processes of breathing

the journey of a breath of air

Breathing is only part of the process of bringing oxygen to where it is needed in the body. After oxygen enters the lungs, what happens? 1. The oxygen enters the bloodstream from the alveoli, tiny sacs in the lungs where gas exchange takes place ( Figure 1.1). The transfer of oxygen into the blood is through simple diffusion. 2. The oxygen-rich blood returns to the heart. 3. Oxygen-rich blood is then pumped through the aorta, the large artery that receives blood directly from the heart. 4. From the aorta, oxygen-rich blood travels to the smaller arteries and, finally, to the capillaries, the smallest type of blood vessel. 5. The oxygen molecules move, by diffusion, out of the capillaries and into the body cells. 6. While oxygen moves from the capillaries and into body cells, carbon dioxide moves from the cells into the capillaries. Gas exchange is the movement of oxygen into the blood and carbon dioxide out of the blood. 7. Carbon dioxide is brought, through the blood, back to the heart and then to the lungs. Then it is released into the air during exhalation. Why is oxygen needed by each cell in your body? To make ATP, the usable form of cellular energy. Oxygen is needed in the final stage of cellular respiration, which is the process of converting glucose into ATP. This process is much more efficient in the presence of oxygen. Without oxygen, much less ATP is produced. As ATP is needed for the cells to function properly, every cell in your body needs oxygen. Getting that oxygen begins with inhaling. The oxygen moves into your blood, where it travels to every cell in your body.


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every cell in your body needs atp to make oxygen.

a. true

-->  b. false

the lungs pump oxygen to every cell in your body.

a. true

-->  b. false

what artery receives blood directly from the heart?

-->  a) the aorta

b) the coronary artery

c) the pulmonary artery

d) the main artery

which best characterizes the blood that returns to the heart from the lungs?

a) blood-rich

b) blood-poor

-->  c) oxygen-rich

d) oxygen-poor

through what type of blood vessel does oxygen move from the blood into the cells?

a) the aorta

b) the arteries

c) the veins

-->  d) the capillaries

where does gas exchange occur in the lungs?

-->  a) the alveoli

b) the aorta

c) the capillaries

d) all of the above

what gas moves in the blood back to the lungs to be exhaled?

a) carbon gas

b) oxygen

-->  c) carbon dioxide

d) nitrogen gas

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