In this video, we're going to begin our introduction to the endomembrane system and to one of its major functions, which is protein secretion. The endomembrane system can be defined as a group of membrane-bound organelles inside a eukaryotic cell. The root "endo" in endomembrane system means "inside," indicating that we're discussing membranes found within the cell. The system is composed of a group of organelles, all of which are membrane-bound, meaning their boundaries consist of membranes. The endomembrane system includes many different organelles that we will mention later in this table.

However, all these organelles that are part of the endomembrane system are interconnected by structures called vesicles. Vesicles are essentially tiny membrane bubbles that can transport materials internally. As we progress in our course, we will see examples of vesicles. The endomembrane system performs multiple functions, but we will primarily focus on two: protein secretion and cellular digestion.

In the example below, we have a table showing the organelles of the endomembrane system, with a green color coding linking those involved in protein secretion and a yellow color for those involved in cellular digestion. The cell membrane, not the focus of this part of the lesson, is shown with a white background. We'll discuss cell membranes more in a later lesson. The numbers displayed represent organelles of the endomembrane system, grouped based on their functions. Going forward, we will mainly focus on organelles involved in protein secretion, including the nuclear envelope or nucleus of the eukaryotic cell, the endoplasmic reticulum, the Golgi apparatus, and transport vesicles. Later, we will discuss organelles involved in cellular digestion, such as lysosomes, peroxisomes, and vacuoles, including central vacuoles.

This outline categorizes the organelles of the endomembrane system by their functions, and we will delve deeper into each as we progress in our course. That being said, I'll see you all in our next video.