Chapter 10.2 Flashcards
Why do muscle fibres rarely fatigue?
Because during active use, some are contracting and some are relaxing
What results in muscle tone?
The continuous low-level activity of muscles
What is muscle tone important for?
Maintaining posture
What would happen if there was low muscle tone in the in the body?
That would mean that all the muscles would relax and the body would collapse
What can cause muscles to become impaired?
- Sudden stress placed on muscles and tendons
- Lack of use
What is atrophy?
The reduction of size, tone, and power of muscle due to lack of use
What happens if a skeletal muscle experiences reduced stimulation?
It fibres decrease in size and become weaker
Why is physical therapy important for people with temporary injuries?
Because dead or dying muscle fibres cannot be replaced because damage is permanent.
What is hypertrophy?
An exercise induced increase in muscle mass
What cause hypertrophy?
An increase in size of muscle fibres
How does being more physically fit change the enzymes within muscle fibres?
The enzymes are more active and numerous. The mitochondria are also more abundant
Why can a runner’s muscles endure more than an untrained person’s muscles?
Because a runner’s muscles are more abundant in the mitochondria so they can go longer without having to resort to fermentation
They also receive more blood through additional blood vessels and store more glycogen
What is a muscle twitch?
A muscular contraction that lasts for a fraction of a second
What can a muscle twitch be divided into?
- Latent Period
- Contraction Period
- Relaxation Period
What is the Latent Period?
The period of time between the stimulation and initiation of contraction
What happens during the Contraction Period?
This is when the muscle shortens
What happens during the relaxation period?
This is when the muscle returns to its former length
What is summation?
A cumulative response to stimulus when the muscle doesn’t completely relax before the next stimulus
What is tetanus?
A maximal sustained contraction that results when there are multiple stimuli before the muscle contracts
How long does tetanus sustain?
It is sustained until the muscle fatigues due to depletion of energy reserves
What is another name for Slow Twitch Fibres?
Type I fibres
What is another name for Fast Twitch Fibres?
Type II fibres
What is the method that Slow Twitch fibres use to bring ATP to Myofibrils?
Aerobically
What is the method that Fast Twitch Fibres tend to bring ATP to myofibrils?
Anaerobically
What do Slow Twitch Fibres do?
The contract slowly but resist fatigue
Which kinds of fibres have more endurance?
Slow Twitch Fibres
Why do Slow Twitch fibres have more endurance?
Because they contract slowly but resist fatigue
What activities are Slow Twitch fibres good for?
Biking
Jogging
Swimming
Long-Distance Running
When do Slow Twitch fibres tire?
Because they produce energy aerobically, they tire when their energy supply is gone
What do slow twitch fibres have many of?
Mitochondria and myoglobin
Why can slow twitch fibres maintain long term production of ATP?
Because they are surrounded by dense capillary beds
They also have large reserves of glycogen and fat
What are Fast twitch fibres adapted for?
Rapid generation of power
Which activities use Fast twitch fibres?
Sprinting
Weightlifting
Tennis
What are Fast Twitch fibres rich in?
Glycogen
Why are fast twitch fibres light in color?
Because they have little or no myoglobin and mitochondria, and blood vessels
Why are Fast Twitch fibres susceptible to fatigue quickly?
Because they produce ATP anaerobically, they are more susceptible to a buildup of lactate which causes fatigue
What are the 3rd intermediate form of fibres like?
- They are fast twitch but have high oxidative capacity
- More resistant to fatigue
What increases the amount of the 3rd intermediate form of fires?
Endurance training
They are also hereditary
Why can adaptation that spares glycogen and remove lactate help with endurance?
Because the depletion of glycogen and build up of lactate place a limit of exercise
How can muscle be enlarged?
By frequent high intensity exercise where the muscles work against high resistance
What happens to muscle fibres as a result of resistance training?
Fast twitch fibres become thicker so the muscle grow hypertrophy
What happens to myofibrils during hypertrophy?
Myofibrils with the muscle fibre thicken do to synthesis of actin and myosin and the addition of new material.
What can happen if a myofibril reaches a certain thickness?
It may split into 2 myofibrils which may also become thicker
What is the decline in physical strength in old people due to?
Reduced muscle mass which is caused by the loss of muscle fibres and a decrease of fast-twitch muscles
How does aging affect the blood?
It reduces the capillaries that surround muscle fibres which decreases oxidative capacity
What can resistance training do in old people?
Can cause muscle fibres to hypertrophy and become stronger
What can endurance training do in old people?
Can cause increase the density of blood capillaries in the muscles improving the ability of blood to deliver oxygen to the muscles
What is a stroke?
The inability of the body to cope with elevated body temperature due to very high air temperature
what is shivering initiated by?
Temperature sensitive cells in the hypothalamus in the brain
