Ex Phys Chapter 1 Flashcards
sometimes called involuntary muscle is not under direct conscious control
smooth muscle
muscle found only in the heart, composing the vast majority of the heart’s structure
Cardiac muscle
These muscles are under conscious control and are so named because most attach to and move the skeleton
Skeletal muscles
Skeletal muscles and bones make up the _____ system
Musculo-skeletal system
the body contains more than ______ skeletal muscles
600
out connective tissue covering of the muscle
epimysium
small bundles of fibers wrapped in a connective tissue sheath of the muscle
fascicles
the connective tissues sheath surrounding each fascicle
perimysium
inside the perimysium, these muscle cells take the form of
muscle fibers
unlike most cells, these cells are multinucleate
muscle cells
this sheath of connective tissue also covers each muscle fiber
endomysium
the basic unit of a myofibril
sarcomere
surrounding each individual muscle fiber is the plasma membrane AKA the ____
plasmalemma
the plasmalemma is part of a larger unit known as the ____
sarcolemma
the sarcolemma is composed of _____ &________
The plasmalemma and basement membrane
These cells are located between the plasmalemma and the basement membrane. They’re involved in growth, and dev. of muscle
Satellite Cells
A gelatin-like substance filling the spaces of the myofibrils. (the cytoplasm of the muscle fiber) it contains a high amount of myglobin and glycogen
Sarcoplasm
The sarcoplasm houses an extensive network of ___. (extensions of the plasmalemma that pass laterally through the muscle fiber)
Transverse tubules. (T tubules)
A longitudinal network of tubules known as_____ are also found within the fiber. It runs parallel to the myofibrils and loop around them. It’s a storage site for calcium.
Sarcoplasmic reticulum
Each muscle fiber contains several hundred to several thousand _____. They’re made up of the basic contractile elements of skeletal muscle-the sarcomeres.
myofibrils
the dark regions of myofibrils
A band
The light regions of myofibrils
I band
The lighter band within the A band.
H zone
The dark line in the H zone
m-line
The light I band has a dark stripe known as the
z disk or z line
The basic functional unit of a myofibril, and the basic contractile uint of muscle
sarcomere
Thinner filaments are composed mostly of _____ (lighter parts of sarcomere)
actin
Thicker Filaments are mostly composed of ___ (darker parts of sarcomere)
Myosin
Although each filament is referred to as an actin filament is actually composed of actin, _______ & _______. each end has one end inserted into a z disk, with opposite end extending toward the center of the sarcomere.
Actin, tropomyosin and troponin.
______ an anchoring protein for actin, co-extends with actin and appears to be playing a regulatory role in mediating actin and myosin interactions.
nebulin
a tube shaped protein that twists are the actin strands
tropomyosin
a nerve cell that connects with and innervates many muscle fibers
A motor neuron
a single motor neuron and all the muscle fibers it signals collectively termed as a
motor unit
The synapse of gap between the motor neuron and muscle fiber are known as the ___
the neuromuscular junction
The complex sequence of events that triggers a muscle fiber to contract is termed as _______
excitation-contraction coupling
a nerve impulse is also known as
action potential
the action potential arrives at the motor neuron’s
dendrites
axon terminals leave a signaling molecule or neurotransmitter called
Acetylcholine
___ binds to troponin on thin filament
Calcium
_____ binds to actin when tropomyosin is gone
myosin
the explanation for how muscle fibers shorten
the sliding filament theory
The tilting of the myosin head is called the
power stroke
after the power stroke ends
- myosin heads detach
- myosin head rotates back to original position
- myosin attaches to another active site further down
In addition to the binding site for actin, a myosin head contains a binding site for the molecule _____
Adenine triphosphate
energy from _____ breakdown is used to power the tilting of the myosin head
(ATP) Adenine triphosphate
This enzyme is located in myosin head and splits the atp to yield adenosine diphospahate (ADP) and inorganic phosphate, and energy. The breakdown of this energy is used to tilt the myosin head.
adenine tripohosphatase
After Action potential (AP) ends
- electrical stimulation of SR ends
- calcium is pumped back into SR
- Stored until next AP arrives
- Requires ATP
without calcium present:
tropomyosin and troponin return to resting conformation.
- covers myosin-binding site
- prevents actin-myosin bridging
Fast myosin ATPase
fast contraction cycling
Slower myosin ATPase
slower contraction cycling
- Type II fibers have a more highly developed ____
- & 5times faster release of ______
Sarcoplasmic reticulum
Ca2
Type ___ motor units are smaller neurons with less than 300 fibers
1
Type ___ motor units have larger neurons and contain more than 300 fibers
2
-fibers per motor neuron:
type I
- fibers per motor neuron: >300
- motor neuron size: larger
- conduction velocity : faster
- contraction speed (ms): 50
- Type of myosin ATPase: fast
- Sarcoplasmic reticulum: high
Type IIa and type IIx
Can maintain exercise for a prolonged period, requires oxygen for atp production, low-intensity aerobic exercise, daily activities.
Type 1
- poor aerobic endurance, fatigue quickly,
- produce atp anaerobically
Type II fibers
- More force, faster fatigue than type 1
- short, high intensity endurance events (1,600 m run)
Type IIa
- Seldom used for everyday activities
- short explosive sprints (100m)
type IIx
training can induce a ___% change in fiber type
10%
the motor unties decrease as individual ages
type II
- Muscle shortens while producing force
- Most familiar type of contraction
- Sarcomere shortens, filaments slide toward center
Concentric contraction
- Muscle lengthens while producing force
- Cross-bridges form but sarcomere lengthens
- Example: lowering heavy weight
Eccentric contraction
- Muscle produces force but does not change length
- Joint angle does not change
- Myosin cross-bridges form and recycle, no sliding
Static (isometric) contraction
- Muscle produces force and changes length
- Joint movement produced
Dynamic contraction
- Optimal sarcomere length = optimal overlap
- Too short or too stretched = little or no force develops
Length-tension relationship
- Concentric: maximal force development decreases at higher speeds
- Eccentric: maximal force development increases at higher speeds
Speed-force relationship
