Endocrine II Flashcards
Describe the covering of the parathyroid glands.
Covered by a collagenous connective tissue capsule which send septa that carry blood vessels, lymphatic vessels, and nerve fibers into the glands
What forms the supporting framework of the parathyroid glands.
Septa and reticular fibers form a supporting framework
What type of capillary network is found in the parathyroid glands?
a fenestrated capillary network
What percentage of the parathyroid gland is adipose tissue in the adult?
60-70%
How are epithelial cells arranged in the parenchyma of the parathyroid gland?
as cords or clusters
True or False: Chief cells are basophilic.
FALSE
eosinophilic
What do the secretory granules of chief cells contain?
parathyroid hormone PTH
enclosed by secretory granules and liberated by exocytosis
Describe the synthesis of PTH.
1) Ribosomes on the rER manufacture preproparathyroid hormone
2) Split as it is carried to rER lumen to form proparathyroid hormone and polypeptide
3) When it enters the golgi, it is split again to parathyroid hormone and polypeptide
What is the function of oxyphil cells?
function unknown
may be dormant, inactive chief cells
How do oxyphil cells stain?
intensely eosinophilic [due to mitochondria]
Which is larger: chief cells or oxyphil cells?
oxyphil cells
What is the function of intermediate cells?
function unknown
What are the three cell types found in parathyroid glands?
chief cells, oxyphil cells and intermediate cells
Is PTH essential for life?
Yes
What does PTH regulate?
calcium and phosphate levels in the blood
[ * it increases blood calcium level, and simultaneously decreases serum phosphate]
What do gland cells detect?
calcium
gland cells have calcium-sensing receptors
How do low levels of serum calcium affect PTH? high levels of calcium?
low serum Ca 2+ –> stimulate release of PTH
high serum Ca 2+ –> inhibit release of PTH
How does PTH influence bone?
- PTH attaches to osteoblast receptors
- casuses osteoblasts to release osteoclast simulating factor which triggers osteoclast activity
- therefore, frees calcium from bone to enter the bloodstream
How does PTH influence kidneys?
PTH prevents calcium loss in the urine
PTH promotes phosphate loss in the urine
How does PTH influence the GI tract?
- By regulating the formation of vitamin D in the kidneys
PTH controls the rate of calcium absorption from the GI. Vitamin D facilitates Ca 2+ absorption from the GI
How do PTH and calcitionin work together?
PTH increases low calcium levels in the blood to normal
Calcitonin decreases elevated calcium levels in the blood to normal
Why can’t surgeons completely remove the parathyroid glands?
Complete removal of the parathyroid glands will drop blood calcium level. This will cause tetanic contraction of muscles, including the laryngeal and respiratory muscles —> death
Describe the connective tissue capsule of the pancreas.
The capsule gives rise to septa which 1) partition the gland into poorly defined lobules and 2) carry blood vessels, lymphatic vessels, and gland ducts
What does the exocrine portion of the pancreas produce?
digestive enzymes
What does the endocrine portion of the pancreas produce?
hormones
Where are islets of Langerhans found?
in the endocrine pancreas
What are the 5 cells found in the islets of Langerhans?
Alpha cells Beta cells Delta cells G cells PP cells (F cells)
How can the different cells int eh islets of Langerhans be differentiated?
immunocytochemical procedures
What hormone is associated with alpha cells?
Glucagon