The Cardiac Cycle Flashcards
What happens during atrial systole
Atrial muscle contracts
Blood is forced through the atrial ventricular valves to the ventricles
What happens during ventricular systole
Ventricular muscle contracts
Blood is forced through the semi lunar valves into the arteries
What happens during diastole/isovolumetric relaxation
The muscle of the ventricle relaxes and blood can flow back into the atria
What happens when the pressure is greater in the atrium than in the ventricles
The AV valve is forced open and blood flows through to the ventricles
What happens when the pressure is greater in the ventricles than in the atrium
The AV valve is forced shut, preventing backflow
What happens when the pressure is greater in the ventricles than in the aorta
The semilunar valve is forced open and blood flows in to the aorta
What happens when the pressure is greater in the aorta than in the ventricles
The semilunar valve is forced shut, preventing backflow
Define stroke volume
Volume of blood pumped out of the left ventricle during one cycle
What is the equation for cardiac output
Cardiac output = Stroke volume x Heart rate
What are the risk factors of cardiovascular disease
Too much salt
Too much saturated fat/cholesterol
High blood pressure
Cigarette smoking
High blood cholesterol
Gender/age/genetics
Alcohol
Lack of exercise/obesity
Stress
What is atheroma
A plaque/fatty substance that builds up along the inner lining of your arteries
How does atheroma form? What are the effects of it
Cholesterol plaque forms in the artery wall in the endothelium
This blocks the coronary artery
Because the coronary artery is blocked, the O2 and glucose supply to the heart tissue is reduced
This means the heart tissue is unable to respire so it dies
Myocardial infarction (a type of heart attack) can occur
There is also an increased risk of clot/thrombosis/embolism/aneurysm
What is the heart made of
Cardiac muscle
Which of the chambers of the heart have thin walls? Why
The atria. They receive blood from the body or the lungs and only need to pump it down to the ventricles
What is the function of the coronary artery
It branches over the surface of the heart (and into the walls) supplying the cardiac muscle cells with oxygen and glucose for aerobic respiration
What is the function of valves? What causes them to open/close
Valves prevent blood flowing in the wrong direction
The pressure difference either side causes it to open/close
Why is the right ventricle thicker compared to the right atrium
Atria are thinner walled as they only generate enough of a force to pump blood into the ventricles below
Why is the left ventricle thicker compared to the right ventricle
The left ventricle needs to thicker than the right to generate the pressure required to pump blood at high pressure to ALL the organs of the body, whereas the right ventricle only needs to pump blood to the lungs
What is the function of AV valves
To separate the atria from the ventricles, preventing blood from flowing back into the atria when ventricular systole occurs. They open when the atria contracts
What is the function of semi lunar valves
To separate the ventricles from the arteries to prevent blood from flowing back into the ventricle when ventricular diastole occurs. They open when ventricle contracts, this is called systole
Name the order of the cardiac cycle (the way blood pumps through the heart)
BODY
Vena cava
Right atrium
Right ventricles
Pulmonary artery
LUNGS (blood becomes oxygenated)
Pulmonary veins
Left atrium
Left ventricle
Aorta
BODY
What happens when the pressure in the atrium is greater than in the ventricles
The atrial ventricular valve is forced open and blood flows into the ventricles
What happens when the pressure in the ventricles is greater than in the atrium
The atrial ventricular valve is forced shut, preventing back flow
What happens when the pressure in the ventricles is greater than in the aorta
The semi lunar valve is forced open and blood flows into the aorta
