Topic 10: Skeletal Muscle Physiology - Muscle Fiber Relaxation and Applications Flashcards
What are the steps to muscle fiber relaxation? (4)
1) ACh broken down by AChE on motor end plate fscing cleft
2) SR actively takes up Ca++ (Ca2+ ATPase)
3) ATP binds to and releases myosin heads
4) Tropomyosin moves back to cover myosin binding sites on action
ACh broken down by AChE on motor end plate diagram
Why is ATP necessary in muscle fiber relaxation? (4)
- Cross bridge release (ATP not broken down)
- Activation of myosin (ATP -> ADP + Pi)
- Pump Ca2+ into SR
- fiber Na+/K+ ATPase activity
What is botulism caused by? (2)
- improper canning
- C. botulinum
What does botulism cause in the body? (2)
- prevents exocytosis of ACh
- flaccid paralysis
How do you treat botulism medically? Cosmetically?
- treat uncontrolled blinking, crossed eyes
- cosmetic would be Botox (wrinkles, sweating)
What is Rigor Mortis? (3)
stiffness of death
- starts 3 hours after death, max at about 12 hours
- gradually subsides over days as cells break down
What happens during Rigor Mortis? (3)
- intracellular calcium increased from ECF, SR (there is leakage)
- binding sites exposed (crossbridges)
- myosin heads not released from actin , so no new ATP produced
What occurs in Myasthenia gravis? (2)
- decrease in ACh receptors (autoimmune)
- flaccid paralysis
How do you treat Myasthenia gravis? (2)
- AChE inhibitors
- they increase binding to remaining receptors
What occurs in curare poisoning? (2)
- prevents ACh from binding to receptors
- flaccid paralysis (was used in surgery)
What occurs when you take nicotine? (2)
- mimic ACh effect (binds to receptors)
- get muscle spasms
What occurs when you take Black Widow Spider venom? (2)
- triggers massive release of ACh
- muscles continuously contract until you stop breathing
