There are different mechanisms used by the body to transport substances across the cell membrane. One of these methods is called Simple diffusion. Simple diffusion involves molecules diffusing from an area of higher concentration to an area of lower concentration. Simple diffusion happens through random movement of particles through the cell membrane. Carbon dioxide and other gases such as oxygen and ethanol uses simple diffusion as a method of cell transportation. Several factors affect the rate of diffusion including high temperatures and the size of the molecule. A smaller molecule will diffuse much quicker than a larger one as it is able to move about without difficulty. Concentration gradient and the distance of diffusion also makes a …show more content…
Simple and facilitated diffusion require no energy and transportation is completed using rapid and random movement from molecules. In contrast to this, for Active transport to complete, an input of energy is necessary from the cell. This energy molecule is called ATP. Cells in the small intestine use active transport to make best use of the absorption of glucose.
Bulk transport
Bulk transport is another transportation method requiring energy from the cell. There are two types of bulk transport, exocytosis and endocytosis. The process of exocytosis requires movement of substances in the cells cytoplasm to the outside of the cell. The process of exocytosis is seen in neuron cells and with the excretion of neurotransmitters. Hormones are also released into the body using this process. In contrast to this, endocytosis, is a transportation method in which cells take molecules from outside of the cell into the cell. This take place by an engulfing of the molecule by the cell membrane. The cell membrane forms a vesicle which surrounds the molecule and the vesicle is taken into the cell. This process occurs because important molecules can be polar and consist of large molecules and cannot be transported using other transportation