Mass transport Flashcards
Which blood vessel carries blood at the lowest blood pressure?
Vena cava
What system is the heart part of in animals?
Double circulatory system
Describe pulmonary circulation
The blood passes through the heart and is pumped to the lungs, returning back to the heart
Describe systematic circulation
The blood now passes through the heart a
second time and pumped round the body organs before returning to the heart
How does blood move around the body?
Due to pressure difference between the pressure in the heart and the pressure in the vessels
What is an example of mass flow?
Blood moving in the body due to pressure difference between the pressure in the heart and the pressure in the vessels
Heart structure
Superior/inferior vena cava
Right/left atrium
Atrioventricular valves
Right/left ventricle
Semilunar valves
Aorta
Pulmonary artery
Pulmonary vein
Describe blood flow in the heart (no reference to pressure)
Deoxygenated blood returns from the body in the vena cava and enters the right atrium.
The blood then passes, via an atrio-ventricular valve into the right ventricle and out, via the semi-lunar valve, into the pulmonary artery.
The blood now passes through the lungs and returns to the left atrium via the pulmonary vein.
The blood passes through a second atrio-ventricular valve into the left ventricle and then through the semi-lunar valve into the aorta and then onto the body tissues
Features of the left ventricle with explanations
The left ventricle is pumping blood through a much larger number of capillaries, branching off from the aorta around the body.
The left ventricle requires more pressure
SO the wall of the left ventricle is much thicker than that of the right ventricle, providing more muscle fibres for a greater contraction force
What is the purpose of the coronary arteries?
The coronary arteries branch off from the aorta and supply the heart muscle with blood.
What are the changes in pressure in the heart chambers a result of?
The changes in the volume of blood within the chambers
The contractions of the heart muscle.
State the blood pressure changes and muscles contracting/relaxing from the left atrium to the aorta
1) Blood enters atrium - Blood volume increases pressure in atrium - Pressure in atrium greater than in ventricle - atrio ventricular valve opens. Atrium muscles contract - Further increases pressure - Remaining blood forced into ventricle from atrium
2) Blood enters ventricle - increases pressure in ventricle due to volume of blood - Pressure in ventricle greater than in atrium - atrio ventricular valve closes.
3) Ventricle muscles contract - Further increases pressure in ventricle until greater than in aorta - Semi Lunar valve opens. Blood enters aorta - Blood is pumped to body left
4) Ventricle muscles relax - Pressure in ventricle is less than in aorta- Semi lunar valves close Blood enters atrium - Blood volume increases pressure in atrium - (back to 1)
What happens to the AV valves when there is greater pressure in the atria than ventricles?
They open
What happens to the AV valves when there is greater pressure in the ventricles than atria?
Close
What happens to the SL valves when there is greater pressure in the ventricles than arteries?
open
What happens to the SL valves when there is greater pressure in the arteries than ventricles?
Close
How is cardiac output calculated?
Stroke Volume x Heart rate
