Although fixed into place, these ribs do allow for some outward movement, and this helps stabilize the chest during inhalation and exhalation. The human rib cage is made up of 12 paired rib bones; each are symmetrically paired on a right and left side. Of all 24 ribs, the first seven pairs are often labeled as true. These bones are connected to the costal cartilage, while the five other false sets are not. Three of those connect to non-costal cartilage, and two are deemed to be floating, which means they only connect to the spine.
1 Allows diffusion of large, membrane insoluble compounds such as sugars (glucose) and amino acids. 2  Does not require energy (passive transport). 3  Substance binds to membrane transport protein. 4  Molecules may enter the cell and leave the cell through the transport protein.ctive Transport. 1  Movement across membrane with an energy cost because if moves the molecule against a concentration gradient. 2  Used to pump specific compounds in or out of the cell. 3  Requires energy to overcome the concentration gradient. 4  Requires specific membrane transport proteins.
Facilitated diffusion is the way in which cells are able to import larger molecules through the cell membrane. The cell membrane is a barrier which surrounds all cells and only allows small and uncharged molecules to pass through freely. Larger molecules, such as glucose, require special transporting proteins. The transporters for glucose bind to glucose molecules and then facilitate their transfer into the cell. There are five different types of glucose transporters, named GLUT 1-5.