Chapter 10 - Muscle Tissue Flashcards
Muscle functions
- movement
- stabilizing body positions
- storing and moving substances within the body
- heat generation
Properties of muscular tissue
- electrical excitability
- contractility
- extensibility
- elasticity
Electrical excitability
triggers an action potential
Contractility
generates tension
Extensibility
ability to stretch without being damaged
Elasticity
ability to return to its original length/shape
Types of muscle tissue
- skeletal
- cardiac
- smooth
Epimysium
surrounds entire muscle cell
Perimysium
surrounds fascicles, bundles of muscle cells (fibers)
Endomysium
surrounds individual muscle fibers
Sarcolemma
- cell membrane
- transverse tubules
Sarcoplasm
- cytoplasm
- contains glycogen and myoglobin (contains oxygen to help make ATP)
Myofibril
contractile, allows muscle to get shorter
Triad
2 terminal cisterns budded up with transverse tubules
Sarcoplasmic Reticulum (SR)
- sac-like structure
- contains calcium
Myofilaments
gives striated appearance
Thin myofilaments
- between sarcomeres
- composed of actin
Thick myofilaments
- in single sarcomere
- composed of the protein myosin
Z disc
- separates sarcomeres
- keeps thin filaments in place
I band
- only see thin filaments
- Z disc passes through center of each I band
A band
- may contain parts of thin filament
- length of thick filament
H zone
- contain only thick filaments (unlike A band)
- located in the center of each A band
M line
- middle of sarcomere
- hold thick filaments in place
Myosin
- motor protein
- tails touch M line
- binding site for ATP (heads)
- binding site for actin
- ATPase
- thick myofilaments
Actin
- myosin-binding site
- contractile protein
- thin myofilaments
Contractile proteins
myosin and actin
Regulatory proteins
tropomyosin and troponin
-help switch muscle contraction process on/off
Tropomyosin
- prevents constant state of contraction/myosin-binding sites on actin covered
- component of a thin filament
Troponin
- TnI (actin)
- TnT (tropomyosin)
- TnC (calcium)
- troponin changes shape when binded with Ca+
- shape change moves tropomyosin away from myosin-binding sites on actin molecules (muscle contraction begins as myosin binds to actin)
