Midterm - Lecture 7 Flashcards
What is the normal concentration of calcium in the blood?
.45% in plasma and extracellular fluids
10 mg/dl
What is the normal concentration of phosphorus in the blood?
4-8 mg/dl
What is the normal concentration of Magnesium in the blood?
1.8-2.4 mg/dl
How can the normal concentration of magnesium in the blood be lowered?
by increasing renal excretion of Mg once plasma Mg exceeds threshold
What are the extracellular functions of Ca?
skeletal tissue, transmission of nerve-impulses, excitation of skeletal and cardiac muscles, blood clotting, component of milk and egg shells
What are the intracellular functions of Ca?
critical for activity of enzymes and second messenger for hormone signals
What do low levels of blood Ca lead to?
hypocalcemia
What can hypocalcemia cause?
tetany, paresis, reduced cardiac muscle strength, bone dissoultion, osteoporosis, osteodystrophy
What do high levels of plasma Ca lead to?
hypercalcemia and calcification of soft tissues
What is phosphorus’ role in the blood?
control of blood pH
What is the role of the parathyroid hormone?
it is critical to keep blood Ca at 9-10 mg/dl
used to decrease the Ca excretion by the kidney
When does passive paracellular calcium absorption happen?
only occurs if diet calcium is high enough to raise Ca in the lumen of the gut above 6 Mm ionized calcium
What does active transcellular transport of calcium require?
the hormone form of Vitamin D to transport it across the intestinal wall
How do hindgut fermentors absorb calcium?
intestine absorbs calcium with high efficiency all the time even in the absence of Vitamin D
What is the role of Vitamin D?
- required nutrient only in the absence of adequate exposure to sunlight for many species
- required for the active transcellular transport across the intestinal wall
- required for the absorption of phosphorus
What is the roll of fibroblast growth factor 23?
- shuts off production of the vitamin D hormone
- If blood P is low, bone cells cease the production of this to allow more vitamin D production hence more P absorption
When does milk fever occur?
when the blood calcium levels are low
alkalosis
What are some side effects of milk fever?
reduces muscle function, reduces feed intake, reduces immune function
When does caged layer fatigue occur?
when the blood calcium levels are low, hens pull calcium out of their bones and put it into the shell of the eggs they are laying
What are the side effects of caged layer fatigue?
long term bone fractures, lay eggs with very thin eggshells, will cause osteoporosis
What happens during eclampsia in dogs, mare, and sow?
the mammary gland will remove more calcium from the blood than the diet can replace
What is Vitamin D3?
choleocalciferol
How is Vitamin D3 synthesized?
made by irradiating skin of most species - dog and cat skin cannot make
What is Vitamin D2?
Eragocalciferol
