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70 Cards in this Set
- Front
- Back
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where is PTH gland
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2 posterior and 2 anterior nodules within the thyoid gland (LOOK AT SLIDE 1)
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4 roles of Ca
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1. signal transduction
2. membrane potential 3. muscle contraction 4. enzyme cofactor |
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2 specific roles of Ca in signal transduction
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secretory vesicle release
transcriptional activation |
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Is Ca necessary for muscle relaxation
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yes
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effect of abnormal Ca in muscle
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tetanus - sustained contraction
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4 roles of the skeleton
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support and protection
locomotion hematopoiesis calcium regulation |
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% of body's Ca in bone
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99
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3 ways Ca is found in blood
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protein bound
complexed ionized |
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which form of Ca is biologically active
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ionized
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what is Ca complexed with
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Citrate
phosphate |
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% skeletal weight that is Ca
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50
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how is Ca found in bone
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Ca phosphate
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net input/output of Ca
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0 in a healthy person
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how is Ca transported
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in and out of gut
in and out of bone in and out of urine |
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name of transporter that brings in Ca
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CAT1
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how Ca gets into the body
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CAT1
then binds to CaBP then CaATPase on the basolateral membrane |
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% Ca that gets into the kidney that is reabsorbed
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98
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2 factors about Ca transport in the kidney
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saturable
hormone regulated |
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where in the kidney does Ca occur
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loop of henle
distal convoluted tubule |
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how is it absorbed in the loop of henle
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passive diffusion
CaMg transporter more Ca there = more reabsorbed |
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where in the kidney is Ca transport passive diffusion
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loop of henle
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where in the kidney is Ca transport regulated by PTH
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DTC
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how is Ca transported in distal convoluted tubule
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regulated by PTH
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2 regions of bone
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1. inner spongy trabecular
2. outer compact calcified |
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role of outer bone
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protection
locomotion |
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role of inner bone
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hematopoiesis
bone turnover metabolic activity support of outer bone |
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% bone remodelling at any given time
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15-18
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scaffold renews itself how often
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6 years
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pathological condition that can result if we don't remodel bone
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osteoporosis
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3 types of bone cells
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osteoblasts
osteoclasts osteocytes |
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role of osteocytes
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maintain communication and detect stress
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every time bone is remodel we are left with
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a little deficit
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after osteoclasts dig a hole they differentiate into
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mononuclear cells
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relationship between osteoblasts and osteoclasts
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activity is tightly coupled
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which cell type has PTH receptors
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osteoclasts
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what happens when PTH activates osteoclasts
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increased remodelling
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note about remodelling
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osteoblasts and osteoclasts are recruited to the surface in undifferentiated pro-form
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name of cells in the parathyroid
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chief cells
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negative feedback on chief cells
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high Ca
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how PTH is synthesized
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84 AA hormone
cleaved to leave first N terminal 34 Aas |
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what else can bind PTHR (the PTH receptor)
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PTHrP - GF made in prostate
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PTHrP
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GF made in prostate that can bind PTHR
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HHM
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hormone related hypercalcemia
caused by PTHrP excess binding to PTH |
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where is PTHR expressed
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bone and kidney
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PTHR is what type of receptor
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GPCR
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what is PTHR GPCR coupled to
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Galpha s
G alpha q11 |
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G alpha s signalling
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cAMP
PKA Ca increase |
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G alpha q 11 signalling
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PLC beta -> dag/IP3 -> Ca increase
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note about Ca and PTH
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plasma Ca has tight limits
see slide 16 there is a small region of plasma Ca change that will cause a massive change in PTH output |
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DCT
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distal convoluted tubule
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what is effect of PTH on kidney
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1. increased reabsorption
2. increase 1 alpha hydroxylase activity |
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what does 1 alpha hydroxylase do
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make vit D3 (1, 25 OH)
1000 times more active than vit D |
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what does vit D3 do
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increase Ca absorption in the GI tract
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vitamin D metabolism
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1. cholcalciferol found in skin and diet
2. 25-hydroxylase in the liver converts it to 25-dihydroxycholcalciferol 3. 1 alpha hydroxylase in the kidney converts it to 1,25 dihydroxycholcalciferol (vit D3) |
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sources of cholcalciferol
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precursor in skin converted to cholcalciferol via sunlight
fortified foods (ex. fortified milk) |
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roles of vit D3
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increased bone resorption
increased mineralization increased Ca absorption in Gi tract |
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what causes vit D deficiency in society
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pollution/smog
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vitamin D deficiency
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rickets = lack of vit D/Ca
weak bones |
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primary hyperparathyroidism - typical cause
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tumor
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effects of too much Ca
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high bp
pancreatitis kidney stones stomach ulcers osteopenia osteitis fibrosa cystica depression psychosis |
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too much or too little Ca
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same effect
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cause of secondary hypothyroidism
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PTH or vit D resistance
not enough in diet renal failure -> hypocalcemia |
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GO BACK TO SLIDE 20
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ok
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4 other causes of hypercalcemia
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1. humoral hypercalcemia of malignancy (HHM)
2. excess vit D 3. sarcoidosis 4. milk alkali (burnett's) syndrome |
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HHM AKA
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pseudohyperparathyroidism
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cancers that commonly cause HHM
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lung and kidney
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sarcoidosis
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granulatomous activation of vit D (inflammation of lymph nodes, lung)
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milk-alkali (Burnetts syndrome)
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metabolic alkolosis
back pain excessive urination |
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hypoparathyroidism -> hypocalcemia -> effects
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impaired memory
personality change numbness (particularly oral) carpopedal spasm (violent muscle spasm) convulsions and tetanus |
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usual cause of true hypoparathyroidism
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iatrogenic (post thyroidectomy)
rare autoimmune disease |
