Final Exam 3 Flashcards
What is the composition of bones (general)?
Organic matric (30%) and bone salts (70%)
What is the organic matrix made up of?
collagen fibers and ground substance (homogenous gelatinous substance)
What is the salt in bone composition?
hydroxyapatite
What is calcium needed for?
intracellular reactions such as muscle contraction and nerve cell release of neurotransmitters
What is calcium and phosphorus needed for?
bone and teeth structure
What is most of calcium and phosphorus stored as?
hydroxyapatite
How is calcium stored?
intracellularly and in extracellular fluid
What is the site if hematopoiesis?
bone marrow
What is hematopoiesis?
Production of red blood cells
What can immature cells in bone marrow develop into?
RBCs, WBCs, and platelets
What are the closely linked processes of calcium?
- Formation of bone and teeth
- Regulation of Vitamin D, Parathyroid Hormone (PTH) and Calcitonin
What three organs control calcium levels?
bone, gastrointestinal tract, and kidneys
Bone remodeling occurs continually, breaking down ______ via ______
Hydroxyapatite by Osteoclasts
How is calcium absorbed?
by the GI tract
How is calcium excreted?
By the kidneys
True/False: Most calcium is excreted.
False; most is resorbed
What are the three major actions of vitamin D?
- Promotes intestinal absorption of calcium and phosphate
- Increases renal reabsorption of calcium and phosphate (minor)
- Enhances bone calcification (by increasing calcium transport, activating osteoblasts?)
What part of the kidneys absorb calcium?
the renal tubules
What happens when calcium concentration is low?
The kidneys absorb more
What controls the rate of calcium excreteion?
Parathyroid Hormone (PTH)
How is renal phosphate controlled?
By overflow mechanism
_____ can greatly increase phosphate excretion by kidneys.
PTH
True/False: Vitamin D (active form) can increase Calcium Absorption from the Intestinal Tract.
True
True/False: Your body can not produce its own vitamin C
False; your body can produce its own vitamin c
