Exam Three - Muscle 1& 2 Flashcards
What are the three types of muscle?
skeletal
smooth
cardiac
Which type of muscle has striations?
skeletal and cardiac
which type of muscle has no striations
smooth
What makes cardiac muscle unique?
- involuntary control
- contractions produce pumping of heart chambers
- cardiomyocytes joined by intercalated disks
- single or double nuclei
intercalated disks are held together by?
desmosomes
What makes smooth muscle unique?
- involuntary control
- contractions produce constriction
- organized in multidirectional contractile units
- single nucleus
What are the different fiber types of skeletal muscle?
- type 1
- type 2 (a,x,b)
Fibers are made of?
myofibrils
myofibrils are organized by?
sarcomeres
Give an example of antagonistic muscles
flexors and extensors
What type of fibers are used for aerobic activity?
type 1
What are examples of type 2 B fibers?
humans have very few and they are in the eyes and muscles of mastication
What type of fibers do power lifters probably have a lot of?
Type 2 x
What makes up a triad?
- continuous with sarcolemma
- made of T-tubule and 2 flanking terminal cisternae
- allows for AP to penetrate deeper into the internal structure of the fiber
Myofibrils are the ______ of the muscle
contractile structure
thin filament is?
actin
thick filament is?
myosin
What are the regulatory proteins of myofibrils
tropomyosin
troponin
What are the accessory proteins in a myofibril
titin
nebulin
A sarcomere is defined as…
the space between 2 z lines
The H zone contains only…
thick filaments
The A band contains…
thick and thin filaments and is in the center of the sarcomere
The I band contains…
the z line, made of only thin filaments
The z line is made of…
thin filaments
The m line is made of…
thick filaments
Which protein is the largest known protein?
titin
which protein acts as a structural support and molecular spring to the myofibril
titin
which protein provides passive tension to the myofibril
titin
which protein is located in the thin filaments and binds actin?
nebulin
which protein acts as a molecular ruler for thin filament assembly
nebulin
What structure stores calcium?
sarcoplasmic reticulum
What is the second messenger that starts the excitation contraction coupling process?
Ca+
Ca+ binds to…
troponinC
contraction step one
tight binding in the rigor state. The crossbridge is at a 45 degree angle relative to the filaments
contraction step two
ATP binds to nucleotide-binding site on myosin. myosin then dissasociates from actin
contraction step three
the ATPase activity of myosin hydrolyzes the ATP to ADP and inorganic phosphate. both products remain bound to myosin
contraction step four
the myosin head swings over and binds weakly to a new actin molecule. the cross bridge is now at 90 degrees relative to the filaments
contraction step five
release of P initiates the power stroke. in the power stroke the myosin head rotates on its hinge, pushing the associated actin filament past it
contraction step six
at the end of the power stroke, the myosin head releases the ADP and resumes the tightly bound rigor state
What are the 3 types of muscle contraction
- isometric
- isotonic
- isokinetic
isometric
constant length
isotonic meaning
constant tension
isotonic 2 types
concentric - shortening
eccentric - lengthening
isokinetic
constant velocity
force-velocity curve
you have the max force when velocity is zero
no velocity
- isometric
- force = Po
positive velocity
- concentric force
- force < Po
negative velocity
- eccentric force
- force > Po
effects of strength training on force-velocity curve
Vmax is not changing but the force is changing
strength of muscle contraction depends on…
- size of muscle
- number and size of motor units recruited
- number and size of fibers within the motor unit
- total amount of contractile protein
- amount of force per individual actin-myosin (crossbridge) interaction
- fraction of crossbridges bound and producing force
motor unit =
one motor neuron and all the fibers innervated by that neuron
one AP induces ____ fibers within that motor unit to contract
all
all fibers within that motor unit are the _________
same type
smaller motor units are for…
fine motor skills and are low force contractions
larger motor units are for more….
crude, gross movements, high force
motor units are activated via the…
size principle
size principle
small units are recruited first, then larger ones
which fiber type will be recruited first according to the size principle?
- slow type 1
- fast fatigue resistant type 2a
- fast fatiguable type 2x and 2b
is there is not enough thick and thin filament overlap what will happen to muscle contraction?
there wont be a lot of force because the sarcomere is too stretched out
length - tension curve
lose ability to generate force when too stretched or compressed
power =
force x velocity
what is passive tension
relaxed muscle is elastic, force is required to stretch it
what contributes to passive tension?
connective tissue
titin (elasticity)
What are some calcium handling mechanisms
- twitch process
- ryanodine
- dihydropyridine
- SERCA
dihydropyridine
located in sarcolema
voltage gated Ca+ channel
ryanodine
connects to dihydropyridine and releases Ca+ from sarcoplasmic reticulum
SERCA
reuptakes Ca+ to sarcoplasmic reticulum and helps to maintain concentration gradient
force parameter
peak twitch tension (Pt)
velocity parameters
- contraction time (CT)
- relaxation time (RT)
- one-half relaxation time (1/2 RT)
fusion of twitches to make ______-
tetanus
single stimulus
Ca+ rises to near saturating levels, but since contraction is slow, force does not reach maximal
multiple stimuli
calcium stays high long enough for force to reach maximal
what ca+ release systems are responsible for actomyosin contraction
- excitation contraction coupling
- DHPR
-RYR - sarcoplasmic reticulum
- calsequestrin (holds Ca+)
What is the main Ca removal system we need to know?
- SERCA
explain SERCA methods
- 2 Ca+ ions into the SR for each ATP hydrolyzed
- uses 20% of ATP in muscle
control mechanisms of SERCA
- sarcolipin (SLN)
- phospholamban (PLN)
- myoregulin (MLN)
why can SERCA be modulated?
you can stop Ca+ from moving into the SR but SERCA can still use ATP up because the by product is heat. Shivering to stay warm is example of why our body does this
