Muscles Flashcards
What zone gets smaller when contraction occurs?
The H-zone
What are the main characteristics of the fast twitch fibres?
- quick contraction time
- mor force
- large neurone
- fatigue quickly
- large anaerobic capacity
- lots of glycogen
- low capillary density
- high PC stores
- low mitochondrial density
Main characteristics of slow twitch fibres?
- slow contraction
- low force
- resistant to fatigue
- high aerobic capacity
- small fibre
- high triglyceride stores
- high capillary density
- high mitochondrial density
What fibre is recruited for :
Low intensity?
V high intensity?
High intensity?
- slow twitch
- fast glycosidic
- fast oxidative glycosidic
What is spatial summation?
Greater force of contraction is achieved when the brain recruits more and bigger motor units
What is wave summation?
Some fibre groups fire repeatedly, will build force
Start to relax, contract again, start from higher level a not fully relaxed
What is tetanic contraction?
Cramp, lock of muscles
What is multi fibre spatial summation?
Different fibre groups stimulated in quick succession
- total force is sum of effect of different fibres
- share workload and reduce fatigue
What is gradation of contraction?
Vary from light to maximum force
- the freq of stimulus
Explain the process of the sliding filament theory?
- nerve impulse stimulated the sarcoplasmic reticulum to release calcium
- calcium binds to troponin, which changes its shape, moving tropomyosin which uncovers the actin active site
- myosin attaches to actin active site forming a cross bridge
- the myosin head contracts ( powerstroke) moving the actin filament closer to the centre of the sarcomere
- ATP binds to myosin head, myosin detaches from the actin
- ATP is broken down now myosin can re-attach to another actin active site
