An echocardiogram--or echo--is a diagnostic test used to take pictures of the heart and surrounding blood vessels.It is more detailed than an X-ray and uses sound waves versus radiation.n echocardiogram--or echo--is a diagnostic test used to take pictures of the heart and surrounding blood vessels.
The term simple diffusion refers to a process whereby a substance passes through a membrane without the aid of an intermediary such as a integral membrane protein. The force that drives the substance from one side of the membrane to the other is the force of diffusion. In order for substances to pass through a cell membrane by simple diffusion it must penetrate the hydrophobic core of the phospholipid bilayer. The types of molecules that can do this are themselves substantially hydrophobic in nature such as carbon dioxide, oxygen or ethanol. In the figure below the green triangle indicates a concentration gradient of carbon dioxide. The blue arrow indicates the direction of net flow of carbon dioxide.
Diffusion is one of the processes that allows this to happen. Diffusion diffusion: The movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration occurs when particles spread.They move from a region where they are in high concentration to a region where they are in low concentration.he higher concentration of carbon dioxide in the air diffuses into the leaf for photosynthesis. Oxygen produced during photosynthesis builds up to higher concentrations and diffuses out of the leaf into the air which has a lower concentration of oxygen. Page: 1  1. 2  2.