How Do Sodium Ions Enter Cells?
Quick Answer
The cell membrane is not very permeable to sodium ions, so they must enter through a process known as facilitated diffusion. In facilitated diffusion, sodium passes through the cell membrane in a voltage-gated ion channel, which is opened by a change in electrical current across the membrane.
Continue ReadingFull Answer
These channels only remain open for approximately one millisecond, but more than 7,000 sodium ions pass through into the cell in this time. This type of facilitated diffusion of sodium only occurs in certain types of excitable cells, such as muscle cells and neurons.
In order to remove excess sodium from cells, energy must be expended in the form of adenosine triphosphate, ATP. In this process of active transport, each unit of ATP results in the removal of three sodium ions out of the cell and takes in two potassium ions.
There are many different types of facilitated diffusion, which are used by cells to take in large molecules that cannot otherwise pass across the cell membrane, such as sugars, minerals and amino acids. In this process, the molecules usually attempt to move from areas of high concentration to areas of low concentration. For this reason, diffusion is also fully reversible, as the molecules can move in either direction.
Learn more about CellsRelated Questions
-
Q:
What Is the Relationship Between Cell Size and Diffusion?
A: As the size of a cell increases, its ability to facilitate diffusion across its cell membrane decreases. This is because the internal volume of a growing c... Full Answer >Filed Under: -
Q:
How Do Oxygen and Glucose Reach the Cells?
A: Oxygen and glucose are carried in the bloodstream and enter individual cells by passing through the cell membrane via diffusion. Oxygen enters the cells th... Full Answer >Filed Under: -
Q:
What Is the Similarity Between Simple Diffusion and Facilitated Diffusion?
A: Simple diffusion and facilitated diffusion both allow molecules to cross the cell membrane without any expenditure of energy by the cell. They are each cla... Full Answer >Filed Under: -
Q:
What Do Facilitated Diffusion Carrier Proteins and Cell Membranes Both Pump?
A: Facilitated diffusion uses carrier proteins to pump substances across the cell membrane that would not normally be able to cross the membrane on their own.... Full Answer >Filed Under:
