Teško je prevesti ovaj clanak jer se radi o veoma strucnim terminima koje nije moguće razumjeti ukoliko se ne posjeduje znanje o:
A. Prometu minerala i elektrolita u organizmu
B. Način održavanja acidobaznog stanja organizma.
C. Znanje o stanicama, receptorima i kanalima
Ja ću vam u kratkim crtama o tome reci ako ih mognete razumjeti:
A. Govorit ću samo o Calciumu (CA). To je jedan od vaznih minerala u organizmu koji se nalazi u u najvecoj kolicini u kostima ali igra važnu ulogu za rad srca i ostalih stanica, zgrusavanje krvi, održavanju acidobaznog stanja te brojnim drugiim vaznim procesima. Za promet kalciuma u organizmu odgovorni su:
1. D vit. i njegovi metaboliti (Holecalciferol, Dihidroholecalciferol i 1.25 dihidroholecalciferol ili Calcitriol). Ovaj zadnji metabolit se stvara iz D vit u bubregu i on ima najace djelovanje na promet Ca.
2. PTH hormon (Hormon paratiroidne zljezde)
3. Calcitonin (Hormon stanica C u stitnoj-Thyroide zljezdi)
Ova tri regulatora regulisu resorpciju Ca u crevima, odlaganje u kostima i izlucivanje preko mokrace. Svaki od ovih ima razlicit učinak na creva (resorpcija Ca), bubrege (Izlucivanje) i na kosti (osteoblaste-ulaganje Ca ili osteoklaste otapanje Ca)
B. Regulacija acidobaznog stanja organizma je presudna za normalan rad stanica. pH organizma se kreće u uskim granicama između pH 7.35 do 7.45. Pad pH ispod ili iznad navedenih vrednosti ima odraza na rad stanica a time na brojne funkcije orgama i organizma kao cjeeline.
Šta je novina kada je u pitanju pH i promet Ca ?
Primjeceno je da je kod normalnog rada tri mehanizma (prethodno navedeno) za održavanje prometa Ca, ipak desava da dolazi do ospetoporoze. Spoznaja nova je da na osteoklaste koji otapaju-razgradjuju kosti djeluje i acidoza, tj pad pH ispod 7.30 a najveci je kod pH 7.0 dok se aktivnmost osteoklasta gasi kod pH 7.4
C. Kada je u pitanju stanice-cels te organele, kanali, receptori itd to je suvise strucno i nije moguće na ovaj način prokomentarisati
Zakljucak:
Ishrana je bitna za stanje održavanja zdravlja organizma pa time i za sam pH organizma. Primjeceno je da na pH organizma ima veliki odrza unos bjelancevina zivotinjskog porekla, unos voca i povrca. Dok proteini zivotinjskog porekla povecavaju acidozu, voce i povrce u prosjeku smanjuju kiselost i povecavaju alkalozu organizma.
Ovo bi bila sustina navedenog clanka o kome je riječ tj da je pH tekucine izvan stanica u kostima, ima odraza na funkciju stanica osteoklasta.
-----------------------------------------------------------------
A sad taj clanak:
Extracellular pH regulates bone cell function.
Arnett TR.
Department of Anatomy and Developmental Biology, University College London, London WC1E 6BT, UK.
[email protected]
The skeletons of land vertebrates contain a massive reserve of alkaline mineral (hydroxyapatite), which is ultimately available to buffer metabolic H+ if acid-base balance is not maintained within narrow limits. The negative impact of acidosis on the skeleton has long been known but was thought to result from passive, physicochemical dissolution of bone mineral. This brief, selective review summarizes what is now known of the direct functional responses of bone cells to extracellular pH. We discovered that bone resorption by cultured osteoclasts is stimulated directly by acid. The stimulatory effect is near-maximal at pH 7.0, whereas above pH 7.4, resorption is switched off. In bone organ cultures, H+-stimulated bone mineral release is almost entirely osteoclast-mediated, with a negligible physicochemical component. Acidification is the key requirement for osteoclasts to excavate resorption pits in all species studied to date, and extracellular H+ may thus be regarded as the long-sought osteoclast activation factor. Acid-activated osteoclasts can be stimulated further by agents such as parathyroid hormone, 1,25-dihydroxycholecalciferol, and receptor activator of nuclear factor kappaB ligand. Osteoclasts may respond to pH changes via H+-sensing ion channels such as transient receptor potential vanilloid 1, a nociceptor that is also activated by capsaicin. Acidosis also exerts a powerful, reciprocal inhibitory effect on the mineralization of bone matrix by cultured osteoblasts. This is caused by increased hydroxyapatite solubility at low pH, together with selective inhibition of alkaline phosphatase, which is required for mineralization. Diets or drugs that shift acid-base balance in the alkaline direction may provide useful treatments for bone loss disorders.
Sve najbolje Galeb