Anatomy and Physiology Guided Reading- Muscular System

Name ______Date ______

1. What are the functions of the muscular system? a.

2. Briefly describe each of the four functional properties of muscle tissue a.

1 Name ______Date ______

3. What are the 3 main types of muscle? For each type, briefly state where in the body they would be found and what their function is?

4. Draw sample skeletal muscle fibers and label the following in your diagram: fiber, nucleus and striations.

2 Name ______Date ______

5. The diagrams below show a part of a skeletal muscle attached to a bone. Label the following terms in the top diagram: bone, tendon, muscle, epimysium, perimysium, endomysium, fascicule, muscle fibers, nuclei, capillaries (small blood vessels), sarcolemma (cell membrane of muscle cells), mitochondria, myofibrils, striations, sarcomere, actin and myosin. Also, in the bottom diagram label: sarcomere, actin, myosin, Z-disk and cross bridge. In the bottom diagram, color the actin purple and the myosin green.

3 Name ______Date ______

6. The following diagram shows the structure of actin and myosin. Label the following in the diagram below: sarcomere, actin, myosin, Z-disk, troponin, tropomyosin, attachment sites on actin. Color actin purple, myosin green, troponin orange and tropomyosin blue.

4 Name ______Date ______

7. Now that we know a bit about the structure of muscles and muscle cells, let’s start talking about how muscles move. FIRST, a muscle needs to receive an impulse from your nervous system in order to contract. This is the FIRST step and it happens at the NEUROMUSCULAR JUNCTION. That is the place where a nerve and a muscle connect (hence the junction). In the following diagram, you can see one single nerve connecting with one single muscle fiber. Label the following on that diagram: muscle fiber, axon branch from sending neuron, neuromuscular junction, myofibrils, presynaptic terminals, synapse, sarcolemma (muscle cell membrane).

5 Name ______Date ______

8. Just like there were steps on how the action potential was passed from one neuron to other neurons, there are steps in how the action potential from the neuron (the message to contract) is passed onto a muscle fiber at the neuromuscular junction. Look at the diagram below and do the following: FIRST, label action potential, pre-synaptic terminal, calcium channel, calcium ions, synapse (same as synaptic cleft), Ach (acetylcholine), receptor molecule in sarcolemma, sarcolemma, sodium ions, Ach vesicles, acetic acid, choline, Ach- ase. SECOND, look at the steps listed below the picture and write down the number for each step in the diagram where it belongs (wherever that step is being represented in the picture).

6 Name ______Date ______

1. Action potential (electrical signal) arrives at pre-synaptic knob of neuron 2. Action potential opens calcium channels in pre-synaptic knob à calcium rushes into pre-synaptic knob 3. Calcium triggers release of acetylcholine (Ach) from vesicles into synapse 4. Ach in synapse binds to receptors in muscle fiber membrane; receptors are attached to sodium channels 5. Once enough Ach is attached to receptors, sodium channels are open and sodium enters the muscle fiber 6. Sodium entering the muscle fiber passes the action potential (message) to the muscle 7. In the synapse, Ach-ase is an enzyme that breaks down Ach into acetic acid and choline in the synapse so that the impulse is stops 8. Acetic acid and choline are re-absorbed into the pre-synaptic knob where they can be reattached and used again ______

9. Bob Canner improperly canned some homegrown tomatoes. As a result, bacteria built inside his jars and when he ate the tomatoes a few months later, Bob contracted botulism, a condition in which the botulinum toxin released by bacteria inhibit the release of Ach from the pre-synaptic knob. Bob went tot the doctor and his symptoms were the following: difficulty swallowing, breathing and moving. Finally he died of respiratory failure (his respiratory muscles would not contract and he could not breathe). Explain how the toxin caused his symptoms and ultimate death. Explain by telling me what the toxin is doing at the neuromuscular junction and how this would cause his symptoms.

7 Name ______Date ______

10.Sue just got diagnosed with Myasthenia Gravis. MG is a disease in which Sue’s own immune system attacks the Ach receptors in the sarcolemma of her muscle cells. Explain what symptoms you would expect Sue to have and why by using what would happen at the neuromuscular junction.

11.Bob is given a drug that his doctor says is an “Ach-ase inhibitor”, meaning that it does not allow Ach-ase to do its job. What effect do you think a drug like this would have and why? When and why would you use this drug on someone?

8 Name ______Date ______

12.Now that we know how muscles get the message to contract, we have to figure out how they actually contract. Muscles are made of million of fibers and fibers are made out of myofibrils … The muscle contracts and lengthens at this microscopic level. The following section is known as the SLIDING FILAMENT THEORY, and it provides the microscopic explanation for muscle contraction. The first thing is to examine what effect the action potential has inside the muscle fiber. In the picture below label: action potential, sarcolemma, sarcoplasmic reticulum, T-tubule, sarcomere, actin, myosin, tropomyosin, troponin, calcium ions, active sites and cross bridges.

For each numbered step in the diagram on the left (1-4) write a brief description of what is happening at each step: 1.

9 Name ______Date ______

13.Alright, so now that the active sites are exposed and myosin has finally attached to actin, the muscle fiber is FINALLY ready to contract and shorten. Here is how it happens. In the picture below label sarcomere, Z-disk, actin, myosin, troponin and tropomyosin. Write a brief description summarizing what happens at each step.

14. There are two main types of

1. Exposure of attachment sites

2. Cross-bridge formation

3. Power stroke

4. ATP binds to myosin heads

5. Cross-bridge release

6.Recovery stroke 10 Name ______Date ______

muscle contractions: isometric and isotonic. What is the difference between the two? Give me an example of a time when your muscles contract isometrically vs isotonically.

15.There are 2 types of isotonic contractions: eccentric and concentric. What is the difference between the two? Give me an example of your muscle contracting in each way.

11 Name ______Date ______

16.What is the difference between slow twitch and fast twitch muscle fibers? Which ones are better for sprinting? Which ones are better for endurance running? What is the difference between the two regarding the following factors: speed of contraction, diameter, amount of blood supply, amount of mitochondria, amount of myoglobin, fatigue resistance, primary source of ATP (aerobic vs anaerobic); what type of activity it is adapted to (long term vs short term contraction)

17.Muscle needs a lot of energy. The energy must be in the form of ATP. What is ATP? Explain how ATP is used for energy (talk about the ATP cycle).

12 Name ______Date ______

18.Compare and contrast aerobic and anaerobic respiration. Which one makes more ATP? Which one is used by our bodies when jogging vs when sprinting? What molecules does your body use to make ATP? What is the formula for cellular respiration?

19.What type of molecules that you eat are used for energy (carbs, fats, proteins …)?

20.Which molecule do we use FIRST for energy?

13 Name ______Date ______

21.What causes muscle fatigue?

22.Why are your bodies so good at storing fat and why is it so hard to lose weight?

23.What types of molecules are used to build muscle?