Module 4: Lecture 1 Flashcards
Muscle physiology
Structure dictates what?
Function
What does “Excitation Contraction Coupling” mean?
we excite the muscle
and it is couples with contraction
What is the largest group of tissues in our body?
muscles
What percentage of our body mass is muscle?
50% with 35-40% being skeletal
When muscles develop tension and shorten what does that create?
muscle contractions
We have 2 structure classifications of muscles which are?
- Striated muscle
- Unstriated muscle
What are the 2 subtypes of striated muscle?
- Skeletal muscle
- Cardiac muscle
Is Skeletal muscle voluntary or involuntary?
voluntary
ie. bicep curl
Is Cardiac muscle voluntary or involuntary?
involuntary
ie. heart beats
Is Smooth muscle voluntary or involuntary?
involuntary
Muscle are 4 sub-functions of the muscle?
- protecting out internal organs
- warmth (through shivering if we get to cold)
- contains/stores many amino acids
- huge component to our metabolic rate
What is muscles main function?
contraction
One single skeletal muscle cell is also referred to as what?
myofibre
What are myoblasts?
- mono nucleotide aka one nucleus
- undifferentiated cell
How do we get the multinucleated cell?
lot’s of myoblasts fuse together to create a myofibre
- the myoblasts keep their nuclei
In adults what is the range diameter and length of myofibres?
- 20-100 microns in diameter
- up to 20 cm length
*vary greatly depending on body type
What is the purpose of intercalated discs in regards to cardiac muscle?
- binds cell together
- allows cells to communicate with each other
What are the Macro-organization tiers of a “generic” muscle?
- Muscle
(epimysium wraps around it) - Fascicle (bundle of muscle fibres, surrounded by perimysium)
- Muscle Fibre
(surrounded by endomysium) - Myofibril
(where all our contractile proteins reside)
What is the epimysium?
it is a layer of connective tissue that binds the entire muscle together
- it will continue on into the tendon sheath
- very dense and irregular
What is the perimysium layer?
it is a layer of connective tissue that binds groups of fibres/cells
- it will continue on into the tendon sheath
- very dense and irregular
What is the endomysium layer?
it is a layer of connective tissue that binds individual fibres/cells
- it will continue on into the tendon sheath
- very dense and irregular
What is muscular dystrophy?
where you have a degradation of certain structural proteins that are responsible for some connective tissues, which will affect the mobility and the health of your skeletal muscles
What gives muscles striations?
- Dark A band
- Light I band
*is where our thick and thin filaments stay
Actin is which filaments?
thin
Myosin is which filament?
thick
What is a sarcomere?
repeating pattern along the length of the myofibril
- Dark and Light band
Within the
“I” band theres these little straight lines, which are known as what?
Z-lines/ Z discs
- represents what a sarcomeres
What is the smallest unit of muscle that can contract?
sarcomeres
Where are your myosin molecules located?
thick filaments
What are your thick filaments called?
A band
- an isotropic bond
What does A band mean?
scatters light, meaning when you pass light through it the light scattered and it looks darker to us
What does I band mean?
it allows light to pass through it isotropically, making it appear brighter
What is the Z line?
network of connective tissue proteins, structural proteins
What anchors a single sarcomere on either side?
Z line
True or False
One sarcomere is between two Z lines
true
What are your thin filaments called?
I band
What is the H zone?
center of band A where without any thin filament overlapping the thick ones
What does the H band hold?
contractile proteins
True or False
The thin filaments are anchored directly to the Z-line
True
True or False
The thick filaments are anchored at the M line and the Z line via Titin
True
What is the M-line?
center of the thick filament
What is the largest SINGLE protein in the body?
Titin
What anchors the Thick filaments to the Z-line?
Titin
What are the Thick filaments made of?
- Myosin head
- Myosin tail
What are thin filaments made of?
- Majority actin
Regulatory proteins:
- troponin
- tropomyosin
Why is troponin and tropomyosin important?
key for muscle contractions
What is a cross bridge?
- responsible for force generation
- where the myosin molecules extend to reach the thin action filaments for muscle contraction
What is the sliding movement?
where our thick and thin filaments move towards the center of the sarcomere for muscle shortening and muscle tension
For any given thick filament how many actin molecules
(think filaments) will be surrounding it?
6 in a hexagonal pattern
For any given thin filament how many molecules
(think filaments) will be surrounding it?
3 in a triangular shape
