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.
Introduction: Simple passive diffusion occurs when small molecules pass through the lipid bilayer of a cell membrane. Facilitated diffusion depends on carrier proteins imbedded in the membrane to allow specific substances to pass through, that might not be able to diffuse through the cell membrane.