13115889
Description
Flashcards by J yadonknow, updated more than 1 year ago
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Created by J yadonknow
about 6 years ago
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| Question | Answer |
| Plasma Ca | 2.2-2.6mM |
| Calcium forms | Protein bound - can't diffuse through membranes Chelated/complexed - Phosphate/bicarbonate Free -physiologically active |
| Plasma calcium control | Net absorption GIT Net excretion kidney Temporary storage Bone |
| Osteoblast | Secretes collagen, hydroxyapatite, clast stimulating factors |
| Osteoclast | Bone resorption |
| Osteocyte | Essential role in Ca X between ECF and bone |
| Acute control of Plasma calcium | Maintain constant free [Ca2+] by rapid X between ECF and Bone |
| Chronic control of plasma calcium | Adjust GIT absorption and urinary excretion |
| 3 hormones control | PTH 1,25-Dihydroxycholecalciferol Calcitinon |
| How does PT gland control? | Monitors [Ca2+] in blood perfusing the glands |
| What does removal cause? | Fatal hypocalcaemia |
| PTH | Peptide hormone stored in chief cells |
| t1/2? | 5 minutes |
| When released? | In response to low plasma [Ca2+] |
| Where exert effects? | KBG Mainly KB though |
| What does it do? | ^ reabsorption of Ca from urine ^ Expression of 1alpha-hydroxylase (which + Vit. D). |
| What are the effects on bone? | ^ clast activity indirectly = ^ resorption |
| Draw hormone feedback cycle | Low [Ca] -> PTG -> PTH -> Clast/Kidney reabsorption/Po4 excretion -> ^ Ca |
| D2 name and source | Ergocalciferol, food supplements |
| D3 | Cholcalciferol - diet + skin UV |
| What are they converted to? | 1,25-DHCC |
| Hormone feedback diagram of sunlight exposure | Sunlight skin 7-dehydocholesterol Liver 25-hydroxyvitamin D3 Kidney 1,25-DHCC +Vit D |
| What type of hormone is vit D? | Steroid |
| Calcitriol MOA | ^ Ca transport protein in GIT ^ Ca uptake from GIT Only mech. to ^ Ca stores |
| Used in what kind of treatment? | Kidney failure patients can't make 1alpha-hydroxylase |
| Effects on Kidney/bone | decrease urinary loss ^ Bone resorption rate by ^ ost + factor secretion |
| Calcitonin | Secreted by C-cells (parafollicular cells) of TH gland Minor importance in adults decrease [Ca] free in plasma |
| Calcitonin MOA | Inhibits clast activity -direct effect ^ excretion of Ca+Po4 from kidneys |
| Hyperparathyroidism causes | Hypercalcaemia |
| Vitamin D deficiency causes | Hypocalcaemia |
| Cause of Primary hyperparathyroidism | Autonomous PTH secretion Increases serum Ca, decreases serum PO4 |
| Symptoms of Vitamin D deficiency | Calcification failure Osteomalacia = soft bones in adults Rickets in children |
| What does vitamin D deficinency lead to? | Body sacrifices bone stores and causes a compensatory rise in PTH, doesn't lead to hypocalcaemia |
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