Calcium Flashcards
____ IS THE MOST ABUNDANT MINERAL IN THE BODY
CALCIUM!
about 99% of calcium in the body is found
in the bone and teeth
sources
dairy seafood veggies figs black strap molasses
_____ is the most potent inhibitor of calcium absorption and is found at high concentration in spincach and rhybabrb
oxalate (oxalic acid)
calcium is present in foods as relatively insoluble _____
salts
calcium can be solubilized at an _____pH
acidic
absorption of calcium occurs primarily in the SI and
two routes
- duo and prox jeju
- jeju and ile
- absorption through the duodenum and proximal jejunum
cellular active transport (req ATP) saturable involves calcium binding protein stimulated by 1,25OH and low Ca levels
- absorption through the jejunum and ileum
paracellular passive diffusion- requires no energy unsaturable requires no carrier stim- when high [ ] of Ca intracell and in lumen stim by FOS
factors that enhance calcium absorption
growth pregnancy lactation vitamin d simple sugars protein food
factors that inhibit calcium absorption
oxalate phytate fiber other divalent cations and minerals fal maldigestion
Calcium is transported across the cytoplasm of the enterocyte bound to
CBP
calcium is transported from enterocyte into extracellular fluid by
Ca/Na ATPase
calcium is transported in the blood in three forms
free
proteins (albumin)
sulfate, phosphate, citrate
calcium levels in the___ and ___ must be maintained within a very narrow concentration range for normal physiological functioning
blood and extracellular fluid
extracellular calcium concentration or regulated by
PTH
calcitriol
calcitonin
___ plasma calcium levels stimulate PTH secretion and inhibit calcitonin secretion
low
PTH and calcitriol _____ plasma calcium
increase
PTH increases renal synth of calcitriol from ___
25-OH vit d
PTH and calcitriol increases renal tubular reabsorption of
calcium
calcitriol enhances intestinal ____absorption
calcium
PTH and calcitriol stimulate _____ activity
osteoclast
high plasma calcium levels stimulate ____ secretion, which _____ serum calcium levels
calcitonin, lower
calcitonin secretion inhibits _____activity which stimulates osteoblasts
osteoclasts
calcitonin inhibits ____ production which decreases calcium absorption and increases calcium excretion in the urine
calcitriol
Serum calcium
incr PTH
incr calcitriol
decr calcitonin
bone calcium
decr PTH
dec calcitriol
incr calcionin
renal calcium reabsorption
incre PTH
incr calcitriol
decr calcitonin
intestinal calcium absorption
no effect on PTH
incr calcitriol
no effect on calcitonin
low free calcium concentration are maintained within the ____
cytoplasm
calcium is needed in higher concentrations where
in the cells to carry out fxns
cell activation by ___, ___ or ___ results in increased calcium entering the cell by diffusion or by the opening of calcium channels
depolarization
neurotransmitters
hormones
calcium is a major structural element in ___ and ___
bone and teeth
the mineral component of bone consists mainly of___
hydroxyapatite
_____ begin remodeling by dissolving or resorbing bone
osteoclats
_____ synthesize new bone to replace the bone that was resorbed
osteoblasts
during normal growth, bone formation_____ bone resportion
exceeds
_______ may result when bone resorption chronically exceeds formation
osteoporosis
functions of calcium
bone mineralization
nerve conduction
muscle contraction
coagulation
calcium entering the neuron triggers the release of _____ signalling muscle contraction
acetyl choline
when mm fiber receives nerve impulse to contract, calcium channels in the cell membrane _____ to allow a small number of calcium ions into the muscle cell
open
the binding of calcium is required for the activation of several ______dependent clotting factors in the coagulation cascade
vitamin k
most of the calcium in the blood is filtered and reabsorbed by the ____
kidney
calcium is primarily excreted from the body in the
urine and feces (also perspiration a bit)
Deficiency of calcium results in
hypocalcemia
osteoporosis
T or F calcium deficiency is most common in women over the age of 12, and the elderly
true
hypocalcemia usually implies____ and is rarely due to low dietary calcim intake
parathyroid function
other causes of hypocalcemia
chronic kidney failure
vitamin d deficiency
low blood magnesium
(usually caused by alcoholism)
symptoms of hypocalcemia
tetany and muscle spasm, muscle pain ad parashtesias
low seruum calcium levels cause what
muscle spasms
why does low serum calcium levels cause muscle spasm
because the permeability of neuronal membranes to sodium ions increases, causing a progressive depolarization, which increases the possibility of generating action potentials
tests for hypocalcemia
chvosteks sign
trousseaus sign
what is chvosteks sign
abnormal spasm of facial muscle elicited by a light taps on the cheek
what is trousseaus sign
the wrist and metacarpophalangeal joints flex, the DIP and PIP joints extend and the fingers adduct
how do you elicit a trousseaus sign
a blood pressure cuff is placed around the arm and inflated for three minutes. this will occlude the artery and in absence of flow the patients hypocalcemia and neuromuscular irritability will induce spasm
what is osteoporosis
increase bone fragility and fracture risk
chronically ___ calcium intake may result in a failure to attain optimal bone mass
low
once peak bone mass is acheived, inadequate __ intake may contribute to osteoporosis
calcium
clinical indications for calcium supplementation
osteoporosis
kidney stones
_____resulting from the over consumption of calcium from FOOD has never been reported
hypercalcemia
hypercalcemia has been reported with consumption of large quantities of ___-
calcium supplements
symptoms of mild hypercalcemia include
loss of appetite n/v constipation abd pain dry mouth, thirst freq urination
sever hypercalcemia may result in
confusion
delerium
coma
death
increase dietary calcium has been associated with a _____ risk of kidney stones
decreased
high calcium may decrease the absorption of
non heme iron
zinc
high calcium intake may decrease tissue levels of
mg
high __ intake can increase calcium excretion in the urine
sodium
