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Yr. 11 The heart flow Revision

The heart flow
Valves in the heart
• There are 4 valves you should know for this exam:
These are also called ATRIOVENTRICULAR valves:
1. Bicuspid or Mitral valve (left)
2. Tricuspid valve (right)
These two are also called
3. Aortic semilunar valve
4. Pulmonary semilunar valve
What do valves do?
• They prevent backflow of blood
in the heart.
We also find valves in veins where
they prevent backflow of blood as
veins do not have the pressure
arteries do to push blood throughout
the body.
This is what these valves look from the top:
If you don’t remember
Tricuspid and Bisuspid,
you can use the word
atrioventricular (left or
right). Same thing
applies for the aortic
and pulmonary valves,
you can use semilunar
instead, or viceversa.
How blood flows through the heart.
The right side of the heart receives and pumps DEOXIGENATED BLOOD
The left side of the heart receives and pumps OXIGENATED BLOOD
A systole is a contraction.
When the atria contract the
tricuspid (L) and bicuspid (R)
valves open.
When the ventricles contract, they
open the semilunar valves and they
push blood out into the aorta and the
pulmonary artery.
In other words…
• Atria contract (ventricles relax) =
1. Bicuspid and tricuspid valves open
2. Ventricles are relaxed and they receive blood.
• Ventricles contract (atria contract) =
1. Bicuspid and tricuspid valves close
2. Pulmonary and aortic semilunar valves open
Human circulation is double because blood
passes twice through the heart for each complete
circuit of the body.
- Pulmonary circulation- blood goes from the heart to the lungs and
back to the heart.
- Systemic circulation- blood goes from the heart to the body and back
to the heart.
How blood flows through the circulatory
system: (look at the diagram as you follow the path of blood shown below)
Vena cava- right atrium- tricuspid
valve (atrioventricular valve) - right
ventricle- semilunar valves
(pulmonary)- lungs- pulmonary
vein- left atria- bicuspid valve
(atrioventricular valve) - left
ventricle- semilunar valve (aortic) –
aorta- body……….. Back to vena cava
Coronary heart disease
• The coronary artery becomes blocked.
• The heart muscles does not get glucose and oxygen.
• It starts respiring anaerobically and as a result lactic acid is being produced- this produces angina
(pain in the chest).
• If the heart stops contracting, a heart attack happens.
Coronary heart disease
1. Poor diet- high in
2. Poor lifestylesmoking, lack of
exercise, stress
3. Genetic factorshaving a family
history of heart
disease. Men are
more at risk of CHD
than women.
Coronary heart diseaseWays to deal with it
1. A healthy lifestyle
a) Exercise
- prevents blocked arteries (thrombus formation)
- lowers blood pressure
- lowers cholesterol / lowers fats / reduces risk of atheroma ;
- weight loss / using fats / avoids obesity ;
- lowers stress ;
- (heart) muscle stronger / lower (resting) pulse ;
b) No smoking Nicotine is found in plaque (atheroma)
c) Diets Reducing the amount of saturated fats/ cholesterol in our diets- they also contribute to the
plaque that blocks the arteries.
Coronary heart diseaseWays to deal with it
- Atheroma or plaque
- Stent
- Blood flow
Coronary heart diseaseWays to deal with it
3. Coronay Bypass
When the coronary artery is blocked, a blood vessel can be taken from another part of the body
(example- leg) and connected to the aorta and the unblocked part of the coronary artery.
This increases blood flow to the heart.
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