Transport in Animals Flashcards
circulatory system
the system that contains the heart and the blood vessels with a pump and valves to ensure one-way flow of blood
single circulation of fish
blood flows through the heart once during each circuit of the body.
from the heart, arteries carry the blood to the gills where the blood takes up oxygen. the arteries that leave the gills carry oxygenated blood to various parts of the body. the veins collect blood from the capillaries around the body cells. by the time the blood enters the veins, it is poor in oxygen content. the veins carry the deoxygenated blood back to the heart.
double circulation of mammals
in double circulation, the blood passes through the heart twice in one complete circuit.
the double circulation consists of the pulmonary circulation and the systemic circulation
pulmonary circulation
blood flows from the main circulation of the body to the heart. it then flows to the lungs and back to the heart again before it is pumped back into the main circulation.
the circulation linking the lungs to the heart is known as the pulmonary circulation.
- from the heart, the pulmonary arteries carry the blood to the lungs
- oxygenated blood is returned to the heart by the pulmonary veins
systemic circulation
the circulation of blood around the body is called the systemic circulation.
- oxygenated blood leaves the left side of the heart through the arteries. it is distributed to all parts of the body (except the lungs)
- veins carry the blood from all parts of the body back to the right side of the heart
advantages of a double circulation
- a four chambered heart ensures that oxygenated blood is separated from deoxygenated blood
- blood entering the lungs is at a lower pressure compared to blood leaving the heart. this ensures that the blood flows more slowly through the lungs, allowing sufficient time for the blood to be well oxygenated before it is returned to the heart.
- the heart pumps oxygenated blood at high pressure to the rest of the body (through the systemic circulation) so oxygenated blood is distributed to the body tissues more quickly. this helps to maintain the high metabolic rate in mammals
advantages of a double circulation
- a four chambered heart ensures that oxygenated blood is separated from deoxygenated blood
- blood entering the lungs is at a lower pressure compared to blood leaving the heart. this ensures that the blood flows more slowly through the lungs, allowing sufficient time for the blood to be well oxygenated before it is returned to the heart.
- the heart pumps oxygenated blood at high pressure to the rest of the body (through the systemic circulation) so oxygenated blood is distributed to the body tissues more quickly. this helps to maintain the high metabolic rate in mammals
relative thickness of: the muscle walls of the left and right
ventricles
the ventricles have thicker muscular walls than the atria. this is because the ventricles have to pump blood to other parts of the body.
the left ventricle has a thicker muscular wall than the right, because the left has to pump blood round the whole body which requires a higher pressure.
the right ventricle only pumps blood to the lungs, which are located close to the heart
relative thickness of: the muscle walls of the left and right
ventricles
the ventricles have thicker muscular walls than the atria. this is because the ventricles have to pump blood to other parts of the body.
the left ventricle has a thicker muscular wall than the right, because the left has to pump blood round the whole body which requires a higher pressure.
the right ventricle only pumps blood to the lungs, which are located close to the heart
the muscle walls of the atria compared to those of the ventricles
the atria have thinner muscular walls than the ventricles. this is because, the atria only force blood into the ventricles that lie directly below them. this process doesn’t require high pressure
the importance of the septum
the right and left sides of the heart are separated by a muscular wall called the septum. the septum runs down the middle of the heart.
mixing of deoxygenated blood with oxygenated blood will reduce the amount of oxygen carried to the tissue cells.
the septum prevents their mixing
functioning of the heart in terms
of the contraction of muscles of the atria and ventricles and the action of the valves
the two atria contract, while the ventricles relax. blood passes from the atria into the ventricles.
the ventricles contract, while the atria relax. (contraction of the ventricles is called ventricular systole.) this causes the bicuspid and tricuspid valves to close, producing a loud “lub” sound. blood passes from the right ventricle into the pulmonary arch and from the left ventricle into the aorta.
the atria contract again, while the ventricle relax. the cycle repeats. (relaxation of the ventricles is called ventricular diastole.) as the ventricles relax, the semilunar valves in the aorta and pumonary arch close, to prevent backflow of the blood. a softer “dub” sound is produced.
one-way valves
valves of the heart are known as one-way valves as they prevent backflow of the blood
pumping of blood
blood is pumped away from the heart in arteries and returns to the heart in veins
how to monitor the heart activity
ECG (electrocardiogram) , pulse rate and listening to sounds of valves closing
