Term
| What are some processes that are reliant on a steady Ca concentration? |
|
Definition
action potentials
contraction
motility
cytoskeletal rearrangements
cell division
secretion
modulation of enzyme activites |
|
|
Term
| How is total body calcium determined? |
|
Definition
| Intracellular + extracellular + Ca in bone and teeth |
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|
Term
| What is the total plasma concentration range? |
|
Definition
|
|
Term
| What type of calcium is the biologically active form? |
|
Definition
|
|
Term
| When Ca binds to protien, which one is is normally bound to? |
|
Definition
|
|
Term
|
Definition
Ca that is complexed to other anions:
phosphate, citrate, bicarb, lactate |
|
|
Term
| How does high blood pH affect protien binding of calcium? |
|
Definition
the equalibrium shift to :
protien bound > ionized Ca |
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|
Term
| How does acidosis affect Ca binding? |
|
Definition
Shifts the equalibrium to:
protien bound < ionized calcium |
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|
Term
| What are three instances where ionized calcium decreases? |
|
Definition
1. total body Ca deficit
2. shift causing Ca to be taken up in the bone
3. plasma protien binding Ca increasing (alkalosis) |
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|
Term
| What three body processes are responsible for the turnover of Ca? |
|
Definition
1.Intestinal Absorption
2.Renal Filtraiton
3.Bone Remodeling |
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|
Term
| What enhances intestinal absorption of Ca? |
|
Definition
|
|
Term
| How is excess dietary Ca eliminated? |
|
Definition
|
|
Term
| Where is the majority of Ca reabsorbed in the kidneys? |
|
Definition
| 98% in the renal tubules with the remainder secreted in the kidneys |
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|
Term
| What does bone formation and bone reabsorption do to Ca levels? |
|
Definition
| Respectively: decrease and increase levels |
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|
Term
| What are the two controls on Ca levels in extracellular fluid? |
|
Definition
1. indirect endocrine control
2. direct negative feeback by Ca itself |
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|
Term
| What receptors mediate Ca and where are they located? |
|
Definition
calcium sensing plasma membrane receptors
*found*
1. PTH and Calcitonin secretiong cells of the parathyroid
2. Vit. D producing cells
3. bone forming and resorbing cells
4. renal tubular calcium resorbing cells
5. intestinal ca resorbing cells |
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|
Term
| How are the Ca receptors coupled to adenyl cyclase, phospholipase and kinase? |
|
Definition
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|
Term
| What are some effects of hypoglycemia? |
|
Definition
1. neuromuscular irritability
2. numbness
3. seizures |
|
|
Term
| What are some effects of hypercalcemia? |
|
Definition
reduced neurotransmission
muscle weakness
coma
nephrotoxicity |
|
|
Term
| What are the important moleucles Phophate is part of? |
|
Definition
ATP, NAD, NADP
2*messengers : cAMP and DNA and RNA |
|
|
Term
| What two anions are balanced by P? |
|
Definition
|
|
Term
| What is the normal phosphate concentration range? |
|
Definition
|
|
Term
True or False
Phosphate Turnover uses the same body mechanisims as calcium. |
|
Definition
|
|
Term
| What are some effects of hypophosphatemia? |
|
Definition
cardiac and respiratory weakness
loss of RBC membrane integrity
abnormal bone formation |
|
|
Term
| What causes soft tissue calcification? |
|
Definition
| binding of Ca and P. Ususally occurs with renal failure. |
|
|
Term
| What is the cause of Renal Secondary Hyperparathyroidism? |
|
Definition
excessive dietary phosphorus
insufficent dietary Ca |
|
|
Term
| What is the cause of Nutritional Secondary Hyperparathyroidism? |
|
Definition
| Occurs in horses that are fed exclusively high phosphate grains (wheat or rice bran) |
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|
Term
| What is the function of Magnesium? |
|
Definition
Neuromuscular transmission
co-factor
glucose homeostatsis |
|
|
Term
| What is the acceptable range for plasma Mg? |
|
Definition
|
|
Term
| Where is Mg predominately in the body? |
|
Definition
| Bone > skeletal muscle > heart, liver, other |
|
|
Term
| How is Mg secretion and excretion regulated? |
|
Definition
absorption by the gut
excreted in the urine
self regulate by interacting with Ca receptors |
|
|
Term
| What are the three molecules whose absorption in the gut is enhanced by vitamin D? |
|
Definition
|
|
Term
| Hypomagnesemia mimics what? |
|
Definition
|
|
Term
| what are the effects of hypermagnesemia? |
|
Definition
neuromuscular blockade by supressing aceytlcholine
respiratory blockade
*caused by renal failure, endo disorders, drug overdose) |
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|
Term
|
Definition
|
|
Term
| what is the PTH precursor and what cell secretes it? |
|
Definition
| pre-pro-PTH is secreted by Chief Cells |
|
|
Term
| What are the mechanisims that control PTH secretion? |
|
Definition
1. plasma Ca concentration and - feedback
2.Ca receptor in the PT cell memebrane
3.Mg
4. increased phosphorus (decreases Ca --> PTH secretion
5. Vitamin D |
|
|
Term
| what is the biologically active form of Vitamin D? |
|
Definition
|
|
Term
| What is the overall effect of Vitamin D? |
|
Definition
| to increase plasma ionized calcium |
|
|
Term
| how does PTH work with Vit. D? |
|
Definition
| it increases synthesis of Vit. D |
|
|
Term
| what is the second messenger for PTH? |
|
Definition
| adenylyl cyclase ->cAMP by g-protiens |
|
|
Term
| What is the overal effect of PTH? |
|
Definition
increase plasma Ca
decrease plasma Phosphate |
|
|
Term
| what are the three major organs that PTH acts on? |
|
Definition
|
|
Term
True or False.
PTH receptors are on osteoblasts and osteoclasts. |
|
Definition
|
|
Term
True or False.
PTH accelerates removal of Ca from bone. |
|
Definition
|
|
Term
True or false.
PTH in low intermittent doses has an anabolic action to stimulate bone formation. |
|
Definition
|
|
Term
| where are PTH receptors found in the kidney? |
|
Definition
ascending loop of henle
distal tubules of the kidney |
|
|
Term
| what is the most dramatic effect of PTH on the kidney? |
|
Definition
| inhibition of reabsorption of P which in creases the P in the urine |
|
|
Term
True or False
PTH helps reabsorption of Na and Bicarb in the proximal tubule. |
|
Definition
|
|
Term
| Where is Vit. D synthesized? |
|
Definition
|
|
Term
| What normally causes hyperparathyroidism? |
|
Definition
TUMOR = primary
hypocalcemia with elevated PTH (vit. D deficiency)= secondary |
|
|
Term
| In cancer patients with hypercalcemia what will the PTH levels look like and why? |
|
Definition
| Low PTH because of high PTH related protien that is able to interact with PTH receptors (that increase Ca absorption in the gut by stimulating Vit. D synthesis) |
|
|
Term
| Calcitonin has antagonistic and synergistic relationships with PTH. What are they? |
|
Definition
Antagonistic = Ca plasma levels
Synergistic = P plasma levels |
|
|
Term
| what are the two main sources of vitamin D? |
|
Definition
UV light (Vit. D3)
Dietary ingestion (VitD3 and D2) |
|
|
Term
| what is the process of synthesis of the biologically active form of Vitamin D? |
|
Definition
1. Vit.D3 from skin and diet hydroxylated in the liver
2.forms 25-OH Vitamin D
3.transport to the kidney to be hydroxylated again
4. forms 1,25 OH2 Vit D or
24,25 OH Vitamin D |
|
|
Term
| What is the rold of 24, 25 OH Vit. D? |
|
Definition
| It is the inactive form of 1,25 OH2 Vit. D to prevent excess formation |
|
|
Term
|
Definition
|
|
Term
| what is the mediator of vit. D? |
|
Definition
| calbindins (calcium binding protiens) |
|
|
Term
| Vit D affects what systems and hormones? |
|
Definition
Bone : increases processes with PTH
Kidney: enhance Ca reabsorption
PTH: repress gene for PTH formation
Immune System: stimulate cytokine production |
|
|
Term
| how does Vit. D interact with Ca and Insulin? |
|
Definition
| aids in Ca enhanced Insulin secreation by beta cells |
|
|
Term
| What systems are affected by Vit D deficiency? |
|
Definition
Skeletal
Muscular
Cardiac
**causes a secondary hyperparathyroidsim** |
|
|
Term
| What are the issues connected with excess Vit. D? |
|
Definition
high Ca --> renal calculi
high P --> soft tissue calcification |
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