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Bio 132 -- Comparative Physiology / Section Worksheet - Weeks 6-7, 2/16/06 - 2/21/06
I.
Multiple choice (circle all answers that apply)
1) The primary differences between skeletal and cardiac muscles are:
a.
Cardiac muscle cells can “communicate” directly with each other while
skeletal muscle cells cannot.
b.
Skeletal muscle cells will not contract unless triggered by input from a
neuron while cardiac cells can contract without neural input.
c.
Cardiac muscle fibers contract on the “all or none” principle while skeletal
muscles fibers do not.
d.
Cardiac muscle groups contract on the “all or none” principle while
skeletal muscle groups do not.
e.
The action potential of cardiac muscle lasts up to 100 times longer than
the action potential of skeletal muscles.
2) The atrio-ventricular node (A-V node):
a.
is located near the tricuspid valve on the right ventricle.
b.
increases the transmission speed of the excitatory impulse.
c.
is responsible for timing atrial and ventricular contractions such that blood
is ejected out of the atria and into the ventricles before subsequent ejection
of blood out of the ventricles.
d.
“holds” the signal traveling from the S-A node for ~0.11 seconds before
transmission into the A-V bundle.
II.
Fill in the blank
3) All myocardial tissue of the atria is ___________ connected by __________________
(same for the myocardial tissue of the ventricles).
4) Skeletal muscle is designed for transforming ___________ energy into ____________
work.
III.
True or false
5) Myoglobin binds oxygen more tightly than hemoglobin, so it can effectively extract
oxygen from the blood (think dissociation curves). (T or F)
6) ACh is the link between excitation and contraction of skeletal muscle. (T or F)
7) ATP is required for skeletal muscles to relax. (T or F)
8) One skeletal muscle fiber can be innervated by many motor neurons, but one motor
neuron connects to only one muscle fiber. (T or F)
9) The strength of skeletal muscle contraction is regulated by the frequency of motor
neuron action potentials and the number of muscle fibers excited by motor neurons.
(T or F).
10) Endurance training increases the number and size of your skeletal muscle cells.
(T or F).
11) Striated muscles contain actin, myosin and purkinje fibers. (T or F).
IV.
Short answer
12) What is the sino-atrial node? Where is it located?
13) What are purkinje fibers?
14) What is the function of the sarcoplasmic reticulum?
15) What is the troponin/tropomyosin/actin complex? What does it do?
Review of skeletal muscle anatomy.
Review of Ca2+ action and the role of the sarcoplasmic reticulum (SR) in skeletal muscle
contractions.
Review of skeletal muscle contraction.
Practice adding the labels and think about how the “ratchet” works.