Lab 7 The Muscular System BIO201L
Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet.
Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-
lab Questions
1. How do banding patterns change when a muscle contracts?
The arrangement of bands within muscles alters as a result of muscle contraction, a
phenomenon governed by the sliding filament theory. This theory explains that during
contraction, the sarcomeres, which are the basic units of muscle fibers, undergo a shortening
process. This shortening occurs as actin filaments slide over myosin filaments within the
sarcomere, causing the Z-lines to draw nearer to each other..
2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament?
The mechanism of skeletal muscle contraction hinges on the interplay between actin and
myosin filaments. Calcium ions play a pivotal role in kickstarting muscle contraction by
prompting the detachment of myosin heads from actin. ATP provides the necessary energy for
myosin heads to reattach to actin and execute the power stroke. This cyclic process entails
myosin heads binding to actin, pulling the actin filaments inward toward the sarcomere's center,
and subsequently releasing them. This cycle repeats until the muscle cell ceases to receive
stimulation..
3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used and
why?
Skeletal muscle contraction depends on the interaction between actin and myosin filaments.
ATP is essential for detaching myosin heads from actin and providing the energy required for the
power stroke, which draws actin filaments toward the sarcomere's center.
4. Explain why rigor mortis occurs.
Rigor mortis occurs when muscles become stiff after death due to the absence of ATP, which is
necessary for muscle relaxation. Without ATP, myosin heads remain bound to actin filaments,
causing prolonged muscle contraction.
,Lab 7 The Muscular System BIO201L
EXPERIMENT 1: TENDONS AND LIGAMENTS
Introduction Questions
1. How does the extracellular matrix of connective tissues contribute to its function?
Connective tissues rely on the extracellular matrix (ECM), which is a network of proteins and
sugars outside the cells, to provide structural integrity, organization, and communication among
cells.
2. Why are tendons and ligament tissues difficult to heal?
Healing tendon and ligament tissues poses difficulties because they have limited blood flow,
slow cell renewal rates, and are consistently subjected to mechanical strain.
, Lab 7 The Muscular System BIO201L
Data and Observations
1. Label the arrows in the slide images below based on your observations from the experiment.
A. Chondrocytes.
B. Collagen
C. Collagen fibers
D. Skeletal Muscle fibers
Lab Report Format Expectations
Utilize college level grammar and professional formatting when completing this worksheet.
Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-
lab Questions
1. How do banding patterns change when a muscle contracts?
The arrangement of bands within muscles alters as a result of muscle contraction, a
phenomenon governed by the sliding filament theory. This theory explains that during
contraction, the sarcomeres, which are the basic units of muscle fibers, undergo a shortening
process. This shortening occurs as actin filaments slide over myosin filaments within the
sarcomere, causing the Z-lines to draw nearer to each other..
2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament?
The mechanism of skeletal muscle contraction hinges on the interplay between actin and
myosin filaments. Calcium ions play a pivotal role in kickstarting muscle contraction by
prompting the detachment of myosin heads from actin. ATP provides the necessary energy for
myosin heads to reattach to actin and execute the power stroke. This cyclic process entails
myosin heads binding to actin, pulling the actin filaments inward toward the sarcomere's center,
and subsequently releasing them. This cycle repeats until the muscle cell ceases to receive
stimulation..
3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used and
why?
Skeletal muscle contraction depends on the interaction between actin and myosin filaments.
ATP is essential for detaching myosin heads from actin and providing the energy required for the
power stroke, which draws actin filaments toward the sarcomere's center.
4. Explain why rigor mortis occurs.
Rigor mortis occurs when muscles become stiff after death due to the absence of ATP, which is
necessary for muscle relaxation. Without ATP, myosin heads remain bound to actin filaments,
causing prolonged muscle contraction.
,Lab 7 The Muscular System BIO201L
EXPERIMENT 1: TENDONS AND LIGAMENTS
Introduction Questions
1. How does the extracellular matrix of connective tissues contribute to its function?
Connective tissues rely on the extracellular matrix (ECM), which is a network of proteins and
sugars outside the cells, to provide structural integrity, organization, and communication among
cells.
2. Why are tendons and ligament tissues difficult to heal?
Healing tendon and ligament tissues poses difficulties because they have limited blood flow,
slow cell renewal rates, and are consistently subjected to mechanical strain.
, Lab 7 The Muscular System BIO201L
Data and Observations
1. Label the arrows in the slide images below based on your observations from the experiment.
A. Chondrocytes.
B. Collagen
C. Collagen fibers
D. Skeletal Muscle fibers
