47.1
How Do Muscles Contract? 1005
Sliding filaments cause skeletal muscle
to contract 1005
Actin–myosin interactions cause
filaments to slide 1007
Actin–myosin interactions are
controlled by calcium ions 1008
Cardiac muscle causes the heart to
beat 1010
Smooth muscle causes slow contractions
of many internal organs 1010
Single skeletal muscle twitches are
summed into graded contractions 1012
47.2 What
Determines Muscle Strength and Endurance?
1013
Muscle fiber types determine endurance
and strength 1013
A muscle has an optimal length for
generating maximum tension 1014
Exercise increases muscle strength
and endurance 1014
Muscle ATP supply limits performance
1014
47.3 What Roles Do Skeletal Systems
Play in Movement? 1016
A hydrostatic skeleton consists of
fluid in a muscular cavity 1016
Exoskeletons are rigid outer structures
1016
Vertebrate endoskeletons provide supports
for muscles 1017
Bones develop from connective tissues
1018
Bones that have a common joint can
work as a lever 1019
47.4
What Are Some Other Kinds of Effectors?
1020
Chromatophores allow an animal to
change its color or pattern 1020
Glands secrete chemicals for defense,
communication, or predation 1021
Electric organs generate electricity
used for sensing, communication, defense,
or attack 1021
Light-emitting organs use enzymes
to produce light 1021
