The heart Flashcards
Draw a diagram showing the internal structure of the heart and label the components
What side of the heart does deoxygenated blood flow into?
The right side of the heart
What side of the heart does oxygenated blood flow into?
The left side of the heart
Which side of the heart pumps the blood around the rest of the body?
The left side of the heart
Which side of the heart pumps the blood to the lungs?
The right side of the heart
Which side of the heart is bigger and more muscular?
The left side of the heart
What separates the two sides of the heart?
The septum
What do the coronary arteries do?
They carry oxygenated blood to the cardiac muscles of the heart which enables the heart to keep contracting
How is the heart prevented from over distending with blood?
The heart is surrounded by inelastic pericardial membranes which prevents this from happening
Draw a diagram showing the external structure of the heart and label the components
Which sections of the heart does the blood flow into?
The atriums
How does the deoxygenated blood from the top half of the body enter the heart?
Through the superior vena cava
At what pressure does the blood enter the heart?
At relatively low pressure
How does the deoxygenated blood from the lower part of the body enter the heart?
Through the inferior vena cava
How do the walls of the atria compare to the walls of the ventricles?
The muscular walls of the atrium are relatively thin compared to the walls of the ventricles; which need more muscle in order for a more powerful contraction.
How does the blood move from the right atrium to the right ventricle?
As the blood flows into the right atrium the pressure slowly builds up until the atrio-ventricular valve (tricuspid valve) opens to let the blood pass into the right ventricle.
What happens when both the right atrium and ventricle are filled with blood?
The atrium contracts, forcing all the blood into the ventricle which stretches the ventricle walls
How is the back flow of blood to the atrium prevented as the ventricle starts to contract??
The atrio-ventricular valve closes
What do the tendinous cords do?
They stop the valves from being turned inside out by the pressure from when the ventricles contract.
How does the blood enter the pulmonary artery?
The right ventricle contracts fully and pumps the deoxygenated blood through the semi-lunar valves and into the pulmonary arteries
Where does the pulmonary artery lead to?
The capillary beds of the lungs
How is the back-flow of blood from the pulmonary artery to the heart prevented?
Via the semi-lunar valves
What is the septum and what is its function?
The septum is an inner wall of the heart which divides both sides. It is there to prevent oxygenated and deoxygenated blood from mixing.
When is the development of the septum complete in a human?
Until after birth
What is a gap in the septum referred to?
A hole in the heart
What does a hole in the heart sound like under a stethoscope?
A heart murmur
true or false? Many people have a small hole in their septum
TRUE
What is the cardiac cycle?
It describes the events in a single heartbeat
How long does a single heartbeat last in the average adult human?
0.8 seconds
What is diastole?
When the heart relaxes
What is systole?
When the heart contracts
What happens in the heart during diastole?
The atria and then the ventricles fill with blood. The blood filling the heart creates an increase in the volume and pressure. However, their is little pressure in the arteries
What happens in the heart during systole?
The atria contract which is closely followed by the ventricles. This increases the pressure inside the heart and so the blood is pushed out of the right side of the heart to the lungs and out of the left side of the heart to the rest of the body. After which the volume and pressure inside of the heart drops but the pressure inside the arteries is great.
What is it called when the atria contract?
atrial systole
What is it called when the ventricles contract?
ventricular systole
Draw and label a diagram for an electrocardiogram (ECG)
What does ECG stand for?
Electrocardiogram
What does an ECG represent?
The electrical activity of the heart
What does the heartbeat sound like?
Lub-Dub
What is the sound of the heart beat caused by?
The closing of the valves
What is the Lub sound caused by?
It happens when the blood is forced against the atrio-ventricular valves as the ventricles contract
What is the Dub sound caused by?
It happens when the backflow of blood closes the semilunar valves in the aorta and the pulmonary artery as the ventricles relax.
What is meant by myogenic?
originating in muscle tissue
What does bpm stand for?
Beats per minute
How many bpm does the average healthy adults resting heart rate undergo?
70 bpm
Draw a diagram of the heart and how it’s rhythm is created an maintained. Label the diagram
a
What is the pacemaker of the heart called?
sino-atrial node (SAN)
What does SAN stand for?
sino-atrial node
What is the function of the SAN?
The SAN is where the wave of electrical excitation begins. This causes the atria to contract and so initiating the heartbeat.
What prevents the excitation from the SAN reaching the ventricles?
A layer of non-conducting tissue
What does AVN stand for?
Atrio-ventricular node
What is the function of the AVN?
The electrical activity from the SAN is picked up by the AVN. The AVN then creates a slight delay before stimulating the bundle of his.
What is the bundle of his?
a bundle of conducting tissues made up of fibres
What is another name for the bundle of his?
Purkyne fibres
Where is the bundle of his located?
Between the ventricles, through the septum.
What is the bottom of the heart known as?
The apex
Which part of the heart does the bundle of his conduct a wave of excitation towards?
The bundle of his splits in two and carries the wave of excitation to the apex of the heart
What part of the heart does the contraction start for the ventricles?
The contraction of the ventricles start at the apex and then up through the walls at both sides of the ventricles.
Why is it better for the contraction of the ventricles to start at the apex?
It allows for more efficient emptying of the ventricles
Why is it important for their to be a delay between the SAN and the AVN?
To make sure that the atria have stopped contracting before the ventricles start.
What does an ECG actually measure?
Tiny electrical differences in your skin
What is an ECG used to diagnose?
Heart problems
What heart problem does this ECG represent?
None, this person is healthy
What heart problem does this ECG represent?
Tachycardia
What heart problem does this ECG represent?
Bradycardia
What heart problem does this ECG represent?
Ectopic heartbeat
What heart problem does this ECG represent?
Atrial fibrillation
What is Tachycardia?
The heartbeat is faster than normal (over 100 bpm)
What is Bradycardia?
The heart beat is slower than normal (below 60 bpm)`
What is Ectopic heartbeat
Extra heartbeats that are out of normal rhythm
What is Atrial fibrillation?
It is a form of arrhythmia. Rapid electrical impulses are generated in the atria so they contract very fast. However, they do not contract properly and only some of the impulses are past on to the ventricles; so the ventricles contract much less often. As a result the heart does not pump the blood efficiently.
What arrhythmia?
An abnormal rhythm of the heart.
What is a normal example of tachycardia?
When you are exercising or if you are frightened.
What is a normal example of bradycardia?
When they are fit the heart can beat more slowly and efficiently
A crash course video to help make things clearer
Crash course heart part 2
