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
One neuron can connect to multiple muscle fibres true or false?
True.
explain the neuromuscular junction process
look at sheet in binder
Explain the structure of the motor end plate
- Has acetylcholine receptors that are ligand gated channels that allow for the entrance of sodium
- Has a folded structure in order to increase surface area
What is the enzyme that breaks down acetylcholine
Acetylcholinesterase
What is depolarization?
Making the inside of the membrane more positive compared to its resting state
How is the calcium retrieved and put back into the sarcoplasmic reticulum?
A protein called calsequestrin brings the calcium back
Explain the process of the neuromuscular junction from the action potential coming down the motor neuron until the release of calcium from the terminal al cisternae
look at page in binder
What is the series of events starting from the action potential ending with muscle contraction called?
Excitation contraction coupling
What is tension, what is load?
Tension: The force placed on a load, coming from the muscle
Load: The force placed on the muscle coming from the load
Changes in muscle length depend on…
- Amount of load
- Amount of tension
What is the load velocity relationship?
How fast a muscle can change lengths in relation to the load
When the load>tension what kind of contraction is it
Eccentric contraction (muscle lengthening)
When is the muscle shortening speed the fastest?
When the load = 0
What determines tension?
Amount of cross bridges formed. More cross bridges = more tension
What 2 types of tension add together to make total tension
Active tension: thick and thin filaments contracting
passive tension: Tension is generated non activly and is produced by “hanging off of your joints”
explain the Length tension relationship
Active tension has an optimal length of contraction ion where it produced the most amount of tension.
Muscle is too contracted: Thin filaments overlap onto of each other therefor myosin heads on the thick filament won’t be able to bind to all off the active sites on the thin filament
Muscle too stretched: Thin filaments are stretched out so much that not all of the myosin heads are in contact with actin therefor not as much cross bridges
Name the 3 different deep facia layers and what they surround
Epimysium: surround the muscle
Perimysium: Surround the fascicles
Endomysium: surrounds the muscle fibres
Explain what summation is
High frequency of action potentials reaching the muscle leads to continuous contractions. The muscle isn’t allowed to fully relax before its contracted again leading to increased tension
Summation leads to tetinus. what is tetinus?
Frequent muscle twitches lead to a smooth muscle contraction
How far apart do the twitches have to be to not build up tension?
200ms
What are the 2 types of teninus and what are they?
Unfused: Some relaxation is allowed between contractions
Fused: Action potential frequency so high no relation of the muscle between contractions
What are the 3 phases of a muscle twitch
- Latent period: Time between the action potential reaching the motor end plate to when calcium is released from the terminal cisternae
- Contraction phase: Time during cross bridge cycling
- Relaxation phase: Time when tension decreases and calcium is being retuned to the sarcoplasmic reticulum
Explain what muscle recruitment is
Process where multiple motor units work together to produce force
Explain the difference in use between smaller motor units and larger motor units (what their used for)
Larger motor units: Nerve innervates more muscle fibres and can produce more power
Smaller motor units: Nerve enervates less muscle fibres, but is more precise
Explain Heinemann size principal and explain why it happens
Theirs a specific order of muscle recruitment that happens. Smaller motor units gets recruited first then progresses to the bigger ones.
Why: its easier for the brain
What is maximum muscle tension
All motor units are recruited
What is Muscle tone
Passive muscle contraction that is always present. (eg. holding our head up without thinking about it) due to a constant level of action potential always being produced
What is the first change seen when. beginning to workout?
Muscle tone increases leading to a more defined look of the muscles
What are the two types of muscle growth that occurs when doing resistamce training. explain what they are.
Transient hypertrophy: Increase in muscle size developed right after a workout due to fluids accumulating around the cells. (getting a pump)
Chronic hypertrophy: Increase in muscle size as a result of long term exercise.
Explain the structure of ATP
Nitrogenous base + % carbon carb + 3 phosphates
What are the 4 ways ATP is generated?
- Phosphocreatine system
- Glycolysis (Anaerobic)
- Glycolysis (aerobic) and oxidative phosphorlation
- Oxidative phosphorylation of fat
Explain the Rate, location, production, oxygen requirement, and duration of… The Creatinephosphate system
Rate: immediate
Location in the cytosol
Production: very little
Oxygen: No
Duration: 3-15 seconds
Explain the Rate, location, production, oxygen requirement, duration and process of… anerobic glycolysis
Rate: fast
Location in the cytosol
Production: 2 net ATP
Oxygen: No
Duration: 30 seconds - 2 minutes
process:
-Start with glucose (6 carbon molecule)
- Split into 2 molecules of pyruvate (3 carbon molecule)
- Without oxygen pyruvate turns to lactate
- produces 2 ATP
Explain the Rate, location, production, oxygen requirement, duration and process of… Aerobic glycolysis and oxidative phosphorlation
Rate: Slow
Location in the mitochondria
Production: 34 ATP
Oxygen: Yes
Duration: 40 minutes
Process:
- Glucose splits into 2 pyruvate molecules
- Instead of turning into lactate, the presence of oxygen turns the pyruvate into acetyl co-A
- Acetyl Co-A enters the Krebs cycle
-Produces 34 ATP
Explain the Rate, location, production, oxygen requirement, and duration of… Oxidative phosphorylation of fat
Rate: Very slow
Location in the mitochondria
Production: >130 ATP
Oxygen: Yes
Duration: Energy lasts for hours
What are the 3 types of muscle fibres?
- Slow oxidative fibers (type 1)
- Fast oxidative glycolytic fibers (type 2a)
- Fast glycolitic fibers (type 2b)
Explain slow fibres (type 1)
- Small diameter = least powerfull
- Required the most oxygen therefore its structure produces the most oxygen by having…
- High capillary density
- High mitochondrial density
- High myoglobin density
- fatigue resistant
- slow speed of contraction
Explain fast fibres (type 2a)
- medium diameter = medium power
- medium capillary density
- medium mitochondria density
- medium myoglobin density
- Relies on both glycolysis and oxidative phosphorylation
- Medium resistance to fatigue
- Fast speed of contraction
Explain fast fibres (type 2b)
- large diameter = most powerful
- Low capillary density
- low mitochondria density
- low myoglobin density
- Relies on anaerobic processes for ATP
- very fatiguable
- Fastest speed of contraction
