Term
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Definition
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Term
| What are the major Hormones which regulate CA and Po Ballance? |
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Definition
| PTH (from Parathyroid) , Vitamin D (dietary), Calcitonin (thyroid) |
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Term
| What Does PTH do in bone tissue? |
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Definition
| When circulating calcium is too low, PTH is released which stimulates bone reabsorbtion (release of ca into blood stream) |
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Term
What does PTH do in the kidney? |
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Definition
| Stimulates the hydroxylation of dietary Vitamin D into it's active form (at the 1 position). The active form is Calctriol. It also stimulates the kidney to release stored calcium and phosphate. |
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| What does the active form of vitamin D do, and what is it called? |
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Definition
Calcitriol. It increases intestinal absorbtion of Ca, releases bone, and prevents kidney from filtering Ca into urine. also "Vitamin D induces synthesis of a calcium-binding protein in intestinal epithelial cells that facilitates efficient absorption of calcium into blood. " From http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/thyroid/pth.html |
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Term
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Definition
calcitonin counteracts the effects of PTH inhibits CA loss from bone, and increases the concentration of Ca in urine (renal excretion) |
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Term
what is a Pre Propeptide? |
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Definition
| A Pro peptide is a protien that can be made active by posttranslational modification, so after it is sythesized by mRNA it is changed into the "real" protien. a Pre propeptide is then. Protiens that have a signal peptide attached contain the prefix pre. So, therefore, a pre propeptide is one that can be made biologically active and has a signaling mechanism to be cleaved off in the ER when this is to happen. |
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Term
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Definition
| Chief cells are the cells in the Parathyroid gland which synthesize ans secrete PTH |
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Term
| Where is calcitonin secreted? |
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Definition
| in the c cells of the thyroid gland |
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Term
| how many amino acids are in PTH? |
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Definition
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Term
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Definition
| both pulsitile and tonic. 70% tonic 30% in 6-7 pulses/ hour. because it is under tight Ca control when ca goes low PTH has a bi phasic response the PTH which has been made and stored is rapidly release and production is also increased |
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Term
| Describe the Parathyroid CA receptor. |
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Definition
| it is on the parathyroid chief cells, it is G protien coupled (signal binds to outside of membrane, starts a cascade inside of cell). It is a negative regulation receptor ie. when Ca binds, parathyroid knows that CA levels are up and so decreases release of PTH. |
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Term
| Describe the parathyroid CA receptor cascade |
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Definition
| 1st it activates the phosphoralation/activation of phospholipase A2. "A phospholipase is an enzyme that converts phospholipids into fatty acids and other lipophilic substances "(wikipedia). this activates the arachidonic acis cascade, and increases leukotrine sysnthesis. it is the Leukotrine which inhibits PTH release, both by slowing production and speeding degradation. |
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Term
| Name 3 things that stimulate PTH release |
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Definition
Hypocalcemia Hyperphosphatemia Catecholamines |
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Term
Name 3 things that supress PTH release |
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Definition
Hypercalcemia Vitamin D severe hypomagnesemia |
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Term
What, besides calcium regulates PTH Levels? |
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Definition
| Phosphate and Magnesium levels |
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Term
How do phosphate levels regulate ca? |
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Definition
elevated phosphate levels cause increased PTH because they decrease phospholipase A2 Levels. This decreases arachidonic acid production to be suppressed and inhibitory control over PTH to be released. It can also affect calcium and vit d levels in circulation |
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Term
what are the two primary sites of action of PTH? |
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Definition
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Term
| What are bone osteoblasts? |
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Definition
| immature bone cells responsible for creating and mineralizing new bone tissue. They are the site of action (where the receptor PTHR1) is located along with kidney. |
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Term
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Definition
| It is PTH related protien. Not very similar, share only 13 AA, but binds to PTHR1. involved in metastecies. |
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Term
| Describe the signaling cascade after PTH binds to PTHR1 |
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Definition
binds to alpha sub-unit. which increases cAMP in turn increasing protien kinase A and phosphorlation of target protiens @ serine residues. The result is activation of and mrna translation of protiens http://en.wikipedia.org/wiki/Cyclic_adenosine_monophosphate |
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Term
| what does 1α-hydroxylase do? |
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Definition
| it is the enzyme responsible for creating the active form of vitamin D |
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Term
| what are the two ways that calcium gets reabsorbed in the kidney? |
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Definition
distal and proximal tubules (parts of kidney) transcellular (active transport from waters around cell) paracellular (passive transport between cells) |
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Term
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Definition
A protein kinase is a kinase enzyme that modifies other proteins by chemically adding phosphate groups to them (phosphorylation). This class of protein is further separated into subsets such as PKC alpha, PKC beta, and PKC gamma, each with specific functions. Phosphorylation usually results in a functional change of the target protein (substrate) by changing enzyme activity, cellular location, or association with other proteins. Up to 30% of all proteins may be modified by kinase activity, and kinases are known to regulate the majority of cellular pathways, especially those involved in signal transduction, the transmission of signals within the cell. The human genome contains about 500 protein kinase genes; they constitute about 2% of all eukaryotic genes. The chemical activity of a kinase involves removing a phosphate group from ATP and covalently attaching it to one of three amino acids that have a free hydroxyl group. Most kinases act on both serine and threonine, others act on tyrosine, and a number (dual specificity kinases) act on all three. (Wikipedia) |
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Term
| How does calcium move through the kidney? |
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Definition
| PTH opens a calcium ion channel, which lets in calcium to the apical end of the cell, inside the cell tyhe Ca binds to calcibindin which allows it to move through the cell and through the membranes |
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Term
| What does PTH do in bone? |
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Definition
| PTH causes bone degradation causing Ca release they are mediated in osteoblasts. |
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Term
What are the the three types of bone cells |
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Definition
Osteoblasts- responsible for bone formation and mineralization and PTH receptors are expressed here. Osteoclasts-bone reabsorbing cells is a type of bone cell that removes bone tissue by removing the bone's mineralized matrix. This process is known as bone resorption. Osteoclasts and osteoblasts are instrumental in controlling the amount of bone tissue. Osteoblasts form bone; osteoclasts resorb bone. Osteoclasts are formed by the fusion of cells of the monocyte-macrophage cell line.[1] Osteoclasts are characterized by high expression of tartrate resistant acid phosphatase (TRAP) and cathepsin K -wikipedia Osteocytes-small flattened cells within the bone matrix |
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