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![2- Paracellular transport :
occurs between cells The process allows the movement
(Diffusion) of Ca .
Occurs when :
- High [ Ca ] in lumen.
- Gradient of [ Ca ] between the lumen and basoletral side .](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-8-320.jpg)
![3 types of bone cells :
• Osteoblast :
- called (Bone building cells)
- Produce matrix
- secret collagen and ground substance .
- become ostocytes .
• Osteocytes :
- Star shaped
- mature bone cells
• Osteoclasts :
- Phagocytic cell
-role in increasing blood [Ca2+ ]
-contain lysosomes and enzymes capable of breaking down.](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-18-320.jpg)
![Blood
Low [Ca]
Gastrointestinal
Tract
Basolate
membrane
Brush border
membrane
Calcitriol
Ca2+
Figure 5: Blood Ca2+ regulation by calcitriol in response to low blood [Ca2+ ] .](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-30-320.jpg)
![:Figure 5
Regulation of intracellular [calcium]](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-33-320.jpg)
![Lower [Ca2+ ] By
• Buffering free Ca2+ via molecular sequestration.
• compartmentalization* of Ca2+ through uptake in to cellular
organells.
• Removal of excess Ca2+ from the cell via energy-dependent Ca2+
pumps found on Plasma membrane.
* compartmentalize meaning : to separate something into parts and
not allow those parts to mix together.
Removal of Ca2+ stimulus](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-34-320.jpg)
![Assessment
• Difficult to assess : same indicators of Vitamin D
status , bone disease , hormonal imbalance.
methods :
• presence of normal [albumin]
• CT scans
• DEXA : the best “ change in mass over time”](https://image.slidesharecdn.com/calcium-180421211800/85/Calcium-42-320.jpg)
More Related Content
Calcium
- 1. Vitamins And MineralsIn Nutrition NF773 2018-3-14 Calcium Supervisor : prof. sana janakat By : Haya abumater
- 2. Calcium • Most abundantmineral in the human body • Total Calcium in the human body is about 1 to 1.5 kg, 99% of which is found in bone together with phosphate. • Small amounts are found in soft tissue & 1% in extracellular fluid .
- 3. Chemical properties ofCa2+ • Belong to ( group IIA ) . • The biological Activity & regulation of Ca2+ are influenced by Concentration of ionized or free Ca2+ in solution. • Binding of Ca2+ to the protein components of cell membrane : - Change the fluidity of the membrane . - Allow passage of ions .
- 4. Calcium is foundin blood plasma : • Bound to plasma proteins (albumin) (35-40%) • As free-ionized (45-50%) • Complex with sulfate , phosphate or citrate 10%
- 5. Sources • The bestsources of Ca2+ are: • milk and dairy products. • Sea food ( salmon , sardines with bones , oyster . • Vegetables : turnip , broccoli , Kale . • Legumes : tofu . • Dried fruits . https://sacramentodentistry.com/oral-health/got-calcium/ access at 8-3- 2018
- 6. Digestion Calcium as insolublesalt food dietary supplements Acidic PH 1 hour Free soluble Ca2+
- 7. Absorption Tow transport processare responsible for the absorption : 1. Transcellular transport • Epithelial Ca channel .e.g: TRPV6 • Calbindin D9K , CRP. Stimulated by : - Calcitriol ( Vitamin D ) - Low Ca diets
- 8. 2- Paracellular transport: occurs between cells The process allows the movement (Diffusion) of Ca . Occurs when : - High [ Ca ] in lumen. - Gradient of [ Ca ] between the lumen and basoletral side .
- 9. Figure 1 Ca digestion,absorption , transport Gropper et al.2009
- 10. Absorption Mechanism of calciumabsorption: • About 40% of dietary calcium is absorbed from the gut • Absorption occurs from the first & second part of duodenum • Absorbed against a concentration gradient & requires energy
- 11. Table 1 : Interactionbetween Calcium and selected Nutrients/Substances Whose Absorption May be Inhibited by Excessive Ca Enhancing Urinary Ca Excretion Inhibiting Ca absorption Enhancing Ca absorption IronSodiumFiberVitamin D Fatty AcidsProteinPhytateSugars and sugars alcohols CaffeineOxalateProtein Excessive divalent cations (Zn,Mg) Unabsorbed fatty acids
- 12. Transport • Calcium isTransported in the blood via : 1- bound to proteins . ( albumin & prealbumin ) 40% 2- Complex with sulfate , phosphate or citrate . 10% 3- Found free (Ionized) in blood. 50% * the total calcium and ionized calcium measurements are available in many laboratories
- 13. Functions of Calcium •Formation of bone mineral . • Regulation of enzyme activity . • Second messenger in the cell . • Nerve conduction • Blood coagulation
- 14. Bone mineralization • 99%of total body Calcium is found in bone And teeth. • Ca2+ is found in the body as : Calcium Phosphate compound Hydroxyapatite ( Ca10(PO4)6(OH)2) Functions of Calcium …
- 15. Bone mineralization Types ofBone Tissue : • cortical bone • trabecular bone Trabecular and Cortical Bone (Cowin, 2001) https://www.researchgate.net/figure/Trabecular- and-Cortical-Bone-Cowin-2001_fig1_230822645 8-3-2017
- 16. Figure 2 :Characteristics of cortical and trabecular Bone . Trabecular BoneCortical Bone Spongy appearanceCompact or dense Represents about 20% to 25% of bone in the body . 75% to 80% of total bone in the body Consists of an interconnected system of protein (mostly collagen) Consist of layers of mineralized protein ( mostly collagen ) Found in high conc. In the axial skeletonFound on the surfaces of all bones and the shaft of long bones of the limbs and wrist .
- 17. Calcium Binding proteinin Bone • Osteonectin ( the most aboundant noncollagenous protein in bone ) • Gla protein ( Vitamin K dependent protein ) • Osteocalcin ( biomarker of bone formation in serum) • Protein S ( the deficiency associated with osteopenia )
- 18. 3 types ofbone cells : • Osteoblast : - called (Bone building cells) - Produce matrix - secret collagen and ground substance . - become ostocytes . • Osteocytes : - Star shaped - mature bone cells • Osteoclasts : - Phagocytic cell -role in increasing blood [Ca2+ ] -contain lysosomes and enzymes capable of breaking down.
- 19. • Osteoblasts cell(gray blobs forming an oval) create new bone tissue. https://www.sciencenewsforstudents.org/article/bo nes-hard-scaffold-influencing-other-tissue access at 7-3-2018 https://www.sciencephoto.com/media/301684/view access at 7-3-2018
- 20. Osteocytes cells, instructingthe other bone cells what to do. https://www.sciencenewsforstudents.org/article/bo nes-hard-scaffold-influencing-other-tissue access at 7-3-2018 http://www.anatomybox.com/tag/false-color/ access at 7-3-2018
- 21. Scanning electron micrographof activated osteoclast and resorption pits. https://boneresearchsociety.org/resources/gallery/3 8/ access at 7-3-2018
- 22. Functions of Calcium… • Second Messenger : are molecule that relay signals from receptors on the cell surface to target molecules inside the cell. Ca2+ acts as a second messenger in two ways: • it binds to an effector molecule, such as an enzyme, activating it. • it binds to an intermediary cytosolic calcium binding protein such as calmodulin.
- 23. Figure 3: therole of Calcium and IP3 in Signaling. pathwhttps://www.youtube.com/wa
- 24. • Cytosolic Ca2+can bind to cellular Ca2+ binding proteins, including Camodulin Activate cellular Kinases and Enzymes • Calmodulin is a calcium binding regulatory protein .. Contain 4 calcium-binding (EF-hand). Full-length Ca4-calmodulin X-ray: pdb 1cll; Chattopadhyaya, R., Meador, W.E., Means, A.R., Quiocho, F.A. J. Mol. Biol. 228, 1177-1192 (1992) accses at 7-3-2018 • Activation of enzymes Functions of Calcium ..
- 25. The EF hand https://www.quora.com/What-is-the- difference-between-EF-Hand-and-helix- 10/2/2018turn-helix-protein-motifs •Found in large family of Ca2+-binding protein , such as : calmodulin and calbindin D . Composed of : • 10- to 12-amino acid alpha helices • 12-residue calcium binding loop region . * most EF- hand proteins at position 12 is glutamate . Ca2+
- 26. • Muscles • Calciummediates excitation & contraction of muscles - interacts with troponin C to trigger muscle contraction - activates ATPase, increases action of actin and myosin and facilitates excitation-contraction coupling. - decreases neuromuscular irritability. - Calcium deficiency causes tetany. Functions of Calcium…
- 27. • Nerve conduction Itis necessary for transmission of nerve impulses . • Blood coagulation - Calcium is known as factor IV in blood coagulation process - Prothrombin contains γ-carboxyglutamate residues which are chelated by Ca2+ during the thrombin formation Functions of Calcium…
- 28. Regulation of Calciumconcentrations Extracellular Hormones involved in Ca2+ homeostasis : • Parathyroid hormone(PTH) • Calcitriol • Calcitonin
- 29. Stimulus : Falling bloodCa level Parathyroid glands release PTH PTH Increase Ca2+ uptake in kidneys. Increase Ca2+ uptake in .intestines Stimulates Ca2+ release from bone . Active vitamin D Stimulus : Rising blood Ca2+ level Parathyroid glands release calcitonin Calcitonin Stimulates Ca2+ deposit in bone . reduces Ca2+ uptake in .intestines reduces Ca2+ uptake in kidneys. Figure 4: Blood Ca2+ regulation by PTH & Calcitonin
- 30. Blood Low [Ca] Gastrointestinal Tract Basolate membrane Brush border membrane Calcitriol Ca2+ Figure5: Blood Ca2+ regulation by calcitriol in response to low blood [Ca2+ ] .
- 31. Table 2: Asummary of the Effects of PTH , calcitiol ,calcitonin on Ca2+ Balance. CalcitoninCalcitriolPTH Serum calcium * Bone Calcium Renal Ca2+ reabsorption No effect Intestinal Ca2+ absorption * Works with PTH
- 32. Regulation of Calciumconcentrations Intracellular • Ca2+ enters cells by diffusion of channels and exerts its actions. • Ca2+ can be removed from the cytoplasm in tow ways : 1- ATP-dependent pumps use Mg++ and Na++ to export Ca2+ out of the cell, and Atpase . 2- pumped can sequester Ca2+ in organelles such as the endoplasmic reticulum or mitochondrion.
- 33. :Figure 5 Regulation ofintracellular [calcium]
- 34. Lower [Ca2+ ]By • Buffering free Ca2+ via molecular sequestration. • compartmentalization* of Ca2+ through uptake in to cellular organells. • Removal of excess Ca2+ from the cell via energy-dependent Ca2+ pumps found on Plasma membrane. * compartmentalize meaning : to separate something into parts and not allow those parts to mix together. Removal of Ca2+ stimulus
- 35. Table 3: Causes andClinical sequences of Hypocalcemia and Hypercalcemia Clinical sequencesCauses •Fatigue •Neuromuscular irritability (tetany ..) •Cardiomyopathy •Seizures •Hypoparathyroidism •Inadequate vitamin D production • PTH resistance ( Mg deficiency) •Acute critical illnessHypocalcemia •Fatigue •Vomiting •Hyprcaciuria .. Kidny stones •Constapation •Abdominal pain •Hayperabsorption of Ca2+ •Decrease urinary excretion • increased bone resorption . •Idiopathic hypercalcemiaHypercalcemia
- 36. Calcium excretion • 140mgday of Ca2+ enter the intestinal lumen in digestive secretion . • 29% of this is reabsorbed . • Only 100-240 mgday. By urine . • 1-2.5% of Ca2+ filtered by the kidney.
- 37. Adequate intake For men/women: •19-50 years : 1000 mg/day • <50 years : 1200 mg/day • 1500 mg/day for women not treated with estrogen , “ because its influences bone mineralization “
- 38. Calcium deficiency • Tetany“ fail muscle contraction” • Rickets : in children . • Osreoporosis “ loss of bone mass” . https://www.orthobullets.com/basic- science/9031/ricketshttp://qpilates.net.au/osteoporosis-pilates/ access at 8-3-2018 Rickets
- 39. Should increased needof Ca2+ : • High phytate diets • Fat malabsorption • Immobilization • Decreased gastrointestinal transit time • Use of thiazide diuretics (long time)
- 40. Excess Calcium Supplementation •usually does not result in hypercalcemia, but may cause mineral imbalances by : Interfering with the absorption of other minerals, such as iron, magnesium, and zinc.
- 41. Toxicity • Upper intake: 2500 mg/day • Hypercalcemia • Constipation • Kidney stones • Deposition of ca in soft tissue https://step1.medbullets.com/msk/112035/gout 8-3-2018 http://faressaad.com/blog/2017/06/beirut-residents-getting-much- calcium/ access at 8-3-2018
- 42. Assessment • Difficult toassess : same indicators of Vitamin D status , bone disease , hormonal imbalance. methods : • presence of normal [albumin] • CT scans • DEXA : the best “ change in mass over time”
- 43. References : 1- (6thed.) Gropper, S. A. S., Smith, J. L., & Groff, J. L. (2009). Advanced nutrition and human metabolism. 2- Stipanuk, M. H. (2006). Biochemical, physiological, & molecular aspects of human nutrition. St. Louis: Saunders Elsevier.
Editor's Notes
- #9 Fructose , oligosaccharides, insulin … enhance paracullular Ca absorption
- #10 Bacteria in the colon may release Ca, that bound to some fermentable fiber as : Pectins.
- #25 Calmodulin is part of various regulatory kinases Enzymes activated by Ca2+ include pancreatic lipase, enzymes of coagulation pathway, and rennin.
- #43 Ct : computerized tomography DEXA : dual energy X-ray absorpitiometry