Respiratory System

2. Surface – Gases dissolve in moisture to diffuse more easily across membranes.
3. – The large air passages that lead from the trachea to the lungs.
7. Surface – The area (like alveoli) where gases are exchanged.
10. – A muscle that helps in breathing by moving up and down to change lung pressure.
11. Area – Alveoli have a large surface area to maximize gas exchange.
12. Dioxide (CO₂) – A waste gas produced by cells, exhaled from the lungs.
16. – Also called the windpipe; it connects the throat to the lungs.
17. – The act of breathing in air (containing oxygen).
19. – The movement of gases from an area of high concentration to low concentration.
21. Respiration – The use of oxygen in cells to produce energy (ATP).
22. – Small blood vessels surrounding alveoli that allow gas exchange between blood and air.
23. Membrane – Alveolar walls are thin to allow fast diffusion of gases.
24. Vein – Carries oxygenated blood from the lungs to the heart.

1. – The chemical process in cells that uses oxygen to release energy from glucose.
4. – A protein in red blood cells that carries oxygen and some carbon dioxide.
5. exchange – The process by which oxygen is taken into the body and carbon dioxide is removed.
6. – The body's ability to maintain stable internal conditions, like gas levels.
8. – The act of breathing out air (removing carbon dioxide).
9. – Tiny air sacs in the lungs where gas exchange occurs.
13. Pressure – The pressure each gas in a mixture contributes; important in diffusion.
14. Artery – Carries deoxygenated blood from the heart to the lungs.
15. – The movement of air in and out of the lungs.
18. – Organs in the chest responsible for taking in oxygen and releasing carbon dioxide.
20. Blood Cells – Blood cells that transport oxygen from the lungs to the body.
25. (O₂) – A gas essential for cellular respiration, absorbed from the air into the blood.