gas exchange (humans)

• the alveoli is adapted for gas exchange by its one cell thick walls, large surface area, and short diffusion distance
• gas exchange is the movement of oxygen into the red blood cells from the alveoli. as well as carbon dioxide moving out of the red blood cells into the alveoli. the occurs due to diffusion
• When breathing in/ inhaling:

  The external intercostal muscles contract and tighten, the internal relax

  The diaphragm contracts and moves downwards to increase space

  The muscles between the ribs contract and pull down

  Lung volume increases air air pressure decreases

  Thorax volume increases
• When breathing out/ exhaling:

  The internal intercostal muscles contract, the external relax

  The diaphragm relaxes and moves back forwards

  Lung volume decreases, air pressure increases

  Air pressure is pushed out of the lungs

  Thorax volume decreases
• nicotine, tar and carbon monoxide makes smoking harmful
• cilia are tiny hair like structures on the surface of the cell
• cillia sweeps hair, mucus, trapped dust & bacteria up to the back of the throat to be swallowed
• when a person smokes, the cillia stops moving which leads to a buildup of mucus, bacteria & dirt to build up producing a smokers cough
• cardiovascular diseases are diseases that affect the heart and blood vessels