Editing Common ostrich (section)

=====Biochemistry=====
The majority of the common ostrich's internal solutes are made up of [[sodium]] ions ({{chem2|Na(+)}}), [[potassium]] ions ({{chem2|K(+)}}), [[chloride]] ions ({{chem2|Cl(-)}}), total [[short-chain fatty acid]]s (SCFA), and [[acetate]].<ref name=Skadhaugeetal /> The caecum contains a high water concentration with reduced levels nearing the terminal colon and exhibits a rapid fall in {{chem2|Na(+)}} concentrations and small changes in {{chem2|K(+)}} and {{chem2|Cl(-)}}.<ref name=Skadhaugeetal /> 
The colon is divided into three sections and takes part in solute absorption. The upper colon largely absorbs {{chem2|Na(+)}} and SCFA and partially absorbs KCl.<ref name=Skadhaugeetal /> The middle colon absorbs {{chem2|Na(+)}} and SCFA, with little net transfer of K<sup>+</sup> and Cl<sup>−</sup>.<ref name=Skadhaugeetal /> The lower colon then slightly absorbs {{chem2|Na(+)}} and water and secretes {{chem2|K(+)}}. There is no net movements of {{chem2|Cl(-)}} and SCFA found in the lower colon.<ref name=Skadhaugeetal />

When the common ostrich is in a dehydrated state, plasma osmolality, {{chem2|Na(+)}}, {{chem2|K(+)}}, and {{chem2|Cl(-)}} ions all increase; however, {{chem2|K(+)}} ions return to controlled concentration.<ref name=hormones>{{cite journal |doi=10.1016/0300-9629(88)91088-2 |title=Plasma arginine vasotocin and angiotensin II in the water deprived common ostrich (''Struthio camelus'') |year=1988 |last1=Gray |first1=D.A. |last2=Naudé |first2=R.J. |last3=Erasmus |first3=T. |journal=Comparative Biochemistry and Physiology A |volume=89 |issue=2 |pages=251–256}}</ref> The common ostrich also experiences an increase in [[haematocrit]], resulting in a [[Hypovolemia|hypovolemic state]].<ref name=hormones /> Two antidiuretic hormones, [[Vasopressin|Arginine vasotocin (AVT)]] and [[angiotensin]] (AII), are increased in blood plasma as a response to [[hyperosmolality]] and [[hypovolemia]].<ref name=hormones /> AVT triggers [[Vasopressin|antidiuretic hormone]] (ADH) which targets the [[nephrons]] of the kidney.<ref name=zool241 /> ADH causes a reabsorption of water from the lumen of the [[nephron]] to the [[extracellular fluid]] osmotically.<ref name=zool241 /> These extracellular fluids then drain into blood vessels, causing a rehydrating effect.<ref name=zool241 /> This drainage prevents loss of water by both lowering volume and increasing concentration of the urine.<ref name=zool241 /> Angiotensin, on the other hand, causes [[vasoconstriction]] on the systemic arterioles and acts as a [[dipsogen]] for ostriches.<ref name=zool241 /> Both of these antidiuretic hormones work together to maintain water levels in the body that would normally be lost due to the osmotic stress of the arid environment.

Ostriches are [[uricotelic]], excreting nitrogen in the form of [[uric acid]] and related derivatives.<ref name=zool241 /> Uric acid's low solubility in water gives a semi-solid paste consistency to the ostrich's nitrogenous waste.<ref name=zool241 />