chloride transmembrane transport

Definition

Target type: biologicalprocess

The process in which chloride is transported across a membrane. [GOC:TermGenie, GOC:vw]

Chloride transmembrane transport is a fundamental process in cellular physiology, crucial for maintaining cellular volume, membrane potential, and pH balance. It involves the movement of chloride ions (Cl-) across cell membranes, facilitated by various transmembrane proteins. The process can be either passive, driven by electrochemical gradients, or active, requiring energy input.

**Passive Chloride Transport:**

* **Simple Diffusion:** Chloride ions can move across the membrane passively down their concentration gradient, a process facilitated by the lipid bilayer's permeability to small, charged ions.
* **Facilitated Diffusion:** Specific transmembrane proteins, such as chloride channels, provide pathways for chloride ions to cross the membrane more efficiently. These channels exhibit selectivity for chloride ions, ensuring efficient transport while minimizing the movement of other ions.

**Active Chloride Transport:**

* **Primary Active Transport:** Proteins like the sodium-potassium pump (Na+/K+ ATPase) indirectly contribute to chloride transport. This pump maintains a sodium gradient across the membrane, driving secondary active transport mechanisms.
* **Secondary Active Transport:** Chloride transport can be coupled to the movement of other ions, such as sodium or potassium, via cotransporters or exchangers. These proteins utilize the electrochemical gradient of one ion to drive the movement of another ion against its own gradient.
* **Cotransporters:** Chloride ions move in the same direction as the driving ion (e.g., sodium-chloride cotransporter).
* **Exchangers:** Chloride ions move in the opposite direction to the driving ion (e.g., chloride-bicarbonate exchanger).

**Physiological Roles of Chloride Transport:**

* **Cellular Volume Regulation:** Chloride transport plays a critical role in maintaining cell volume. By adjusting chloride ion concentrations, cells can regulate the movement of water across the membrane, preventing swelling or shrinking.
* **Membrane Potential:** Chloride ions contribute significantly to the resting membrane potential of cells, influencing the excitability of neurons and muscle cells.
* **pH Regulation:** Chloride transport is involved in pH homeostasis by facilitating the movement of bicarbonate ions (HCO3-) across the membrane.
* **Digestion and Absorption:** Chloride ions are essential for gastric acid production, enabling the breakdown of food. They are also involved in the absorption of nutrients in the intestines.
* **Neurotransmission:** Chloride ions play a role in neurotransmitter release and synaptic transmission, affecting the excitability of nerve cells.

The regulation of chloride transport is complex and involves various factors, including hormones, neurotransmitters, and changes in cellular conditions. Dysregulation of chloride transport can lead to various diseases, such as cystic fibrosis, Bartter syndrome, and epilepsy.'
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Proteins (35)

Compounds (253)