I had the same problem: I plug in headphones, and sound comes out of the headphones and my laptop speakers. Here's how I fixed this problem: Go to Sound Preferences [click on the Sound icon in the top-right, on the bottom of the menu, you'll see sound preferences ].Next, go to the Output tab.Here, look at the bottom, where it says  Connector: . I think mine was on Analog Speakers [or possibly Analog Headphones]. had the same problem: I plug in headphones, and sound comes out of the headphones and my laptop speakers. Here's how I fixed this problem: Go to Sound Preferences [click on the Sound icon in the top-right, on the bottom of the menu, you'll see sound preferences ].
Amino acidâbased hormones (amines and peptide or protein hormones) are water-soluble and act on the surface of target cells via second messengers; steroid hormones, being lipid-soluble, move through the plasma membranes of target cells (both cytoplasmic and nuclear) to act within their nuclei. Hormone secretion may occur in many tissues.
The movement of macromolecules such as proteins or polysaccharides into or out of the cell is called bulk transport. There are two types of bulk transport, exocytosis and endocytosis, and both require the expenditure of energy (ATP). In exocytosis, materials are exported out of the cell via secretory vesicles. In this process, the Golgi complex packages macromolecules into transport vesicles that travel to and fuse with the plasma membrane. This fusion causes the vesicle to spill its contents out of the cell. Exocytosis is important in expulsion of waste materials out of the cell and in the secretion of cellular products such as digestive enzymes or hormones. Endocytosis, on the other hand, is the process by which materials move into the cell. There are three types of endocytosis: phagocytosis, pinocytosis, and receptor-mediated endocytosis. In phagocytosis or âcellular eating,â the cellâs plasma membrane surrounds a macromolecule or even an entire cell from the extracellular environment and buds off to form a food vacuole or phagosome.