The heart and heart disease

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  • Created by: r98
  • Created on: 30-04-16 07:36
Is the heart made of one or two pumps?
Two separate pumps lying side by side.
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Does the pump on the left deal with oxygenated or deoxygenated blood?
Oxygenated blood from the lungs.
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Does the pump on the right deal with oxygenated or deoxygenated blood?
Deoxygenated blood from the body.
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How many chambers does each pump have?
2.
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What are the two types of chambers of a pump?
The atrium & the ventricle.
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What are some physical properties of the atrium?
It's thin-walled, elastic and stretches as it collects blood.
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Does the atrium have a thick muscular wall? Why?
No, it has a thin muscular wall as it only has to pump blood to the ventricles.
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Does the ventricle has a thicker or thinner muscular wall than the atrium? Why?
It has a thicker muscular wall as it has to pump blood to either the lungs or the rest of the body.
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In mammals, why is the blood returned to the heart before it's distributed to the rest of the body?
To increase the its pressure, as when blood passes through the capillaries in the lungs, its pressure drops, so blood flow to rest of body would be very slow.
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Why does the right ventricle have a thinner muscular wall than the left ventricle?
Because the right ventricle pumps blood to the lungs (a shorter distance) whereas the left ventricle has to create enough pressure to pump blood to the extremities of the body, so it needs a thicker muscular wall to create this pressure.
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What are the two sets of valves between atria and ventricles?
The left atrioventricular (bicuspid) valves & the right atrioventricular (tricuspid) valves.
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What are the left atrioventricular valves formed of?
They're formed of two cup-shaped flaps on the left side of the heart.
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What are the right atrioventricular valves formed of?
They're formed of three cup-shaped flaps on the right side of the heart.
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Do the left and right sides of the heart both contract together or at different times?
They both contract together.
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Where do the ventricles pump blood to?
They pump blood away from the heart and into the arteries.
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Where do the atria receive blood from?
From the veins.
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What are the vessels connecting the heart to the lungs called?
Pulmonary vessels.
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Which blood vessel is connected to the left vetricle?
The aorta.
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What type of blood does the aorta carry and where to?
It carries oxygenated blood to all parts of the body except the lungs.
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Which blood vessel is connected to the right atrium?
The vena cava.
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What type of blood does the vena cava carry and where form?
It brings deoxygenated blood back from the tissues of the body.
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Which blood vessel is connected to the right ventricle?
The pulmonary artery.
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What type of blood does the pulmonary artery carry and where to?
It carries deoxygenated blood to the lungs.
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Which blood vessel is connected to the left atrium?
The pulmonary vein.
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What type of blood does the pulmonary vein carry and where from?
It brings oxygenated blood back from the lungs.
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How does the heart meet its own respiratory needs?
Its oxygen is supplied by its own blood vessels, called coronary arteries.
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What can blockage of the coronary arteries lead to?
Myocardial infarction, heart attack, because an area of the heart muscle is deprived of oxygen and so dies.
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Is contraction of the heart also known as systole or diastole?
Systole.
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Is relaxation of the heart also known as systole or diastole?
Diastole.
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How is the direction of blood flow through the heart maintained?
By pressure changes and the action of valves.
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Via which two blood vessels does blood return to the atria?
Pulmonary vein and vena cava.
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What happens to the pressure in the atria as they fill with blood? How does this pressure change affect the AV valves?
The pressure in them rises, pushing open the AV valves and allows blood to pass into the ventricles.
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During diastole the muscular walls of both the atria and ventricles are relaxed, how does this affect the pressure in the ventricles? How does this pressure affect the semi-lunar valves?
The pressure in the ventricles is reduced, causing the pressure within the ventricles to beelower than that in the aorta and the pulmonary artery and so the semi-lunar valves close.
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Into what two stages is systole divided?
Atrial systole & ventricular systole.
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What happens during atrial systole? How is this linked to the muscular walls of the atria being so thin? During this stage, are the muscular walls of the ventricle relaxed?
The muscles of the atrial walls contract, forcing the remaining blood they contain into the ventricles. The blood only has to be pushed a short distance, therefore the muscular walls of the atria are thin. The muscles of ventricle wall are relaxed.
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What happens during ventricular systole? How is backflow of blood into atria prevented?
After a short delay to allow ventricles to fill with blood, their walls contract simultaneously. This increases the pressure within them, forcing shut the AV valves, preventing backflow.
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What happens to the pressure in ventricles as a result of the AV valves being closed? What happens to the semi-lunar valves?
The pressure rises, forcing open the semi-lunar valves and pushing blood into the pulmonary artery and aorta.
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What do valves prevent?
The backflow of blood.
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How are the valves in the cardiovascular system designed to work?
So that they open whenever the difference in blood presssure either side of them favours the movement of blood in the required direction.
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When are valves designed to close?
When blood would tend to flow in the opposite direction to that which is desirable.
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What are three types of valves in the cardiovascular system?
Atrioventricular, semi-lunar & pocket valves.
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Where are the AV valves situated? When do they prevent backflow of blood?
They're between the left atrium and left ventricle, and the right atrium and right ventricle. They prevent backlfow when ventricles contract, as ventricular pressure would exceed atrial pressure.
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Where are the semi-lunar valves situated? When do they prevent backflow of blood?
They're in the aorta and pumonary artery. They prevent backflow into ventricles when the recoil action of the elastic walls of the vessels creates a greater pressure in the vessels, than in the ventricles.
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Where are the pocket valves situated? When do they prevent backflow of blood?
They're in veins. They ensure that when the veins are squeezed (e.g skeletal muscles contacting), blood flows back to the heart rather than away from it.
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What are valves made up of?
They're made up of a number of flaps of tough, but flexible, fibrous tissue, which are cusp-shaped.
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What happens to the flaps of the valve, when pressure is greater on the convex side of the cusps rather than the concave side?
They move apart to let blood pass between the cusps.
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What happens to the flaps of the valve, when pressure is greater on the concave side of the cusps rather than the convex side?
Blood collects within the 'bowl' of the cusps. This pushes them together to form a tight fit that prevents the passage of blood.
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How is the risk of valves becoming inverted prevented?
The valves have string-like tendons that are attached to pillars of muscle in the wall (of ventricle e.g.)
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What is caridac output?
The volume of blood pumped by one ventricle of the heart in one minute.
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What are the usual units of cardiac output?
dm^3 min^-1.
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What two factors does cardiac output depend upon?
The heart rate (rate at which heart beats) & the stroke volume (volume of blood pumped out at each beat).
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What is the formula for calculating cardiac output?
Cardiac output = heart rate x stroke volume.
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Is cardiac muscle myogenic or neurogenic? What does it mean?
it's myogenic, as the contraction is initiated from within the muscle itself, rather than by nervous impulses from outside (neurogenic).
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Where does the initial stimulus for contraction (of heart) come from? Where abouts is this group of cells located?
From the sinoatrial node (SAN), which is within the wall of the right atrium of the heart.
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Why is the SAN often referred to as the pacemaker?
Because it has a basic rhythm of stimulation that determines the beat of the heart.
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What does the SAN release? Where does this spread across?
A wave of electrical activity, that spreads across both atria, causing them to contract .
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What prevents the wave of electrical activity, released from the SAN, crossing to the ventricles?
A layer of non-conductive tissue (the atrioventricular septum).
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After passing through both atria, where does the wave of electrical activity pass through?
The atrioventricular node (AVN), which lies between the atria.
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What does the AVN do after the wave of electrical activity has passed through it?
After a short delay, it conveys a wave of electrical activity between the ventricles along a series of specialised muscle fibres called the bundle of His.
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What is the role of the bundle of His?
It conducts the wave of electrical activity through the atrioventricular septum to the base of the ventricles, where the bundle branches into smaller fibres.
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What causes the ventricles to contract?
The wave of electrical activity when it's released from the fibres of the bundle of His, from the apex of the heart upwards.
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What is an atheroma?
A fatty deposit that forms within the wall of an artery.
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What are the fatty streaks, that an atheroma begins as, made of?
They are accumulations of white blood cells that have taken up low-density lipoproteins (LDLs).
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What is the irregular patch that's formed when the fatty streaks (of an atheroma) enlarge, called?
An atheromatous plaque.
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What are atheromatous plaques made up of?
Cholesterol, fibres and dead muscle cells.
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How does the build up of atheroma affect blood flow through that artery?
The atheroma (atheromatous plaque) bulges into the lumen of the artery, causing it to narrow so that the blood flow through it is reduced.
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What two conditions does atheromas increase the risk of?
Thrombosis & aneurysm.
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Hiw can an atheroma result in the formation of a thrombus? What is this condition known as?
If the atheroma breaks through the lining (endothelium) of the blood vessel, it forms a rough surface that interrupts the smooth flow of blood, which could result in a blood clot (thrombus), in a condition known as thrombosis.
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How does a thrombus affect the supply of blood to tissues? What can happen to that region of tissue?
A thrombus may block the blood vessel, reducing or preventing the supply of blood to tissues beyond it. This region of tissue often dies as a result of lack of oxygen, glucose and other nutrients that the blood normally provides.
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What is an aneurysm?
Weakened point of artery wall, that swells to form a balloon-like, blood-filled structure (aneurysm).
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How can atheromas (indirectly) cause an aneurysm?
Atheromas that lead to the formation of a thrombus also weaken the artery walls (which are the poits that swell).
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What does an aneurysm bursting lead to?
This leads to a haemorrhage, therefore loss of blood to the region of the body served by that artery.
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What can a brain aneurysm (cerebrovascular accident (CVA)) also be known as?
A stroke.
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What can a myocardial infarction be known as?
A heart attack.
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What does a myocardial infarction result from? What happens to the blood supply to the heart?
From a blockage in the coronary arteries. The heart will stop beating because its blood supply will be completely cut off.
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Why are the symptoms of a myocardial infarction milder if the blockage is further along the coronary artery?
Because a smaller area of muscle will suffer oxygen deprivation
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What four factors are associated with coronary heart disease (CHD)?
Smoking, high blood pressure, blood cholesterol, and diet.
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What are the 2 main constituents of tobacco smoke that increase the likelihood of heart disease?
Carbon monoxide & nicotine.
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How does carbon monoxide (in tobacco smoke) lead to raised blood pressure which increases the risk of CHD and strokes?
Carbon monoxide combines easily, but irreversibly, with haemoglobin (forming carboxyhaemoglobin), it reduces the oxygen-carrying capacity of the blood. So the heart must work harder to supply the equivalent quantity of oxygen to the tissues.
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How does nicotine (in tobacco smoke) lead to raised blood pressure which increases the risk of CHD and strokes? In what other way does nicotine increase risk of CHD?
It stimulates the production of adrenaline (hormone), which increases heart rate and raises blood pressure. It also makes the platelets in the blood more 'sticky' leading to a higher risk of thrombosis, and hence myocardial infarction or strokes.
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What lifestyle factors increase the risk of high blood pressure?
Excessive prolonged stress, certain diets and lack of exercise.
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In what 3 ways does high blood pressure increase the risk of heart disease?
The heart must work harder to pump blood in arteries, so more probe to failure. The arteries are more likely to develop an aneurysm ad burst, causing haemorrhage. To resist high pressure the artery walls thicken & harden which restricts blood flow.
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How is cholesterol carried in the blood?
It's carried in the plasma as tiny spheres of lipoproteins (lipid and protein).
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What are the 2 main types of lipoproteins, which transport cholesterol?
High-density lipoproteins (HDLs) & low-density lipoproteins (LDLs).
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What do high-density lipoproteins do with cholesterol?
They remove it from tissues and transport it to the liver for excretion. They help protect arteries against heart disease.
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What do low-density lipoproteins do with cholesterol?
They transport cholesterol foom the liver to the tissues, including artery walls, leading to the development of atheroma and hence heart disease.
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What are 2 aspects of diet that increase the risk of heart disease? How do these aspects increase the risk of heart disease?
High levels of salt, raise blood pressure and high levels of saturated fat, increase LDLs levels and hence blood cholesterol concentration.
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What foods reduce the risk of heart disease?
Foods that act as antioxidants, e.g. vitamin C & dietary fibre.
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Other cards in this set

Card 2

Front

Does the pump on the left deal with oxygenated or deoxygenated blood?

Back

Oxygenated blood from the lungs.

Card 3

Front

Does the pump on the right deal with oxygenated or deoxygenated blood?

Back

Preview of the front of card 3

Card 4

Front

How many chambers does each pump have?

Back

Preview of the front of card 4

Card 5

Front

What are the two types of chambers of a pump?

Back

Preview of the front of card 5
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