Where is the heart located in the body?
in the thoracic cavity behind the sternum
Which side of the heart deals with oxygenated blood?
left side
Which side of the heart deals with deoxygenated blood?
right side
Why is the atrium thin muscular wall?
because blood only needs to pumped a short distance
Why is the ventricle a much thicker muscular wall?
because it has to pump blood all around the body to all the extremities of the body.
What are the names of the atrioventricular valves in the heart?
Bicuspid valves (left side), tricuspid valves (right side)
What do the atrioventricular valves do?
Prevent the backflow of blood into the atria
Through which vessels is blood pumped out of the heart?
Arteries - the Aorta and Pulmonary artery
Through which vessels does blood enter the heart?
The veins - the Vena Cava and pulmonary veins
What does the aorta do?
pumps oxygenated blood from the left ventricle around the the body
What does the vena cava do?
receives deoxygenated blood in the right atrium
What does the pulmonary artery do?
carries deoxygenated blood to the lungs from the right ventricle
What does the pulmonary vein do?
carries oxygenated blood from the lungs to the left atrium
Which arteries supply the heart muscle with oxygen?
the coronary arteries
Which blood vessel does the coronary artery branch off?
the aorta
How is a myocardial infarction caused?
A blockage in the coronary artery due to an atheroma or a thrombus menas that the heart muscle isn’t supplied with oxygen so that area of the heart dies, causing a heart attack.
What are the two phases to the beating of the heart?
systole - contraction
diastole - relaxation
What happens during diastole?
Talk about the pressure changes in the heart, the valves that are opened/closed, where the blood is entering and whether the heart muscle is relaxed or not.
- Blood returns to atria via pulmonary vein and vena cava.
- Atria fill causing the pressure to rise.
- Atrioventricular valves open as a result, so blood enters ventricles.
- Both muscular walls of atria are relaxed.
- there is less pressure in ventricles compared to the aorta and pulmonary arteries so semi-lunar valves closed.
What happens during atrial systole?
- the atrial walls contract, forcing remaining blood out through atrioventricular valves into ventricles.
- ventricle walls still relaxed.
What happens during ventricular systole?
Talk about the pressure changes in the heart, the valves that are opened/closed, where the blood is entering and whether the heart muscle is relaxed or not.
- there is a short delay to allow blood to fill ventricles
- the ventricles walls are contracting to build pressure
- this causes atrioventricular valves to close as pressure is higher in the ventricles compared to atria.
- the semi-lunar valves open as lower pressure in aorta and pulmonary artery, and
- ventricles contracts to pump blood to lungs and around body.
How does blood travel around the body (refer to pressure)?
From a region of high pressure to a region of low pressure.
Why are valves important?
to prevent backflow of blood.
What cause the valves in the cardiovascular system to open and close?
the pressure difference on either side of them.
Where are the semi-lunar valves located?
in the aorta and pulmonary artery.
Where are pocket valves found in the body?
in veins, so that blood flows back to heart.
How do you measure cardiac output?
Cardiac output = heart rate x stroke volume
What is cardiac output measured in?
dm3 min-1
Why is the heart described as myogenic?
because it initiates its own contractions.
What does neurogenic mean?
that a contraction is initiated by a nerve impulse.
What does SAN stand for?
Sinoatrial Node
Where is the SAN located?
in the right atrium
What is the SAN also called?
The Pacemaker
Where the initial stimulus in the heart start?
In the SAN
Describe the sequences of events that occur to make the heart beat.
- Wave of electrical energy spreads from SAN over atria causing them to contract.
- A non-conductive tissue prevents the electrical energy continuing to ventricles.
- AVN detects the electrical wave and conveys the activity down the Bundle of his
- They branch to the purkyne fibres which causes ventricles to contract, apex up.
What does AVN stand for?
Atrioventricular node
Why is it important that the electrical wave is stopped and delayed to the ventricles?
so it allows time for the ventricles to fill with blood.
What does CHD stand for?
Coronary Heart Disease
What does CHD do?
affect the coronary arteries which supply the heart muscle with glucose and oxygen. Blood flow is restricted due to atheroma which leads to myocardial infarction.
What is atheroma?
A fatty deposit that forms in the wall of arteries.
What are the fatty streaks in atheromas made of?
Fatty streaks of white blood cells that have taken in LDLs
What are LDLs?
Low density lipoproteins
How is an atheromatous plaque formed?
When fatty streaks containing LDLs enlarge to form an irregular patch in an artery.
Where are atheromatous plaques usually found?
in large arteries.
What is an atheromatous plaque made up of?
deposits of cholesterol fibres and dead muscle cells.
Why is it dangerous to develop an atheroma in your arteries?
because they bulge into the lumen of an artery, narrowing the passageway so less blood can flow through.
Which two conditions does atheromas increase the risk of getting?
Thrombosis and aneurysm
How does thrombosis occur?
When an atheroma breaks through the endothelium lining to form a rough surface that interrupts the smooth flow of blood
What is a thrombus?
blood clot
What is a thrombus dangerous?
because they block the blood vessel, reducing blood supply to tissue beyond it, causing tissues to die due to lack of oxygen and glucose.
A thrombus can be carried to different places and block important arteries (coronary arteries).
What is an aneurysm?
When weaken points of artery walls swell to form a balloon like, blood-filled structures
How are aneurysms caused?
When atheromas that lead to the formation of thrombus weaken the artrial walls.
Why are aneurysm dangerous?
Because if they burst, they lead to haemorrhaging and loss of blood to that region of the body.
What are brain aneurysms also know as?
Stroke
What is a myocardial infarction?
a heart attack
What causes a myocardial infarction?
when there is reduced blood supply to heart resulting from a blockage.
Part of the heart muscle does not receive glucose or oxygen and cause that tissue to die.
What are the four main risk factors associated with CHD?
- Smoking
- High Blood Pressure
- Diet
- Blood Cholesterol
How does carbon monoxide from smoking increase risk of CHD?
- CO combines irreversibly with haemoglobin to form carboxyhaemoglobin.
- This reduces the oxygen carrying capacity of blood
- Increases BP as a result as heart needs to compensate for less oxygen and glucose.
- Increases risk of CHD.
How does nicotine in cigarrettes increase the risk of developing CHD?
- Nicotine stimulate production of adrenaline
- Adrenaline increase heart rate and raises BP
- Increases risk of CHD
- Nicotine makes red blood more sticky, increasing risk of thrombosis, stroke and myocardial infarction.
What different factors lead to high blood pressure?
Stress, genes, certain diets, lack of exercise
Why does high blood pressure increase risk of CHD?
- High pressure in arteries means heart has to work harder to pump blood, therefore more prone to failure
- High blood pressure makes it more likely for arteries to develop an aneurysm and burst.
- Arteries try to resist the high pressure by thickening - this restricts blood flow further.
How is cholesterol transported into blood?
in tiny spheres of lipoproteins
What do high density lipoproteins do?
remove cholesterol from tissues and transports it to the liver for excretion
What do low density lipoproteins do?
transport cholesterol from liver to tissues including artery walls. Cause formation of atheroma.
How does poor diet increase risk of developing CHD?
- High salt levels increase BP
- High levels of saturated fats increase LDL levels so increase blood cholesterol concentration
