Muscles Flashcards
what are the 3 types of muscle and their percent of body weight
- Cardiac (cardiac + smooth = 10%)
- Smooth
- skeletal (30-40%)
What are the 4 properties of muscle and what they do?
- Contractibility: can shorten and thicken to produce force
- Excitability: able to conduct a electrical signal
- Elasticity: returns to its original shape
- Extensibility: able to stretch without damage
What is myogenisis?
The creation of new muscle tissue
What do myoblasts do?
multiple myoblasts form together to create a new muscle fibre (called fusion)
Another word for myocytes?
myotubuals
What is a satellite cell?
stem cells in skeletal muscle that helps with repair and growth
Name the structure of a muscle starting from largest to smallest units. Include the facia layers covering them.
- Muscle - covered by epimysium
- Fasicles - surrounded by perimysium
- muscle fibers - surrounded by endomysium
- Myofibrils
Where are the sarcomeres located?
the myofibrils
what is the roll of the sarcoplasmic reticulum and where is it located?
It encases the myofibrils and is used as a transport system for calcium
Superficial facia vs deep facia
Deep: surrounding muscles and bones
Superficial: just below the skin
What is apponeurosis?
large sheet of connective tissue that connects bone to muscle. eg. at top of skull
Define muscle contraction
Tension in the muscle (Does not need to change length)
What are the 3 types of muscle contraction
Isotonic: Muscle changes in length (concentric and eccentric)
Isometric: Muscle length does not change but theirs tension in muscle
Isokinetic: Muscle changes length at a constant velocity
Describe all the steps of the sliding filament theory
look at page in binder
What needs to happen in order for cross bridges to form and a power stroke to occur?
Calcium must bind to troponin, which removes tropomyosin from the active sites on the actin. Myosin heads must be in an energized state. When ADP and Pi de attach it causes a power stroke.
What causes the cross bridge to de attach?
ATP binds to the myosin head causing it to de attach. ATP is then hydrolyzed
Explain why theirs still tension is isometric contractions
Myosin heads get stretched out causing tension. Myosin heads don’t attach to new active sites causing the muscle to not change lengths
Eccentric contract
the load is more than the tension and the muscle can’t hold up the weight. Myosin heads get forcefully ripped of the actin. This means that no ATP is used but more damage is done
Name the contractile proteins
- Actin
- Myosin
Name the regulatory proteins
- Troponin
- Tropomyosin
Name the structural support proteins and what they do
- Titin: connects the thick filaments to the Z-line
- Actinin: protein that makes the Z-line
- Dystrophin: Protein that helps make the costameres
- Nebulin: Part of the thin filament that helps hold the actin together
What are costameres and where are they found?
Links actin to the sarcolemma and transfers the force produced at the sarcomeres to the muscle. (eg. drive shaft in a car)
What’s a disease called where the costameres aren’t working properly?
Muscular dystrophy
What are the sections of the sarcomere
A band: Length of the thick filaments
H- zone: Zone where theirs only thick filament
I- zone: Zone with only thin filament
Z-line: Connects the thin filaments together
M- line: Midline. Connects the thick filaments together
Zone of overlap: Zone where their is both thick and thin filament
Explain the structure of the sarcoplasmic reticulum
- Terminal cisternae: Enlarged region at each end of the sarcoplasmic reticulum that stores calcium
- Tubes connect the terminal cisternae
What are T-Tubuals and where are they located
They are part of the sarcolemma (membrane of the muscle fibre) that dip down and are part of the process that releases calcium