Question

My question is related to transportation topic under chapter 1 life processes and the question is if human need blood for transportation of oxygen for oxidation in cells where do this blood comes from is it in fixed amount since birth or generated and if generated then how

Answer 1

No, there is no fixation of blood in body since birth it produces as it contains cells which dies and grows
Hemopoiesis ( hematopoiesis) is the process that produces the formed elements of the blood. Hemopoiesis takes place in the red bone marrow found in the epiphyses of long bones (for example, the humerus and femur), flat bones (ribs and cranial bones), vertebrae, and the pelvis. Within the red bone marrow, hemopoietic stem cells ( hemocytoblasts) divide to produce various “blast” cells. Each of these cells matures and becomes a particular formed element.

You know what blood is — it's that red stuff that oozes out if you get a paper cut. The average person has about 1 to 1½ gallons (4-6 liters) of it. But what is blood, really, and where does it come from?

How Does the Body Make Blood?

It's not made in a kitchen, but blood has ingredients, just like a recipe. To make blood, your body needs to mix:

• red blood cells, which carry oxygen throughout the body
• white blood cells, which fight infections
• platelets, which are cells that help you stop bleeding if you get a cut
• plasma, a yellowish liquid that carries nutrients, hormones, and proteins throughout the body