Test Two Muscle Flashcards
What are the three types of muscle
Skeletal, cardiac and smooth
Where are smooth muscles found
In organs
Describe the smooth muscle
Involuntary, non striated, cells are fusiform with centrally placed nucleus that is elongated into the long axis of the cell
What does smooth muscle look like in cross section
Numerous sizes of of muscle cells with nucleus in the center
Where is cardiac muscle found
In the heart only
Describe cardiac muscle
Involuntary and striated, branching elongated fibers with centrally placed nucleus
What occurs in intercalated disk in cardiac muscle
Where the cell membranes come together in gap junctions
What is also found in cardiac muscle
Intercalated discs
Function of intercalated discs
Mechanisms to hold the cell together and form tunnels in between cells, this helps move ions from one cell to another
What does the cross section of the cardiac muscle look like
Cells will be same size, centered nucleus, granular appearance due to striations
Where are skeletal muscles located
Found in the muscles of the limbs and trunk
Describe skeletal muscle
Voluntary and striated, long muscles that are parallel and contain multiple peripheral nuclei
What does a cross section of skeletal muscle look like
Nuclei off to the edges, will see granules due to striations
What are the three coverings of the muscle
Endomysium, perimysium and epimysium
Describe endomysium
Loose aerolar connective tissue that wraps around each muscle cell
Purpose of endomysium
Cuts down the friction between each individual muscle cell
Purpose of having loose tissue in the endomysium
When the muscle cell contracts, it will increase in diameter
What is a fascicle
Groups of muscles cells that are bundled together
What covers a muscle fascicle
Perimysium
As we increase the thickness of the fascicles then there is a decrease in
The control on the muscle itself
What surrounds the entire muscle
Epimysium
Purpose of epimysium
Responsible for separating that muscle from all other tissues
Under a light microscope, when can be seen in a sarcomere
Light and dark bands
The light band in a sarcomere under a light microscope is called what
The I band
The dark band in a sarcomere under a light microscope is called what
A band
What is a sarcomere
Functional unit of muscle contraction
What line is located in the “I” band
Z line
The in the A band, what is the dark staining line in the middle called
The M line
What is the area around the M line called
The H zone
What range is known as the sarcomere
Z line to Z line
What is included in one sarcomere
2 z lines, complete A band, two halves of I band, H zone and M line
What happens to sarcomere during contraction
Distance between Z lines decrease
How does staining work with the sarcomere
Staining has to deal with the configuration of the thick filaments vs thin filaments, thick stains dark
What is in an “I” band
Only thin filaments, so has small diameter and is light staining
M line contains what type of filaments
Linking filaments
What are linking filaments
Hook thin and thick filaments together
M line is what type of staining and why
Dark staining, contains both thick and thin filaments with globular proteins
H zone is made up of
Thick filaments
Describe appearance of thick filaments
Contains a lot of extensions known as fibers. The fibers pick up stain but gets diffused due to the fibers
What makes up the A zone
Thick and thin filaments and stains darker due to more material due to the increased amount of fibers
Thin filaments are made up of how many proteins
Three different proteins
What are the three proteins that thin filaments are made up of
Actin, tropomyosin, and troponin
Actin is made up of what
Microfilaments
What are the individual filaments in actin
G actin (globular actin)
How do you get F actin
String G actin together
F actin stands for what
Filamentous
What forms the thin filament of actin
Two of the F strands twist together
Where is tropomyosin found
Actin/ thin filament
Describe tropomyosin
Thin linear protein that is double stranded and it is weaved through the F actin strands
Function of tropomyosin
Protein that holds (glues) the F stands together
Where is troponin found
Thin filaments
What makes up troponin
TnC, TnT and TnI
Function of TnC
Binds calcium
Function of TnT
Binds to the tropomyosin
Function of TnI
Troponin inhibitory so it blocks the interaction between the actin and myosin
Where is TnI located in the thin filament
Sits in between the actin and myosin
For muscle contraction, what happens to TnI
Remove the TnI
Thick filaments are also known as
Myosin
Myosin are made up of what two subunits
Light meromyosin and heavy meromyosin
Light meromyosin forms what
The shaft of the entire myosin
The heavy meromyosin forms what
The head of the myosin
Describe the heavy meromyosin
Has two different binding sites on the head, one site for ATP and one for Actin
What is needed for muscle contraction
ATP and calcium
What picks up the stain in thick filaments
The heads due to the fibers in the filaments
Type one muscle stains
Dark
Why does Type one muscle stain dark
Due to myoglobin
Function of myoglobin
Carrier molecule for O2 and CO2
What type of contraction with type one muscle
Continuous slow types of contraction
What type of energy does type one muscle
Uses oxidative phosphorylation and fatty acids for energy, uses adipose tissue
What is the staining like for type two muscle
Lighter
Why is type 2 muscle lighter staining
Less myoglobin
What type of contraction is type two muscles
Very rapid ability to contract
What type of energy production does type two muscles have
Glycolysis and sugar for energy
What is the normal person ratio of type one and type two
50:50
What controls the percentage of type one or two fibers
Genetics
What are the three subtypes of Type 2 fibers
2A, 2B, and 2C
What subtype of Type 2 fibers is the fastest action and uses glycolysis for energy
2B
What is the sarcoplasmic reticulum made of
Modified smoother ER
What is the sarcoplasmic reticulum consist of
Terminal cisternae and tubules
Function of terminal cistern
Storage of calcium
Where is the true sarcoplasmic reticulum
Tubules in between the two terminal cisternae
Function of the tubules in between the two terminal cistern
Allows for balancing of calcium between the two terminal cistern
Function of T tubules
Allows for action potential to move to muscle
What occurs when action potential hits T tubules
The terminal cistern release calcium which allows muscle contraction to occur at the muscle cell next to the terminal cistern
What is the triad of the sarcolemma
Two terminal cistern and one T tubule
The sarcoplasmic reticulum that surrounds what
Myofilaments
T tubule is responsible for the conduction of what
The action potential
Where are triads located specifically in the sarcolemma
A and I band
If a skeletal muscle does not have innevervation what happens
No muscle contraction
If the nerve fails to develop for the skeletal muscle what occurs
Muscle does not develop
What brings the action potential to the muscle
Nerves
What is the presynaptic terminal made of
Nerve
What happens to the presynaptic terminal as it reaches the muscle
Begin to swell and form a knob
What does the knob do at the presynaptic terminal
Increase surface area
What will you see in the knob of the presynaptic terminal
Vesicles that contain neurotransmitters
What is the neurotransmitter for skeletal muscle
Acetylcholine
What other organelle do you see in the presynaptic cleft
Mitochondria
Why is there mitochondria present in the presynaptic terminal
Need energy for muscle to contract
The neuron passes through what of the muscle for each muscle cell to be innervated
Perimysium
What is the postsynaptic terminal made up of
Muscle
Why is the postsynaptic terminal folded
Increase surface area which increases number of receptors
The receptors of the postsynaptic terminal binds with what
Acetylcholine
As action potential comes down the nerve what occurs
Coming to cause acetylcholine to leave the vesicles, acetylcholine will attach to the receptors on membrane, if action potential reaches threshold then contraction occurs
Number of muscle cells that are innervated by an individual nerve fiber is going to be proportional to what
To the control on that muscle
More muscle contraction then
Less muscle control