Question 1

Active tension

Accepted Answer

A)  Is the increment in force caused by excitation of the muscle 
B)  Is directly related to the passive force 
C)  Varies biphasically with muscle length, being m aximal near the rest length 
D)  Is caused by phosphorylation of myosin light chains 
E)  Both A and C are correct 
A)  Is the increment in force caused by excitation of the muscle 
B)  Is directly related to the passive force 
C)  Varies biphasically with muscle length, being m aximal near the rest length 
D)  Is caused by phosphorylation of myosin light chains 
E)  Both A and C are correct A

Question 2

A muscle twitch in a human returns to baseline 50 ms after the initial stimulus. This muscle is

Accepted Answer

A)  Sm ooth m uscle 
B)  Cardiac m uscle 
C)  Fast twitch muscle 
D)  Slow twitch muscle 
E)  Fatigue-resistant 
A)  Sm ooth m uscle 
B)  Cardiac m uscle 
C)  Fast twitch muscle 
D)  Slow twitch muscle 
E)  Fatigue-resistant C

Question 3

The advantage of m uscle pennation is that it

Accepted Answer

A)  Increases the velocity of muscles 
B)  Increases the force of muscles, but slows their speed 
C)  Increases the endurance of muscles 
D)  Decreases the metabolic cost of muscles 
E)  Packs more muscle into a given volume 
A)  Increases the velocity of muscles 
B)  Increases the force of muscles, but slows their speed 
C)  Increases the endurance of muscles 
D)  Decreases the metabolic cost of muscles 
E)  Packs more muscle into a given volume B

Question 4

Physiological recruitment of muscle fibers

Accepted Answer

A)  Is random 
B)  Begins with the small motor units and progresses to large m otor units 
C)  Begins with large motor units and then the smaller motor units 
D)  Is inversely related to muscle velocity 
E)  Begins with slow twitch fibers and progresses to fast twitch fibers 
A)  Is random 
B)  Begins with the small motor units and progresses to large m otor units 
C)  Begins with large motor units and then the smaller motor units 
D)  Is inversely related to muscle velocity 
E)  Begins with slow twitch fibers and progresses to fast twitch fibers

Question 5

A muscle with a radius of 3 cm exerts about 20 N cm-2 of force at zero velocity. W hich of the following afterloads would cause an eccentric contraction? Use g = 9.81 m s-2. Assume the muscle is a right circular cylinder with a pennation angle of 0o.

Accepted Answer

A)  60 g 
B)  600 g 
C)  6kg 
D)  60 kg 
E)  600 kg 
A)  60 g 
B)  600 g 
C)  6kg 
D)  60 kg 
E)  600 kg

Question 6

The muscle twitch

Accepted Answer

A)  Lasts 5 ms or less in humans 
B)  Is involuntary 
C)  Takes less time in slow twitch muscles 
D)  Is the contraction resulting from a single action potential on each of a set of muscle
fibers 
E)  Lasts longer in fast twitch muscles 
A)  Lasts 5 ms or less in humans 
B)  Is involuntary 
C)  Takes less time in slow twitch muscles 
D)  Is the contraction resulting from a single action potential on each of a set of muscle
fibers 
E)  Lasts longer in fast twitch muscles

Question 7

Maximum force in muscle is produced

Accepted Answer

A)  At about one-third maxim um length 
B)  At zero afterload 
C)  W hen the velocity of contraction is zero 
D)  During eccentric contractions 
E)  During concentric contractions 
A)  At about one-third maxim um length 
B)  At zero afterload 
C)  W hen the velocity of contraction is zero 
D)  During eccentric contractions 
E)  During concentric contractions

Question 8

Maximum power in muscle is produced

Accepted Answer

A)  At about one-third maxim um length 
B)  At about one-third of the maximum isometric force 
C)  At zero afterload 
D)  W hen the velocity of contraction is zero 
E)  At sub-maximal recruitment 
A)  At about one-third maxim um length 
B)  At about one-third of the maximum isometric force 
C)  At zero afterload 
D)  W hen the velocity of contraction is zero 
E)  At sub-maximal recruitment

Question 9

Passive force

Accepted Answer

A)  Has a biphasic relationship with muscle length, being m axim al at rest length 
B)  Is the force exerted by a muscle without nervous excitation 
C)  Is inversely related to muscle velocity 
D)  Is inversely related to the active force 
E)  Is directly related to the active force 
A)  Has a biphasic relationship with muscle length, being m axim al at rest length 
B)  Is the force exerted by a muscle without nervous excitation 
C)  Is inversely related to muscle velocity 
D)  Is inversely related to the active force 
E)  Is directly related to the active force

Question 10

Tetanic force is typically about

Accepted Answer

A)  10% greater than twitch force 
B)  50 % greater than twitch force 
C)  5 times the twitch force 
D)  20 times the twitch force 
E)  50 times the twitch force 
A)  10% greater than twitch force 
B)  50 % greater than twitch force 
C)  5 times the twitch force 
D)  20 times the twitch force 
E)  50 times the twitch force

Question 11

In an isometric contraction

Accepted Answer

A)  The muscle lengthens 
B)  The muscle shortens 
C)  Muscle length does not change 
D)  Maximum force is generated 
E)  Maximum muscle velocity is recorded 
A)  The muscle lengthens 
B)  The muscle shortens 
C)  Muscle length does not change 
D)  Maximum force is generated 
E)  Maximum muscle velocity is recorded

Question 12

The muscles with the greatest endurance are the

Accepted Answer

A)  Fast twitch glycolytic muscles 
B)  Slow twitch oxidative muscles 
C)  Fast twitch oxidative muscles 
D)  Fast twitch intermediate muscles 
E)  Slow twitch glycolytic muscles 
A)  Fast twitch glycolytic muscles 
B)  Slow twitch oxidative muscles 
C)  Fast twitch oxidative muscles 
D)  Fast twitch intermediate muscles 
E)  Slow twitch glycolytic muscles

Question 13

A motor unit is

Accepted Answer

A)  A motor neuron and all of the muscle fibers it innervates 
B)  A single muscle fiber innervated by a single motor neuron 
C)  All of the m uscle fibers within a muscle fasicle 
D)  A single muscle fiber innervated by several motor neurons 
E)  A piston, spark plug, intake valve and exhaust valve 
A)  A motor neuron and all of the muscle fibers it innervates 
B)  A single muscle fiber innervated by a single motor neuron 
C)  All of the m uscle fibers within a muscle fasicle 
D)  A single muscle fiber innervated by several motor neurons 
E)  A piston, spark plug, intake valve and exhaust valve

Question 14

“Recruitment” refers to

Accepted Answer

A)  Increasing muscle force by repetitive stimulation 
B)  Increasing muscle force by stretching prior to activation 
C)  Excitation or activation of additional motor units 
D)  Excitation of additional muscle fibers by a given motor neuron 
E)  Increasing the force of already active muscle 
A)  Increasing muscle force by repetitive stimulation 
B)  Increasing muscle force by stretching prior to activation 
C)  Excitation or activation of additional motor units 
D)  Excitation of additional muscle fibers by a given motor neuron 
E)  Increasing the force of already active muscle

Question 15

If a muscle twitch lasts 0.08 s, it first begins to show summation upon repetitive stimulation at a stimulation frequency of

Accepted Answer

A)  8 Hz 
B)  80 Hz 
C)  12.5 Hz 
D)  125 Hz 
E)  1.25 Hz 
A)  8 Hz 
B)  80 Hz 
C)  12.5 Hz 
D)  125 Hz 
E)  1.25 Hz

Question 16

The contraction that results from a single action potential on each of a set of motor neurons is called

Accepted Answer

A)  Tetany 
B)  Tetanus 
C)  A tic 
D)  A muscle twitch 
E)  A muscle spasm 
A)  Tetany 
B)  Tetanus 
C)  A tic 
D)  A muscle twitch 
E)  A muscle spasm

Question 17

If a muscle twitch is 0.2 s long, it will first begin to show sum mation upon repetitive stimulation at a frequency of about

Accepted Answer

A)  2 Hz 
B)  5 Hz 
C)  20 Hz 
D)  50 Hz 
E)  500 Hz 
A)  2 Hz 
B)  5 Hz 
C)  20 Hz 
D)  50 Hz 
E)  500 Hz

Question 18

Skeletal m uscle is described by all of the following EXCEPT

Accepted Answer

A)  It is striated 
B)  It consists of large multinucleated cells or fibers 
C)  It is controlled voluntarily 
D)  It generally connects one bone to another 
E)  Its contraction is controlled by hormones 
A)  It is striated 
B)  It consists of large multinucleated cells or fibers 
C)  It is controlled voluntarily 
D)  It generally connects one bone to another 
E)  Its contraction is controlled by hormones

Exam 20: Skeletal Muscle Mechanics

Active tension

A muscle twitch in a human returns to baseline 50 ms after the initial stimulus. This muscle is

The advantage of m uscle pennation is that it

Physiological recruitment of muscle fibers

A muscle with a radius of 3 cm exerts about 20 N cm-2 of force at zero velocity. W hich of the following afterloads would cause an eccentric contraction? Use g = 9.81 m s-2. Assume the muscle is a right circular cylinder with a pennation angle of 0o.

The muscle twitch

Maximum force in muscle is produced

Maximum power in muscle is produced

Passive force

Tetanic force is typically about

In an isometric contraction

The muscles with the greatest endurance are the

A motor unit is

“Recruitment” refers to

If a muscle twitch lasts 0.08 s, it first begins to show summation upon repetitive stimulation at a stimulation frequency of

The contraction that results from a single action potential on each of a set of motor neurons is called

If a muscle twitch is 0.2 s long, it will first begin to show sum mation upon repetitive stimulation at a frequency of about

Skeletal m uscle is described by all of the following EXCEPT

Physical Foundations Ii: Electrical Force Potential Capacitance and Current

Chemical Foundations I: Chemical Energy and Intermolecular Forces

Chemical Foundations Ii: Concentration and Kinetics

Diffusion

Electrochemical Potential and Free Energy

Cell Structure

Dna and Protein Synthesis

Protein Structure

Biological Membranes

Passive Transport and Facilitated Diffusion

Active Transport: Pumps and Exchangers

Osmosis and Osmotic Pressure

Cell Signaling

ATP Production I: Glycolysis

Atp Production Ii: Tca Cycle and Oxidative Phosphorylation

Atp Production Iii: Fatty Acid Oxidation and Amino Acid Oxidation

Origin of the Membrane Potential

The Action Potential

Propagation of the Action Potential

Contractile Mechanisms in Skeletal Muscle

Neuromuscular Junction and Ec Coupling

Muscle Energetics Fatigue and Training

Smooth Muscle

Organization of the Nervous System

Cells Synapses and Neurotransmitters

Cutaneous Sensory Systems

Spinal Reflexes

Balance and Control of Movement

the Chemical Senses

Hearing

Vision

Autonomic Nervous System

Overview of the Cv System and Blood

Plasma and Red Blood Cells

White Blood Cells and Inflammation

The Heart As a Pump

Cellular Basis of Cardiac Contractility

the Cardiac Function Curve

Vascular Function: Hemodynamics

Microcirculation and Solute Exchange

Regulation of Perfusion

Integration of Cardiac Output and Venous Return

Regulation of Arterial Pressure

Mechanics of Breathing

Lung Volumes and Airway Resistance

Gas Exchange in the Lung

Oxygen and Carbon Dioxide Transport

Acid Base Physiology I Bicarbonate Buffers and Respiratory Compensation

Control of Ventilation

Anatomy and Renal Overview

Glomerular Filtration

Tubular Reabsorption and Secretion

Concentration and Dilution of Urine

Mouth and Esophagus

The Stomach

Intestinal and Colonic Motility

Pancreatic and Biliary Secretion

Digestion and Absorption of the Macronutrients

Energy Balance and Regulation of Food Intake

General Principles of Endocrinology

Hypothalamus and Pituitary Gland

A muscle with a radius of 3 cm exerts about 20 N cm^-2 of force at zero velocity. W hich of the following afterloads would cause an eccentric contraction? Use g = 9.81 m s^-2. Assume the muscle is a right circular cylinder with a pennation angle of 0^o.