cardiovascular system Flashcards
1
Q
what are the 4 chambers of the heart
A
left ventricle, left atrium, right ventricle, right atrium
2
Q
which chambers of the heart are larger and why
A
ventricles are larger as they store the blood and send it out
3
Q
which side of the heart is larger and why
A
left ventricle - has to send more oxygenated blood to the body
4
Q
what are the 4 valves and where are they located
A
- tricuspid = right atrium + ventricle
- bicuspid = left atrium + ventricle
- aortic semi lunar valve = aorta + left ventricle
- pulmonary semi lunar valve = pulmonary artery + right ventricle
5
Q
what is the main function of the valves
A
prevnt back flow of blood
6
Q
what is the pathway of blood through the heart
A
1) deoxygenated blood from the muscles comes back through the right atrium through the vena cava
2) blood from right atrium moves through tricuspid valve into the right ventricles
3) right ventricles force blood out of the right side of the heart through the pulmonary semi lunar valve and into the pumonary artery
4) pulmonary artery carries deoxygenated blood to the lungs
5) blood is oxygenated in the lungs and taken the left atria via the pulmonary vein
6) moves through left AV through the bicuspid valve into the left ventricle
7) travels through aorta via aortic semi lunar valve
8) aorta transports oxygenated blood to the muscle and organs
7
Q
what is myogenic
A
the heart has the capacity to generate its own electrical impulse
8
Q
what makes up the cardiac conduction system
A
- sino atrial node
- atrioventricular node
- bunde of his
- bundle branches
- purkinje fibres
9
Q
what does the sino atrial node do in the cardiac conduction system
A
initiates a cardiac impulse which travels across the left and right atrial walls causing both atria to contract.
The SA node is the pacemaker
10
Q
what does the atrioventricular node do in the cardiac conduction system
A
the impulse reaches the AV node in the right atrium which causes a slight delay ( 0.15 )
11
Q
what does the bundle of his do in the cardiac conduction system
A
AV node passes impulse down to bundel of his in the septum of the heart
12
Q
what do the bundle branches do in the cardiac ocnduction system
A
bundle of his splits into 2 seperate branches spreading the impulse down the bottom of the heart and up around the walls of the ventricles
13
Q
what do the purkinje fibres do in the cardiac conduction system
A
the network of purkyne fibres causes both ventricles to contract from the base up. The ventricles then relax and the cycle is repeated.
14
Q
How long does it take to complete a cycle at rest
A
0.8 seconds
15
Q
what is cardiac diastole
A
relaxation phase of the cardiac muscle
atria first and then ventricles
16
Q
what is cardiac systole
A
contraction phase of the cardiac muscle
atria first and then ventricles
17
Q
what happens in the cardiac cycle.
A
1) atria fill with blood, AV valves closed
1.1) atrial blood pressure rises above ventricular pressure
1.2) AV valves open and blood passively passes into both ventricles
2) contraction of both atria, actively forcing the remaining atrial blood into ventricles
2.2) ventricles fill with blood
2.3) semi lunar valves close
3.1) contraction of the ventricles increases ventriculal pressure
3.2) aortic and pulmonary valves forced open. AV valves closed
3.3) blood forced out: the aorta to body tissues/muscles
18
Q
how does the conduction system and cardiac cycle link together
A
- no electrical impulse;
causes diastole
cardiac muscles relaxes
SL valves close, atria fill with blood, opening the AV valves, blood starts to enter the ventricles ( passively ) - SA node fires an electrical impulse through the atria walls to the AV node. AV node delays impulse;
causes atrial systole, atrial muscle contracts, AV valves ar eforced open ( actively ), blood is pushed into the ventricles until the atria finish contracting - bundle of his splits and passes the impulse through two branches to the purkyne fibres in both ventricle walls
causes ventricular systole, ventricular muscle cpntracts, the AV valves close and blood is pushed out into the arteries, forcing the SL valves to open until the ventricles finish contracting
19
Q
what factors affects the rate at which the SAN fires
A
1) neural control
2) intrinsic control
3) hormonal control
20
Q
what is neural control
A
- sympathetic NS stimulates heart to beat faster. involves parasympathetic NS which returns heart to resting levels
- autonomic nervous system involuntarily regulates HR and determines the firing of the SAN. The higher the firing rate, the higher the HR
- from the medulla oblongata of the brain, the cardiac control centre recieves info from the sensory neurones and send direction through motor nerves to change HR
21
Q
what are chemoreceptors
A
- located in carotoid arteries and arotic arch
- detect chemical changes in the blood
- co2 detection is important as it has the effect pf stimulating the SNS and increasing HR
22
Q
what are baroreceptors
A
- sensors located in tissues
- detect changes in blood pressure past a set point
- once above or below this set point, the baroreceptors send signal to the MO
23
Q
what are proprioreceptors
A
- located in the muscles, tendons and joints
- detect changes in movement
- increase in muscle movement at the start of excerise directing the body too increase HR
24
Q
what is the intrinsic control mechanism
A
changes occur in the body when we excersise, and we stop excersisng these include;
- temperature changes = affect viscosity of the blood and speed up nerve impulse transmission
- venous return changes = changes in VR affect the stretch in the ventricle walls, force of ventricular contraction and therfore starlings law
25
what is the hormonal control mechanism
- adrenaline = stress hormone released by the sympathetic nerves and cardiac nerev during excersise causing an increase in heart rate.
stimulates teh SAN which results in an increase in speed and force of contraction
this results in an increase of cardiac output and therefore more blood pumped to the working muscles
26
what is heart rate
number of heart beats per minute
average resting HR = 72
tachycardia = 100+
bradycardia = -60
27
what is stroke volume
volume of blood ejected from the left ventricle during each contraction
average resting = 70ml
average trained = 110ml
28
what is cardiac output
volume of blood ejected from the left ventricle per minute
average = 5 l/min
29
what is venous return
volume of blood returning to the hert via the veins. If VR increases, stroke volume will also increase
30
elasticity of cardiac fibres
the degree of stretch of cardiac tissue during the diastole cycle. The more fibres can stretch, the greater the force of contraction.
A greater force of contraction can increase the ejection fraction ( starlings law )
31
what is ejection fraction
percentage of blood pumped out by the left ventricle per beat
calculated by:
stroke volume / end diastole vol
32
what is starlings law
increased VR, greater diastolic filling of the heart, cardiac muscle stretched, more force of contraction, increased ejection fraction
33
what is the contractillity of cardiac tissue ( myocardium )
the greater contractillity of the cardiac tissue, the greater the force of contraction. This results in an increase in SV. Also can be seen by increase in ejection fraction.
At rest approx 40% of blood that enters the heart remianing 60% is ejected. However, this can increase up to 85% following a period of training
34
how to find mac HR
220-AGE
35
what is sub maximal excersise
excersise at low to moderate intensity within a performers areobic capacity or below anaerobic threshold, it is associated with aerobic work
36
what is maximal excerise
excersise at a high intensity above a performers aerobic capacity which will take a performer to exhaustion, it is associated with anaerobic work and fatigue
37
how does heart rate change with submaximal excerise
1) anticipatory rise
2) rapid increase as excersise intensity increases
3) steady state - heart rate increases with intensity but reach plateau during sub maximal work ( supply meets demand)
4) decrease rapidly after excersise due to decreased demand for o2
5) gradual increase towards resting values but still remian elevated to allow the body to recover
38
hpw does heart rate change with maximal excerise
1) anticipaory rise
2) rapid increase as excerise intensoty increases
3) HR continues to rise due to maximal workloads and does not plateau. HR will continue to increase until it reaches maximal values or excersise decreases
4) rapid recovery stage - decrease rapidly after excersise due to decreased deman for oz
5) a more gradual decrease towards resting values ( oxygen debt ) but still remain elevated to allow the body to recover - termed o2 debt
39
what is cardiovascular disease
diseases of the heart of blood circulation
-coronary heart disease
- atherosclerosis
- heart attack
- strokes
- high blood pressure
- cholesterol
40
what is coronary heart disease
- results from atherosclerosis of the cornary arteries which suplly the heart muscle with oxygenated blood
- reduction in blood flow and oxygen supply limits cardiac muscles ability to respire and an angina or heart attack may occur
41
what is athersclerosis
- build up of fatty deposits that form hard plauque on the arterial walls
- progressively narrows the lumen and reduces blood flow
- increases likilihood of clots forming
- arterial walls become thick and hardened, reducing their ability to vasodilate and constrict to regulate blood pressure
- chronic high blood pressure is known as hypertension and is the first indicator of the disease
42
how does a heart attack occur
- peice of fatty plaque ( atheroma ) breaks away from an arterial wall, a blood cot may form
- if the clot blocks the coronary artery it will cut off oxygen supply to an area of the cardiac muscle causing death of cells and permanent damage
43
what is high blood pressure
- force exerted by the blood against the blood vessel walls
- pressure comes from the heart as it pumps the blood around the body
- high blood pressure puts extra strain on the arteries and heart if left untreated increases the risk of heart attack
44
how can you reduce high blood pressure
regular aerobic excersise can reduce blood pressure
it can lower both systollic and diastolic blood pressure by up to 5-10 mmHg
45
what are low density lipoprotiens
transport cholesterol in the blood to the tissues and are classed as bad cholesterol as they are linked to an increased risk of heart disease
46
what are high density lipoprotiens
transport excess cholesterol in the bloof back to the liver where it is broken down. they are classed as good cholesterol since they lower the risk of developing heart disease
47
what is the effect of excersise on ldls and hdls
lowers bad LDL cholesterol whilst increases HDL levels
48
what causes a stroke
- a blockage in a cerebral artery cutting off the blood supply to the brain, known as an ischaemic stoke
- or a blood vessel bursting within or on the surface of the brain known as a haemorrhagic stroke
49
what is the effect of excerisise on strokes
lowers bp and hekos maintain healthy weight, reducing risk of a stroke by 27%
50
what is the effect of regular excerisise on the heart
- can pump more blood around the body as heart hypertrophy occurs
- increases stroke volume
- miantains flexibility of blood vessels ensuring good blood flow, normal blood pressure and low cholesterol levels
51
what is the vascular system
dense network of blood vessels in the blood which carry in one direction around the body
52
what does the blood consist of
45 % cells ( red and white blood cells )
55% plasma
53
what are the two seperate circuits in the heart
- pulmonary
- systemic
54
what does the pulmonary system do
- carries deoxygenated blood to the lungs and oxygenated blood back to the heart
- blood is circulated through the pulmonary artery to the lungs and pulmonary vein back to the heart
55
what happens in the systemic circuit
- carries oxygenated blood to the body and deoxyganeted blood back to the heart
- blood is circulated through the aorta to the body and vena cava back to the heart
56
structure and function of arteries/arterioles
- transport o2 from heart to muscles and organs
- main artery is the aorta
- arteries contain a large layer of smooth muscle surrounding the entry of a capillary bed called the pre capillary sphincter , these constrict to control blood flow.
57
structure/fucntion of capillaries
- bring the blood slowly into close contact with the muscle and organ cells for gaseous exchange
- composed of a single layer of cells thin enough to allow gas, nutrients and waste exchange
58
structure/ function of veins and venules
- transport deoxygenated blood from the muscles and organs back to the heart
- venules leaving capillary beds reconnect to form veins
- the main wein is the vena cava
- contains a small layer of smooth muscle allowing them to venodilate and venoconstrict
- veins contain one way pocket valbves to prevent backflow of blood
59
what is systollic pressure
the pressure in the arteries when the ventricles are contracting
60
what is diastollic pressure
the pressure exerted on te arteries when the ventricles are relaxing
measured by blood flow x resistance
61
where is blood pressure measured
at the brachial artery in the upper arm
62
what is venous return
the return of blood to the right side of the heart through the vena cava, largely against gravity
63
what happens to venous return durign excerisse
increases
also means more blood will be pumped out of the heart so stroke volume will also increase
64
what are the mechanisms of venous return
- skeletal muscle pump
- respiratory pump
- pocket valves
- smooth muscle
- gravity
- suction pump of the heart
65
what is a skeletal muscle pump
- when muscles relax/contract they change shape
- this change in shape means that the muscles press on the nearby veins causing a pumping effect and squeezes blood to the heart
66
what is teh respiratory pump
- during the breathing process, pressure changes occur in the thoracic and abdominal cavity
- this pressure change compresses the nearby veins and assist blood return to the heart
67
what are pocket valves
- prevents backflow of blood
68
what is smooth muscle
- layer of smooth muscle in the veins walls venoconstricts to create veno motor tone
- this aids the movement of the blood back towards the heart
69
what is gravity needed for in the mechanism of VR
helps the blood that is flwoing in the upper body to return to the heart
70
what is blood pooling
when blood sits in the pocket valves and pool
feeling of " heavy legs "
71
what is the impact on BP on VR
- when systollic blood pressure increases, there is an increase in VR
- VR is determined by a pressure gradient
- the average systemic pressure minus the right atrial pressure, and resistance is the total peripheral vascular resistance
- increasing right atrial pressure decreases VR
- decreeasing RA pressure increases VR
72
what is oxyhaemoglobin
oxygen + haemoglobin
73
how many molecules of o2 does hb carry
4
this occurs when the partial pressure of oxygen in the blood is high
74
what is oxyheamoglobin dissociation
at the tiisue, oxygen is released form oxyhb due to lower ppo2 that exists there
75
what is o2 stored as in the muscles
myoglobin
this has a hifher affintiy for o2 and will store the o2 in the mitochondria until it is used by the muscles
76
what is oxygen association
oxygen attaches to hb
77
what is the oxyhaemoglobin association curve
- hb that is fully loaded with o2 is saturated
- there is a high ppo2 in the lungs
- o2 unloads into the tissues which has a lower ppo2
- as excerisise intensiry increase, po2 lowers in the muslce celss and more oxygen dissociates from hb
78
what is the bohr shift
a move in the oxyhaemoglobin association curve to the right caused by an increased acidity in the blood stream
79
what are the 4 factors resposible for the increase in dissociation of o2 from hb
Carbon dioxide = increase pco2 which will increase co2 diffusion gradient meaning o2 will dissociate faster
Oxygen = decrease in po2 within the muscle due to excersise increasing , o2 will dissociate fatsre
Acidity = nohr effect, increased acidity due to lactic acid, causes o2 to dissociate faster
Temperature = increase in blood and muscle temp, o2 dissociates faster
80
po2 in the alveoli and the muscles
- in the alveoli po2 is high and o2 readily diffuses into the capillaries to associate with hb
- blood is fully saturated with o2 as it leaves the alveoli
- in the muscles p02 is low and o2 dissociates readily from hb and diffuses into the muscle cells to produce energy for excerisise
- during excerisise a far greater volume of o2 is released from the hb and diffuses into the muslces at a greater rate
- this allows muscles to produce more energy, which means a performer can increase the duration and intensity of performance
81
what is a vascular shunt
redistribution of blood
82
where does blood get redistributed to via the vascular shunt
- skin as energy is needed to cool down the body
- brain to ensure brain function is maintained as the brain needs o2 for energy
- heart for energy to beat faster
- muscles for energy
83
how does redirection of blood occur via the sympathetic NS
- when sypathetic stimulation increases, vasoconstriction occurs and blood flow reduces so it can be dsitributed to other parts of the body
- when sympathetic stimulation decreases, vasodilation occurs and increases blood flow to that body
84
how do pre capillary sphincters aid blood flow
- when they contract, blood flow is restricted through the capillary and when they relax, blood flow is increased
- during excerisise, capillary networks supplying skeletal muscles will have relaxed PCS to increase blood flow and saturate the tissue with o2
85
why is redirection of blood flow important
- increase the supply of o2 to the working muscles
- remove waste products from the muscles such as co2 and lactic acid
- direct more o2 to the heart
86
what is A- VO2 diff
arterio venous oxygen difference
the difference in o2 content od the arterial blood arriving at the muscles and the venous blood leaving the muscles
87
what happens to A- Vo2 diff during excerisise
- more o2 needed from the blood for the muscles and therefore the arterio venous differnece is high
- the increase during excerisise will affect gaseous exchange at the alveoli so more 02 is taken in and more co2 is removed
- training will increase arterio venous difference as trained performers extract a greater amount of 02 from the blood
