Physio Ex Exercise 2 Activity 1 PDF

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5/6/2020

PhysioEx Exercise 2 Activity 1

PhysioEx Lab Report Exercise 2: Skeletal Muscle Physiology Activity 1: The Muscle Twitch and the Latent Period Name: Samih Abdurehim(11190066) Date: 6 May 2020 Session ID: session-c7282f64-b9f3-4798-f045-c6e4ef4a3a17

Pre-lab Quiz Results You scored 100% by answering 5 out of 5 questions correctly. 1 Skeletal muscles are connected to bones by You correctly answered: tendons. 2 Skeletal muscles are composed of hundreds to thousands of individual cells called You correctly answered: fibers. 3 The term motor unit refers to You correctly answered: one motor neuron and all of the skeletal muscle fibers it innervates. 4 The motor neuron and muscle fiber intersect at what is called You correctly answered: the neuromuscular junction. 5 A twitch is You correctly answered: one contractile response to a single action potential.

Experiment Results Predict Question 1 Predict Question: Will changes to the stimulus voltage alter the duration of the latent period? Your answer: No, changing the stimulus voltage will not change the latent period duration. Stop & Think Questions 1 What is the period of time that elapses between the generation of an action potential and the start of muscle tension development in a muscle fiber? You correctly answered: The latent period. 2 What occurs during the latent period of these isometric contractions? https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex2/act1/

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PhysioEx Exercise 2 Activity 1

You correctly answered: All the steps of excitation-contraction coupling occur. Experiment Data Voltage (v)

Length (mm)

Active Force Passive Force

Total Force

Latent Period (msec)

0

75

0

0

0

----

3

75

1.04

0

1.04

----

4

75

1.32

0

1.32

----

6

75

1.65

0

1.65

2.80

8

75

1.81

0

1.81

2.80

10

75

1.82

0

1.82

2.80

Voltage = 0 V

Voltage = 3 V

Voltage = 4 V

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PhysioEx Exercise 2 Activity 1

Voltage = 6 V

Voltage = 8 V

Voltage = 10 V

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PhysioEx Exercise 2 Activity 1

Post-lab Quiz Results You scored 100% by answering 6 out of 6 questions correctly. 1 An action potential in a motor neuron triggers the release of which neurotransmitter? You correctly answered: acetylcholine. 2 The term skeletal muscle fiber refers to You correctly answered: an individual skeletal muscle cell. 3 The graded depolarization in the skeletal muscle fiber that is elicited in response to one action potential from the motor neuron is called You correctly answered: an EPP (end-plate potential). 4 Which of the following is not a phase of a skeletal muscle twitch? You correctly answered: hyperpolarization phase. 5 A skeletal muscle twitch is You correctly answered: one contractile response to a single action potential. 6 Which of the following correctly matches the twitch phase with its definition? You correctly answered: the contraction phase: the time between the end of the latent period and peak muscle tension.

Review Sheet Results

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PhysioEx Exercise 2 Activity 1

1 Define the terms skeletal muscle fiber, motor unit, skeletal muscle twitch, electrical stimulus, and latent period. Your answer: skeletal muscle fiber: are skeletal muscle cells motor unit: is made up of a motor neuron and the skeletal muscle fibers innervated by that motor neuron's axonal terminals skeletal muscle twitch: the mechanical response to a single action potential Electrical stimulus: the stimulus that activate the end plate potential Latent period: time between the action potential and the muscle contraction. 2 What is the role of acetylcholine in a skeletal muscle contraction? Your answer: Acetylcholine binds to receptors in the motor end plate, initiating a change in ion permeability that results in the end-plate potential. 3 Describe the process of excitation-contraction coupling in skeletal muscle fibers. Your answer: Excitation–contraction coupling is the physiological process of converting an electrical stimulus to a mechanical response. It is the link (transduction) between the action potential generated in the sarcolemma and the start of a muscle contraction. step 1: Action potential spread along the sarcolemma to the T-tubules (transverse tubules) step 2: Calcium is released into the sarcoplasmic reticulum step 3: Calcium binds to actin and the blocking action of the tropomyosin is removed step 4: Myosin heads attach to begin contraction step 5: Calcium is removed and the binding sites on actin become blocked again by tropomyosin step 6: Muscle relaxes. 4 Describe the three phases of a skeletal muscle twitch. Your answer: latent period: time between action potential and muscle contraction Contraction phase: starts at the end of the latent period and ends when muscle tension peaks Relaxation phase: period of time from peak tension until the end of muscle contraction. 5 Does the duration of the latent period change with different stimulus voltages? How well did the results compare with your prediction? https://media.pearsoncmg.com/bc/bc 0media ap/physioex/10/ex2/act1/

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PhysioEx Exercise 2 Activity 1

Your answer: No it didn't change as i predicted in the beginning. 6 At the threshold stimulus, do sodium ions start to move into or out of the cell to bring about the membrane depolarization? Your answer: Sodium would move into the cell to bring about membrane depolarization.

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