory period?
The period following ventricular contraction when the heart cannot respond to new electrical stimuli
47
What is happening when the QRS complex is seen on ECG?
Ventruclar depolarisation
48
When the atria are depolarising, what is seen on the ECG graph?
The P wave
49
What two things influence the pressure in blood vessles?
Cardiac output and Total Perferal Resistance
## Footnote
BP = CO x TPR
50
What percentage of cardiac output does the myocardium recieve when the body is at rest?
4-5%
51
What percentage of oxygen is extracted from coronary blood flow by the myocardium when the body is at rest?
70%
52
What specialised receptors are responsible for responding to blood pressure changes?
Baroreceptors
53
Where are the baroreceptors?
In the carotid sinus and in the aortic arch.
54
When the blood pressure drops below normal there is a reflex that causes...what?
An increase in heart rate and vasoconstriction
55
What has happened to cause vasodilation?
An increase in blood pressure
56
What is cardiac output
The volume of blood pumped by each ventricle per minute
57
The nervous system and circulating hormones influence what two things that affect cardiac output?
Heart rate and stroke volume
58
What influence does the vagus nerve have on heart rate?
It slows the heart rate down by slowing impulse conduction
59
True or false?
Acetylcholine is the main neurotransmitter released by sympathetic nervous system activity
False
## Footnote
The parasympathetic nervous system controls acytylcholine release
60
What is the heart rate prior to neural and hormonal influences ie generated by the cardiac electrical system solely?
100 bpm
61
What are the adrenergic receptors called, where are they located and what hormones do they respond too?
Beta-1 receptors
Heart
Chatecholamines (Adrenaline & Noradrenaline)
62
Which part of the nervous system elicits a speeding up effect on the heart rate and an increase force of contraction?
Sympathetic NS
63
What else is speeds up heart rate (other than the release of sympathetic neurotransmitters)
Blood-bourne Adrenaline
64
The volume of blood that is ejected from each ventricle with each beat of the heart is called...?
Stroke volume
65
What is ejection fraction?
The amount of blood ejected from the ventrical with each contraction
66
What is end diastolic volume?
The amount of blood contained in the ventricles immediately prior to contraction
67
What is the ejection fraction of a healthy adult at rest?
66%
| 1/3rd remains in terms of L ventricle. The rest is ejected.
## Footnote
This corresponds to a stroke volume of 70-80 beats per min
68
What influences the amount of blood ejected?
The forecfulness of the ventricle's contraction
## Footnote
Ventricles do not empty completely during contraction
69
What are the three main things that influence stroke volume?
1. End diastolic ventricular volume
2. Blood bourne adrenaline
3. Activity of the sympathetic nervous system
70
What causes distension of the ventricle walls and a more forceful contraction?
An increased end diastolic voume
71
What is pre-load?
The tension exerted on the ventricle walls
## Footnote
This is as a direct consequence of the volume of blood they contain.
72
What cirmcumstances increase pre-load?
1. Anything that influences venus return positively
2. Increased noradrenaline through sympathic nervous system response
3. Blood bourne adrenaline
## Footnote
More blood returning to the heart = more end diastolic volume = more forceful contraction
73
The sum of all the vascular resistnce within the systemic circulation is called...
Total Periferal Resistance
74
True or false?
The brain is able to survive without a continuous suply of glucose
False
## Footnote
It needs a continuous supply
75
Adequate perfusion of the tissues all around the body is dependant on what?
Maintaining adequate blood pressure
76
How much blood is circulating in the average human?
5-6 litres
77
What two mechanisms help to maintain adequate blood flow and pressure?
1. Blood directed away from areas of less need toward more needy areas eg muscles during exercise using vasoconstriction of arterioles
2. Increased cardiac ouput
78
During intense exercise, what percentage of the circulating blood will the muscles reiceive?
80%
79
What 3 things are happening in the body to allow the higher redistribution of blood volume to the muscles during exercise?
1. Blood flow increases to active skeletal muscles
2. Beta 2 receptors facilitate local vasodilation in the arterioles
3. Alpha-andrenergic receptors facilitate vasoconstriction in less active tissues
80
What two waste products are building up in the muscles that stimulates arteriolar dilation?
1. Lactic Acid
2. Carbon Dioxide
81
Noradrenaline & circulating adrenaline acting on beta 2 adrenergic receptor in the arterioles of skeltal muscle cause what?
Vasodilation and increased blood flow to active skeletal muscle
82
Less active tissue such as kidneys require less blood flow during exercise. How does the body achieve this?
Noradrenaline and circulating adrenaline acting on alpha-adrenergic recepors in arterioles cause vasoconstriction
83
What enzyme is released by the kidneys that leads to the production of angiotensin II which causes vasoconstriction of arteries & veins?
Renin
84
Where are the baroreceptors located?
In the Aortic arch AND in the Carotid Sinuses
85
What happens to the walls of the arteries in which the baroreceptors are located?
The stretch, activating vasodilation and a reduced heart rate
86
What is the term used to describe dizziness when a person stands up or moves from lying to upright too quickly causing a transient drop in blood pressure?
Orthostatic Hypotension
87
What is blood pooling?
The accumulation of blood in the veins, often in the lower extremities, due to inadequate venous return to the heart.
88
What happens during systole?
Blood is ejected from the ventricles into the stystemic circulation
89
Why does very little blood enter the coronory circulation during ventricular contraction?
To avoid the small coronory arteries from recieving blood under extreme pressure
90
What two anatomical processes protect the coronary arteries from too much pressure during systole?
1. The cusps of the aortic valves close to partially cover the coronary arteries that arise from the base of the aorta
2. The myocardium compresses the coronary arteries and obstructs blood flow
91
What percentage of blood flow into the coronary arteries during diastole?
80%
92
Whether at rest or during exercise the coronary circulation remains the same (at 4 or 5%). True or false?
True
93
What muscle fibres in the body have the highest concentration of mitochondria?
Myocardial Muscle Fibres
94
What 4 factors affect how much work the myocardium has to perform?
1. Heart rate
2. Contractility
3. Preload and Afterload
4. Myocardial mass
| A big fast rate tensed up heart works hard
95
Name three things that the heart does to increase it's blood supply when there is more demand for oxygen during exercise?
1. It increases coronary blood flow through dialation
2. Inreased sympathetic activity also causes dilation
3. An increase in Aortic pressue (through increased systolic BP) increased the coronory blood flow
96
What three processes control coronary artery dilation?
1. increased metabolic activity
2. release of nitric oxide from the endothelium
3. increased sympathetic activity
97
True or False?
Cardiac muscle has the ability to resythesise ATP anaerobically?
False
| It only has a limited ability
98
True or False?
If the myocardial mass is larger, the heart needs less oxygen
False
| It needs more oxygen to perform harder as it has larger demand due to it
99
Is the heart working harder if the person has a high heart rate?
Yes
100
If there is a smaller volume of blood in the ventricles at the end of diastole (pre-load), is the heart working harder?
No
101
What is happening if there is more resistance from the systemic circulation just before ejection?
After load is increased
| If systolic blood pressure is high, the heart has to work hard to eject
102
Does a healthy heart require more oxygen if there is a higher preload, afterload, heart rate and mycardial mass?
Yes
103
What is RPP?
The product of heart rate and systolic pressure
| Rate Pressure Product
104
What is the formula used to calculate the rate pressure product?
RPP = HR x SBP
Multiplying how often the heart works (HR) with how hard it works per beat (SBP) you get a good estimation of its overall workload and oxygen demand
105
What is the RPP used to calculate?
The amount of estimated work that the heart muscle has to do
106
What is pre-load?
The tension exerted on the heart wall at the end of diastole which is a direct result of the volume of blood contained in the ventricles
## Footnote
The greater the stretch of the ventricles and the greater the contraction
