Unit 3 Muscles Flashcards
Groups of muscle are covered by…
deep fascia
Muscle is covered by…
epimysium
Fascicle is covered by…
perimysium
Muscle fiber is covered by…
endomysium
Which cells do muscle “fibers” arise from?
Myoblasts
Hypertrophy
Increase in size
Hyperplasia
Increase in number
Can muscle fibers undergo mitosis?
No
What performs the conduction of electrical signals?
Sarcolemma
What controls muscle contraction?
Sacroplasmic reticulum
What allows for muscle contraction?
Myofibrils inside muscle fibers
Longitudinal bundles of protein filaments inside the muscle fiber
Actin and Myosin
Highly organized into repeating units
Sarcomeres
Contractile proteins
Actin and myosin
Regulatory proteins
Troponin and tropomyosin
Actin
- found in thin filaments
- has myosin binding sites for crossbridge formation
Myosin
- motor protein found in thick filaments
- head of myosin binds to the binding site on actin during muscle contraction
In which filament is actin found?
thin
In which filament is myosin found?
thick
Which part of myosin binds to the actin binding cite?
the head
Sarcomeres
Functional unit of contraction
The binding site on actin is covered by what?
regulatory proteins
Which muscle protein gives muscles elasticity and extensibility?
Titin
Which muscle protein helps the sarcomere return to its resting length?
Titin
What is a cytoskeletal protein that links thin filaments to the sarcolemma?
Dystrophin
Which muscle protein is attached to the extracellular proteins in the connective tissues surrounding the muscle fibers?
Dystrophin
Which muscle protein helps transmit tension from sarcomeres to tendons?
Dystrophin
Which muscle protein spans the length of the thin filament?
Nebulin
Which muscle protein anchors thin filaments to Z disc?
Nebulin
Which muscle protein is found in the Z disc?
α-actinin
Which muscle protein binds to actin molecules of the thin filament to titin?
α-actinin
Which muscle protein is found in the M line?
myomesin
Which muscle protein binds titin and thick filament to connect them together at the M line?
Myomesin
Myosin heads bind to actin to form a ________
crossbridge
Conformational change is energized by ________ to cause thin filaments to slide along thick filaments
ATP hydrolysis
As thick / thin filament overlap increases….
I band length decreases
A band length remains constant
H zone length decreases
Zone of overlap increases
the attached head group after the power stroke is called a _______
Rigor complex
Rigor mortis
the rigor of death because lack of ATP to detach the crossbridge
Functions of skeletal muscle
- locomotion
- facial expression
- heat production
Function of cardiac muscle
pump blood into systemic circulation
Functions of smooth muscle
- propel food
- mix food
The immediate source of energy to support development of tension
ATP
Hydrolysis by the myosin head group fuels _________
tension generation
Hydrolysis by the Ca-pump of the SR supports ________
relaxation
What are three ways ATP re-synthesizes?
- creatine phosphate
- anaerobic glycolysis
- aerobic metabolism
How long does ATP support force?
2 seconds
How long does creatine phosphate support force?
15 seconds
Creatine phosphate pool after a meal
ATP + C –> ADP + CP
Creatine phosphate pool during exercise
ADP + CP –> ATP + C
Small amino acid-like molecule
Creatine
Where is creatine synthesized?
Liver, kidney, and pancreas
Where is creatine transported?
Muscle fibers
In a relaxed muscle fiber what is 3-6x more plentiful than ATP
Creatine phosphate
How long does glycolysis support force?
2 minutes
Where does glycolysis occur?
Rapidly, cytoplasm
How long does aerobic respiration support contraction?
40 minutes to several hours
Fatigue is caused by
- glycogen depletion
- lactic acid buildup
- phosphate buildup from creatine phosphate metabolism
- potassium accumulation
What structural muscle protein spans the z disc to m line
Titin
Which structural protein stabilizes thick filament?
titin
Which muscle protein gives muscle its elasticity and extensibility?
Titin
Which structural muscle protein helps the sarcomere return to its resting length?
Titin
Which regulatory proteins are found in thin filaments?
Tropomyosin and troponin
Which regulatory protein covers the myosin binding sites on actin?
Tropomyosin
Which regulatory protein holds tropomyosin in place?
Troponin
During muscle contraction, what binds to troponin?
Calcium
Contraction cycle
- Binding sites exposed
- Myosin heads bind (crossbridges)
- Myosin heads pivot
- ATP binds –> detachment
- ATP Hydrolyzed
BCMDH
Excitation
Electrical signal from neuron to muscle fiber
Excitation Contraction Coupling
Releases CA from SR
Contraction
Crossbridges form
Relaxation
removal of Ca
Pyruvic acid turns into what during anaerbic glycolysis
Lactic acid
At rest, myosin heads cannot bind because
Tropomyosin is covering the binding sites on actin
When ATP is hydrolyzed by the myosin ATPase, which immediate step occurs
The myosin head moves into a cocked position
In the cori cycle, lactic acid…
is converted into glucose in liver cells
Tetanus (tetanic contraction)
summation of individual twitches over time
Mechanism for increasing tension
Tetanus (temporal summation) is a mechanism for increasing tension
Motor Unit
A motor neuron and all of the muscle fibers it innervates
Spatial Summation
Activating increasing numbers of motor units to increase tension
The first motor units recruited are…
small
innervate few fibers
As more force is required activate fibers…
larger motor units are recruited
Motor united are recruited in order from…
small to large
Standing required what size motor units?
Smallest motor units
Sprinting and jumping require what sized motor units?
Large to largest
Isometric means …
same length
During isometric contraction …
muscle generates tension but does not shorten
every contraction begins …
isometrically
Isotonic means …
same tension
During isotonic contraction …
after sufficient tension is generated to move the load, the muscle changes length
What does creatine phosphate donate to?
Donates a phosphate to ADP to create ATP
Lactic acid can be transformed back into glucose where?
Liver
What does lactic acid inhibit
Glycolysis
Pyruvate –> lactic acid
anaerobic
pyruvate –> mitochondria
aerobic
How will capillary density change during exercise?
Increase
How does mitochondrial density change from exercise?
Increase
How does the cross sectional area change from exercise?
Increase
How long does increased capillary density take?
3-4 weeks
Increased mitochondria help improve…
aerobic capacity
How fast do slow fibers contract?
Slowly
Are small fibers slow in diameter?
no
What type of metabolism do slow fibers use?
Aerobic
What metabolism do fast fibers use?
Anaerobic
How fast do intermediate fibers move?
Relatively fast
What metabolism do intermediate fibers use?
Primarily anaerobic
Within a motor unit all the fibers are…
the same type
Slow fibers are which type
Type I
Type I fibers
- Low ATPase speed
2. High resistance to fatigue
Slow oxidative type I fibers rely on which metabolism
aerobic
Slow oxidative fibers have a ____ myoglobin content
high
Slow oxidative fibers have a ____ capillary supply
dense (for O2)
Myoglobin is a protein that carries ______ through the cell
oxygen
Fast- glycolytic IIb fibers
- High ATPase speed
2. Low resistance to fatigue
FG type IIb fibers rely on what metabolism?
anaerobic glycolysis
FG IIb fibers have _____ mitochondria
few
FG IIb fibers have _____ myoglobin content
low
FG IIb fibers have ______ glycolytic enzyme content
high
FG IIb has _____ creatine kinase content
high
Glycolytic and cratine kinase enzymes are used for
anaerobic
Intermediate, fast oxidative glycolytic, Type IIa fibers
- Moderate ATPase speed
2. Intermediate resistance to fatigue
FOG type IIa fibers rely on what metabolism?
glycolysis but have a higher aerobic capacity compared to IIb
Myoglobin contains _____ that allows it to bind to oxygen
heme (iron)
What is responsible for muscles red color?
myoglobin
Slow oxidative fibers have more fat because
they have better aerobic respiration
Latent period can be compared to…
excitement- contraction coupling with no tension development
The more calcium is present…..
the more crossbridges form
The eye muscles twitch at which speed?
Fast twitch
What is the time course for the soleus?
Slow twitch
Muscles that slow twitch are more for which purposes….
posture
In a second class lever
the load is between the fulcrum and the effort
Nodding your head yes involves
flexion of the head at the first class lever
ATP binds to the myosin head and causes
the detachment of myosin from actin
The type of contraction that generates tension while they lengthen
eccentric
In skeletal muscle, what acts as ATPase during the contraction cycle?
myosin head groups
Characterization for intercalated discs
cardiac muscle
characterization for numerous large mitochondria
cardiac muscle
Which muscle allows for tubes like blood vessels to change in diameter?
smooth muscle
In which contraction is the effort greater than the load
Concentric
What are two common muscle themes?
Sliding filament
Regulation of cytoplasmic Ca
Cardiac muscles compared to skeletal muscles have a _____ extensive T-tubule and SR system
less
gap junctions are…
channels that allow signals to pass between cells
Desmosomes help to…
keep cardiac cells together
For cardiac muscle SR Ca…
is not enough to support contraction
What initiates cardiac muscle contraction?
Cardiac muscle has its own signal… not the nervous system
Autorhythmicty
pacemaker cells —> generation of APs
Cardiac muscle cells have no _____ ________
motor units
Cardiac muscle cells have no _____ ________
motor units
Twitch
the response of the cell of one electrical signal
Every cardiac muscle contraction is considered a _______
twitch
In skeletal muscle it is considered _______ not twitches
tetanus
Describe smooth muscles nucleus
small single nuclei
Describe the structure of smooth muscle
lacks a clearly organized structure
Does smooth muscle have sarcomeres
no
Describe smooth muscle t-tubule/SR system
has none
In smooth muscle Ca DOES NOT interact with….
regulatory proteins
In smooth muscle contraction what does Ca bind to
calmodulin
