BIOM PART TWO - Lecture 3 Flashcards
Where is 99% of calcium found?
In the bones
What is calcium stably stored as?
Hydrooxyapatite
What is the hydroxyapatite made out of?
Calcium salts and phosphate which provide structural integrity
What is 1% of calcium found in?
Soft Tissues
How much is intracellular?
0.9%
How much is extracellular?
0.1%
What are intracellular and extraceullar calcium ions in the soft tissue essential for?
Neuromuscular excitation, blood coagulation, hormone secretion, enzyme activity, fertilization
What are characteristics of extraceullar calcium?
Very tightly regulated
50% ionized
40% Protein-Bound
10% complexed with phosphate and citrate
Extraceullar fluid/plasma
Bone
What are characteristics of Intracellular Calcium?
Highly regulated
More abundant than extraceullar
Largely associated with membranes in mitochondria, ER, plasma membrane
How is the total body Ca2+ calculated?
Intake - Output
What is the intake of Ca2+?
Diet
1/3 absorbed in small intestine
Absorption is hormone regulation
Recommended = 1000mg/day
What is the output of Ca2+?
Kidney’s
Body can’t make it so it has to be replaced
What are three hormones that regulate movement of calcium between bone, kidney’s and intestine
Parathyroid Hormone (PTH)
Calcitriol (Vitamine D3)
Calcitonin
What is PTH?
A peptide made by parathyroid hormone
How is PTH secrete?
Secretly continuously (not stored)
What does PTH help with?
Regulating calcium
Can Parathyroid gland be surgically removed?
No - thyroid gland can however.
What are the Two types of cells in the Parathyroid Gland?
Chief Cells
Oxyphils
What do Chief Cells do?
Secrete PTH
What happens when plasma Ca2+ falls?
PTH acts to raise the CA2+ levels back to normal via 3 mechanisms
What is the first mechanism?
Stimulate Osteoblasts to reabsorb bone
What is the Second Mechanism?
Stimulate kidneys to reabsorb Ca2+
What is the Third Mechanism?
Stimulate the kidneys to produce an enzyme that will activate Vitamin D to better absorb Ca in the intestinal epithelium
What is Hypocalcaemia?
Too low of Ca2+ in the blood
What does Hypocalcaemia do?
Increase PTH secretion, stimulates the reabsoprtion of Ca2+ back into the blood
What is Hypercalcameia?
Too much Calcium
What happens with Hypercalcemia?
Decrease in PTH
What is your bone constantly doing?
Constantly being formed and reabsorbed
What does your bone contain?
Calcified ECM
How does the calcified ECM form?
When the calcium phosphate crystals (hydroxyapatite) precipitate and attach to lattice for structural support
What is the most common form of calcium phosphate?
Hydooxyapatate
What happens in Bone Deposition?
Osteoblasts are going to secrete a matrix of collagen proteins which become hardened by deposits of hydroxyapatite
What happens in Bone reabsorption?
Osteoclasts dissolve hydroxyapatite and return the bone Ca2+ into the blood
