Week 3 Lecture Flashcards
what are the 4 basic properties of muscle?
- Excitability
- Contractility
- Extensibility
- Elasticity
what are the 3 main muscle types?
skeletal muscle
cardiac muscle
smooth muscle
what are the characteristics of cardiac muscle?
- striated involuntary
- short cells w one central nucleus
- incapable of contracting
what are the characteristics of smooth muscle?
- non striated involuntary
- short cells w one nucleus
- can divide and regenerate
what are the characteristics of skeletal muscle?
- striated voluntary muscle
- long cells that are multinucleate
- incapable of cell reproduction
what are 5 main functions of skeletal muscles?
produce skeletal movement
maintain posture and body position
support soft tissue
regulate entering and exiting of material
maintain body temp
what are the three layers of connective muscle tissue?
Epimysium
perimysium
endomysium
what is a myofibril?
a highly organized bundle of contractile protein
what is the sarcomere?
smallest functional unit of skeletal muscle
what is the difference between actin and myosin?
actin - thin protein filament
myosin - thick protein filament
M-line
centre of A-band where myosin filaments are held together
Z-disc
centre of I-band where actin filaments are held together
I-band
made of only actin filaments (light region)
A-band
myosin filaments with overlapping actin filaments at edges (dark region)
H-zone
made of only myosin filaments, centre of A-band
name every region of the sarcomere
I-band
a-band
m-line
h-zone
z-line
Skeletal muscles consist of…
Muscle Fascicles
muscle Fascicles consist of…
muscle fibers
muscle fibers consist of…
myofibrils
myofibrils consist of…
sarcomeres
sarcomeres consist of…
myofilaments
myofilaments are made of…
actin and myosin!
what are the 2 steps of muscle fiber contraction
- Excitation phase
- contraction phase
what happens during the excitation phase? (5 steps)
- an impulse travels down the axon of a nerve
- ach is released from the end of the axon into the neuromuscular synapse
- results in an action potential, and causes the s.r. to release its stored calcium ions
- calcium binds to troponin (uncovering the binding sites of actin)
- begins the contraction of the muscle
what happens during the contraction phase?
- contraction cycle begins
- active-site exposure
- cross-bridge formation
- myosin head pivoting (power stroke)
- cross bridge detachtment
- myosin reactivation
what is the triad on a muscle fiber made up of?
the sarcoplasmic reticulum and the T-tubules
ex. of a parallel muscle
biceps brachii
ex of parallel muscle w bands
rectus abdominus
wrapping muscle
supinator
convergent muscle
pectoralis
unipennate muscle
extensor digitorum
bipennate muscle
rectus femoris
multipennate muscle
deltoid
circular muscle (lips)
orbicularis oris
what are the factors influencing the motion and power of muscles?
of muscle fibers
shape:
number:
size: (of muscle fibers)
orientation relative to tendon
first class lever
neck (resistance, fulcrum, AF)
Second class lever
plantar flexion (fulcrum, resistance, AF)
third class lever
elbow flexion (fulcrum, AF, resistance)
ex of a pulley in the body
lateral malleolus or patella
changing direction of force
