Transcript Chap 30 – Muscle

Chapter 30
How Animals Move
PowerPoint Lectures for
Campbell Biology: Concepts & Connections, Seventh Edition
Reece, Taylor, Simon, and Dickey
© 2012 Pearson Education, Inc.
Lecture by Edward J. Zalisko
MUSCLE CONTRACTION
AND MOVEMENT
© 2012 Parson Education, Inc.
Muscle
fiber
Unit of
muscle
contraction
Muscle
fiber
(cell)
Nuclei
Intercalated discs
Nucleus
Cardiac
muscle*
Junction
between
two cells
Muscle
fiber
Nucleus
Skeletal
muscle
Smooth
muscle*
*Under INVOLUNTARY control
Muscle
 Muscle fibers =
single muscle cell
Several muscle fibers
– have many nuclei
Single muscle fiber
(cell)
Nuclei
Plasma membrane
Myofibril
Light
band
Dark Light
band band
Z line
Sarcomere
Thick
filaments
(myosin)
Thin
filaments
(actin)
Z line
Sarcomere
Z line
– Contains myofibrils
Single muscle fiber
(cell)
Nuclei
Plasma membrane
 Myofibrils = protein
cables of
overlapping
Myofibril
– thick filaments
Light
band
Dark Light
band band
Z line
– composed of the
protein myosin and
– thin filaments
Sarcomere
– composed of the
protein actin.
 Sarcomeres =
contractile unit
of muscle fiber
Light
band
– repeating
groups of
overlapping
thick and thin
filaments
Dark Light
band band
Z line
Sarcomere
Thick
filaments
(myosin)
Thin
filaments
(actin)
Z line
Sarcomere
Z line
Sarcomere contracts
(shortens) when its thin
filaments slide across its
thick filaments
Z
Sarcomere
Dark band
Z
Relaxed muscle
Contracting
muscle
Fully contracted
muscle
Contracted sarcomere
Detailed structure of thin filaments
Actin
associated with
two other
proteins:
-Tropomyosin
- troponin
Motor Motor
unit 1 unit 2
Spinal cord
Nerve
Motor neuron Motor neuron
cell body
axon
Synaptic
terminals
Nuclei
Muscle fibers
(cells)
Muscle
Tendon
Bone
 A motor neuron
– carries an action potential (nervous signal) to a muscle cell,
– initiates a muscle contraction by triggering release of Ca2+ from ER
Motor neuron
axon
Mitochondrion
Action potential
Synaptic
terminal
T tubule
Endoplasmic
reticulum (ER)
Ca2
released
from ER
Myofibril
Plasma membrane
Sarcomere
Myosin-binding sites blocked
Tropomyosin
Actin
Role of Ca in muscle contraction
Ca2-binding sites
Troponin complex
Ca2 floods the
cytoplasmic
fluid
Myosin-binding sites exposed
Myosin-binding site
Calcium ions
bind to
troponin,
moving
tropomyosin
away from
the myosinbinding sites
on actin.
Sliding Filament Model
of Muscle Contraction:
Sarcomere contracts
(shortens) when its thin
filaments slide across its Z
thick filaments
Sarcomere
Dark band
Z
Relaxed muscle
Contracting
muscle
Fully contracted
muscle
Contracted sarcomere
A muscle contracts when thin filaments slide
along thick filaments
Thick filament
Thin
filaments
Z line
© 2012 Parson Education, Inc.
Figure 30.9B_s2
Thick filament
Thin
filaments
Z line
Actin
1 Thin
filament
Thick
filament
ATP
Myosin head (lowenergy configuration)
Figure 30.9B_s3
Thick filament
Thin
filaments
Z line
Actin
1 Thin
filament
ATP
Myosin head (lowenergy configuration)
ADP
P
Myosin head (highenergy configuration)
Thick
filament
2
Figure 30.9B_s4
3
ADP
P
Cross-bridge
Figure 30.9B_s5
3
ADP
P
Cross-bridge
New
position
Thin filament
of Z line
moves toward center.
ADP  P
4
Myosin head
(pivoting)
Figure 30.9B_s6
3
ADP
P
Cross-bridge
New
position
Thin filament
of Z line
moves toward center.
ADP  P
4
Myosin head
(pivoting)
5
ATP
Myosin head
(low-energy)
A muscle contracts when thin filaments slide along thick filaments
ATP required to
power myosin
movement and
RELEASE from
actin
Aerobic respiration supplies most of the energy
for exercise
 Aerobic respiration
– requires a constant supply of glucose and oxygen
– provides most of the ATP used to power muscle
movement during exercise.
 Lactic acid fermentation
– can provide ATP faster than aerobic respiration but
– is less efficient.
© 2012 Parson Education, Inc.
Figure 30.11
Supplying Fuel for
High Performance
 Muscles can adapt to exercise by increasing the
– levels of myoglobin,
– number of mitochondria, and/or
– number of capillaries going to muscles.
© 2012 Parson Education, Inc.
Table 30.12
Percentage of total muscle
Figure 30.12
100
80
Slow
Intermediate
Fast
60
40
20
0
World- Average Average Middle- World- Extreme
class
couch
active distance class endurance
sprinter potato person runner marathon athlete
runner