Muscles Flashcards
What does the Epimysium surround?
The entire muscle
What does the Perimysium surround?
The bundles of muscle fibers
What does the Endomysium surround?
Each individual muscle fiber
What part of contraction do Sarcomeres perform?
Shortening in contraction
Where is the sarcomere located?
Between Z discs in a myofibril
What is a Z disc?
It separates sarcomeres and defines the boundaries of each
What does a thin filament consist of?
Two strands of actin twisted into a helix, and the two regulator proteins troponin and tropomyosin
What is the function of troponin?
It promotes muscle contraction by binding Ca+ which moves tropomyosin away
What is the purpose of Tropomyosin?
It blocks muscle contraction
What is Dystrophin?
It links the outermost thin myofilaments to sarcolemma, which strengthens muscle fibers
What happens to myofilaments during contraction?
Thin filaments slide past thick filaments causing actin and myosin to overlap more
What is a cross bridge?
When myosin heads bind to actin which causes sliding (contraction) process to begin
What are the four steps of muscle fiber contraction?
- Nerve stimulation
- Action potential (electrical current generated in sarcolemma)
- Action potential is propagated along sarcolemma
- Intracellular Ca2+ levels rise
What is spastic paralysis?
A state of continual contraction of the muscles because pesticides bind to acetylcholinesterase and prevent the degrading of AcH
What is flaccid paralysis
A state in which the muscles are limp and cannot contract
What is curare
A plant poison that competes with ACh for receptor sites, but do not stimulate the muscles
What is direct phosphorylation?
Uses the ATP already in muscles. A big burst of ATP to jumpstart activity. About 15 seconds of energy provided.
What is an anaerobic pathway?
The anaerobic fermentation of glycolysis into pyruvate.
What is an aerobic pathway
When oxygen is used to release energy from carbohydrates and lipids
Slow-oxidative fibers
Low intensity, endurance activities. Ex: Maintaining posture
Fast-oxidative fibers
Medium intensity. Ex: Sprinting or walking
Fast glycolytic fibers
Short term, intense or powerful movements. Ex: Hitting a baseball
What are the characteristics of cardiac muscles?
-Located in walls of the heart
-Contracts without need for nerve stimulation, much like a pacemaker with rhythmically set off contractions
-Uses aerobic respiration
-Highly fatigue resistant
What are the characteristics of smooth muscle?
-Found in walls of most hollow organs except heart
-Spindle shaped fibers. Thin and short.
-Only contains endomysium
