Concept Check 27.5

1. Explain how muscles work in pairs in moving limbs.
When a muscle contracts, it pulls the bone. The muscles cant push, only pull, therefore, in order to do certain movements, the muscles need to work in pairs. One muscle has to pull, and the other muscle has to relax, because it cant push. If we would only have one muscle, we could only move in one direction.
2. Identify the structures that make up a skeletal muscle.
The Muscle fiber: Long cylindrical muscle that contains nuclei.Myofibrils: found inside muscle fibers. Sarcomere: unit that contracts in the muscle and has two kinds of filaments, thin: actin, thick:myosin. Myosin: Bump like projections composed of proteins. Actin: twisted structure and are made up of protein.
3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.
The eyes because it sences the presence of the other person, sending images to the brain.
The Brain, because it sends orders to the muscles to move.
The Muscles, because it needs to contract and relax in order to give a handshake.
4. Explain how actin and myosin interact as a muscle cell contracts.
The myofibrils have the actin which is the thin filament inside the myofibrils and the myosin which is the thick filament inside the myofibril.
Proteins used to work out muscle contraction.

Andrea Alarcon

Concept check 27.5
1. Explain how muscles work in pairs in moving limbs.
Muscles work in pairs because it can only pull but not push. Therefore, a muscle contracts while the other relaxes creating the movement in the limbs.

2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.

• muscle fiber: single long cylindrical muscle with many nuclei.
• myofibrils: small bundles of smaller units that are inside the mucle fiber.
• actin: is the protein that makes up the thin filament of the sarcomere.
• myosin: is the protein that makes up the thick filament of the sarcomere.
• sarcomere: basic unit of action of the muscle fibers.
• fascicle: small bundle of a nerve, tendon, or muscle fibers.

3. Identify at least 3 organ systems involved in a handshake. Describe what each system contributes to the handshake.

• muscular system: the muscular system will be the one to allow all the muscles needed for a handshake to move.
• nervous system: the nervous system will send the signals from the brain through the nerves to make the muscles work.
• circulatory system: the circulatory system will provide the nutrients and oxygen to the muscles so they can work properly.

4. Explain how actin and myosin interact as a muscle cell contracts.

In each contraction, myosin heads first bind to thin filaments. Then, myosin heads bends pulling the thin filaments to the centre of the sarcomere. ATP finally realeases the myosin heads from the thin filaments allowing to bind with other filaments to make other muscle contractions.

Concept Check 27.5 Maria Alicia Jaramillo

Concept Check 27.5 Maria Alicia Jaramillo

1. Explain how muscles work in pairs in moving limbs.

Muscles in our body are only able to pull not push the attached bones, thus they need force so they can be go back to their original position. Skeletal muscles all have and opposing muscle, therefore when one muscle contracts the opposing muscle relaxes.
2. Identify the structures that make up a skeletal muscle.

• Muscle fiber: Long cylindrical muscle that contains nuclei.
• Myofibrils: found inside muscle fibers.
• Sarcomere: unit that contracts in the muscle and has two kinds of filaments, thin: actin, thick:myosin.
• Myosin: Bump like projections composed of proteins.
• Actin: twisted structure and are made up of protein.

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.

Eyes: perceive the presence of the other person and send these images or messages to the brain.

Brain: The brain sends messages to the muscles through the nerves. (control center)

Muscles: The muscles of: the back, shoulder, upper arm, forearm and wrist contract and relax during a handshake.

4. Explain how actin and myosin interact as a muscle cell contracts.

For the contractions myosin binds to the actin (thin filament), then they move towards the center of the sarcomere. ATP binds to each myosin head and releases it from the actin.

Homework Concept 27.5 Pedro Leon

1. Explain how muscles work in pairs in moving limbs.

Muscles move body parts by contracting and realaxing, by working in pairs: flexors and extensors. One muscle contracts while the other relaxes.

2. Identify the structures that make up a skeletal muscle.

They are voluntary muscles in the bones. They contain the muscle fibers (inside the muscle), the fibrils (inside the fibers), the myofibrils (inside the fibrils), and finally the actin (thin filament) and the myosin (thick filament). Both located inside the myofibrils.

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.

The Intergumentary System: The sensation of the skin.
The Nervous System: The nerves react while toaching the others persons hand.
The Skeletal System: The bones move while the handshake is being made.
The Muscle System: The muscles is what do the movement.

4. Explain how actin and myosin interact as a muscle cell contracts.

Actin is the thin filament inside myofbrils, and myosin the thick filament inside the myofibrils. Both are proteins that pruduce the muscle contraction.

CONCEPT 27.5 Karolina Sotomayor

1. Explain how muscles work in pairs in moving limbs.
The muscles in our body are only able to pull the atached bones, therefore they need an opposing force so that they can go back to their original position. All skeletal muscles have an opposing muscle or pair. When one of the muscles contracts, the opposing relaxes.
2. Identify the structures that make up a skeletal muscle.

• Muscle fiber: contains nuclei and is a long cylindrical muscle.
• Myofibrils: are found inside the muscle fibers
• Sarcomere: is the unit that contracts in the muscle and has two kinds of filaments: Thick=myosin and thin= actin.
• Myosin: composed of proteins and have bumplike projections.
• Actin: have a twisted structure and are composed of protein.

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.

Eyes: the eyes can perceive the precense of the other person and send these images or messages to the brain.

Brain: is the control center of the body. The brain sends messages to the muscles through the nerves.

Muscles: The muscles of the back, shoulder, upper arm, forearm and wrist perform contractions and relaxations in order to give the handshake.

4. Explain how actin and myosin interact as a muscle cell contracts.

For each contraction, the myosin head bind to the actin or thin filament, then the myosin heads bend letting the actins move towards the center of the sarcomere. ATP binds to each myosin head and releases it from the actin.

Concept check 27.5
1. Explain how muscles work in pairs in moving limbs.

Muscles can only pull not push another motion is needed to bring the bone to its original position that is why muscles work in pairs. When skeletal muscles contracte there is an opossing muscle that is relaxed but can contract and pull the bone back on its opposite direction.

2. Identify the structures that make up a skeletal muscle. Include these terms: muscle fiber, fascicle, myofibrils, actin, myosin, sarcomere.

muscle fiber: single long cylindrical muscle cell that contains many nuclei.

myofibrils: bundles of smaller units.

sarcomere: unit of contraction in a muscle fiber.

Myosin: composed of proteins and have bumplike projection

Actin: have a twisted structure and are composed of protein.

3. Identify at least 3 organ systems involved in a handshake. Describe WHAT each system contributes to the handshake.

Brain: the main control center in your body, decides to initiate the handshake sends messages through the nerves. 

eyes: persive the presence of another person and sends this message to the brain. 

Muscles: Perform contractions and relaxations to preform the handshake. 

4. Explain how actin and myosin interact as a muscle cell contracts.

The myosin binds to the actin, then the myosin heads bend living the actins move towards the center of the sarcomere. ATP binds to each myosin head and becomes relased  from the actin.

Fernanda Murray Concept check 27.5

Concept Check 27.5
1. Explain how muscles work in pairs in moving limbs.
As one muscle contracts the opposite one relaxes

2. Identify the structures that make up a skeletal muscle.
two types of muscle fibers: actin (the thin one) and myosin( thick one)

3. Identify at least three organ systems involved in a handshake. Describe what each system contributes to the handshake.
Nerves: eyes sense the presence of someone and thins about the handshake
Muscle: the muscles contract ( back, shoulder, upper arm, forearm, and wrist)
Bone: 27 bones are manipulated for a good hand shake

4. Explain how actin and myosin interact as a muscle cell contracts.
When actin contracts myosin doesnt move and then actin relaxes and myosin contracts