Model 2: Comparing Relaxed and Contracted
Sarcomeres
Figure 1. Relaxed sarcomeres.
:
100
Figure 2. Contracted sarcomeres.
:
QUESTIONS:
8. In Figures 1 and 2 above, label the A-bands, I-bands, and H-zones. Measure and record
the lengths (in mm) with a ruler (you can do this on your computer screen) of these
structures and the thick and thin filaments in the chart below:
Structure
Length in
Length in
Did the length change
Relaxed
Contracted
between Figures 1 and 2?
Sarcomere (mm)
Sarcomere (mm)
(Y/N)
Thick filament
40 mm
40 mm
no
Thin filament
19 mm
19m
no
A band
40 mm
40 mm
no
I band
17mm
6 mm
yes
H zone
34mm
16 mm
yes
Sarcomere
72mm
53mm
yes
9. Describe what happens to thick and thin filaments when muscles contract:
The myosin and actin stay the same
10. Why is there a limit to the amount of shortening that can occur in a sarcomere during
muscle contraction? Because the actin will be touching
