Muscle Flashcards
What types of contraction are there?
Isometric, cocentric and eccentric
What’s isometric contraction?
When the muscle is held at a constant length
When force increases with no change in muscle length
The force generated during an isometric contraction is dependent on?
The length of the muscle while contracting
Max isometric contraction is produced ?
At the muscles optimum length
What’s a concentric contraction ?
When the muscle shortens
What’s an eccentric contraction and how does it work?
This is when the muscle lengthens.
When the muscle is generating force but it’s not enough to shorten the muscle so the muscle extends instead
All these types of contraction are ..?
Isotonic contractions. Where the length of the muscle changes
What’s the functional unit of the skeletal muscle ?
Motor unit
What’s the motor unit made of ?
-alpha motor neurons (located in spinal cord)
-it’s axon
Muscle fibres
What are the types of skeletal muscle fibres?
- slow twitch oxidative fibres (type 1)-
- fast twitch oxidative
- fast twitch glycolytic
What’s slow twitch oxidative fibres ?
Contract slowly and use aerobic respiration (glucose and oxygen) to produce ATP
What are fast twitch oxidative fibres?
They have fast contractions and primarily use aerobic respiration but can switch to anaerobic respiration so fatigue quicker than SO fibres.
(Type 2a)
Generate force quickly
What’s fast twitch glycolytic fibres ?
They produce very fast contractions and primarily use anaerobic respiration
Fatigue more quickly than others
(Oxidative fibres contain more mitochondria )
What are SO fibres good for and why?
As they can function for a long time without fatiguing, they are good for maintaining posture,
Producing isometric contractions
Stabilising bones and joints
Making small movements that happen often but don’t require lots of energy
What are FO fibres good for ?
They produce ATP relatively quickly (can produce high amounts of tension) have lots of mitochondria
Don’t fatigue quickly
Don’t have myoglobin so they have a lighter red
Useful for walking (as they produce more tension that SO fibres but are more fatigue resistant than FG fibres)
What are FG fibres used for?
(They have lots of glycogen used in glycolysis to generate ATP)
Don’t have mitochondria or myoglobin so their white
Produce rapid contractions for quick movements (only for short time ) running
How is a muscle attached to a bone?
Via a tendon
Where is cardiac muscle found?
In the heart
Where is smooth muscle found ?
Blood vessels and hollow organs (stomach, bowels)
How is smooth muscle and cardiac muscle controlled ?
Automatically/involuntary
How is skeletal muscle controlled?
It’s voluntary
Which muscles are slow and which muscles are fast?
The smooth muscle is the slowest and the skeletal muscle is the fastest
What’s the structure of smooth muscle ?
It’s spindle shaped (like an eye/almond)
It has one nuclei in the middle
What’s the structure of a cardiac cell?
-it’s quite branched
-1 or 2 nuclei
-
What’s the structure of the skeletal cell?
-have LOTS of nuclei (on the edges)
-straight (not branched)
-
Which muscles have stripes/striated?
Cardiac and skeletal
The main site of regulation of contraction in smooth muscle is?
Myosin. In smooth muscle as myosin heads need to be phosphorylated, the main site of regulation of this type of muscle is myosin.
In skeletal muscle what is the main site of regulation of contraction?
Actin.
The main parasympathetic neurotransmitter associated with smooth muscle function is ?
Noradrenaline
When does maximum force production occur ?
The force velocity relationship demonstrates that max force production occurs when velocity of shortening is 0 (isometric contraction)
As power is = force x velocity , max power occurs at 1 third of velocity of shortening.
