Hello, in this video we will study the endoplasmic reticulum. Let's get started. Needless to say, the endoplasmic reticulum is one of the organelles inside the cell. It's a network of interconnected tubules and flat vesicles. It's distributed extensively throughout the cytosol. It can be divided into two parts. Rough endoplasmic reticulum and smooth endoplasmic reticulum. They both are connected to each other. So endoplasmic reticulum is one continuous organelle. Now let's see the rough endoplasmic reticulum in more detail. It's like many flat vesicles connected to each other. Its membrane is continuous with the outer membrane of the nuclear envelope. The space inside the endoplasmic reticulum is continuous with space in between two membranes of the nuclear envelope. The outer surface of the rough endoplasmic reticulum contains ribosomes. In fact, it's the ribosomes that give this part of the endoplasmic reticulum a rough appearance. These ribosomes synthesize proteins that are to be exported out of the cell and membrane proteins. The proteins to be exported, enter the endoplasmic reticulum right when they are being synthesized. See the cytoplasm also contains free ribosomes. These ribosomes synthesize the proteins required in the cytosol. Once synthesized, these proteins cannot cross the membrane. Thus the proteins for cytoplasm and proteins to be exported are kept separate right from the synthesis. The proteins to be exported are further modified inside the endoplasmic reticulum. Simultaneously they travel towards the outer side of the network. Here they are packed into tiny vesicles. These vesicles take the proteins to the Golgi apparatus. In the Golgi apparatus, they are further processed and sent to their final destination. Membrane proteins also follow same path but along the membrane. Thus the rough endoplasmic reticulum is involved in protein synthesis. So it's abundant in cells that secrete a large quantity of proteins. For example cells of the exocrine pancreas producing digestive enzymes. So this was the rough endoplasmic reticulum. Now let's see the smooth endoplasmic reticulum. It's a network of tubules. It has no ribosomes and that's why it's smooth. It contains enzymes for lipids synthesis. So yes, one of its functions is synthesis of lipids . And it is found abundantly in cells involved in lipid metabolism. For example, cells synthesizing steroid hormones. It's also abundant in the liver cells where it is involved in detoxification. Harmful substances produced by body or those that enter the body from outside are detoxified by enzymes present on smooth endoplasmic reticulum. In muscle cells, the smooth endoplasmic reticulum exists in a modified form called the sarcoplasmic reticulum. It stores Ca and plays role in intracellular signaling. So this was about the endoplasmic reticulum. Let's have a quick summary. The endoplasmic reticulum is a network of interconnected tubules and flat vesicles. It's divided into two types. Rough endoplasmic reticulum and smooth endoplasmic reticulum. The rough endoplasmic reticulum is a network of flat vesicles. It contains ribosomes that synthesize proteins that are to be exported and membrane proteins. The smooth endoplasmic reticulum is network of tubules. Its smooth because it has no ribosomes. It's involved in the synthesis of lipids, detoxification and as sarcoplasmic reticulum, it store Ca2+. That's it for this video. If you feel this video will help your friends and colleagues, please share it with them too. And don't forget to subscribe because lots more to come. At nonstop neuron, learning medical concepts is as easy as watching cartoons. Thanks for watching, see you in the next video.