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Questions and Answers
The normal total serum calcium level is _______________________ mmol/L.
The normal total serum calcium level is _______________________ mmol/L.
2.5
What is the function of protein-bound calcium in the body?
What is the function of protein-bound calcium in the body?
- Inactive and not biologically available (correct)
- Involved in subcellular signalling
- Regulated for biological availability
- Involved in bone formation
Match the following components of total calcium with their percentages:
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.
Calcium ions destabilize the cell membrane.
What is the role of calcium in biological membranes?
What is the role of calcium in biological membranes?
Every month, an adult resorbs about 1% of their bone, while reforming about 1% of their bone.
Every month, an adult resorbs about 1% of their bone, while reforming about 1% of their bone.
What is the theory that describes the process of bone remodeling?
What is the theory that describes the process of bone remodeling?
The study of biological control systems, whereby signaling molecules act via the ___________, is called Endocrinology.
The study of biological control systems, whereby signaling molecules act via the ___________, is called Endocrinology.
Match the following bones with their respective types:
Match the following bones with their respective types:
What is the purpose of the three hormones PTH, CT, and 1,25(OH)2D in the body?
What is the purpose of the three hormones PTH, CT, and 1,25(OH)2D in the body?
Alkaline Phosphatase levels increase with age.
Alkaline Phosphatase levels increase with age.
Haversian canals are found in the ______________ bone.
Haversian canals are found in the ______________ bone.
What is the primary function of PTH in the body?
What is the primary function of PTH in the body?
PTH is an example of a positive feedback loop.
PTH is an example of a positive feedback loop.
What is the aim of the negative feedback loop involving PTH?
What is the aim of the negative feedback loop involving PTH?
When you eat 1000 mg of calcium, you absorb _______ mg.
When you eat 1000 mg of calcium, you absorb _______ mg.
What is the approximate total serum calcium level in the blood?
What is the approximate total serum calcium level in the blood?
Match the following health conditions with their corresponding PTH levels:
Match the following health conditions with their corresponding PTH levels:
Calcium is completely absorbed from food into the bloodstream.
Calcium is completely absorbed from food into the bloodstream.
What is the normal bone condition in relation to calcium levels?
What is the normal bone condition in relation to calcium levels?
What is the amount of calcium absorbed by the body if enough vitamin D is present?
What is the amount of calcium absorbed by the body if enough vitamin D is present?
Vitamin D is necessary for poor calcium absorption.
Vitamin D is necessary for poor calcium absorption.
What is the result of poor calcium absorption?
What is the result of poor calcium absorption?
The two types of bone structures in the human skeleton work together to _______________ and prevent bending.
The two types of bone structures in the human skeleton work together to _______________ and prevent bending.
What is the amount of calcium excreted in the urine if enough vitamin D is present?
What is the amount of calcium excreted in the urine if enough vitamin D is present?
Osteoporosis is a condition characterized by high bone density.
Osteoporosis is a condition characterized by high bone density.
What is the amount of calcium absorbed by the body if not enough vitamin D is present?
What is the amount of calcium absorbed by the body if not enough vitamin D is present?
Match the following terms with their descriptions:
Match the following terms with their descriptions:
What is the effect of calcium on the cell membrane?
What is the effect of calcium on the cell membrane?
Low calcium levels lead to hyperexcitability of neuromuscular tissues.
Low calcium levels lead to hyperexcitability of neuromuscular tissues.
What is the primary purpose of bone in the body?
What is the primary purpose of bone in the body?
The concentration of calcium in the bloodstream is tightly regulated, with a coefficient of variation (CV) of ______________.
The concentration of calcium in the bloodstream is tightly regulated, with a coefficient of variation (CV) of ______________.
What is the effect of low calcium levels on the threshold voltage for firing in neurons?
What is the effect of low calcium levels on the threshold voltage for firing in neurons?
Bone growth stops after puberty due to the mineralization of the growth plate.
Bone growth stops after puberty due to the mineralization of the growth plate.
Match the following terms with their descriptions:
Match the following terms with their descriptions:
What is the process of bone growth from fetus to adult?
What is the process of bone growth from fetus to adult?
What is the effect of sufficient vitamin D on calcium absorption?
What is the effect of sufficient vitamin D on calcium absorption?
What happens to calcium absorption when there is insufficient vitamin D?
What happens to calcium absorption when there is insufficient vitamin D?
What is the normal outcome when sufficient vitamin D is present?
What is the normal outcome when sufficient vitamin D is present?
What are the two types of bone structures in the human skeleton?
What are the two types of bone structures in the human skeleton?
What is the consequence of poor calcium absorption?
What is the consequence of poor calcium absorption?
What is the condition characterized by low bone density?
What is the condition characterized by low bone density?
What is the amount of calcium passed to the stool when sufficient vitamin D is present?
What is the amount of calcium passed to the stool when sufficient vitamin D is present?
What is the amount of calcium excreted in the urine when sufficient vitamin D is present?
What is the amount of calcium excreted in the urine when sufficient vitamin D is present?
How does the body respond to insufficient vitamin D levels?
How does the body respond to insufficient vitamin D levels?
What is the significance of calcium in maintaining healthy bones?
What is the significance of calcium in maintaining healthy bones?
Calcium is the 3rd most abundant element in the earth's crust.
Calcium is the 3rd most abundant element in the earth's crust.
Ionized plasma calcium is biologically available for membranes or bone.
Ionized plasma calcium is biologically available for membranes or bone.
The lipid bilayer of cell membranes is destabilized by calcium ions.
The lipid bilayer of cell membranes is destabilized by calcium ions.
Sea water contains about 10 mmol/L of calcium.
Sea water contains about 10 mmol/L of calcium.
The normal total serum calcium level is 2.2 mmol/L.
The normal total serum calcium level is 2.2 mmol/L.
Every year, an adult loses about 0.1% of their bone due to the remodeling process.
Every year, an adult loses about 0.1% of their bone due to the remodeling process.
The three hormones PTH, CT, and 1,25(OH)2D serve to regulate ionized Magnesium in the blood.
The three hormones PTH, CT, and 1,25(OH)2D serve to regulate ionized Magnesium in the blood.
Alkaline Phosphatase levels decrease with age.
Alkaline Phosphatase levels decrease with age.
The primary function of calcium in biological membranes is to make them more permeable to other substances.
The primary function of calcium in biological membranes is to make them more permeable to other substances.
The study of biological control systems, whereby signaling molecules act via the nervous system, is called Endocrinology.
The study of biological control systems, whereby signaling molecules act via the nervous system, is called Endocrinology.
Epiphyseal fusion occurs before the stoppage of longitudinal growth.
Epiphyseal fusion occurs before the stoppage of longitudinal growth.
The concentration of calcium in the bloodstream has a coefficient of variation (CV) of 10%.
The concentration of calcium in the bloodstream has a coefficient of variation (CV) of 10%.
High calcium levels lead to hyperexcitability of neuromuscular tissues.
High calcium levels lead to hyperexcitability of neuromuscular tissues.
The growth plate also mineralizes before puberty, and longitudinal growth stops.
The growth plate also mineralizes before puberty, and longitudinal growth stops.
The primary purpose of bone is to provide structural support for the body.
The primary purpose of bone is to provide structural support for the body.
When you eat 400 mg of calcium, you absorb all of it if you have enough vitamin D
When you eat 400 mg of calcium, you absorb all of it if you have enough vitamin D
Osteoporosis is a condition characterized by high bone density
Osteoporosis is a condition characterized by high bone density
Vitamin D is necessary for poor calcium absorption
Vitamin D is necessary for poor calcium absorption
The two types of bone structures in the human skeleton work together to prevent bending and promote vertical collapse
The two types of bone structures in the human skeleton work together to prevent bending and promote vertical collapse
When there is not enough vitamin D, you absorb 200 mg of calcium if you eat 400 mg
When there is not enough vitamin D, you absorb 200 mg of calcium if you eat 400 mg
The majority of calcium consumed from food is absorbed into the bloodstream.
The majority of calcium consumed from food is absorbed into the bloodstream.
PTH serves the purpose of regulating the body's calcium levels through a positive feedback loop.
PTH serves the purpose of regulating the body's calcium levels through a positive feedback loop.
The total serum calcium level is the sum of free and protein-bound calcium, approximately equal to 2.5 mmol/L.
The total serum calcium level is the sum of free and protein-bound calcium, approximately equal to 2.5 mmol/L.
When calcium is absorbed from food, it is directly utilized by the bones for growth and development.
When calcium is absorbed from food, it is directly utilized by the bones for growth and development.
The normal bone condition in relation to calcium levels is characterized by high calcium levels in the bloodstream.
The normal bone condition in relation to calcium levels is characterized by high calcium levels in the bloodstream.
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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
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