Question

How does oxygen travel in the blood?

Answer 1

Oxygen transportation in blood:

1. In terms of human physiology, oxygen transport can be divided into two types: convection and diffusion. Convection in this sense refers to the flow of oxygen inside the circulatory system by bulk transport. This is an active activity that requires energy, which in this case comes from the heart's pounding.
2. Diffusion, on the other hand, refers to the passive transport of oxygen along a concentration gradient, such as from the microcirculation to the tissues (and ultimately the mitochondria).
3. Oxygen is transported in the blood and dissolved in plasma by hemoglobin (and intracellular fluid). Hemoglobin is an allosteric protein that is made up of four protein (globin) chains, each of which has a haem moiety, which is an iron-porphyrin complex connected to it. Each hemoglobin molecule has two pairs of globin chains.
4. Once oxygen has diffused across the alveolar membrane, it binds reversibly to hemoglobin in the pulmonary capillaries, generating oxyhemoglobin in a cooperative manner.
5. One hemoglobin molecule can carry up to four oxygen molecules at the same time. When an oxygen molecule attaches to a haem, the shape of the globin chain changes, causing hemoglobin's quaternary structure to change.
6. Following that, subsequent oxygen molecules are attached with a higher affinity. This relationship is best described by the sigmoid-shaped oxyhemoglobin dissociation curve.