Bone and Calcium Homeostasis Flashcards
_____is the most abundant mineral in bone
Calcium
____is the most abundant mineral in the human body.
calcium
Calcium ions are needed not only for bone mineralization but for tooth health, regulation of the heart rate and strength of contraction, blood coagulation, contraction of smooth and skeletal muscle cells, and regulation of nerve impulse conduction.
Ise read it and say T/F
Ttttttt
The normal level of calcium in the blood is about ____.
10 mg/dL
When the body cannot maintain a normal level of calcium , a person will experience ___ or ____
hypo- or hypercalcemia.
Calcium metabolism or calcium homeostasis is the mechanism by which the body _____calcium levels.
maintains adequate
Derangements of calcium metabolism lead to ____ or _____, both of which can have important consequences for health.
hypercalcemia or hypocalcemia
calcium flow to and from the bone is neutral
T/F
T
about ___ mmol of calcium from bone is turned over a day.
five
Bone serves as an important storage point for calcium, as it contains ___% of the total body calcium.
99
Calcium release from bone is regulated by _____ hormone.
parathyroid
_____stimulates incorporation of calcium in bone.
Calcitonin
Hypocalcemia
-A condition characterized by abnormally ___ levels of calcium
-it can have an adverse effect on a number of different body systems including circulation, muscles, nerves, and bone.
T/F
low
T
Without adequate calcium, blood (has difficulty coagulating or over coagulates?) , the heart may ___ or _____ altogether, muscles may have difficulty _____, nerves may have difficulty functioning, and bones may become ____.
has difficulty coagulating
skip beats or stop beating
contracting
brittle
The causes of hypocalcemia can range from ____ to____
hormonal imbalances
an improper diet.
Treatments for hypocalcemia are constant irrespective of the cause
T/F
F
vary according to the cause
prognosis for hypocalcemia are generally (good or bad?)
Good
when calcium level reduces below normal, ____ glands release ____ that increases the activity of osteo___ to ____ calcium from ___, __reased calcium reabsorption from kidneys and calcium’s absorption in the ____increases with__ synthesis
parathyroid; PTH
clasts
release ; bone
inc
small intestine ; vitD
Hypercalcemia
- a condition characterized by abnormally —- levels of calcium
- the nervous system is (overactive or underactive?) , which results in ___,___ reflexes, constipation and ___ of appetite, confusion, and in severe cases,___.
high
Underactive
lethargy
sluggish
loss
coma
calcium homeostasis is critical.
T/F
T
The ___,____, and____ systems play a role in this, but the kidneys do, too.
-These body systems work together to maintain a normal calcium level in the blood
skeletal
endocrine
digestive
when calcium level rises above normal, ____ gland releases____ that ____ osteoclasts activity and____ calcium’s rate of reabsorption in the kidney and calcium level decreases back to normal
thyroid
calcitonin
inhibits
reduces
The body deposits calcium in the bones when blood levels get too___, and it releases calcium when blood levels drop too___.
-This process is regulated by____,____, and____.
high
low
PTH
vitamin D
calcitonin
Calcium is a chemical element that can be produced by some biological processes.
T/F
F
Can’t be produced by any
The only way calcium can enter the body is through the ____
diet.
The ___ act as a storage site for calcium
bones
Cells of the parathyroid gland do not have plasma membrane receptors for calcium.
T/F
F
They do
When calcium is not binding to parathyroid gland membrane receptors, the cells release___, which stimulates osteo__ proliferation and ____ of bone by osteo___.
-This demineralization process ___ calcium into the blood.
PTH
clast; resorption;clasts
releases
PTH promotes ___ of calcium from the urine by the kidneys, so that the calcium ___ to the blood.
-Finally, PTH stimulates the synthesis of____, which in turn, stimulates calcium absorption from any_____ in the______.
reabsorption
returns
vitamin D
digested food
small intestine
When blood levels of calcium get too high, the ____ gland is stimulated to release____, which ____ osteoclast activity and ___ calcium uptake by the bones, but also ____ reabsorption of calcium by the kidneys.
-All of these actions ___ blood levels of calcium.
thyroid
calcitonin
inhibits
stimulates
decreases
lower
High calcium intake may be a risk factor in the development of osteoporosis.
T/F
F
Low calcium levels
With a better bone balance, the risk of osteoporosis is lowered.
T/F
T
Supplementation with _____ and _____ slightly improves bone mineral density.
vitamin D
calcium
Vitamin D and Calcium Homeostasis
- Vitamin D is converted to____(also called _____) in the liver.
- Part of it is converted by the ___ to ____, the biologically active form of vitamin D.
- It circulates as a hormone in the blood, regulating the concentration of____ and____ in the bloodstream and promoting the healthy growth and remodeling of bone.
calcidiol
calcifediol
kidneys
calcitriol
calcium; phosphate
Responses to Blood Calcium Changes
- When blood calcium concentration rises
- the ______ cells of the thyroid gland increase calcitonin secretion into the blood.
- At the same time, the parathyroid glands (increase or reduce?) parathyroid hormone secretion into the blood.
- The resulting high levels of calcitonin in the blood stimulate the bone to remove calcium from the___ and deposit it as____.
- Removal of calcium from the bone is also (facilitated or inhibited?)
parafollicular
Reduce
blood plasma
bone
Inhibited
When the blood calcium level is too low
-calcitonin secretion is ____ and PTH secretion is _____.
-This results in the ___ of calcium from the___ to correct blood calcium levels.
inhibited
stimulated
removal; bone
calcitriol: The active metabolite—_________—that is involved in the_____ of calcium.
1,25-dihydroxycholecalciferol
absorption
calcidiol: A ______ that is produced in the ___ by the____ of vitamin D3 (____) by the enzyme ____________
prehormone
liver
hydroxylation
cholecalciferol
cholecalciferol 25-hydroxylase.
