section 4.2: muscles
Essential Questions
1. How do muscles assist with movement of the body and of substances around the body?
They contract and expand, pulling on bones and bending joints in certain ways. Involuntary muscles around veins can contract and cause vasoconstriction.
2. How do the structure and function of the three types of muscle tissue compare?
Skeletal: Striated; connected to bones; allows for voluntary movement
Smooth: Not striated; usually around organs; responsible for involuntary movements (peristalsis, GI Tract, vasoconstriction, etc.)
Cardiac: Striated; found only in heart; pumps blood throughout the body
3. How are muscle fibers and membranes organized to form a whole skeletal muscle?
One fiber surrounded by endomysium => a group of fibers (fasicle) surrounded by perimysium => group of fasicles surrounded by epimysium
4. What do skeletal muscle structure and attachment to bones tell you about function?
It means that it connects to bone and creates movement by moving the bones.
5. How are muscles named?
They can be named by their size, location, function, shape, and type of action it creates, among other things.
6. What are the requirements for muscle contraction?
1) Signal received from sensory neurons and sent to brain
2) Motor neuron activated and action potential passed to spinal cord
3) Action Potential conveyed by axon branches
4) Action potential enters the inside of a muscle fiber
5) Sarcoplasmic reticulum releases Calcium ions (Ca++)
6) Results in movement of troponin and tryptomyosin so that myosin molecule can "grab and swivel" its way across the thin filament, which drives muscle contraction
7. What role do calcium and ATP play in muscle contraction?
Calcium binds to troponin and moves tryptomyosin away from actin strand so that the myosin strand can attach to actin and facilitate muscle contraction.
8. What is a sarcomere?
A structural unit of a myofibril in striated muscle.
9. How does a sarcomere contract and lengthen to cause muscle contraction?
Myosin pulls actin, which pulls the sarcomere's ends to the middle.
10. How is the condition rigor mortis related to muscle contraction?
Skeletal muscles partially contract, but cannot relax, so the joints are locked in place as they are.
11. How do nerves interact with muscles?
Nerves send signals to muscles about when to contract, so that the muscles pull the bones in a certain way to create movement.
12. How can we assess muscle function?
Different tests are performed that assess whether or not a muscle is able to move to the extent that it should move, which can also detect whether or not there is any weakness to be found in the muscle.
4.2.1 Conclusion Questions
1. Describe the differences you see in the three types of muscle tissues.
Skeletal Muscle: Striated
Smooth Muscle: Not Striated
Cardiac Muscle: Striated; fibers very close together
2. What does it mean when we say a muscle contracts involuntarily? Describe one body function that is linked to an involuntary muscle contraction.
The contraction of the muscle does not occur whenever we consciously desire them to move. Peristalsis, how the esophagus gets food to the stomach, is an example of involuntary muscle contraction.
3. Describe how the structural makeup of a muscle contributes to the muscle’s ability to do its job.
The fibers and connective tissue that make up the muscle both have properties, like elasticity and distensibility, that ensure that they will be able to return the same shape after moving in a certain direction.
4. Using your knowledge of tissues, what type of tissue do you think makes up the three layers of membrane you encountered in your muscle?
Endomysium, Paramysium, and Epimysium.
5. Explain how you know which attachment of a muscle is the origin and which attachment is the insertion.
Whichever one moves when you flex a joint should be the insertion point. Origins tend to be more proximal than insertions.
6.Your mom comes back from the doctor and says she has pulled her tibialis anterior. She knows you are taking Human Body Systems and asks you to tell her about her injury. Based on the classroom discussion, what can you deduce about this muscle?
It is most likely located around the front of her tibia bone.
7. When you are cold, your muscles begin to contract involuntarily and cause you to shiver. Why do you think this occurs? How does the contraction of muscles help the body maintain homeostasis?
Contractions generate heat because they help the body to burn sugar within the muscles, which will generate heat and bring the body's temperature back up to where it is supposed to be.
4.2.2 Conclusion Questions
1. Look at your Maniken®. Explain to your client why you need multiple exercises to effectively build and tone the muscles of the chest.
Exercises will only help tone and strengthen one group of muscles, so to effectively work a region of the body, one needs to perform more than one type of exercise.
2. Think about the action of the muscles you have built. Describe at least two exercises that will strengthen the muscles of the chest. Make sure to note the specific muscles that are targeted in each exercise. Add information about these exercises to your lab notebook.
Push-Ups: Pectorals
Jabs: Pectorals
3. Explain how the structure and function of one of the muscles of the chest relates to some of muscle rules you learned in Activity 4.2.1.
The Pectoralis Major crosses over the ball-in-socket shoulder joint, has an origin on the clavicle and insertion on the proximal humerus, and has striations that show the direction of flexion.
4. Explain how the muscles pectoralis major and serratus anterior show two different ways in which muscles are named.
The pectoralis is named by the muscles it is associated with, while the serratus anterior is named by its location around the ribs.
5. Are the muscles of pectoralis major adductors or abductors? Explain.
Adductors. They bring the arms forward or down. Ex: When performing Pec-Flys, it is the Pectoralis Major that brings the arms back in front of the body.
4.2.3 Conclusion Questions
1. What did you find to be the most challenging part of independent muscle building?
Shaping the muscle before placing it on the maniken and trying to fit the muscle on without disturbing and previously place clay.
2. How can you determine function of a muscle simply by looking at the anatomy?
The striations show which direction the muscle either flexes or extends. The origin and insertion can be determined by observing the proximity of the attachment to the body.
3. Using your muscular system graphic organizer and your notes, identify and describe the particular muscles that are involved in generating movement at a specific joint of the body.
The brachialis head is found on the ventral side of the humerus and is also known as the bicep. The tricep medial head is more dorsal of the humerus. Together, these two muscles help to flex and extend the arm. The brachialis functions as the flexor, while the tricep medial head functions as the extensor.
4. Describe how an injury to the muscle group you built on your Maniken® would impact total body function.
If the muscle group of the arm was damaged, one would not be able to extend or flex his/her arm in any way.
4.2.4 Conclusion Questions
1. When you see the glycerinated muscle fibers shorten, what do you think is actually happening in the muscle cells? Think about what you just saw under the microscope.
Within the muscle cells, the space between the fibers is shortening and they begin to contract. This forces the fibers to shorten and decrease in length.
2. Did your muscle samples eventually relax and return to the length they were before contraction? Thinking back to the muscles rules and how your know muscles work, why does this make sense?
Yes, they did. They ought to expand and lengthen again as the glycerol that forced them to contract began to seep out of the muscle fiber again.
3. Which solution produced the greatest percent contraction of the muscles? What does this tell you about the requirements for contraction?
ATP+Salt. It means that, for the best muscle contraction, ATP and Salt together must be present.
4. Think about the way in which organ systems work together to kick your leg or swing your arm. Besides the skeletal and the muscular system, what other systems do you think are involved in moving the human machine?
Nervous System, Endocrine System, and Cardiovascular System.
4.2.5 Conclusion Questions
1. How do multiple human body systems work together to cause muscle contraction and movement of the body?
Nervous system receives signals and creates stimulation; The muscular system is the power that moves the body; The skeletal system provides the structure and support that allows the body to move.
2. Your friend tried to convince you that the only reason to drink milk and to make sure you get enough calcium is so you can build strong bones. Can you offer him/her another reason?
Calcium is an important component that allows for and aids in muscle contractions.
3. Explain how it is that actin and myosin in the sarcomere never actually shorten and yet the muscle as a whole does.
The myosin and sarcomere pull the muscle fibers together, so the fibers themselves shorten, but the myosin and sarcomere just move.
4. How do ions and electrical charges play a role in communication with the muscle?
The signals sent and received by the nervous system by a system of neurons and nerves can only move along a neuron if the proper charge is present. A proper charge is maintained by a system of ions that move back and forth across the neuron.
5. Summarize the science behind rigor mortis. Why is this state a temporary condition?
At death, the muscles contract, but are unable to relax because the body is using up all of the calcium and ATP left over. Once all of the ATP and Calcium are used, the muscles can relax.
6. Using what you know about rigor mortis and about energy, what do you think happens inside your muscle when you get a muscle cramp? Why is this not a permanent condition?
Muscle Cramps can be caused by overuse, dehydration, or locking a muscle in one position for a long time. They can be relieved by stretching or massaging.
4.2.6 Conclusion Questions
1. Given the placement of the ulnar nerve, what type of forearm muscles do you think this nerve stimulates? Explain. HINT: What type of muscles is found on the ventral side of the body?
The flexor digitorum profundus. Flexor muscles in general.
2. Explain how the placement of the ulnar nerve is linked to the pain and discomfort you feel when you bang your “funny bone.”
Hitting any nerve can cause pain by stimulating it all at once. The "funny bone" unfortunately extends all the way to the pinkey so whenever it is hit, the pain is felt on a much larger scale.
3. Given the placement of the radial nerve, what type of muscles do you think this nerve stimulates? Explain. HINT: What type of muscles is found on the dorsal side of the body?
Muscles that flex the thumb and allow for the thumb to move and the fingers to extend and the wrist to flex.
4. What do you think would happen to a person’s ability to use his/her arm if the radial nerve were damaged?
It would be difficult to straighten the arm and move the wrist and fingers.
5. Explain how the central and the peripheral nervous system work together to allow you to pick up a can of soda. Mention muscles of the forearm in your answer.
PNS receives and interprets signals from the surround environment, sends the signal(s) to the brain by way of the CNS. The reaction to the signals sent are decided by the brain, sent back down the PNS to the arm, where the ventral muscles are stimulated to contract and grab the can.
6. Describe at least three different jobs that put the worker at risk for carpal tunnel syndrome. How can these individuals lower their risk of injury?
Writing, typing on a computer all day or a professional gymnast. They can take frequent breaks from their career, stretch their wrist often and be sure not to press their body to the limit at which their wrist can stretch.
7. What happens at the junction between a nerve and a muscle to initiate muscle contraction?
The axon terminals of the motor neurons send the electrical signal that they have carried from the brain into the muscle. As the electrical signal passes through the muscle fibers, the action potential is activated and the ions within and outside the muscle begin to switch places to create contraction.
1. How do muscles assist with movement of the body and of substances around the body?
They contract and expand, pulling on bones and bending joints in certain ways. Involuntary muscles around veins can contract and cause vasoconstriction.
2. How do the structure and function of the three types of muscle tissue compare?
Skeletal: Striated; connected to bones; allows for voluntary movement
Smooth: Not striated; usually around organs; responsible for involuntary movements (peristalsis, GI Tract, vasoconstriction, etc.)
Cardiac: Striated; found only in heart; pumps blood throughout the body
3. How are muscle fibers and membranes organized to form a whole skeletal muscle?
One fiber surrounded by endomysium => a group of fibers (fasicle) surrounded by perimysium => group of fasicles surrounded by epimysium
4. What do skeletal muscle structure and attachment to bones tell you about function?
It means that it connects to bone and creates movement by moving the bones.
5. How are muscles named?
They can be named by their size, location, function, shape, and type of action it creates, among other things.
6. What are the requirements for muscle contraction?
1) Signal received from sensory neurons and sent to brain
2) Motor neuron activated and action potential passed to spinal cord
3) Action Potential conveyed by axon branches
4) Action potential enters the inside of a muscle fiber
5) Sarcoplasmic reticulum releases Calcium ions (Ca++)
6) Results in movement of troponin and tryptomyosin so that myosin molecule can "grab and swivel" its way across the thin filament, which drives muscle contraction
7. What role do calcium and ATP play in muscle contraction?
Calcium binds to troponin and moves tryptomyosin away from actin strand so that the myosin strand can attach to actin and facilitate muscle contraction.
8. What is a sarcomere?
A structural unit of a myofibril in striated muscle.
9. How does a sarcomere contract and lengthen to cause muscle contraction?
Myosin pulls actin, which pulls the sarcomere's ends to the middle.
10. How is the condition rigor mortis related to muscle contraction?
Skeletal muscles partially contract, but cannot relax, so the joints are locked in place as they are.
11. How do nerves interact with muscles?
Nerves send signals to muscles about when to contract, so that the muscles pull the bones in a certain way to create movement.
12. How can we assess muscle function?
Different tests are performed that assess whether or not a muscle is able to move to the extent that it should move, which can also detect whether or not there is any weakness to be found in the muscle.
4.2.1 Conclusion Questions
1. Describe the differences you see in the three types of muscle tissues.
Skeletal Muscle: Striated
Smooth Muscle: Not Striated
Cardiac Muscle: Striated; fibers very close together
2. What does it mean when we say a muscle contracts involuntarily? Describe one body function that is linked to an involuntary muscle contraction.
The contraction of the muscle does not occur whenever we consciously desire them to move. Peristalsis, how the esophagus gets food to the stomach, is an example of involuntary muscle contraction.
3. Describe how the structural makeup of a muscle contributes to the muscle’s ability to do its job.
The fibers and connective tissue that make up the muscle both have properties, like elasticity and distensibility, that ensure that they will be able to return the same shape after moving in a certain direction.
4. Using your knowledge of tissues, what type of tissue do you think makes up the three layers of membrane you encountered in your muscle?
Endomysium, Paramysium, and Epimysium.
5. Explain how you know which attachment of a muscle is the origin and which attachment is the insertion.
Whichever one moves when you flex a joint should be the insertion point. Origins tend to be more proximal than insertions.
6.Your mom comes back from the doctor and says she has pulled her tibialis anterior. She knows you are taking Human Body Systems and asks you to tell her about her injury. Based on the classroom discussion, what can you deduce about this muscle?
It is most likely located around the front of her tibia bone.
7. When you are cold, your muscles begin to contract involuntarily and cause you to shiver. Why do you think this occurs? How does the contraction of muscles help the body maintain homeostasis?
Contractions generate heat because they help the body to burn sugar within the muscles, which will generate heat and bring the body's temperature back up to where it is supposed to be.
4.2.2 Conclusion Questions
1. Look at your Maniken®. Explain to your client why you need multiple exercises to effectively build and tone the muscles of the chest.
Exercises will only help tone and strengthen one group of muscles, so to effectively work a region of the body, one needs to perform more than one type of exercise.
2. Think about the action of the muscles you have built. Describe at least two exercises that will strengthen the muscles of the chest. Make sure to note the specific muscles that are targeted in each exercise. Add information about these exercises to your lab notebook.
Push-Ups: Pectorals
Jabs: Pectorals
3. Explain how the structure and function of one of the muscles of the chest relates to some of muscle rules you learned in Activity 4.2.1.
The Pectoralis Major crosses over the ball-in-socket shoulder joint, has an origin on the clavicle and insertion on the proximal humerus, and has striations that show the direction of flexion.
4. Explain how the muscles pectoralis major and serratus anterior show two different ways in which muscles are named.
The pectoralis is named by the muscles it is associated with, while the serratus anterior is named by its location around the ribs.
5. Are the muscles of pectoralis major adductors or abductors? Explain.
Adductors. They bring the arms forward or down. Ex: When performing Pec-Flys, it is the Pectoralis Major that brings the arms back in front of the body.
4.2.3 Conclusion Questions
1. What did you find to be the most challenging part of independent muscle building?
Shaping the muscle before placing it on the maniken and trying to fit the muscle on without disturbing and previously place clay.
2. How can you determine function of a muscle simply by looking at the anatomy?
The striations show which direction the muscle either flexes or extends. The origin and insertion can be determined by observing the proximity of the attachment to the body.
3. Using your muscular system graphic organizer and your notes, identify and describe the particular muscles that are involved in generating movement at a specific joint of the body.
The brachialis head is found on the ventral side of the humerus and is also known as the bicep. The tricep medial head is more dorsal of the humerus. Together, these two muscles help to flex and extend the arm. The brachialis functions as the flexor, while the tricep medial head functions as the extensor.
4. Describe how an injury to the muscle group you built on your Maniken® would impact total body function.
If the muscle group of the arm was damaged, one would not be able to extend or flex his/her arm in any way.
4.2.4 Conclusion Questions
1. When you see the glycerinated muscle fibers shorten, what do you think is actually happening in the muscle cells? Think about what you just saw under the microscope.
Within the muscle cells, the space between the fibers is shortening and they begin to contract. This forces the fibers to shorten and decrease in length.
2. Did your muscle samples eventually relax and return to the length they were before contraction? Thinking back to the muscles rules and how your know muscles work, why does this make sense?
Yes, they did. They ought to expand and lengthen again as the glycerol that forced them to contract began to seep out of the muscle fiber again.
3. Which solution produced the greatest percent contraction of the muscles? What does this tell you about the requirements for contraction?
ATP+Salt. It means that, for the best muscle contraction, ATP and Salt together must be present.
4. Think about the way in which organ systems work together to kick your leg or swing your arm. Besides the skeletal and the muscular system, what other systems do you think are involved in moving the human machine?
Nervous System, Endocrine System, and Cardiovascular System.
4.2.5 Conclusion Questions
1. How do multiple human body systems work together to cause muscle contraction and movement of the body?
Nervous system receives signals and creates stimulation; The muscular system is the power that moves the body; The skeletal system provides the structure and support that allows the body to move.
2. Your friend tried to convince you that the only reason to drink milk and to make sure you get enough calcium is so you can build strong bones. Can you offer him/her another reason?
Calcium is an important component that allows for and aids in muscle contractions.
3. Explain how it is that actin and myosin in the sarcomere never actually shorten and yet the muscle as a whole does.
The myosin and sarcomere pull the muscle fibers together, so the fibers themselves shorten, but the myosin and sarcomere just move.
4. How do ions and electrical charges play a role in communication with the muscle?
The signals sent and received by the nervous system by a system of neurons and nerves can only move along a neuron if the proper charge is present. A proper charge is maintained by a system of ions that move back and forth across the neuron.
5. Summarize the science behind rigor mortis. Why is this state a temporary condition?
At death, the muscles contract, but are unable to relax because the body is using up all of the calcium and ATP left over. Once all of the ATP and Calcium are used, the muscles can relax.
6. Using what you know about rigor mortis and about energy, what do you think happens inside your muscle when you get a muscle cramp? Why is this not a permanent condition?
Muscle Cramps can be caused by overuse, dehydration, or locking a muscle in one position for a long time. They can be relieved by stretching or massaging.
4.2.6 Conclusion Questions
1. Given the placement of the ulnar nerve, what type of forearm muscles do you think this nerve stimulates? Explain. HINT: What type of muscles is found on the ventral side of the body?
The flexor digitorum profundus. Flexor muscles in general.
2. Explain how the placement of the ulnar nerve is linked to the pain and discomfort you feel when you bang your “funny bone.”
Hitting any nerve can cause pain by stimulating it all at once. The "funny bone" unfortunately extends all the way to the pinkey so whenever it is hit, the pain is felt on a much larger scale.
3. Given the placement of the radial nerve, what type of muscles do you think this nerve stimulates? Explain. HINT: What type of muscles is found on the dorsal side of the body?
Muscles that flex the thumb and allow for the thumb to move and the fingers to extend and the wrist to flex.
4. What do you think would happen to a person’s ability to use his/her arm if the radial nerve were damaged?
It would be difficult to straighten the arm and move the wrist and fingers.
5. Explain how the central and the peripheral nervous system work together to allow you to pick up a can of soda. Mention muscles of the forearm in your answer.
PNS receives and interprets signals from the surround environment, sends the signal(s) to the brain by way of the CNS. The reaction to the signals sent are decided by the brain, sent back down the PNS to the arm, where the ventral muscles are stimulated to contract and grab the can.
6. Describe at least three different jobs that put the worker at risk for carpal tunnel syndrome. How can these individuals lower their risk of injury?
Writing, typing on a computer all day or a professional gymnast. They can take frequent breaks from their career, stretch their wrist often and be sure not to press their body to the limit at which their wrist can stretch.
7. What happens at the junction between a nerve and a muscle to initiate muscle contraction?
The axon terminals of the motor neurons send the electrical signal that they have carried from the brain into the muscle. As the electrical signal passes through the muscle fibers, the action potential is activated and the ions within and outside the muscle begin to switch places to create contraction.