Muscular System Flashcards
Types of Muscles
- Skeletal
- Cardiac
- Smooth
Abilities of Skeletal Muscles
• Contractility: ability to shorten • Excitability: respond to stimulus • Extensibility: can stretch • Elasticity: recoil
ability to shorten
Contractility
respond to stimulus
Excitability
can stretch
Extensibility
recoil
Elasticity
• Makes up 40% of body weight
Skeletal Muscle
connective tissue that surrounds entire skeletal
muscle (outside)
Epimysium
bundle of muscle fibers
Muscle fasciculus
connective tissue around each muscle fasciculus
Perimysium
- skeletal muscle cells
- many nuclei
Muscle fiber
connective tissue that surrounds each muscle
fiber
Endomysium
thread-like proteins that make up muscle fibers
Myofibril
- proteins that make up myofibrils
- Ex. actin and myosin
Myofilament
cytoplasm of muscle fiber (cell)
Sarcoplasm
- cell membrane
- contains T-tubules
Sarcolemma
- wrap around sarcomeres at A band
- associated with sarcoplasmic reticulum
T-tubules (transverse)
type of SER
- surrounds myosin
- stores and releases Ca+
Sarcoplasmic reticulum
- thin myofilament
- resemble 2 strands of pearls
Actin
thick myofilament
- resemble golf clubs
Myosin
attachment site on actin for Ca+
Troponin
- filament on grooves of actin
- attachment site on actin for myosin
Tropomyosin
- contractile unit
- contains actin and myosin
Sarcomere
protein fibers that form attachment site for actin
Z disk
- center of sarcomere
- contains only myosin
H zone
contains only actin
I band
where actin and myosin overlap
A band
where myosin are anchored
M line
Na+
+ charge
Na+ channel closed
Outside cell
K+
- charge
Some K+ channels open
Inside Cell