Muscular System (Lecture) Flashcards
What are the characteristics of a motor unit?
- all or nothing contractions
- uses recruitment to stimulate more or fewer muscle fibers depending on the strength needed
What are types of muscle contractions and their definition?
- Isotonic/concentric: muscle gets shorter
- Isometric: Muscle contracts, but maintains the same length
- Eccentric: Lengthened muscle contraction. (damaging to muscle, but builds more muscle)
Define hypertrophy
Muscle fibers growing in size (not numbers) to adapt to heavy resistance
Define Atrophy
Muscle fibers decreasing in size due to lack of activity
Define Type I muscle fibers
- Slow-twitch
- lots of mitochondria and myoglobin
- less prone to fatigue
smallest diameter
Define Type II muscle fibers
- fast-twitch
- fewer mitochondria and myoglobin
- more prone to fatigue
- large diameter
Define Type IIa muscle fibers
- medium speed twitch
- medium amount of mitochondria and myoglobin
- intermediate endurance
- medium diameter
In descending order, name the organizational level of a skeletal muscle
Muscle (organ)
Fascicle
Muscle Fiber (cell)
Myofibril (organelle)
Sarcomere
Myofilament/filament
Name the tissue that wraps the muscle and what kind of tissue it’s made of
Epimysium; made of dense irregular CT
Name the tissue that wraps fascicles and what kind of tissue it’s made of
Perimysium; dense irregular CT
Define fascicle
a bundle of muscle fiber
What tissue wraps an individual muscle fiber and what kind of tissue is it made of?
Endomysium; areolar CT
Define myofibril
rodlike contractile organelles composed of sarcomeres
Define sarcomere
a contractile unit that makes up myofibrils and is made of contractile myofilaments
What holds sarcomeres in place
Titin proteins
Which is the thick myofilament and which one is thin?
Myosin-Thick
Actin-Thin
Name three components of a muscle fiber with differentiating names than a generic cell and their equivalent
Sarcolemma-plasma membrane
Sarcoplasm-cytoplasm
Sarcoplasmic Reticulum-Endoplasmic Reticulum
Define Class I levers and give an example
- Effort, Fulcrum, Resistance
- Extension at the elbow
Define class II levers and give an example
- Effort, Resistance, Fulcrum
- plantar flexion at the ankle
Define class III levers and give an example
- Resistance, effort, fulcrum
- Flexion at the elbow
What is a muscle agonist?
The primary muscle that will be doing the moving
What is a synergist muscle?
Secondary muscles that help the agonist muscle perform movements. Can be direct or indirect
What is an antagonist muscle?
A muscle that performs opposite contraction movement of an identified muscle agonist
What part of the sarcomere is identified and what is its composition?
A-Band
Consists only of the length of the myosin
