Paper 28
How can a sheep be grown as large as a cow?
Written by Ramin Amir Mardfar
Paper 29

You write a very interesting article.
Two quick questions if you don't mind:
I understand that the SHAPE & DESIGN for a creature is perhaps determined by its circulatory design, but i'm not sure why its SIZE would be determined that way? For example if you took a cockroach and kept the design the same but made him 10 times bigger, what problems would result, and why?

Would you say that the elephant/whale/giraffe's circulatory system is more advanced than humans, allowing them to be a larger size? And if so, how is their design more advanced than ours?
Thanks for your time,
How can a sheep be grown as large as a cow?

Consider a muse, a sheep, a caw, an elephant and a whale. All these animals belong to the mammals' class. The body structure of all mammals is similar. Mammals are warm blooded and bear child. They breathe with lungs. Their heart has 4-chambred and etc. but as we see, their body size is very different. Here is the question that:
What cause the difference in the size of the mammals?
Of course a physiological reason would cause these differences. We study the circulatory system of their body in order to find the reason.
For an animal to have a large body size, the first point is getting enough food and oxygen by its cells.
The oxygen molecules are taken from the air by lungs and then sent to the blood. These oxygen molecules are mixed with the red cell hemoglobin and then are carried by the red cells in the blood.
Then they enter the heart through the lungs and then are sent to all the body cells. The oxygen molecules move a distance inside about 20 meters the body of the whale with the red cells to reach its tail. However it moves only a few centimeters inside the body of the mouse. On the other hand, the oxygen molecules inside the body of the mouse are separated from the red cells only a few centimeters away from the heart: but for some meters in the body of elephant or whale.

Here is the example to clarify it:
Consider a village with its in habitants. There is an apple garden near it. A person should feed the inhabitants from this garden. This person has only one tray picks up the apples and puts them in the tray, and then he goes to the village. On the way, some of the apples slip from the tray. Because the village is near, he could carry some of them to the village. But if the village was far away, all the apples would slip from the tray and the inhabitants would die without apples. So this person should find a way to carry the apples for a long distance. We compare this example with the mammals' body. The villages are like the body's tissues, the in habitants are the cells, the garden is the lungs, the apples are the oxygen molecules, and the way is the blood vessel. That person is the blood and the tray is the red cells. Here, the thing that causes the oxygen molecules stick on the red cells is our point. Now we study how oxygen molecules stick on the red cell. There is hemoglobin in red cells. The oxygen molecules are joined with the hemoglobin and this causes that the oxygen molecules stick to the red cells. With a little consideran, we find that the oxygen molecules do not stick to the red cells with a similar strength in the body of the mammals. This stickiness is much stronger in some species and is weaker in some other. This stickiness is related to the size of the mammal. The more this stickiness, the more the oxygen molecules can be carried in the blood. This will cause the body to be larger. On the contrary, if the stickiness is weaker, the oxygen molecules would move less in the blood and so the body has to be small.
Look at the following information:

The mammal species and the oxygen pressure in which the red cell's hemoglobin sends most of it's oxygen to the tissues.

Mouse..................45 mmHg
Rat.......................42 mmHg
Cat......................38 mmHg
Fox.......................35 mmHg
Sheep...................30 mmHg
Horse...................25 mmHg
Elephant...............22.5 mmHg

The oxygen molecules enter into the blood from lungs and stick to the red cells. After moving a distance they reach the tissues and get separated from the red cells and then the cell use them. What the oxygen molecules mix with hemoglobin and stick to the red cell? What causes the oxygen molecules be separated from the hemoglobin in the tissues? And the most important is that, what causes the oxygen molecules be separated from the red cells soon or late?
The transfer of oxygen to the blood is done by circulation. So the reason is the oxygen's thickness or pressure. The oxygen's pressure in lungs is more than the lung's capillaries. So the oxygen enters into the blood from the lungs. these oxygen molecules mix with the hemoglobin in the red cells then move to the heart and after it, move to the tissues. When these molecules reach near the tissues, they get separated from the red cells because of the lowness of oxygen pressure. But this separation is different among the mammals' species. As it is shown in the table above, most of the oxygen molecules get separated from the red cell's hemoglobin in mouse's body in 45 mmHg. But this happens in 22.5 mmHg in elephant's body. It means that the oxygen molecules mix with hemoglobin very weakly in mouse's body. Getting a little far from the lungs the oxygen's thickness gets weaker and so they get separated from the hemoglobin and so the red cells can not move for longer distances. But in elephant's body have stronger stickiness; the oxygen's pressure gets lower by getting far from the lungs. But most of oxygen molecules still stick to the hemoglobins and move to the far tissues. On the other hand, the mouse's tissues can not be far from the lungs and heart because the oxygen can move a long distance but it is different in whale and elephant's body because they are sure that all their tissues will get oxygen. Now we have question, why do we have this difference in stickiness among the mammals? To say it simply, why the mixture of oxygen molecules with hemoglobin is stronger in elephant's blood than the mouse?
The answer to this question relates to the organic phosphate like (DPG) which exists in mammal's blood. The more organic phosphate the less the stickiness between oxygen and hemoglobin, like the hemoglobin of mouse. On the contrary, the less these organic phosphate the more the stickiness power, like the elephants body. Simply, organic phosphates make the stickiness between the oxygen molecules and hemoglobin weaker so there is an opposite relation between the amount of organic phosphate and the stickiness power. The less the amount of organic phosphates, the larger the size of mammals.
Knowing these things we can easily answer the first question.
Question: how can we grow a sheep as large as a cow?
Answer: by decreasing the amount of organic phosphates mixed with hemoglobin.
There would some other questions too. The most important one is:
Despite the fact that all mammals have strong blood circulatory system, Why the nature did not make all of mammals in the large size? And by decreasing or increasing the hemoglobin's organic phosphates body has grown small or big?
How big can a mammal be (Maximum)? Why there isn't any mammal larger than the elephant on the land? Or taller than giraffe?
Why today the different species of animals like the reptiles, birds, amphibians, insects and mollusks, can't be as large as the big mammal species?
Why could the mammals be as large as the mammoth and Baluchithere in the past but now they can't? Why could the reptiles. Be as large as the dinosaurs in the past but now they can't?
Are you eager to know the answer of these questions?

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