Without them you couldn’t survive, but you probably know nothing about them. We’re referring to an organelle called smooth endoplasmic reticulum.
This lesson will explain why this organelle is important as well as look at its structure and function.
Smooth Endoplasmic Reticulum Defined
Inside of your cells there are tiny cities. These cities function in some ways just like regular cities: they have bosses or mayors, postal services, power plants, and even walls to keep invaders out. We are going to focus on one part of this tiny city – the factories.Of course there aren’t actual cities in your cells, but the organelles, or tiny parts of the cell that have a specific function, are like the parts that make up a city. You can also think of an organelle as a type of cell organ.
Just like your heart, liver, and lungs have certain jobs in your body, your organelles have certain jobs to carry out in your cells. Bacteria and archaebacteria (a group of microorganisms) have prokaryotic cells and, therefore ,do not have organelles. Eukaryotic cells do have organelles and are found in animals, plants, fungi, and protista (like an amoeba).
Back to the tiny factories, which are called smooth endoplasmic reticulum or smooth ER for short. Now endoplasmic reticulum sounds pretty scary, but its name actually translates into ‘within cytoplasm network,’ which makes sense because it is found within the cytoplasm, or the jelly-like material found inside of a cell, and it is made up of a network of membranes.There are actually two types of ER, rough ER and smooth ER.
Rough ER has ribosomes on its surface that give it a rough appearance and name, whereas smooth ER is ribosome-free. The lack of ribosomes also gives smooth ER a different function than rough ER. Smooth ER is the one that operates just like a factory.
Smooth Endoplasmic Reticulum Function
Smooth ER is like a factory inside of your cells, so its primary function is making stuff and breaking it down. Depending on the location of the cell, the smooth ER may have different functions. A list of some of the things smooth ER does includes:
- Makes fats (lipids)
- Metabolizes (breaks down and builds up) carbohydrates (things like sugars or starches)
- Makes steroids (steroids can include hormones and vitamins)
- Detoxifies (breaks down harmful substances and turns them into safe substances)
Let’s examine that list a little closer. Fats made by smooth ER are used in the manufacturing of phospholipids, which are important ingredients in cellular membranes (a cell’s skin).
Some of the steroids produced by smooth ER include sex hormones like testosterone (an important hormone for men and women). In fact, the cells that make these hormones, like those in testes, have more smooth ER than cells elsewhere in the body. Smooth ER found in the liver metabolizes carbohydrates, which helps regulate the amount of sugar in your blood.
But there’s more. Smooth ER detoxifies drugs and alcohol in your system, changing these toxins into substances that can be easily removed from the body. Finally, muscle cells use smooth ER to pump calcium ions (charged calcium atoms) so the muscle can contract. So without smooth ER, your cell’s membranes wouldn’t hold up, testosterone wouldn’t get made, your blood sugar would be unregulated, your body would be toxic, and your muscles wouldn’t work right.
These little factories are sounding more and more important!
It was previously mentioned that smooth ER is like a labyrinth of membranes. These membranes eventually hook up with the nucleus, or mayor of the cell, which streamlines the production process. When the nucleus says, ‘I need some fats,’ the command goes directly to the smooth ER.In smooth ER, membranes look like tubes, whereas in rough ER, they look more like sheets. These membranes form sacs called cisternae, and when smooth ER makes a product, like steroids, the cisternae get pinched off and become vesicles that contain the product.
These vesicles get sent off to another organelle where they can be further processed.You might be wondering why smooth ER needs to have a maze of membranes. There’s not a lot of extra room in a tiny cell, so the smooth ER maximizes surface area by having a network of folded membranes. This increased surface area allows the smooth ER to maximize production.
Who knew these tiny factories were so important?! In fact, you couldn’t survive without smooth ER.
So the next time you flex your muscles or have a beer, you can thank this network of membranes for pumping calcium ions or detoxifying you. Let’s review some important terms and concepts:
- Smooth ER is an organelle, or tiny organ, found in eukaryotic cells
- Smooth ER found in different cells may have different functions
- Like a factory, smooth ER makes a variety of products (like fats and steroids)
- Other functions include pumping calcium ions, metabolizing carbohydrates, and detoxifying
- The membranes are made up of cisternae that can become vesicles, which get sent off to other locations
- Smooth ER has a maze of membranes, which allow for increased surface area