Assignment Problem: When Amy received the phone call from her cousin Claire, she was surprised to hear of her harrowing experience.
"I never thought anything so dangerous could happen while getting my wisdom teeth out!" Claire exclaimed. "Do you understand what caused such my sudden reaction to the anesthesia?"
"Actually, I have heard of this condition before," Amy replied. "It's caused by a sudden excessive release of calcium ions into your muscle cells."
"Calcium ions?" Claire asked in confusion. "How could that be dangerous?"
"Well, to explain it all... we should start by describing the structure of a muscle cell," replied Amy.
Give a description of each of the following structures of a skeletal muscle cell. Which one is involved in calcium ion storage?
- Sarcolemma:
- Sarcoplasm:
- Sarcoplasmic reticulum:
- T-tubules:
Amy explained that in certain people with a rare genetic condition, general anesthetic drugs can trigger excessive release of calcium ions from the sarcoplasmic reticulum into the sarcoplasm of muscle cells.
"Ok... but then how does that result in muscle contraction?" asked Claire.
"To answer that, we'll need to review the structure of a sarcomere and the proteins found in it," said Amy.
1. What is the definition of a sarcomere?
2. According to sliding filament theory, which of the following regions of a sarcomere become narrower as the sarcomere contracts? Which stay the same width?
A band:
I band:
H zone:
Distance between two Z disks:
3. Describe the structure of a thick filament. What protein is found in a thick filament?
4. Describe the structure of a thin filament. What proteins are found in a thin filament?
5. Describe the role of calcium in allowing interactions between thick and thin filaments. How does this relate to muscle contraction?
After learning about the structure and function of the sarcomere, Claire can finally understand why excess calcium in the sarcoplasm of a muscle cell could cause uncontrollable muscle contractions. Now, she just wants to understand how this could be life-threatening.
6. Why are the excessive muscle contractions caused by malignant hyperthermia so dangerous? Related to this: how do they result in elevation of body temperature?