Chloride is the most abundant anion in extracellular fluid, neutralizing sodium's positive charge. Approximately 88% is in extracellular fluid and 12% intracellular. Chloride is absorbed in the small intestine through sodium-glucose cotransport and sodium-chloride cotransport, and follows sodium passively. It is important for gastric acid production, immune function through phagocytosis, and the chloride shift in red blood cells. Chloride is excreted through the GI tract, skin, and kidneys similarly to sodium. Deficiency can cause metabolic alkalosis while toxicity is rare with intake under 28g daily.

1. CHLORIDE

2.  Most abundant anion in the extracellular fluid
 Neutralizes the positive charge of the sodium
ions in the fluid because of its negative charge
 Approx 88% in the extracellular fluid and 12% in
the intracellular fluid
 Recommended intake = 2300mg

3. Sources
 Abundantly found in sea salt or table salt
 High in snack items such as Tortillas, Pringles,
Lays etc
 Found in dietary proteins such as eggs, fresh
meats and seafood

5. Absorption, Transport and
Secretion
 Most of the absorption occurs in the small
intestines
 From the Na+- glucose cotransport system
chloride follows the Na+ passively through a
paracellular or tight junction pathway.
 This allows for the creation of an electrical
gradient which produces energy allowing for the
inward diffusion of Cl-

6.  The electroneutral Na+/Cl- cotransport
absorption allows for Cl- to go into mucosal cells
 Important to note: No matter the absorptive
mechanism of Sodium, Chloride follows in a
similar way

7. Secretory Mechanisms
 Chloride is the major secretory product of the
GI tract
 The only ion secreted by the epithelium and
movement can be monitored by changes in
electrical potentials

9. Intestinal chloride secretory
mechanism
 The cell acquires Cl- from the extracellular
fluid whereby it crosses the basolateral
membrane via the Na+/K+/Cl- cotransport
pathway
 A suitable electrochemical gradient is made
by the Na+/K+ ATPase pump which allows for
Na+ to leave the cell and K+ to enter

10.  Also on the basolateral membrane is potassium
channels which allows for the potassium in the
cell to removed.
 Hence the concentration of Na+ and K+ are
lower intracellularly than extracellularly in this
situation
 The accumulation of the Cl- in the cell is
removed from the cell via Cl- channels found at
the brush border membrane and into the lumen

11. Functions
 Important in the formation of gastric HCl
whereby the chloride ions are secreted along
with protons from the parietal cells of the
stomach
 Released via phagocytosis from the white
blood cells which assist in the destruction of
bacteria

12.  Involved in the chloride shift whereby the
chloride is used as exchanger with HCO3- in red
blood cells
 Chloride bicarbonate exchanger is required to
transport Cl- and HCO3- in opposite direction
across the cell membrane

13. Excretion
 Occurs via 3 primary routes: GI tract, skin and
the kidneys
 Loss of Cl- is very similar to how the Na+ are
removed.
 In the GI tract Cl- is small due to the Cl not
being absorbed.

14. Toxicity
 There has been no known level noted
 A daily intake of more than 28g is known as
excessive
 Excess chloride would be excreted via the
excretion mechanisms noted earlier

15. Deficiency
 Excessive vomiting, diarrhea and sweating
can result in a deficiency
 Metabolic alkalosis can result- Can lead to
elevated blood pH
 Symptoms- Decreased ventilation and a
change in urinary pH from alkaline to acidic

16.  Can be seen in infants fed by chloride
deficient formulae.
 Symptoms - Loss of appetite, lethargy,
muscle weakness and severe hypokalemic
metabolic alkalosis

17. References
 http://www.springboard4health.com/notebo
ok/min_chloride.html#Consequences
 http://www.ncbi.nlm.nih.gov/pmc/articles/P
MC435285/
 http://vitanetonline.com/forums/1/Thread/68
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