Exam 2 – Lecture 11: Muscle Flashcards
What is the only thing muscles can do actively?
Get shorter
What are the names of muscles based on?
Morphology and activity
What is a muscle?
A tissue type
A specific mass of muscle tissue with origin, insertion, and action
What is a myofiber?
Individual muscle cell
What is a myofibril?
Contractile elements within a myofiber
Bundles of myofilaments
What can the shape of a muscle be like?
Flattened or cylindrical
What does the arrangement of myofibers determine?
Mobility/dexterity
What are the layers of a muscle fiber?
Epimysium
Perimysium
Endomysium
What is epimysium?
Connective tissue that surrounds the muscle
What is perimysium?
Connective tissue around a bundle (muscle fascicle)
What is a muscle fascicle made of?
Many myofibers
What is endomysium?
Connective tissue that surrounds each individual myofiber
What is a myofiber like?
Elongated
Frequently multinucleated
Contains filaments or fibrils
What are the different types of filaments?
Actin, thin (6-8 nm)
Myosin, thick (15 nm)
What are the different categories of morphology?
Smooth striated
What are the different categories of activity?
Voluntary
Involuntary
Describe skeletal muscle
Voluntary, striated
Multinucleated
What does skeletal muscle act as?
Syncytium
Where are the nuclei of skeletal muscle located?
In the periphery of the cell
What are the different fiber types of skeletal muscle?
Types 1, IIa, and IIb
What kind of twitch do type I fibers have?
Slow
What kind of metabolism do type I fibers have?
Oxidative
Do type I fibers have many or few mitochondria?
Many
What do type I fibers have a large amount of?
Myoglobin and cytochrome
Because type I fibers are slow twitch, what does that mean in terms of fatigue?
Fatigue resistant
Where can type I fibers be found?
Mammal limbs, migratory bird breast, marathon runners
What kind of twitch do type IIa fibers have?
Fast
What kind of metabolism do type IIa fibers have?
Oxidative glycolytic
Describe type IIa fibers
Many mitochondria
Much myoglobin
Abundant glycogen
Capable of anaerobic function
What kind of twitch do type IIb fibers have?
Fast
What kind of metabolism do type IIb fibers have?
Glycolytic
Describe type IIb fibers?
Large fibers
Less myoglobin and mitochondria
Much glycogen
High lactic acid production
What do myofibrils provide?
Striations
What do myofibrils make up?
Sarcomere
What is within the sarcomere?
A band I band M line Z line H band
What is the A band composed of?
Mostly myosin
What is the I band composed of?
Mostly actin
Where is the M line?
Center of the A band
What happens in the Z line?
Actin filaments conjoin between adjacent sarcomeres
What is the H band?
Space between actin filaments
Know the picture of a sarcomere
Know the picture of a sarcomere
During muscle contractions, what happens to myofilaments?
They remain the same length
When myofilaments remain the same length, what happens to interdigitation? H and I zones? A band?
Increases
Get smaller
Remains
What is muscle contraction controlled by?
Ca++
Where is Ca held?
Sarcoplasmic reticulum
What is the T-tubular system?
Invaginations of plasma membrane
What happens when the T-tubule depolarize?
Ca is released
What makes up the neuromuscular junction?
Axon and myofiber
What is the neurotransmitter in the neuromuscular junction?
Acetylcholine