Section 3: Muscle Physiology Flashcards
type of voluntary muscle
Skeletal
types of involuntary muscles
smooth
cardiac
Muscle composition
4 layers, starting with muscle
muscles made of fascicles, made of muscle cells (muscle fibres) made of myofibrils
sarcomeres
repeating units of actin and myosin
two types of actin
G actin
F actin
A band
contains actin and mysoin
I band
only actin
H zone
only myosin
M line
where myosin attaches to eachother
z line
where actins attach to each other
5 steps to sliding filament theory
1) rigor state
2) ATP binds to myosin head (releases actin)
3) ATP hydrolysis (myosin head swings)
4) Pi released, Power stroke
5) ADP released, rigor state resumes
cause of rigor mortis
lack of ATP, myosin cannot unbind to actin
Function of tropoyosin
binds around actin. blocks myosin binding site
parts of troponin (3)
TnC - Binds Ca2+
TnT - Binds tropomyosin
TnI - binds actin to tropomyosin (inhibits binding, hence I)
t-tubule system
allows action potential to move into interior of cell
motor end plate receptor type
nicotinic
active tension vs passive tension
active - caused by actin / myosin
passive - caused by stretching elastic components
tetanus
no relaxation of the muscle. Produces maximal tension
motor unit
all muscle fibres innervated by a single motor neuron
things that increase force (2)
recruitment - more fibres
can also do asynchronous recruitment to avoid fatigue
Summation - ap frequency
Types of contractions (2)
isotonic - creates a force and moves a load
isometric - does not move load
types of isotonic contractions
concentric - normal
eccentric- muscle lengthens as tension develops (may be damaging)
extrafusal fibres
major contractile fibres
alpha motor neurons
innervate extrafusal fibres