Heart Flashcards
What muscle is the heart made of?
Cardiac muscle
What is a difference between cardiac muscle and skeletal muscle?
Cardiac muscle doesn’t get fatigued as the coronary arteries supply it with the oxygenated blood it needs to contract and relax constantly
Where does deoxygenated blood enter the heart?
The right atrium, and then is pumped out of the right ventricle to the lungs
Through what blood vessel does deoxygenated blood enter the right atrium?
Blood enters through the right atrium through the inferior and superior vena cava
Where does the deoxygenated blood in the inferior vena cava come from?
The lower body
Where does the deoxygenated blood in the superior vena cava come from?
The upper body and head
What are the two types of valves in the heart?
The atrio-ventricular and semi-lunar valve
Where does oxygenated blood enter the heart?
The left artium, and then is pumped out to the rest of the body
What are the two atrio-ventricular valves?
The tricuspid and bicuspid valves
Where is the tricuspid valve found?
In between the right artium and right ventricle
Where is the bicuspid valve found?
In between the left atrium and left ventricle
Through what blood vessel does oxygenated blood enter the left atrium?
Pulmonary vein
Through what blood vessel does oxygenated blood leave the left ventricle?
The aorta
Through what blood vessel does deoxygenated blood leave the right ventricle?
Pulmonary artery
What is systole?
Contraction. There is atrial and ventricular systole and they happen separately
What is diastole?
Relaxation
What are the 3 main stages of the cardiac cycle?
Atrial systole
Ventricular systole
Diastole
What happens during atrial systole?
The atria contract to completely fill the ventricles with blood
What happens during ventricular systole?
The ventricles contract to push blood out of the heart
What happens during diastole?
The artia and ventricles relax to allow the heart to refill with blood
What happens once the ventricular pressure is higher than the atrial pressure?
The atrio-ventricular valves close to prevent back flow of blood into the atria
What happens once the ventricular pressure is higher than aortic/pulmonary artery pressure?
The semi-lunar valves open to allow blood to leave the ventricles through the aorta or pulmonary artery
What happens once the ventricular pressure is lower than aortic/pulmonary artery pressure?
The semi-lunar valves close to prevent back flow of blood into the ventricles
What happens once the ventricular pressure is lower than the atrial pressure?
The atrio-ventricular valves open to allow blood to enter the ventricles from the atria
What is the purpose of tendinous cords in the heart?
Ensures the atrio-ventricular valves are not turned inside out by the pressure exerted when the ventricle contracts
What side of the heart is more muscular?
The muscular wall of the left side of the heart is much thicker than the right
Why is the left side of the heart more muscular than the right?
The right side of the heart has to pump a relatively short distance (to the lungs), and only has to overcome the resistance of pulmonary circulation.
The left side of the heart has to pump blood to all extremities of the body, and has to overcome the resistance of aorta and arterial systems of the whole body
What is the purpose of the septum?
The septum is the inner dividing wall of the heart, which prevents the mixing of deoxygenated and oxygenated blood
What are the lub-dub sounds of the heart caused by?
The closing of the heart valves caused by the pressure of backflowing blood
What is the word to describe how the heart controls its own contractions?
Myogenic
How does the heart control its own contractions?
Through initiating its own electrical impulses
What is the sino-atrial node known as and why?
The natural pacemaker, as it initiates the electrical impulse, causing atrial contraction
What stops the excitation initiated by the SAN from passing directly to the ventricles?
A layer of non-conducting tissue
What does the atrioventricular node do?
Once the excitation reaches the AVN, it imposes a delay before stimulating the bundle of His
Why is it important that the atrioventricular node imposes a delay?
Allows time for the atria to fully contract, and for all the blood in the atria to enter the ventricles before they contract
What is the bundle of His?
A bundle of conducting tissue made up of fibres known as Purkyne fibres, that penetrates through the septum of the ventricles, and splits into two branches surrounding the ventricles
What surrounds the bundle of His and why?
Around the bundle of His is a layer on non-conductive tissue, which prevents the ventricles from being stimulated until the impulse reaches the apex.
Where does the impulse start at the ventricles and where does its spread?
The impulses start from the bottom of the heart (the apex), and then spread impulses along the ventricles to complete ventricular contraction
Why does contraction start at the apex?
Allows for more efficient emptying of the ventricles, ensuring all blood leaves the ventricles
What can be used to measure the electrical activity of the heart?
Electrocardiograms (ECGs)
What is tachycardia?
When heartbeat is very rapid (over 100bpm)
What is bradycardia?
When heartbeat slows down to less than 60 bpm
What is an ectopic heart beat?
An extra beat followed by a pause
What is atrial fibrillation?
Where rapid electrical impulses are generated in the atria, leading to rapid incomplete contraction, but only some of these impulses are passed on to the ventricles which contract much less often
How do you work out cardiac output?
Cardiac output = Stroke volume x Heart rate
