Skeletal muscle Flashcards
What are the 3 types of muscle
- Cardiac
- Skeletal
- Smooth
How many skeletal muscles are there in the human body
650 - 840
What is the primary functions of skeletal muscles
To enable humans to move and perform daily activities
Name structures of the muscle (7)
- Perimysium
- Blood vessel
- Muscle fibre
- Fasicle
- Endomysium
- Epimysium
- Tendon
What are Sacromeres
- Functional unit of the muscle which runs parallel to the fibre
- Also a storage site for calcium
What are the 2 contractile proteins called
- Actin
- Myosin
Actin
Thin filaments
Myosin
Thick filaments
The crossbridge cycle process (6 steps)
- While relaxed myosin cannot interact with actin due to the presence of tropomyosin
- Muscle contraction begins when the nervous system generates a signal called an action potential
- A muscle is stimulated and calcium ions released
- CA2+ binds to troponin, shifting the actin filaments
- Which exposes actin binding sites
- Myosin heads then from a cross-bridge with actin within the muscle cell that is broken by adenosine triphosphate (ATP)
- ATP hydrolysis causes the myosin heads to change orientation, causing them to bind to the actin filament
The sliding fillament theory
- The sliding of actin along myosin shortens the sarcomere causing a muscle to contract
- The nerve impulses to the to the muscle stop and calcium ions are removed by the reuptake into the sarcoplasmic reticulum
- The troponin-tropomyosin complex prevents interaction of actin and myosin
- Actin and myosin return to their unbound state, and the muscle relaxes
What is electrical stimulation of muscles used for
- ACL injuries
- Elderly
- Disabled
- Those with movement restrictions
What are the 3 types of muscle fibres
- Type 1 = Slow oxidative
- Type 2a = Fast oxidative
- Type 2x = Fast glycolytic
Characteristics of Type 1 (slow oxidative) muscle fibres
- Red
- Small
- Large volume of myoglobin
- High levels of mitochondria
- High resistant to fatigue
- Slow and sustained contractions
- Low force of contraction
- High capillary density
- Low glycolytic capacity
Characteristics of Type 2a (fast oxidative) muscle fibres
- Moderate/fast contraction speed
- Medium size
- Fairly high resistance to fatigue
- Medium force production
- High mitochondrial density
- High oxidative capacity
- High glycolytic capacity
- Manufacture ATP
Characteristics of Type 2x (fast glycoytic) muscle fibres
- White
- Low levels of myoglobin
- Low levels of mitochondria
- Low resistance to fatigue
- Fast contraction speed
- Large motor neuron
- Low capillary density
- High oxidative capacity
- High glycolytic capacity
Which muscle fibre is used during a long distance running race
Type 1 (slow oxidative)
Which muscle fibre is used during a 100m sprint
Type 2x (fast glycolytic)
What are the 5 types of muscle contraction
- Isotonic
- Concentric
- Eccentric
- Isometric
- Isokinetic
Isotonic
A muscle contraction where the tension remains the same length of the muscle changes
Concentric
An isotonic contraction where the muscle SHORTENS
Eccentric
An isotonic contraction where the muscle LENGTHENS
Isometric
A muscular contraction in which the length of the muscle does not change
Isokinetic
A muscle contraction where the speed of movement remains constant, but the tension varies
Hypertrophy
An increase in size of individual muscle fibres
