In order to answer why the cell would need aquaporins when the plasma membrane is permeable to water, we need to understand the make-up of water and the cell membrane. The water molecule is polar with its H+ and OH- ions. Cell membranes are selectively permeable.
Anatomy of the Auricle. The auricle or pinna is a relatively large appendage on the side of the head. It is prominent in most people and plays a very important role in hearing â it directs sound waves into the ear canal. The auricle is composed of cartilage which is covered by skin.
The arm consists of three large bones. The humerus bone forms the upper arm. The radius and ulna are the two bones forming the lower arm. You have one radius and one ulna in each arm. The radius and ulna bones connect between the elbow joint and the wrist. One easy way to remember which bone is the radius, and which is the ulna, is that the radius connects to the thumb side of the wrist. Keep reading to learn more about the radius and ulna, and how your lower arm works. On this page: