Red blood cells. Red blood cells (also known as erythrocytes) are cells in the blood that carry oxygen to all parts of the body. They are made in the spongy marrow inside the large bones of the body. Bone marrow constantly makes new red blood cells to replace old ones.
. In vertebrates, it is composed of blood cells suspended in blood plasma. Plasma, which constitutes 55% of blood fluid, is mostly water, and contains proteins, glucose, mineral ions, hormones, carbon dioxide, and blood cells themselves. Albumin is the main protein in plasma, and it functions to regulate the colloidal osmotic pressure of blood. The blood cells are mainly red blood cells, white blood cells and platelets. The most abundant cells in vertebrate blood are red blood cells. These contain hemoglobin, an iron-containing protein, which facilitates oxygen transport by reversibly binding to this respiratory gas and greatly increasing its solubility in blood. In contrast, carbon dioxide is mostly transported extracellularly as bicarbonate ion transported in plasma.
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All cells have selectively permeable membranes, which means that only they let certain important molecules inside the cell, while the others stay outside the cell.
This occurs by the process of diffusion or osmosis.
Answer:
Les alvéoles pulmonaires sont situées au plus profond des poumons, aux extrémités des bronchioles, et sont la structure de base où se réalisent les échanges gazeux entre l'organisme et l'air extérieur.
