Chemical Messengers 3. Hormones â¢Longârange messengersâ¢Secreted into blood by endocrine glands in response to appropriate signalâ¢Exert effect on target cells some distance away from release site 4.hemical Messengers 3. Hormones â¢Longârange messengersâ¢Secreted into blood by endocrine glands in response to appropriate signalâ¢Exert effect on target cells some distance away from release site 4.
Scale box in millimeters. Vesicular texture is a volcanic rock texture characterized by a rock being pitted with many cavities (known as vesicles) at its surface and inside.
Vesicles Carry Cargo. Most molecules, including proteins, are too large to pass directly through membranes. Instead, large molecules are loaded into small membrane-wrapped containers called vesicles. Vesicles are constantly forming - especially at the plasma membrane, the ER, and the Golgi. Once formed, vesicles deliver their contents to destinations within or outside of the cell. A vesicle forms when the membrane bulges out and pinches off. It travels to its destination then merges with another membrane to release its cargo. In this way proteins and other large molecules are transported without ever having to cross a membrane. Some vesicles form with the help of coat proteins.