prompter: What does it mean when a cell is permeable, does it have anything to do with what a cell is used for once its fully developed?

assistant: Yes, the types and amounts of substances allowed to pass through the cell membrane will depend largely on the purpose of that cell. Typically, permeability is discussed regarding a specific compound. A cell is made to be selectively permeable to given compounds; the cell membrane will be permeable to some substances but not others.

prompter: Could you give me a specific example?

assistant: Certainly! One example of a cell with specific permeability characteristics is the red blood cell. The red blood cell is permeable to small molecules such as oxygen and carbon dioxide, but it is not permeable to larger molecules like glucose. This is because the red blood cell's primary function is to transport oxygen and other gases, so it needs to be permeable to those molecules. On the other hand, if a cell's primary function is to store and regulate the levels of glucose in the body, it would need to be permeable to glucose and other similar-sized molecules.

Another example is the cell membrane of neurons, which is selective for positively charged ions such as sodium and potassium ions. This is because the flow of these ions plays an important role in transmitting nerve signals.

assistant: Certainly! Let's consider a red blood cell as an example. Red blood cells are specialized cells that are responsible for carrying oxygen from the lungs to the tissues throughout the body. To do this, they need to be permeable to oxygen, so that it can diffuse into the cell and bind to hemoglobin, a protein found in red blood cells. However, red blood cells also need to be impermeable to other substances such as carbon dioxide, which would interfere with their function. In this case, the cell membrane of the red blood cell is selectively permeable to oxygen and not carbon dioxide, allowing it to perform its role effectively.

In another example, neurons are specialized cells responsible for transmitting electrical signals throughout the body. They need to be selectively permeable to ions such as sodium and potassium, which are involved in the generation of electrical signals. Neurons are also permeable to other substances such as glucose, which provides energy for the cell, but impermeable to large proteins, which would interfere with the electrical signaling.

So, the permeability of a cell will depend on what the cell is used for, and the functions it needs to perform. Different cells may have different levels of permeability to specific compounds, and this permeability helps them to fulfill their roles in the body effectively.

assistant: A permeable cell membrane is one that allows molecules to easily pass through it and enter or exit the cell. Permeability depends mainly on the electric charge and polarity of the molecule, and to a lesser extent the molar mass of the molecule.

prompter: I think you missed the second half of my question. Does it have anything to do with what a cell is used for once its fully developed?

assistant: In basic terms, cell permeability means some compounds can enter and leave the cell. It is an essential property, enabling metabolism and intercellular communication.

prompter: How does it let cells communicate with each other?

assistant: Cells communicate with each other through a variety of ways, including hormones, neurotransmitters, and paracrine signaling. Hormones are secreted by endocrine cells and travel through the bloodstream to target cells, while neurotransmitters are released by neurons and travel through the synapse to target neurons. Meanwhile, paracrine signaling involves the release of small molecules to nearby cells, which signals the cells to perform specific functions. Cell permeability is important in all of these forms of communication, as it allows the molecules to enter and leave the cell.

assistant: Cells communicate by sending signalling ligands which attack to receptors on other cells. In order for a cell to send these molecules, they must be able to pass through its membrane. If cells were completely impermeable, molecules, including those used for communication, could not leave them. Cells have semi-permeable membranes, so while some compounds are allowed to enter and leave, others are blocked.

assistant: Cells of organs and tissues commonly communicate with one another via permeable membrane junctions. Cell-to-cell channels, spanning the width of both membranes of a junction, are thought to provide pathways between adjacent cells which allow for the exchange of ions and small molecules, allowing neighboring cells to communicate.