1. REVIEW AND COMPARISON skeletal smooth cardiac
actin & myosin yes yes yes
sarcomeres (banding) yes no yes
t-tubules yes no yes
sarcoplamic reticulum
source of Ca SR SR & ECF SR & ECF
speed of contraction fast/slow very slow slow
spontaneous contraction no yes/no yes
effect of nerve stimulation excit. excit./inhib. excit./inhib.
stretch prod. contraction no yes/no yes

2. Cardiac Muscle
Autonomic
Myogenic
Slower contraction

3. Smooth Muscle Parts of two muscle cells
Thick and thin filaments interdigitate, but not arranged in sarcomeres
Thin filaments anchored to dense bodies
Muscle fibers connected by gap junctions

4. Muscle Energetics ATP 5 µmol•g-1 in fiber
µmol•g-1•min-1 needed
muscle fiber
myosin ATPase
contraction
relaxation
SR Ca-ATPase
creatine~P
arginine~P
ATP
oxidative metab.
glycolysis
glycogen
lactate O2
glucose
lipids
(amino acids)

5. Although it takes a lot more glucose,
ATP can actually be produced faster by
glycolysis than by oxidative phosphorylation:
Rel. rate Glucose used Lactate prod.
oxidative
metabolism ATP
glycolysis ATP

6. Three types of vertebrate skeletal muscle fibers:
Fast glycolytic (white) (FG)
Fast oxidative-glycolytic (FOG)
Slow oxidative (red) (SO)

7. White and Red Fibers

8. FG FOG SO
Speed of contraction fast fast slow
Source of ATP glycolysis mixed oxid. met.
Myoglobin content low intermed. high
# mitochondria few many many
# capillaries few intermed. many
Glycogen content high intermed. low
Lipid content low intermed. high
Rate of fatigue fast intermed. slow

9. Skeletal muscles may be a combination of fiber types:
e.g. cat soleus - postural muscle - all SO
cat gastrocnemius - 45% FG, 25% FOG
25% SO, 5% FG/FOG
Different fiber types can be recruited in response
to exercise:
e.g. gastrocnemius of sprinter - high in FG
distance runners - high in FOG + SO

10. Insect flight muscle:
Time to relaxation in vert. striated muscle is msec.
Some insect wings beat at > 1000 beats • s-1
(midge with wings clipped beats • s-1)
Must have contraction/relaxation cycle of
< 0.45 msec !! - surpasses electrical
properties of the membrane

11. Indirect or Asynchronous
Direct or Synchronous
Indirect or Asynchronous

13. 1. Stretching of muscle induces contraction - no neural activity or depolarization necessary
2. Resonance of exoskeleton stores energy to stretch
muscles:
notum
wing
pleuron
sternum