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.
Structure Edit. The ulna is broader close to the elbow, and narrows at it approaches the wrist. Close to the elbow, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus.This prevents hyperextension and forms a hinge joint with the trochlea of the humerus.There is also a radial notch for the head of the radius, and the ulnar tuberosity to which muscles attach. Close to the wrist, the ulna has a styloid process.his prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is also a radial notch for the head of the radius, and the ulnar tuberosity to which muscles attach. Close to the wrist, the ulna has a styloid process.