71 Questions
The normal total serum calcium level is _______________________ mmol/L.
2.5
What is the function of protein-bound calcium in the body?
Inactive and not biologically available
Match the following components of total calcium with their percentages:
Protein-bound calcium = 45% Free ionic calcium = 45% Complexed calcium = 10%
Calcium ions destabilize the cell membrane.
False
What is the role of calcium in biological membranes?
Key factor in stability
Every month, an adult resorbs about 1% of their bone, while reforming about 1% of their bone.
False
What is the theory that describes the process of bone remodeling?
The Theory of Remodeling
The study of biological control systems, whereby signaling molecules act via the ___________, is called Endocrinology.
circulation
Match the following bones with their respective types:
Neck of Femur = Trabecular bone Vertebral Body = Trabecular bone Cortical bone = Cortical bone Trabecular bone = Trabecular bone
What is the purpose of the three hormones PTH, CT, and 1,25(OH)2D in the body?
To regulate ionized Calcium in the blood
Alkaline Phosphatase levels increase with age.
False
Haversian canals are found in the ______________ bone.
cortical
What is the primary function of PTH in the body?
Regulate calcium levels
PTH is an example of a positive feedback loop.
False
What is the aim of the negative feedback loop involving PTH?
To normalize back to a setpoint
When you eat 1000 mg of calcium, you absorb _______ mg.
200
What is the approximate total serum calcium level in the blood?
2.5 mmol/L
Match the following health conditions with their corresponding PTH levels:
Primary Hyperparathyroid = 14 pmol/L Hypoparathyroidism = 7 pmol/L Parathyroid OK, but cancer = 0 pmol/L
Calcium is completely absorbed from food into the bloodstream.
False
What is the normal bone condition in relation to calcium levels?
Normal bone
What is the amount of calcium absorbed by the body if enough vitamin D is present?
200 mg
Vitamin D is necessary for poor calcium absorption.
False
What is the result of poor calcium absorption?
LOW BONE DENSITY
The two types of bone structures in the human skeleton work together to _______________ and prevent bending.
prevent vertical collapse
What is the amount of calcium excreted in the urine if enough vitamin D is present?
100 mg
Osteoporosis is a condition characterized by high bone density.
False
What is the amount of calcium absorbed by the body if not enough vitamin D is present?
0.1 g/day
Match the following terms with their descriptions:
Vitamin D = necessary for good calcium absorption Osteoporosis = a condition characterized by low bone density Calcium = essential for bone health Bone structures = work together to prevent vertical collapse and bending
What is the effect of calcium on the cell membrane?
It makes the cell membrane firmer and less permeable
Low calcium levels lead to hyperexcitability of neuromuscular tissues.
True
What is the primary purpose of bone in the body?
to be a reservoir of calcium
The concentration of calcium in the bloodstream is tightly regulated, with a coefficient of variation (CV) of ______________.
3%
What is the effect of low calcium levels on the threshold voltage for firing in neurons?
It decreases the threshold voltage
Bone growth stops after puberty due to the mineralization of the growth plate.
True
Match the following terms with their descriptions:
Chvostek Sign = A condition caused by low calcium levels Trousseau Sign = A condition caused by low calcium levels Epiphysial Fusion = The stoppage of longitudinal growth Endochondral ossification = The process of bone growth from fetus to adult
What is the process of bone growth from fetus to adult?
Endochondral ossification
What is the effect of sufficient vitamin D on calcium absorption?
Sufficient vitamin D enables the body to absorb 200 mg of calcium.
What happens to calcium absorption when there is insufficient vitamin D?
Only 100 mg of calcium is absorbed.
What is the normal outcome when sufficient vitamin D is present?
NORMAL BONE DENSITY
What are the two types of bone structures in the human skeleton?
Two types of bone structures are not specified in the provided content.
What is the consequence of poor calcium absorption?
LOW BONE DENSITY
What is the condition characterized by low bone density?
Osteoporosis
What is the amount of calcium passed to the stool when sufficient vitamin D is present?
200 mg
What is the amount of calcium excreted in the urine when sufficient vitamin D is present?
200 mg
How does the body respond to insufficient vitamin D levels?
Poor calcium absorption, leading to low bone density.
What is the significance of calcium in maintaining healthy bones?
Calcium is essential for maintaining normal bone density.
Calcium is the 3rd most abundant element in the earth's crust.
False
Ionized plasma calcium is biologically available for membranes or bone.
True
The lipid bilayer of cell membranes is destabilized by calcium ions.
False
Sea water contains about 10 mmol/L of calcium.
True
The normal total serum calcium level is 2.2 mmol/L.
False
Every year, an adult loses about 0.1% of their bone due to the remodeling process.
False
The three hormones PTH, CT, and 1,25(OH)2D serve to regulate ionized Magnesium in the blood.
False
Alkaline Phosphatase levels decrease with age.
False
The primary function of calcium in biological membranes is to make them more permeable to other substances.
False
The study of biological control systems, whereby signaling molecules act via the nervous system, is called Endocrinology.
False
Epiphyseal fusion occurs before the stoppage of longitudinal growth.
False
The concentration of calcium in the bloodstream has a coefficient of variation (CV) of 10%.
False
High calcium levels lead to hyperexcitability of neuromuscular tissues.
False
The growth plate also mineralizes before puberty, and longitudinal growth stops.
False
The primary purpose of bone is to provide structural support for the body.
False
When you eat 400 mg of calcium, you absorb all of it if you have enough vitamin D
False
Osteoporosis is a condition characterized by high bone density
False
Vitamin D is necessary for poor calcium absorption
False
The two types of bone structures in the human skeleton work together to prevent bending and promote vertical collapse
False
When there is not enough vitamin D, you absorb 200 mg of calcium if you eat 400 mg
False
The majority of calcium consumed from food is absorbed into the bloodstream.
False
PTH serves the purpose of regulating the body's calcium levels through a positive feedback loop.
False
The total serum calcium level is the sum of free and protein-bound calcium, approximately equal to 2.5 mmol/L.
True
When calcium is absorbed from food, it is directly utilized by the bones for growth and development.
False
The normal bone condition in relation to calcium levels is characterized by high calcium levels in the bloodstream.
False
Study Notes
Calcium Overview
- Atomic weight: 40 g/mol
- Valence: +2 (divalent cation)
- Bone calcium: Tricalcium phosphate
- Abundance: 3.64% of the Earth's crust (5th most abundant element)
- Sea water concentration: 400 mg/L (10 mmol/L)
- Milk concentration: 300 mg/L
- Normal serum calcium: 2.5 mmol/L
Measuring Calcium
- Laboratory testing: measures total serum calcium and ionized plasma calcium
- Normal total serum calcium: 2.5 mmol/L
- Normal ionized calcium: 1.2 mmol/L
- Total calcium composition:
- Protein-bound calcium (45%): inactive, not biologically available
- Free ionic calcium (45%): active, biologically available
- Complexed calcium (10%): eg. Ca citrate
Calcium in Biology
- Key factor in biological membrane stability
- Involved in subcellular signaling
- Essential component of bone
- Stabilizes cell membranes by anchoring to phospholipids
- Makes excitable membranes more resistant to depolarization
- Regulates neuromuscular activity
Bone Disease
- Parathyroid hormone (PTH) measured if calcium is abnormal
- Bone markers (eg. Alkaline phosphatase) provide insight into cellular activity and therapy monitoring
- Calcium is essential for bone growth and maintenance
- Bone structure:
- Cortical bone
- Trabecular bone
- Bone remodeling theory: resorption and formation occur continuously
- Bone loss: 1% per year in adults
Endocrinology
- Study of biological control systems involving signaling molecules in the circulation
- Three hormones regulate ionized calcium in the blood:
- Parathyroid hormone (PTH)
- Calcitonin (CT)
- Calcitriol (1,25(OH)2D)
- PTH serves to regulate calcium levels
- Negative feedback loop: PTH production increases when calcium levels decrease
Calcium from Food
- Only a fraction of ingested calcium is absorbed
- Vitamin D is necessary for calcium absorption
- Calcium absorption efficiency depends on vitamin D levels
- Normal bone density is maintained when calcium intake and absorption are sufficient
Calcium Overview
- Atomic weight: 40 g/mol
- Valence: +2 (divalent cation)
- Bone calcium: Tricalcium phosphate
- Abundance: 3.64% of the Earth's crust (5th most abundant element)
- Sea water concentration: 400 mg/L (10 mmol/L)
- Milk concentration: 300 mg/L
- Normal serum calcium: 2.5 mmol/L
Measuring Calcium
- Laboratory testing: measures total serum calcium and ionized plasma calcium
- Normal total serum calcium: 2.5 mmol/L
- Normal ionized calcium: 1.2 mmol/L
- Total calcium composition:
- Protein-bound calcium (45%): inactive, not biologically available
- Free ionic calcium (45%): active, biologically available
- Complexed calcium (10%): eg. Ca citrate
Calcium in Biology
- Key factor in biological membrane stability
- Involved in subcellular signaling
- Essential component of bone
- Stabilizes cell membranes by anchoring to phospholipids
- Makes excitable membranes more resistant to depolarization
- Regulates neuromuscular activity
Bone Disease
- Parathyroid hormone (PTH) measured if calcium is abnormal
- Bone markers (eg. Alkaline phosphatase) provide insight into cellular activity and therapy monitoring
- Calcium is essential for bone growth and maintenance
- Bone structure:
- Cortical bone
- Trabecular bone
- Bone remodeling theory: resorption and formation occur continuously
- Bone loss: 1% per year in adults
Endocrinology
- Study of biological control systems involving signaling molecules in the circulation
- Three hormones regulate ionized calcium in the blood:
- Parathyroid hormone (PTH)
- Calcitonin (CT)
- Calcitriol (1,25(OH)2D)
- PTH serves to regulate calcium levels
- Negative feedback loop: PTH production increases when calcium levels decrease
Calcium from Food
- Only a fraction of ingested calcium is absorbed
- Vitamin D is necessary for calcium absorption
- Calcium absorption efficiency depends on vitamin D levels
- Normal bone density is maintained when calcium intake and absorption are sufficient
Calcium
- Atomic weight: 40 g/mol
- Valence: +2 (divalent cation)
- Bone Ca: Tricalcium phosphate
- 3.64% of earth's crust (5th most abundant element)
- Sea water contains about 400 mg/L (=10 mmol/L)
- Milk contains 300 mg/L
- Serum calcium: 2.5 mmol/L
Laboratory Testing for Calcium
- Measure total serum calcium and ionized plasma calcium
- Normal total: 2.5 mmol/L
- Normal ionized: 1.2 mmol/L
- Total calcium: Protein-bound (45%) + free ionic calcium (45%) + complexed calcium (10%)
Importance of Calcium in Biology
- Key factor in stability of biological membranes
- Subcellular signaling
- Key component of bone
- Stabilizes cell membrane by linking to negatively charged phosphoric part of phospholipids
- Makes excitable membranes more resistant to depolarization
Bone Disease
- Parathyroid hormone (PTH) measured if calcium is abnormal
- Bone markers (e.g., alkaline phosphatase) provide insight into cellular activity and help monitor therapy
Calcium in Biological Membranes
- Lipids in biological membranes align in a monolayer at an oil-water interface
- The lipid bilayer of cell membranes stabilized by calcium ions
- Calcium ions anchor phospholipids, making the cell membrane firmer and less permeable to other substances
Calcium in Neuromuscular Function
- Low calcium: hyperexcitability of neuromuscular tissues
- Chvostek sign and Trousseau sign
Bone Growth and Development
- Primary purpose of bone: reservoir of calcium
- Structural aspects of bone compromised when calcium is in short supply
- Bone growth: macroscopic and microscopic
- Ossification begins in an area of preformed cartilage
Alkaline Phosphatase and Bone Remodeling
- Normal range of alkaline phosphatase: varies with age
- Theory of remodeling: every month, an adult resorbs about 1% of their bone and reforms about 0.9% of their bone
- Net result: every year, an adult loses about 1% of their bone
Endocrinology and Calcium Regulation
- Study of biological control systems that act via the circulation
- Three hormones regulate ionized calcium in the blood: parathyroid hormone (PTH), calcitonin (CT), and calcitriol (1,25(OH)2D)
- Normal feedback regulation: PTH serves the purpose of calcium regulation
- Circulating PTH and calcium levels: example of a negative feedback loop
Interpreting Lab Test Results
- Parathyroid hormone (PTH) vs calcium in health and disease situations
Calcium from Food
- Only a fraction of consumed calcium is absorbed
- Vitamin D necessary for calcium absorption
- Normal bone density maintained with adequate calcium intake and sufficient vitamin D
Osteoporosis
- Low bone density
- Prevention: adequate calcium intake, sufficient vitamin D, and regular exercise
This quiz covers the overview of calcium, including its atomic weight, valence, and abundance, as well as its measurement in the laboratory and normal serum levels.
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