Lab 7 The Muscular System BIO201L
Student Name: Colin Fiorentno
Access Code (located on the lid of your lab kit): AC-QLY23HC
Pre-Lab Questions
”1. How do banding patterns change when a muscle contracts?”
Muscle contraction causes actin and myosin myofilaments to decrease length and come
together. Both the H and I zones become narrow and the A band has no change.
”2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament?
”
Muscle organs are tissue composed of cells and fibers producing movement throughout the
body that result in contractions. Muscle fibers are composed of myofibrils that contract when
stimulated and they have multiple nuclei. Myofibrils are thread like structures composed of
actin and myosin. And myofilaments are the structures that make up myofibrils.
”3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used
and why? ”
ATP binds to myosin, which then converts ATP into ADP and pi. Calcium and troponin bind
together and create tropomyosin, which allows the myosin heads to form cross bridges. The
ADP and Pi are released, causing actin to slide towards the center of the sarcomere resulting in
a power stroke. ATP is used immediately to create an increase in heart rate and body
temperature to allow the body to be in. homeostasis.
”4. Explain why rigor mortis occurs. ”
This occurs because the muscles partially contract and cannot go to a relaxed state due to no
blood or oxygen flowing through the body.
Experiment 1: Tendons and Ligaments
Post-Lab Questions
”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 fiber.
E- nuclei.
F- collagen fibers.
,Lab 7 The Muscular System BIO201L
, Lab 7 The Muscular System BIO201L
”2. How does the extra cellular matrix of connective tissues contribute to its function? ”
The extracellular matrix binds tissue types that are different like binding the epidermis to the
dermis layer that’s beneath it.
”3. Why are tendons and ligament tissues difficult to heal? ”
Both tendons and ligaments have no blood supply or blood vessels that run through them so
they don’t get nutrients that allow or healing..
”4. What difference do you see between the tendon – muscle insertion image and the tendon
image? ”
The tendon muscle insertion has dense irregular connective tissue and has chondrocytes and
collagen. The tendon is smooth and moves in one direction and contains more than one
nucleus..
”5. What differences do you see between the tendon and ligament sections? ”
The ligament has skeletal muscle fibers, and the tendon seems to be close together while the
tendon is separated..
Student Name: Colin Fiorentno
Access Code (located on the lid of your lab kit): AC-QLY23HC
Pre-Lab Questions
”1. How do banding patterns change when a muscle contracts?”
Muscle contraction causes actin and myosin myofilaments to decrease length and come
together. Both the H and I zones become narrow and the A band has no change.
”2. What is the difference between a muscle organ, a muscle fiber, myofibril and a myofilament?
”
Muscle organs are tissue composed of cells and fibers producing movement throughout the
body that result in contractions. Muscle fibers are composed of myofibrils that contract when
stimulated and they have multiple nuclei. Myofibrils are thread like structures composed of
actin and myosin. And myofilaments are the structures that make up myofibrils.
”3. Outline the molecular mechanism for skeletal muscle contraction. At what point is ATP used
and why? ”
ATP binds to myosin, which then converts ATP into ADP and pi. Calcium and troponin bind
together and create tropomyosin, which allows the myosin heads to form cross bridges. The
ADP and Pi are released, causing actin to slide towards the center of the sarcomere resulting in
a power stroke. ATP is used immediately to create an increase in heart rate and body
temperature to allow the body to be in. homeostasis.
”4. Explain why rigor mortis occurs. ”
This occurs because the muscles partially contract and cannot go to a relaxed state due to no
blood or oxygen flowing through the body.
Experiment 1: Tendons and Ligaments
Post-Lab Questions
”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 fiber.
E- nuclei.
F- collagen fibers.
,Lab 7 The Muscular System BIO201L
, Lab 7 The Muscular System BIO201L
”2. How does the extra cellular matrix of connective tissues contribute to its function? ”
The extracellular matrix binds tissue types that are different like binding the epidermis to the
dermis layer that’s beneath it.
”3. Why are tendons and ligament tissues difficult to heal? ”
Both tendons and ligaments have no blood supply or blood vessels that run through them so
they don’t get nutrients that allow or healing..
”4. What difference do you see between the tendon – muscle insertion image and the tendon
image? ”
The tendon muscle insertion has dense irregular connective tissue and has chondrocytes and
collagen. The tendon is smooth and moves in one direction and contains more than one
nucleus..
”5. What differences do you see between the tendon and ligament sections? ”
The ligament has skeletal muscle fibers, and the tendon seems to be close together while the
tendon is separated..
