Endo Lec 5 Flashcards
parathyroid glands look like
small pearls
chief cells of parathyroid gland secrete
parathyroid hormone(PTH)
conc of free Ca++ is __ in the ECF than ICF
greater
PTH increases ___ and decreases ___ in ___
- [Ca++]
- [phosphate]
- in ECF
conc of bound Ca++ is __ in the ECF than ICF
lower
parathyroid regulates __ Ca++ in __
- free
- ECF
Calcitonin is a __ that
hormone that plays a role in regulating the level of calcium in your blood by decreasing it.
importance of calcium
- Structural role (bone, teeth)
- Blood coagulation
- Intracellular messenger
- Regulation of excitability
importance of phosphate
- Structural role
- Metabolism (ATP, nucleic acids)
- Buffer (maintaining pH balance)
source – hormone – target ? source= parathyroid gland
hormone: PTH
target: bone (kidneys and GIT indirectly)
source – hormone – target ? source= kidneys
hormone: active vitamin D
target: GIT
source – hormone – target ? source= thyroid gland (parafollicular cells)
hormone: calcitonin
target: kidneys (bone and GIT indirectly)
bone (3 components)
- organic framework.matrix, osteoid (1/3 total weight)
- inorganic salts (2/3 total weight)
- bone cells
organic framework.matrix, osteoid (components)
-collagen type 1
inorganic salts (components)
- calcium phosphate
- hydroxyapatite
bone cells (type)
- osteoblasts
- osteocytes
- osteoclasts
osteoblasts
synthesize bone matrix and coordinate the mineralization of the skeleton
addition of Ca++ to bone
osteocytes
cell in mature bone tissue, maintain bone (has dendrites that connects osteoblasts)
osteoclasts
cells that degrade bone to initiate normal bone remodeling
release Ca++ from bone
hormonal control of Ca++ balance
↓ plasma Ca++
↑ parathyroid hormone secretion
kidneys: ↑ Ca++ reabsorption , ↑active Vit-D (↑Ca++absorption in intestine)
vitamin D3 also
cholecalciferol
active vit. D other names
- calcitriol
- 1,25 (OH)2 cholecalciferol
synthesis of active vitamin D3
vitamin D3 (cholecalciferol) --> (in liver) 25-OH cholecalciferol---> (in kidneys by 1-hydroxylase) calcitriol (active vit. D)
PTH influence of 1-hydroxylase
PTH (+) stimulates activity of 1-hydroxylase
absorption of Ca++
- in the presence of vitamin D, ca++ channels, open on the luminal side of duodenal cells
- Ca++ forms complex with calbindin andmoves to basolateral side
- Active transport of Ca++ on basolateral cell through Ca++ ATPase
vitamin D regulated proteins as transcription factor
Epithelial calcium channel (ECaC)
Calbindin protein
Basolateral calcium pump
deficiency of active Vit D
rickets (soft spot on baby head, bony necklace, curved bones, big lumpy joints, bowed legs)
hormones favoring bone formation (6)
- Insulin
- Growth hormone
- Insulin like growth factor-1
- Estrogen
- Testosterone
- Calcitonin
hormones favouring bone reabsorption (3)
- PTH (chronic elevation)
- Cortisol
- Thyroid hormones (T3 and T4)
low calcium disease
tetany
