By which mechanism, oxygen is released out from lungs to cells

Options

A. Diffusion
B. Facilitated diffusion
C. Transpiration
D. Osmosis

Answer

To understand how oxygen is released from the lungs to the cells, we need to explore the process of gas exchange and transport in the body. Here’s a step-by-step explanation:

### Step 1: Inhalation of Oxygen
When we breathe in, air enters the lungs through the trachea and bronchi. The oxygen in the air diffuses across the alveolar walls into the bloodstream.

**Hint:** Remember that the process begins with inhalation, where oxygen-rich air enters the lungs.

### Step 2: Diffusion in Alveoli
The alveoli are tiny air sacs in the lungs where gas exchange occurs. The concentration of oxygen in the alveoli is higher than in the blood in the capillaries surrounding them. This difference in concentration causes oxygen to diffuse from the alveoli into the blood.

**Hint:** Focus on the role of concentration gradients in facilitating the diffusion of oxygen.

### Step 3: Binding to Hemoglobin
Once in the bloodstream, oxygen binds to hemoglobin molecules in red blood cells. This binding forms oxyhemoglobin, which is transported throughout the body.

**Hint:** Think about how hemoglobin acts as a carrier for oxygen in the blood.

### Step 4: Transport to Cells
The oxygen-rich blood is then pumped by the heart through the arteries to various tissues and organs in the body.

**Hint:** Consider the circulatory system's role in delivering oxygen to cells.

### Step 5: Release of Oxygen at the Cellular Level
At the level of the tissues, the concentration of oxygen is lower than that in the blood. This difference in concentration causes oxygen to be released from hemoglobin and diffuse into the cells.

**Hint:** Remember that the process of diffusion is again key here, as oxygen moves from an area of higher concentration (blood) to lower concentration (cells).

### Step 6: Cellular Respiration
Once inside the cells, oxygen is used for cellular respiration, a process that produces energy (ATP) for the cell's functions.

**Hint:** Keep in mind the importance of oxygen in cellular metabolism and energy production.

### Summary
In summary, oxygen is released from the lungs to the cells primarily through diffusion, facilitated by concentration gradients, and transported by hemoglobin in the blood. The entire process involves inhalation, gas exchange in the alveoli, transport via the bloodstream, and release at the cellular level for use in respiration.