Endocrine 1 and 2 Flashcards
What are the 2 ways hormones can be transported?
- Bound to plasma proteins
2. Free in the blood
Which hormones are biologically active?
Those that are free in the blood
What are 3 general characteristics of hormones?
- They have a specific rate of secretion
- Feedback systems, either positive or negative feedback
- Affect only cells with the appropriate receptors
What are the 5 functions of the endocrine system?
- Homeostasis
- Energy metabolism
- Reproduction
- Growth and development
- Response to stress and injury
What are the 3 types of endocrine disease?
- Oversecretion or hyper function
- Undersecretion or hypo function
- Mass effect or tumors
What is mass effect?
A tumor presses on another organ altering its function
Where is the parathyroid gland located? How many are there usually? What is the range of how many there can be?
Located on the posterior part of the thyroid gland. Normally there are 4 of them but can be 1-12
The parathyroid glands are derivatives of?
The third and fourth branchial pouches
What are 3 possible ectopic locations of the parathyroid?
Intrathyroid, intrathymic, anterior mediastinum
Is the parathyroid gland encapsulated? What three things make up the gland?
Yes
Oxyphil cells, chief cells, stromal fat
Describe the appearance of a chief cell?
Polygonal cells with clear cytoplasm (glycogen), central uniform nuclei
Describe an oxyphil cell
Has acidophilic cytoplasm with abundant mitochondria
Stromal fat makes up what percentage of the gland?
30%
What controls the release of PTH?
Free or ionized calcium
How does PTH regulate calcium?
- Causes release of calcium from bone
- Decreases reabsorption of phosphate and increases calcium absorption in the kidney
- Vitamin D3 is hydroxyl and this causes reabsorption of calcium in the intestine
What is the range for serum calcium and free calcium?
Serum is 8-10 mg/dl
Free is 4-5.6 mg/dl
What is the normal range for PTH?
10-65 nanomoles/L
What are the 2 general causes of hypercalcemia?
Raised PTH or lowered PTH
Raised PTH is due to hyperparathyroidism, what are the usual causes of PRIMARY hyperparathyroidism?
Almost always an adenoma but can also be from hyperplasia, (carcinoma 1% of the time)
Does increased PTH always lead to hypercalcemia?
No calcium can be high, low, or normal depending on RENAL FUNCTION
What causes SECONDARY hyperparathyroidism?
Increase in PTH secondary to HYPOcalcemia and HYPERphosphatemia of chronic renal failure
What is TERTIARY hyperparathyroidism?
Autonomous parathyroid hyper function in those with secondary hyperparathyroidism
What can cause decreased PTH?
Malignancy (anywhere like small cell carcinoma of the lung) Vitamin D toxicity Immobilization Thiazide diuretics Granulomatous disease like sarcoidosis
Most cases of hyperparathyroidism are?
Asympomatic (see chart for possible symptoms)
What two effects does excess PTH have on bone?
Osteoporosis and ostelitis fibrosa cystica (brown tumor)
In ostelitis fibrosa cystic what cells are present in marrow?
Multinucleated giant cells, inflammatory cells, also fibrosis
What can ostelitis fibrosa cystica present as?
Cystic lesion in small bones
How can you detect how many parathyroid glands are enlarged?
Sestamibi scanning
Parathyroid adenomas occur more in men or women?
3x more often in women
How do you distinguish an adenoma from hyperplasia?
An adenoma will be sharply demarcated from the gland