The heart Flashcards
(24 cards)
What is the function of the vena cava
To carry deoxygenated blood from the body to the heart
Name the two vena cava blood vessels in the heart
- Superior vena cava
- Inferior vena cava
What are the valves called which separate the atria and the ventricles in the heart?
Atrioventricular valves
(tricuspid for right and bicuspd for left)
What is the function of the septum in the heart?
It separates the right and left heart chambers and prevents the mixing of oxygenated and deoxygenated blood
What is the function of the pulmnary vein?
To carry oxygenated blood from the lungs to the heart
What is the function of the pulmonary artery?
To carry deoxygenated blood from the heart to the lungs
What is the function of the aorta?
To carry oxygenated blood from the heart to the body
What is the blood vessel which supplies oxygen and nutrients to the heart called?
Coronary artery
What is the function of the coronary artery?
To supply the heart with oxygen and nutrients
Describe what happens in diastole in the cardiac cycle
- The atrial and ventricular wall are relaxed
- The pressure in the ventricles is below the blood pressure in the aorta and pulmonary arteries and the semilunar valves close
- Then blood from the pulmonary vein and vena cava fills up the atria and some of the blood flows in to the ventricles.
- The atrioventriular valves are open
Describe what happens in atrial systole in the cardiac cycle
- The atrial walls contract in atrial systole
- The volume of the atria decreases and the pressure in the atria increases until the blood pressure is higher than in the ventricles
- The blood is forced down into the ventricles from the atria down the pressure gradient
- The atrioventricular valves and open ad the semilunar valves are closed
Describe what happens in ventricular systole in the cardiac cycle
- The ventricle walls contract
- The volume in the ventricles decreases and the pressure in the ventricles increass until it is more than the blood pressure in the atria and the atrioventricular valves close
- The blood pressure in the ventricles rises until it is higher than that in the aorta and the pulmonary artery and so the semilunar valves open and the blood is forced up the pulmoanry vein and vena cava and out of the heart
The heart muscle is [blank] because it generates its own heartbeat
fill in the blank
myogenic
Explain how heart action is initiated and coordinated
- An electrical impulse from the Sino-atrial node (SAN) spreads across the atria. This causes the atria to contract and atrial systole occurs
- The electrical impulse cannot pass directly into the ventricles due to a non-conductive layer between the atria and ventricles so the impulse passes through the Atrio-ventricular node (AVN)
- The AVN briefly delays the impulse so that the atria can fully contract before ventricular systole begins
- The AVN is attatched to the bundle of His and the impulse passes through the bundle of His and travels down to the apex.
- The bundle of His is well insulated so the impulse doesn’t pass into the ventricular walls
- Contractions begin down at the apex and travel upwards. The contractions travelling upwards ensures that the maximum amount of blood is pumped out of the ventricles
What are the purkyne fibres also known as?
The Bundle of His
Why does the AVN briefly delay the electrical impulse in the heart
To ensure that the atria has fully contracted before ventricular systole begins
Why is it good that contractions begin at the apex of the heart and travel upwards?
This ensure that the maximum amount of blood has been pumped out of the ventricles
If you calculated from an ECG trace that 1 heart beat happens in 0.8 seconds, how many heart beats does this person have per minute?
60/0.8 = 75 beats per minute
What is a slower than normal heartbeat called?
Brachycardia
What is a faster than normal heartbeat called?
Tachycardia
Give a cause of Bachycardia
Regularly excercising and being a generally fit person.
Give a treatment for severe bradycardia
An artificial pacemaker
Give a treatment of Tachycardia
Medication or surgery
Give some treatments of atrial fibrilation
Medication or surgery
