Smooth and Skeletal Muscle

• what is excitability

  muscles can respond to stimuli
• what is contractility

  muscles can shorten and generate pulling force
• what is extensibility

  muscles can be stretched back to original length
• what is elasticity

  muscle can recoil to original length
• what is the covering of the whole muscle called

  epimysium
• what is the covering of the fascicles called

  perimysium
• what is the covering of the muscle fibres called

  endomysium
• what is the repeating unit of a myofibril called

  sarcomere
• what is the thin filament

  actin
• what is the thick filament

  myosin
• what does tropomyosin do

  regulate actin and myosin head interaction
• what innervates muscle fibres

  motor neurons
• where is the neuromuscular junction

  between motor neuron and skeletal muscle fibre
• steps at the motor end plate

  action potential reaches axon

  causes opening of calcium channels

  releases acetylcholine

  diffuses across synaptic cleft to bind with receptor

  binding causes sodium channels to open

  causes depolarisation of motor end plate

  causes generation of new action potential

  acetylcholine destroyed by acetylcholinesterase
• what controls muscle contraction

  calcium influx
• how is calcium released from t tubules

  action potential

  dihydropyridine receptor detects change

  calcium released causes contraction
• what does temporal summation do

  enhance contractile force of muscle
• what is lambert eaton myasthenic syndrome

  immune system attacks calcium channels

  causes muscle weakness
• what is botulism

  bacteria blocks acetylcholine release

  causes paralysis and weakness
• what is myasthenia gravis

  antibodies attack nicotinic acetylcholine receptors
• what do single unit smooth muscles do

  produce slow contractions

  found in walls of visceral organs
• what do multi unit smooth muscles do

  make precise muscle contractions

  found in blood vessels and airways
• how does a direct constrictor work for smooth muscles

  calcium binds to activate myosin and form cross bridge
• how does a receptor mediated constrictor work for smooth muscles

  adrenaline and dopamine open calcium channels
• how does a direct relaxant work for smooth muscles

  nitric oxide activates guanylate cyclase
• how is the smooth muscle cross bridge activated

  increase intracellular calcium

  calmodium binds to it

  activates myosin light chain kinase

  increases myosin ATPase activity
• how does tonic contraction work

  low level tension for long periods
• ..

  A) skeletal

  B) smooth

  C) cardiac

  D) intercalated disks

  E) gap junction

  F) A band

  G) i band

  
• ..

  A) myofibril

  B) sarcolemma

  C) motor neuron

  D) endomysium

  E) muscle fibre

  F) fascicle

  G) perimysium

  H) epimysium

  
• ..

  A) Z disks

  B) M line

  C) Z disks

  D) thick filament

  E) thin filament

  F) H zone

  G) I band

  H) I band

  I) A band

  
• ..

  A) single unit

  B) multi unit