Busy. Please wait.

show password
Forgot Password?

Don't have an account?  Sign up 

Username is available taken
show password


Make sure to remember your password. If you forget it there is no way for StudyStack to send you a reset link. You would need to create a new account.
We do not share your email address with others. It is only used to allow you to reset your password. For details read our Privacy Policy and Terms of Service.

Already a StudyStack user? Log In

Reset Password
Enter the associated with your account, and we'll email you a link to reset your password.
Don't know
remaining cards
To flip the current card, click it or press the Spacebar key.  To move the current card to one of the three colored boxes, click on the box.  You may also press the UP ARROW key to move the card to the "Know" box, the DOWN ARROW key to move the card to the "Don't know" box, or the RIGHT ARROW key to move the card to the Remaining box.  You may also click on the card displayed in any of the three boxes to bring that card back to the center.

Pass complete!

"Know" box contains:
Time elapsed:
restart all cards
Embed Code - If you would like this activity on your web page, copy the script below and paste it into your web page.

  Normal Size     Small Size show me how

Phys3 Ca & Phosph

Phys3 Renal Ca+ & Phosphorus

Ca+ exists in 3 forms 1.40% is non-filterable b/c it is protein bound. 2.15% of Ca+ is complexed with small anions (ex: carbonate, citrate, phosphate, & sulfate). 3.45% is ionized Ca+ (this is what is tightly regulated by the body).
How is moment to moment extracellular Ca+ regulation achieved? By shifting Ca+ in and out of BONE
How many hydroxylations does Vit D undergo? TWO: 1.Liver. 2.Kidney (stimulated by PTH).
Vit D in gut facilitates the absorption of what? 1.Ca+ (entry, buffering, absorption into plasma). 2.Phosphate.
Vit D is critical in the synthesis of what in the GI Enterocytes? Intracellular Ca-Binding proteins. **these aid Ca+ entry into the cell through apical membrane & minimize the free Ca+ within the cell.
2 ways Ca+ exits the GI enterocyte's basolateral membrane? 1.Ca ATPase. 2.Na/Ca exchanger when Ca ATPase is saturated.
What stimulates the Ca-ATPase on the basolateral membrane of the enterocytes? Vitamin D
Dec Plasma [Ca] Inc PTH: 1.Kidney: Inc hydrolysis of Vit D, Inc Ca+ reabsorption. 2.GI: Inc Ca+ absorption. 3.Bone: Inc osteoclast activity
Where is the Renal tubule does PTH cause an Inc in Ca+ reabsorption in response to Dec plasma [Ca+]? 1.Thick Ascending limb (25%). 2.Distal convoluted tubule (. 3.Connecting tubule/Collecting Ducts (1.5%).
What are the 3 sites of Ca+ regulation? 1.GI enterocytes. 2.Bone. 3.Kindey
Where is 65% of filtered Ca+ reabsorped? is it subject to hormonal control (ex: PTH)? Proximal Tubule via paracellular reabsorption. NO. **tied to Na+ & water reabsorption, Inc when they Inc b/c water leaving creates an Inc concentration gradient.
How much of the filtered load of Ca+ to you actually excrete? 0.5 to 1% of FL.
How is Ca+ reabsorbed in the Thick Ascending Limb? 1. 50% passive & paracellular (from + voltage w/in tubule, this is caused by ADH). 2. 50% active & transcellular (PTH influences).
What is major regulatory site of Ca+ in the kidney Distal Convoluted Tubule (DCT). 1.PTH stimulates Ca channel on apical mem causing Ca+ to move from the tubule into the cell. 2. Vit D buffers Ca+ in the cell and Activates Ca-ATPase on basolateral mem.
Can plasma Ca+ have a direct effect on Ca+ reabsorption in the kidneys? YES. Ca+ sensing receptor on basolateral mem which will block the tri-transporter on apical membrane which with cause the lumen + voltage to disappear and Dec Ca+ reabsorption.
How do Loop diuretics affect Ca+ reabsorption? DECREASE b/c they will interfere with the lumen + voltage driving paracellular reabsorption.
Are loop diuretics used to treat hypercalcemia? NO
How do thiazide diuretics affect Ca+ reabsorption? INCREASE it. **They block the Na/Cl symporter in DCT, Dec Na w/in the cell, Inc activity of Na/Ca exchanger on the basolateral membrane.
How does volume contraction affect Ca+ reabsorption in PT? Inc Ca+ reabsorption by Inc Na+ & water in PT due to SNS and AngII response.
What is the important role of Phosphate in Acid/Base balance? Buffering H+ secreted in tubule lumen and excreted as titratable acid (H2PO4).
Where does most Phosphate reabsorption occur? 80% occurs in the Proximal Tubule via Na/phosphate symporter.
Does Phosphate have limited reabsorption? YES, any Filtered Load above Tm will be excreted
Does PTH Inc or Dec phosphate reabsorption? DECREASES it by promoting renal phosphate excretion. **PTH inhibits apical sodium/phosphate uptake
What 2 things stimulate PTH secretion? 1.Dec plasma [Ca]. 2.Inc plasma [Phosphate].
Acidosis Causes Inc Ca+ and Phosphate release from bone, which is good b/c filtered phosphate can absorb and buffer H+ ions to raise pH.
Primary Hyperparathyroidism Inc PTH!! causes: 1.Inc bone resorption. 2.Inc plasma Ca+. 3.Dec plasma phosphate. 4.Inc Urinary phosphate excretion. 5.Inc Urinary Ca+ excretion (Ca+ is so high it exceeds ability to absorb).
Created by: WeeG