Introduction to pathophysiology of the skeletal muscle (Lecture) Flashcards
What are type IIx muscle fibres?
- transition between type IIa to type IIb
- type IIa and IIb are fast twitch fibres
What effect does endurance exercise have on muscle diameter?
- small change
- muscle becomes more toned but no major increase in muscle mass
What effect does endurance exercise have on muscle blood supply and mitochondrial number?
1 - reduced mitochondrial number and blood supply
2 - reduced mitochondrial number and increased blood supply
3 - increased mitochondrial number and reduced blood supply
4 - increased mitochondrial number and blood supply
4 - increased mitochondrial number and blood supply
- blood delivery increases and increases oxidation capabilities
- increased mitochondrial content to accommodate oxidative capacity
What happens to the fibre type in muscles following endurance exercise?
1 - switch from IIb to IIa or I
2 - switch from I to IIb only
3 - switch from IIb to I only
4 - switch from IIa to IIb
1 - switch from IIb to IIa or I
- change from fast twitch to slow twitch
- type IIx (fast) can become type IIa or even type I (slow)
During resistance exercise what can happen to muscle fibre type and what affect does this have on muscle force?
1 - switch from IIb to IIa or I
2 - switch from I to IIb only
3 - switch from IIb to I only
4 - switch from IIa to IIb or IIx
4 - switch from IIa to IIb or IIx
- switch from IIa (fast) to type IIx (very fast)
- results in increased muscle force
During resistance exercise what can happen to muscle fibre size, sarcomeres and myofilaments?
- all increase
- increased fibre size due to increased sarcomeres and myofilaments number
- results in increased muscle size and strength
Following an acute injury, such as a sprain, what can ice do in the damaged area?
- reduce swelling and inflammation
- reduce blood flow
- reduce pain
- reduce muscle spasms
What can heat do to a muscle?
1 - stiffen, reduced stiffness, increased blood flow
2 - relax, reduced stiffness, increased blood flow
3 - stiffen, reduced stiffness, reduced blood flow
4 - relax, reduced stiffness, reduced blood flow
2 - relax, reduced stiffness, increased blood flow
What affect do NSAIDs and aspirins have on muscle pain?
- inhibit COX-1 and 2 that produce prostaglandins
- no prostaglandins means less sensitisation of nocioceptors
- reduced pain and inflammation
Long term use of COX-1 and 2 inhibitors can have 2 major side effects and should be avoided. What are they?
- peptic ulcers
- kidney problems (prostaglandins vasodilate afferent arteries) due to reduced blood flow and filtration
Anabolic steroid, such as testosterone can be used to increase muscle size. What affects do anabolic steroid have on the following:
- protein synthesis
- catabolism (by opposing cortisol & glucocorticoids)
- fat
- increases protein synthesis
- decreases catabolism (proteolysis, lipolysis) by opposing cortisol & glucocorticoids
- reduces fat by increasing BMR
Anabolic steroid, such as testosterone can be used to increase muscle size, but large doses are required to see the effects. What are the 4 key side effects of these steroids?
1 - skeletal muscle atrophy, increased organ size, sterility and hair loss
2 - testicle atrophy, organ damage, sterility and hair loss
3 - testicle atrophy, organ damage, hair loss
4 - testicle atrophy, organ damage, sterility
2 - testicle atrophy, organ damage, sterility and hair loss
What affect can space flight and immobilisation have on muscle fibre type?
- decrease in number of type I fibres (slow)
- increased type IIa and IIx fibres
- causes muscle atrophy, especially weight bearing
What affect can space flight and immobilisation have on muscle strength and protein synthesis in muscles?
- reduced protein synthesis
- reduced muscle mass and strength
What is contracture?
- fixed tightening of muscle, tendons, ligaments, or skin when long period of immobilisation
- prevents normal movement of the associated body part
Contracture is a fixed tightening of muscle, tendons, ligaments, or skin that prevents normal movement of the associated body part and is associated with long periods of immobilisation. What happens to the following that can lead to contracture?
- growth process
- sarcomere number
- muscle length
- growth process = reversed
- sarcomeres are lost from myofibrils
- less sarcomeres causing shortening of the muscle
- physical therapy can help
Contracture is a fixed tightening of muscle, tendons, ligaments, or skin that prevents normal movement of the associated body part. What happens to the tendons and fascia that can lead to contracture?
1 - thicken, stiffen, shorten and can becomes fibrotic
2 - thinner, relax, shorten and can becomes fibrotic
3 - thicken, stiffen, lengthen and can becomes fibrotic
4 - thinner, stiffen, lengthen and can becomes fibrotic
1 - thicken, stiffen, shorten and can becomes fibrotic
What do skeletal muscles develop as?
1 - myocytes
2 - myoderm
3 - myotubes
4 - myoblasts
4 - myoblasts
- myo = muscle
- blasts = immature cells
Are muscle cells able to divide and undergo mitosis?
- no
- due to multi-nucleus being present
How do myoblasts create muscle cells resulting in multinucleated muscle cells?
- multiple myoblasts (singular nucleus) fuse together
- results in multi nucleus on peripheries of muscle
Following a muscle injury, what cell, which are normally quiescent can then stimulate muscle growth and repair?
1 - quiescent myogenic cells, called satellite cells
2 - myoblastd proliferate
3 - myoclasts proliferate
4 - muscle cells expand
1 - quiescent myogenic cells, called satellite cells
Following a muscle injury, quiescent myogenic cells, called satellite cells are able to stimulate muscle growth and repair. What do they release to stimulate this muscle growth and repair?
1 - insulin growth factor
2 - hepatocyte growth factor
3 - fibroblast growth factor
4 - myoblast growth factor
- hepatocyte growth factor
Within the muscle cells there is a cell that when activated is able to re-enter the cell cycle and differentiate into new myotubes, myoblasts and eventually new muscle cells. What are these cells called and are they always active?
1 - myoblasts
2 - myoclasts
3 - myosatellite cells
4 - epithelial growth cells
3 - myosatellite cells
- generally quiescent and activated by satellite cells
What does myalgia mean?
- my = muscle
- algia = pain
- so it means muscle pain
What is myopathy?
- myo = muscle
- pathy = disease
- so means diseased muscle
What is dystrophy?
- muscle wasting
What is paresis?
- condition in which muscle movement has become weakened or impaired
- generally due to nerve problems
Paresis is a condition in which muscle movement has become weakened or impaired. What is this caused by?
- upper motor neuron damage, think UMN lesion
- causes muscle weakness
Paresis is a condition in which muscle movement has become weakened or impaired and is commonly caused by upper motor neuron damage, resulting in muscle weakness. What do the following terms refer to:
Monoparesis
Paraparesis
Hemiparesis
Tetraparesis/Quadriparesis
- monoparesis = one leg or one arm is weakened
- paraparesis: both legs are weakened (spinal cord damage at the lower level)
- hemiparesis = one side of the body (arm+leg) are weakened (stroke UMN)
- tetraparesis/quadriparesis: all 4 limbs are weakened due to cervical cord or spinal cord damage at a higher level
What is the name of the muscle grading scale used to assess muscle strength in any muscle disorder?
- MRC muscle grading scale
The MRC muscle grading scale is used to assess muscle strength in any muscle disorders. What score would be expected in a patient with paralysis (loss of muscle function)?
- 0-1
- maximum score is 5 using the scale of 0-5
Dystrophy is a loss of muscle mass and strength. What are dystrophies?
- congenital muscle diseases causes degeneration/regeneration cycle
- results in weakness decreases mobility, making everyday tasks difficult