Transport in Animals Flashcards
Transport Systems: What do all living animal cells need to do to be able to survive?
All living animal cell need a supply of oxygen and nutrients to survive. They also need to remove waste products so that these do not build up and become toxic.
Transport Systems: Why do very small animals not need a transport system?
Very small animals do not need a separate transport system, because all their cells re surrounded by (or very close to) the environment in which they live. Diffusion will supply enough oxygen and nutrients to keep the cell alive.
-Once an animal has a complex anatomy with more than two layers of cells, diffusion alone will be too slow.
Transport Systems: What are the three main factors that influence the need for a transport system?
- Size
- Surface area to volume ratio
- Level of activity.
Transport Systems: How does size influence the need for a transport system?
Once an animal has several layers of cells, any oxygen or nutrients diffusing in from outside will be used up by the outer layers of cells. The oxygen and nutrients will not reach the cells deeper within the body.
Transport Systems: How does surface area to volume ration influence the need for a transport system?
Small animals have a large surface area compared with their volume. This is known as their surface area to volume ratio. This ratio is affected by an animal’s shape. A flatworm has a very thin, flat body, which gives it a large surface area to volume ratio. But such a body form limits the overall size that the animal can reach.
-To allow animals to grow to a large size, they need a range of tissues and structural support to give body strength. Their volume increases as their body gets thicker. But the surface area does not increase as much. So the surface area to volume ratio of a large animal is relatively small and the surface area is not large enough to supply all the oxygen and nutrients needed by the internal cells.
Transport Systems: How does level of activity influence the need for a transport system?
Animals need energy from food so that they can move around. Releasing energy from food by respiration requires oxygen. If an animal is very active, its cells need good supplies of nutrients and oxygen to supply the energy for movement. Those animal, such as mammals that keep themselves warm and carry out thermoregulation need even more energy.
Transport Systems: What are the features of an effective transport system?
- A fluid or medium to carry nutrients and oxygen around the body (blood)
- A pump to create pressure that will push the fluid around the body (heart)
- Exchange surfaces that enable oxygen and nutrients to enter the blood and to leave it again when they are needed.
- Tubes or vessels to carry the blood (efficient)
- Two circuits - one to pick up oxygen and another to deliver oxygen to the tissues (efficient)
Transport Systems: What is a single circulatory system?
A system which passes through the heart once.
-E.g. fish
Transport Systems: What are the advantages of a single circulatory system?
- Quick and takes up less space.
- Blood pressure is reduced as blood passes through the tiny capillaries so they don’t burst.
- Meets energy requirements of cold blooded animals.
Transport Systems: What are the disadvantages of a single circulatory system?
- As the blood pressure is reduced as blood passes through the tiny capillaries, this means it will not flow very quickly to the rest of the body, which limits the rate at which oxygen and nutrients are delivered to respiring tissue.
- Not efficient enough if the organisms is warm blooded.
Transport Systems: What is a double circulatory system?
A system which passes through the heart twice.
-E.g. mammals
Transport Systems: What two circuits are involved in a double circulatory system?
- Pulmonary circuit
- Systemic circuit
Transport Systems: What is the pulmonary circuit in a double circulatory system?
It carries the blood to the lungs to pick up oxygen.
Transport Systems: What is the systemic circuit in a double circulatory system?
It carries the oxygen and nutrients around the body to tissues.
-It is good because it provides the high pressure needed to transport oxygen and glucose to respiring tissues to meet metabolic needs of cells.
Transport Systems: What are the advantages of a double circulatory system?
- The pressure can decrease while in the pulmonary circulation, so it doesn’t damage the delicate capillaries in the lungs.
- The heart can increase the pressure of the blood after it has passed through the lungs, so blood flows more quickly to the body tissues.
- The systematic circulation can carry blood at a higher pressure than the pulmonary circulation.
- Allows for growth of cells.
Transport Systems: What is a closed system?
Closed network of tubes to maintain high pressures and to bathe tissues in tissue fluid. This is due to a concentration gradient between the blood and tissues.
Transport Systems: What is an open system?
Blood flows under low pressure as they have an open system which bathes the cells directly.
What is a mammalian heart?
The mammalian heart is a muscular double pump. It is divided into two sides. On both sides, the heart squeezes the blood, putting it under pressure. This pressure forces the blood along the arteries.
What is pumped on each side of the heart?
The right side pumps deoxygenated blood to the lungs to be oxygenated. The left side pumps oxygenated blood to the rest of the body.
What is the difference between oxygenated and deoxygenated blood?
The difference between oxygenated and deoxygenated blood is that the oxygenated blood has a higher concentration of oxygen.
-Do oxygenated blood has less oxygen, but never no oxygen, otherwise a part of the body would be receiving no oxygen and the cells would die.
Externally, what does the heart look like?
The heart sits slightly off centre to the left of the chest cavity. The main part of the heart consists of dark red muscle which feels very firm. This is the muscle, surrounding the two main pumping chambers, the ventricles. Above the ventricles are two thin-walled chambers - the atria. These are much smaller than the ventricles and easy to overlook. The coronary arteries lie on the surface of the heart.
What are the coronary arteries?
The coronary arteries lie over the surface of the heart. They carry oxygenated blood to the heart muscle itself. As the heart is a hard-working organ, these arteries are very important. If they become constricted, it can have severe consequences for the health of the heart and of the animal. Restricted blood flow to the heart muscle reduces the delivery of oxygen and nutrients such as fatty acids. This may cause angina or a heart attack.
Why is there a layer of fat around the heart?
- To protect the heart
- For insulation
What are the different parts of the heart?
- Right atrium
- Tricuspid valves (atrioventrivular valves)
- Right ventricle
- Septum
- Semilunar valves
- Chordae tendineae (tendinous cords)
- Left Atrium
- Bicuspid valves (atrioventricular valves)
- Left Ventricle
What are the blood vessels in the heart?
- Vena Cava (superior and inferior)
- Pulmonary artery
- Pulmonary veins
- Aorta
What is the vena cava?
- Great veins, superior and inferior
- Transport deoxygenated blood from the body, to the right atrium.
What is the right atrium?
- Thin muscular walls as blood is under low pressure.
- One way valves at entrance to prevent backflow of blood into the vena cava.
What are the tricuspid valves?
- The right atrioventricular valves
- Prevent back flow of blood into the atrium
What is the right ventricle?
-As the lungs are quite close to the heart, muscular walls are not too thick but able to build sufficient pressure to move the blood onto the lung capillaries from the pulmonary artery.
What is the septum?
- Inner dividing wall of the heart.
- Is not complete until after birth, and so mixture of blood occurs in the foetus. It does not need to be separate because blood comes from its mother’s placenta, through the umbilical cord. The gap closes after birth.
What is the pulmonary artery?
-Carries deoxygenated blood from the heart to the lungs to be oxygenated.
What are the semilunar valves?
- Inside both the aorta and pulmonary artery.
- Prevents backflow of blood into ventricles.
What are the pulmonary veins?
-Carried oxygenated blood from the lungs to the heart to be pumped to the rest of the body.
What is the left atrium?
- Thin walled chamber
- Same function as the right atrium
What is the left ventricle?
- Very thick muscular wall
- Thicker than the right ventricle wall because it gas to produce sufficient force to move the blood to all the extremities.
What are chordae tendineae?
- String like structures
- Attached to the papillary muscles and the edges of the valve cusps, thus preventing the valve flaps turning inside out.
What is the aorta?
- The aorta is the biggest artery in the body
- It carries the oxygenated blood to the rest of the body to oxygenate the cells.
What is the pathway of blood around the body?
- Enters through the vena cava into the right atrium.
- Passes through the tricuspid valves and into the right ventricle.
- Passes through the semilunar valves, and exits the heart through the pulmonary artery, where it travels to the lungs to pick up oxygen. It becomes oxygenated.
- Re-enters the heart, through the two pulmonary veins into the left atrium.
- Passes through the bicuspid valves and into the left ventricle.
- Pass through the semilunar valves and exits the heart through the aorta, travelling around the body, providing respiring cells with oxygen. It eventually becomes deoxygenated and the process repeats.
Why does the heart receive the most oxygen?
The heart receives the most oxygen as it is the first place oxygen is delivered because it is closest to the aorta. As the blood travels around the body, more and more oxygen in used up so oxygen concentration decreases.
What is heart disease?
When coronary arteries become narrower and blocked meaning oxygen and nutrients can’t get to the heart, resulting in a heart attack as the heart is unable to function.
What is myocardial infarction?
A heart attack
What is the apex?
The point, made up of the left ventricle.
What does anterior, posterior and lateral mean?
The front, back and side of the heart
Why is pressure in the heart important?
The muscle of each chamber contracts to create increased pressure in the blood. The higher the pressure created in the heart, the further it will push the blood.
Why are the walls of the atria quite thin?
The muscle of the atria is very thin. This is because these chambers do not need to create much pressure. Their function is to push the blood into the ventricles.
Why are the walls of the ventricles thicker than the walls of the atria?
It enables the ventricles to pump blood out of the heart, either to the lungs or the rest of the body.
Why are the walls of the right ventricle much thinner than those of the left ventricle?
The right ventricle pumps deoxygenated blood to the lungs. The lungs are in the chest cavity, so the blood does not need to travel very far. Also, the lungs contain a lot of very fine capillaries that are in close contact with the walls of the alveoli. The alveoli walls are very thin and there is little or no tissue fluid. So the capillaries are not supported and could easily burst. The pressure of the blood must be kept down to prevent the capillaries in the lungs bursting.
Why are the walls of the left ventricle much thicker than those of the right ventricle?
The walls of the left ventricle can be two or three times thicker than those of the right ventricle. The blood from the left ventricle is pumped out through the aorta and needs sufficient pressure to overcome the resistance of the systemic circulation.
Cardiac Cycle: What is the cardiac cycle?
The sequence of events involved in one heartbeat.
-The events happen continuously and simultaneously (in and out at the same time).
Cardiac Cycle: On average how many times does the heart beat per minute?
60-80 times per minute
Cardiac Cycle: What is diastole?
Both the atria and ventricles are relaxed. Blood enters the heart through the Vena Cava (R) and the Pulmonary Veins (L). It flows through the atria and into the ventricles. At this point, the atrial ventricular valves are open and the semilunar valves are closed.
Cardiac Cycle: How long does the diastole phase last?
0.4 seconds
Cardiac Cycle: What are the pressure changes involved in diastole?
- The ventricle walls are relaxed (and recoiling). The ventricular pressure is decreasing and the atrial pressure is higher than the ventricular pressure, as the atrial ventricular valves are open, this causes blood to flow through the atria and into the ventricles.
- As blood enters the atria and then the ventricles, ventricular pressure and atrial pressure slowly increases. The valves remain open as atria begin to contract.
Cardiac Cycle: What is atrial systole?
Atrial Systole is the contraction of the atria. The atria squeeze out the last little bit of blood into the ventricles. At this point, the atrial ventricular valves are open and the semilunar valves are closed.
Cardiac Cycle: How long does the atrial systole phase last?
0.1 seconds
Cardiac Cycle: What are the pressure changes involved in atrial systole?
As the atria contract, the atrial ventricular valves stay open to allow the blood to flow into the ventricles. This is caused by a small increase in pressure in the atria.
Cardiac Cycle: What is ventricular systole?
Ventricular Systole is the contraction of the ventricles and starts when the ventricular pressure is higher than the atrial pressure. At this point, the atrial ventricular valves snap shut and the semilunar valves open.
Cardiac Cycle: How long does the ventricular systole phase last?
0.3 seconds
Cardiac Cycle: What are the pressure changes involved in ventricular systole?
- As the ventricles contract, ventricular pressure becomes a lot higher than atrial pressure. Blood fills the atrioventricular valve flaps causing them to snap shut. This is to prevent backflow because as the pressure becomes higher, the blood tries to return to the atria but can’t as the valves have snapped shut.
- All four valves remain shut for a very short period of time, before the ventricular pressure causes the semilunar valves to open and then the blood exits the heart through the aorta (L) or the Pulmonary Artery (R). The semilunar valves open because the ventricular pressure is higher than the aortic and pulmonary artery pressure. As blood exits the heart through the aorta and pulmonary artery, ventricular pressure decreases, lower than the aortic and pulmonary artery pressure. The semilunar valves close to prevent blood trying to flow back into the ventricles as they are not relaxed again.
Cardiac Cycle: How do the atrioventricular valves work?
- When the ventricular walls relax and recoil after contracting, the pressure in the ventricles drops below the pressure in the atria. This causes the atrioventricular valves to open. Blood entering the heart flows straight through the atria and into the ventricles. The pressure in the atria and the ventricles slowly rises as they fill with blood. The valves remain open while the atria contract.
- As the ventricles begin to contract, the pressure of the blood in the ventricles rises. When the pressure rises above that in the atria, the blood starts to move upwards. This movement fills the valve pockets and keeps them closed. This prevents the blood flowing back into the atria.
Cardiac Cycle: How do the semilunar valves work?
- When the ventricles start to contract, the pressure in the major arteries is higher than the pressure in the ventricles. This means that the semilunar valves are closed. As the ventricles contract, the pressure inside rises above the pressure in the aorta and pulmonary arteries, the semilunar valves are pushed open. The blood is under very high pressure, so it is forced out of the ventricles in a powerful spurt.
- Once the ventricle walls have finished contracting, the heart muscle starts to relax. Elastic tissue in the walls of the ventricles recoils to stretch the muscle out again and return the ventricles to its original size. This causes the pressure in the ventricles to drop quickly. As it drops below the pressure in the major arteries, the semilunar valves are pushed closed by blood starting to flow back towards the ventricles and collecting in the pockets of the valves. This prevents blood returning to the ventricles.
