Lec 28 Flashcards
Muscle cells are used by
Vertebrates
Muscles purposes
Flexing and extension
During flexing biceps
Contract while triceps relax
During extension biceps
Relax while triceps contract
3 types of muscles
Cardiac muscle cells
Skeletal muscle cells
Smooth muscle cells
Contents of muscle cells/fiber
Bundle of muscle fibers
One muscle fiber
Nucleus
Plasma membrane
Myofibril
Sarcomere
Long cells are formed by
Cell fusion
Cell growth
Myoblasts fuse to make
Muscle cells
Muscle cells have several
Nuclei (plenty of DNA to make RNA to make proteins)
Myofibrils
cm to meters long
Contains sarcomeres which is the stripes that contains actin and myosin for contraction
ER of muscle cells
Stores calcium
Heart muscle cells have
Mitochondria (make ATP)
Glycogen/Lipids (fuel)
Sarcomere structure
Z discs
Have one on each end
What is connected to z discs
Actin filaments connected from their plus end
What is connected to the actin
Myosin that is in the middle
Known as the thick filament
Double headed, plus ended myosin
Heads interact with actin
Titins
Connects thick filaments to z discs like a spring
Our largest protein
Tropomyosins
Conceal the myosin-binding sites of actin filaments
Troponin complexes
Regulate tropomyosin
Each thin filament is made of
One actin filament
Tropomyosin
Troponin complexes
Contraction
Resting muscle cell
Tropomyosin are in the way
Contraction
Thin filament activation
Ca++ increases by being released from the ER
Troponins activated
Tropomyosin moved, exposing actin filament and allowing for thick filament to be activated
Thick filament activation
Contraction
Myosin heads take turns walking along actin
Sarcomere contraction
Myosin pull Z discs together
Sarcomere movement leads to the whole cell
Contracting
Light muscle bands
Z-discs
Dark muscle bands
Thick filaments
AS the sarcomeres contract
The light bands shrink
Increase calcium means
All sarcomeres in cell contract
Decrease calcium means
All the sarcomeres have contracted
