-
What does the parathyroid gland arise from
From endoderm of the 4th Pharyngeal arch for the superior glands, 3rd for the inferior
-
What are the two cell types that the parathyroid is made up of
- Principle chief cells (polygonal)
- Oxyphil cells (larger cells with unknown function)
-
How do chief cells respond to low Ca++
Secrete PTH (Parathyroid hormone)
-
What are the three main targets of PTH
- Osteoblasts
- Kidneys
- Intestines
-
What is the effect of PTH on Osteoblasts
Osteoblasts release Osteoclast releasing factors triggering osteoclasts to resorb bone increasing Ca++ into the blood
-
What is the effect of PTH on Kidneys
- Increases Ca++ absorption
- Decrease PO4 absorption
- Cause formation of Vit D (calcitriol)
-
What is the effect of PTH on the intestines
Promotes intestinal absorption of Ca++ via Vit D
-
High Ca+ has what effect on calcitonin
Stimulates
-
Where does the majority of body calcium end up
Bones
-
In what ways can calcium be found in the blood stream
- Bound to plasma proteins
- Bound to extracellular anions (citrate, phophate, ect.)
- Free calcium - ionized and difussible
-
What is the functional calcium in the blood stream that is used for diagnostic testing
Ionized (free calcium) which makes up 50% of the plasma calcium
-
What is the pathway for inhibition of PTH release from Chief cells
- High Ca+ in the blood binds Ca+ receptors
- G-protein activated
- IP3 releases Ca+ from the ER
- Ca+ inhibits the release of PTH from intracellular vesicles
-
How are Ca and Phosphate related
They have an inverse relationship
-
How are Calcitonin and PTH related
They are inversly related with PTH being high in Hypocalcemia and Calcitonin absent, the opposite is true in Hypercalcemia
-
25-hydroxy cholecalciferol
Modified version of Vit D that is converted to 1,25 Vit D (active form of Vit D) in the kidney upon binding of PTH
-
-
What happens to D3 after being made in the kidney
It goes to the intestines to increase Ca+ absorption
-
What inhibits the formation of PTH in the Parathyroids
- High plasma Ca+
- Calcitriol (Vit D3)
-
What are the different names for acitvated Vit D
- D3
- Calcitriol
- 1,25-dihydroxy cholecalciferol
-
Calcitonin is made by
Parafollicular cells of the Thyroid gland
-
How does Calcitonin release relate to Ca+ release
Calcitonin release is directly proportional to plasma Ca+ (Ca+high=Calcitonin release)
-
What is the function of Calcitonin
- Inhibits osteoclast activity
- Inhibits osteoclast formation
- Minor role inhibiting absorption of Ca+ and Phosphorus in the kindeys
- Overall reduces plasma calcium
-
What is the main transporter for Vit D
Vitamin D binding protein
-
What triggers the breakdown of Vit D3
- PO4
- High levels of Vit D3
- (PTH triggers its synthesis)
-
Low PO4 in ECF triggers what actions
- - Increase in Ca+ > Low PTH > Increase PO4 reabsorption in Kidney
- - Increase in Vit D3 > Increase in PO4 uptake in GI tract
- (Overall increase in PO4 in the ECF)
-
What effect does Vit D3 (Calcitriol) have on the bones
It triggers bone resorption increasing Ca+ in the plasma
-
What effects do Androgens and Estrogens have on Bones
They cause bone resorption and Osteoporosis
-
What are the effects of Thyroid hormones, Prolactin, and Cortisol on Ca+
- Thyroid hormones cause bone resorption
- Prolactin causes reabsorption of Ca+ in Kidneys
- Cortisol causes bone resorption and bone synthesis
-
Teriparatide & Cinacalcet are what type of drugs
Parathyroid related drugs
-
What are the two different Vitamin D supplements
- Cholecalciferol D3Ergocalciferol D2 (Plant form)
-
How can obesity effect Vit D
Vit D can get sequestered in fat, trapped from the bodies ability to utilize it
-
What is the primary therapeutic use of Calcitriol
- Used during renal failure when the body is unable to produce it
- It is also used to treat hypoparathyroidism
-
Cinacalcet
- This drug sensitizes the Ca+ receptors response decreasing the release on PTH
- Cin-Ca-lcet
- "Cinsitizes Ca receptors"
-
For what conditions is Cinacalcet used to treat
- Secondary Hyperparathyroidism (in renal disease)
- Primary Hyperparathyroidism
- Sometimes parathyroid carcinoma
-
What are the adverse affects of Cinacalcet
- Hypocalcemia
- Possible cardiac effects
-
What are the Calcium regulating drugs used to suppress high bone turnover
-
Teriparatide is used to treat
Osteoporosis by blocking the action of bone resorption
|
|