Question 1

Describe 3 characteristics that enables skeletal muscle tissue to function as it does

Accepted Answer

1. Excitability: AKA irritability. Ability to be stimulated. Can respond to regulatory mechanisms like nerve signals. 2.Contractility: Ability to contract or shorten. Allow muscle to pull on bones and produce movement.

Question 2

Define endomysium

Accepted Answer

Muscle fiber is muscle cell. Covered by endomysium. Endomysium: is a layer of connective tissue that ensheaths a muscle fiber

Question 3

Perimysium

Accepted Answer

The sheath of connective tissue surrounding a bundle of muscle fibers

Question 4

Epimysium

Accepted Answer

Muscle as a whole is covered by the epimysium

Question 5

Aponeurosis

Accepted Answer

A sheet of pearly-white fibrous tissue that takes the place of a tendon in sheetlike muscles having a wide area of attachment. Fibrous wrappings of muscles may extend as a aponeurosis. Sheet of connective tissue.

Question 6

define tendon sheath

Accepted Answer

Tendon sheaths. Tube-shaped; fibrous connective tissue that enclose certain tendons. Ankle and wrist tendons. Have synovial membrane lining. Allow tendon to move easily within the sheath

Question 7

Know function of sarcoplasmic reticulum

Accepted Answer

function is to store and release calcium ions.

Question 8

Know function of T tubules (transverse tubules)

Accepted Answer

T tubules or Transverse tubules: Unique structure to muscle fibers.

Question 9

Know structure of myofibrils

Accepted Answer

Myofibers are composed of tubular myofibrils. Myofibrils are composed of long proteins such as actin, myosin, and titin, and other proteins that hold them together.

Question 10

What proteins make up thin and thick filaments

Accepted Answer

1. Thin filaments contain actin, tropomyosin, and troponin. 2. Thick filaments are made of myosin

Question 11

Know structure of sarcomere

Accepted Answer

1. Segment of myofibril between 2 successive Z-disks (Z-lines). 2. Each myofibril consists of lineup of many sarcomeres. 3.Each one functions as a contractile unit. 4.Has a 3-D structure. 5.Z-disk looks like a zigzag line in flat diagram.

Question 12

• Know major events of muscle contraction and relaxation

Accepted Answer

Steps must occur in coordinated, stepwise fashion for muscle to contract. 1. Excitation of the sarcolemma. 2. Contraction. 3. Relaxation

Question 13

Excitation of the sarcolemma

Accepted Answer

Muscle fiber is “at rest” until stimulated by a signal from a special type of nerve cell.

Question 14

Contraction

Accepted Answer

Shows how sliding of thin filaments toward center of each sarcomere. This shortens entire myofibril and, thus, entire muscle fiber.

Question 15

Contraction continued

Accepted Answer

This model of contraction has been called sliding-filament model. Muscles generally contract about 80%. Actin-myosin bond is not permanent.

Question 16

Relaxation

Accepted Answer

Ca2+ ions start to be pumped back into the SR directly after the SR releases them to begin contraction. Much is recovered after only a few milliseconds.

Question 17

Information in Table 10-1

Accepted Answer

Table 10-4 shows characteristics of 3 major types of muscle

Question 18

Define myography

Accepted Answer

Myography is one method “Muscle graphing.” Experimental methods used to study contraction of muscles are numerous.

Question 19

Define threshold stimulus

Accepted Answer

Electrical stimulus of sufficient intensity. Applied to the muscle to make it contract. Single, brief threshold stimulus produces quick jerk of muscle called twitch contraction

Question 20

Know different phases of the twitch contraction

Accepted Answer

Latent period, Contraction phase,

Question 21

Know and describe the 4 different types of muscle contractions

Accepted Answer

Twitch, Treppe (staircase phenomenon), Muscle Fatigue, Tetanus (complete and incomplete)

Question 22

Twitch contractions

Accepted Answer

The latent period: When stimulation travels through sarcolemma and T tubules to SR to trigger release of Ca2+ ions into the sarcoplasm.

Question 23

Treppe contraction

Accepted Answer

Gradual step-like increase in strength of contraction seen in a series of twitch contractions that occur about 1 second apart.

Question 24

Muscle fatigue

Accepted Answer

Causes by repeated stimulation of a muscle. Lessens its excitability and contractility. Muscle does not respond to the strongest stimuli. Complete muscle fatigue can be induced in an isolated muscle but rarely occurs in the body.

Question 25

Tetanus

Accepted Answer

Smooth sustained contractions. AKA: tetanic contractions: If series of stimuli come in rapid succession, muscle doesn’t have time to relax completely before next contraction beings. Called multiple wave summation.

Question 26

Define motor unit

Accepted Answer

Motor units fire in an asynchronous, overlapping time sequence – “relay team” effect. All of these result in a sustained contraction

Question 27

Define flaccid and spastic

Accepted Answer

1. Flaccid: Muscles with less tone than normal. 2.Spastic:Muscle with more tone than normal

Question 28

• Define isotonic contraction

Accepted Answer

“Same tension”. In which the tone or tension within a muscle remains the same as the length of the muscle changes.

Question 29

Isotonic contraction: Concentric

Accepted Answer

Movement results in shortening of muscle. Picking up a heavy object

Question 30

Isotonic contraction: Eccentric

Accepted Answer

Movement results in lengthening of muscle being contracted. Lowering a heavy object. Muscle becomes longer but it is still contracted

Question 31

• Define isometric contraction

Accepted Answer

“Same length”. Muscle length remains the same while muscle tension increases. Observed when lifting up on a stationary object.

Question 32

Know roles of ATP in muscle contraction

Accepted Answer

Energy needed for contraction is obtained by hydrolysis of ATP. ATP

Question 33

Role of ATP in muscle contraction continued

Accepted Answer

When myosin binds to actin, stored energy is released. Myosin heads “spring back” to the actin. Energy from ATP is used to do work on pulling thin filaments during contraction. Another ATP binds to myosin head, repeating cycle.

Question 34

The roles of glucose and oxygen in muscle contraction

Accepted Answer

Both required for continued, efficient nutrient catabolism by muscle fibers.

Question 35

Glucose in muscle contraction

Accepted Answer

nutrient molecule with many chemical bonds. Potential energy stored in bonds released during catabolism and transferred to ATP and CP.

Question 36

Oxygen in muscle contraction

Accepted Answer

Needed for aerobic respiration. Also comes from blood. Most is temporarily bound to hemoglobin molecules. Reddish pigment inside RBCs.

Question 37

• Know difference between aerobic and anaerobic respiration

Accepted Answer

1.Aerobic respiration: Catabolic process that requires oxygen. Produces maximum amount of energy from each glucose molecule.

Question 38

Cardiac muscle

Accepted Answer

striated involuntary muscle

Question 39

Smooth muscle

Accepted Answer

nonstriated involuntary muscle

Question 40

Define myopathy

Accepted Answer

Muscle disorders. Disrupt normal movement. Can be mild to very severe.

Question 41

Define strain

Accepted Answer

Strain: Injuries to skeletal muscle by overexertion or trauma. Can result in a tear. Characterized by muscle pain

Question 42

Sprain

Accepted Answer

Injury at area of joint. Ligament is damaged

Question 43

Define myalgia

Accepted Answer

muscle pain.

Question 44

Define myositis

Accepted Answer

Myositis: Muscle inflammation. Can occur during a sprain

Question 45

Fibromyositis

Accepted Answer

Tendon inflammation with myositis. Inflammations can subside after a few hours. Injuries take weeks to repair. Scars in muscle tissue can form

Question 46

Define poliomyelitis

Accepted Answer

Poliomyelitis: Viral infection of nerves that control skeletal muscle. Can be symptomless but also can cause paralysis that could eventually lead to death. Practically eliminated in US due to vaccines.

Question 47

Define duchenne muscular dystrophy

Accepted Answer

Duchenne muscular dystrophy (DMD): Most common type. Muscle atrophy is hidden by replacement with fat and fibrous tissue. “false muscle growth”. Starts with mild leg muscle weakness that eventually affects the shoulder muscles as well.

Question 48

Define hernia

Accepted Answer

Protrusion of abdominal organ through opening in the abdominal wall. Commonly is small intestine or stomach. Caused by weakness of abdominal muscles. There are many types of hernias.

Question 49

Describe the 3 general functions of skeletal muscle

Accepted Answer

1. Movement: Contractions produce movement of entire body (locomotion) and its parts. 2.Heat Production: Muscle cells produce heat by catabolism. Muscle cells are highly active and numerous. Produce a major share of total body heat.

Question	Answer
Describe 3 characteristics that enables skeletal muscle tissue to function as it does	1. Excitability: AKA irritability. Ability to be stimulated. Can respond to regulatory mechanisms like nerve signals. 2.Contractility: Ability to contract or shorten. Allow muscle to pull on bones and produce movement.	Can do work by resisting load without becoming shorter – still said to be contracting.	Contraction is pulling ends together. Muscle fiber is muscle cell. 3. Extensibility: Ability to extend or stretch. Allows muscles to return to original resting length after being contracted. Muscles can extend while still exerting a force.
Define endomysium	Muscle fiber is muscle cell. Covered by endomysium. Endomysium: is a layer of connective tissue that ensheaths a muscle fiber
Perimysium	The sheath of connective tissue surrounding a bundle of muscle fibers
Epimysium	Muscle as a whole is covered by the epimysium
Aponeurosis	A sheet of pearly-white fibrous tissue that takes the place of a tendon in sheetlike muscles having a wide area of attachment. Fibrous wrappings of muscles may extend as a aponeurosis. Sheet of connective tissue.
define tendon sheath	Tendon sheaths. Tube-shaped; fibrous connective tissue that enclose certain tendons. Ankle and wrist tendons. Have synovial membrane lining. Allow tendon to move easily within the sheath
Know function of sarcoplasmic reticulum	function is to store and release calcium ions.
Know function of T tubules (transverse tubules)	T tubules or Transverse tubules: Unique structure to muscle fibers.	Extend transversely across sarcoplasm at right angles to long axis of the cell. Formed by inward extension of sarcolemma. Allows electrical signals or impulses traveling along sarcolemma to move deeper into the cell.
Describe what occurs when action potential reaches and travels down T tubules and induces release of calcium from SR
Know structure of myofibrils	Myofibers are composed of tubular myofibrils. Myofibrils are composed of long proteins such as actin, myosin, and titin, and other proteins that hold them together.	These proteins are organized into thin filaments and thick filaments, which repeat along the length of the myofibril in sections called sarcomeres
What proteins make up thin and thick filaments	1. Thin filaments contain actin, tropomyosin, and troponin. 2. Thick filaments are made of myosin
Know structure of sarcomere	1. Segment of myofibril between 2 successive Z-disks (Z-lines). 2. Each myofibril consists of lineup of many sarcomeres. 3.Each one functions as a contractile unit. 4.Has a 3-D structure. 5.Z-disk looks like a zigzag line in flat diagram.	6.Is actually a dense plate (disk) where thin filaments attach. 7.Useful landmark in separating sarcomeres
• Know major events of muscle contraction and relaxation	Steps must occur in coordinated, stepwise fashion for muscle to contract. 1. Excitation of the sarcolemma. 2. Contraction. 3. Relaxation
Excitation of the sarcolemma	Muscle fiber is “at rest” until stimulated by a signal from a special type of nerve cell.	Motor neuron: Motor neurons connect to sarcolemma at a folded motor endplate.
Contraction	Shows how sliding of thin filaments toward center of each sarcomere. This shortens entire myofibril and, thus, entire muscle fiber.	The impulse (temporary electrical voltage imbalance) is conducted over the sarcolemma and inward along the T tubules. Impulse in T tubules triggers release of flood of Ca2+ from adjacent sacs of SR.	Ca2+ combines with troponin in thin filaments. Troponin normally holds tropomyosin in a position where it blocks the active sites of actin. When Ca2+ binds, tropomyosin shifts to expose active binding sites of actin. Once sites are exposed, energized myos
Contraction continued	This model of contraction has been called sliding-filament model. Muscles generally contract about 80%. Actin-myosin bond is not permanent.	Sarcomeres can’t “lock up” once it is shorted to hold its position passively. Takes energy to actively maintain shortened position. Continually repeating actin-myosin reaction as long as necessary
Relaxation	Ca2+ ions start to be pumped back into the SR directly after the SR releases them to begin contraction. Much is recovered after only a few milliseconds.	Active transport carriers of SR have greater affinity for Ca2+ than troponin does.	Ca2+ stripped off of troponin and returned to sacs of SR. This shuts down contraction process. No Ca2+ on troponin allows tropomyosin to once again bind and block active sites on actin. Myosin heads can’t bind to these sites to thin filaments are no longe
Information in Table 10-1	Table 10-4 shows characteristics of 3 major types of muscle
Define myography	Myography is one method “Muscle graphing.” Experimental methods used to study contraction of muscles are numerous.	They range from very simple. Observing muscle contract. To very complex Electromyography – recording electrical impulses from muscles during contraction.	Force or tension from contraction of isolated muscle is recorded. Line rises and falls as the muscle contracts and relaxes
Define threshold stimulus	Electrical stimulus of sufficient intensity. Applied to the muscle to make it contract. Single, brief threshold stimulus produces quick jerk of muscle called twitch contraction
Know different phases of the twitch contraction	Latent period, Contraction phase,
Relaxation phase
Know and describe the 4 different types of muscle contractions	Twitch, Treppe (staircase phenomenon), Muscle Fatigue, Tetanus (complete and incomplete)
Twitch contractions	The latent period: When stimulation travels through sarcolemma and T tubules to SR to trigger release of Ca2+ ions into the sarcoplasm.	Contraction is not observed until Ca2+ binds to troponin and myofilaments start to slide. After a few milliseconds, relaxation begins.	End of relaxation phase, all of myosin-actin reactions have stopped. This type of contraction rarely happens in our body – even if we try to do it. Our nervous system subconsciously “smoothes out” our movements to prevent injury and make our movements mor
Treppe contraction	Gradual step-like increase in strength of contraction seen in a series of twitch contractions that occur about 1 second apart.	Muscle contracts more forcefully after it has contracted a few times.	Principle used by athletes when they warm up. After first few stimuli, muscle responds to successive stimuli with maximal contractions. Eventually, will respond with less and less strong contractions. Relaxation phase gets shorter and eventually disappear
Muscle fatigue	Causes by repeated stimulation of a muscle. Lessens its excitability and contractility. Muscle does not respond to the strongest stimuli. Complete muscle fatigue can be induced in an isolated muscle but rarely occurs in the body.
Tetanus	Smooth sustained contractions. AKA: tetanic contractions: If series of stimuli come in rapid succession, muscle doesn’t have time to relax completely before next contraction beings. Called multiple wave summation.	As though multiple twitch waves have been added together to sustain tension for a longer time.
Define motor unit	Motor units fire in an asynchronous, overlapping time sequence – “relay team” effect. All of these result in a sustained contraction
Define flaccid and spastic	1. Flaccid: Muscles with less tone than normal. 2.Spastic:Muscle with more tone than normal
• Define isotonic contraction	“Same tension”. In which the tone or tension within a muscle remains the same as the length of the muscle changes.	As muscle moves against a load, energy of contraction changes the length of the sarcomeres. Myosin cross bridges “win” the tug-o-war against a light load and are able to pull the thin filaments. Called “dynamic tension” since muscle is moving.
Isotonic contraction: Concentric	Movement results in shortening of muscle. Picking up a heavy object
Isotonic contraction: Eccentric	Movement results in lengthening of muscle being contracted. Lowering a heavy object. Muscle becomes longer but it is still contracted
• Define isometric contraction	“Same length”. Muscle length remains the same while muscle tension increases. Observed when lifting up on a stationary object.	Tension in arm muscle increase. Work by “tightening” to resist force. Do NOT produce movements. Tension produced when “power stroke” of myosin cross bridges can’t overcome load placed on muscle.	In tug-o-war analogy, cross bridges reach a “draw”. They hold their own in the load place on the muscle but don’t make any progress in sliding the thin myofilaments. Called static tension since muscle remains stable
Know roles of ATP in muscle contraction	Energy needed for contraction is obtained by hydrolysis of ATP. ATP
Role of ATP in muscle contraction continued	When myosin binds to actin, stored energy is released. Myosin heads “spring back” to the actin. Energy from ATP is used to do work on pulling thin filaments during contraction. Another ATP binds to myosin head, repeating cycle.	Cycle continues to repeat as long as ATP is available and actin sites are unblocked. Both ATP and CP resynthesize continuously (or “recharge”) by cellular respiration. Ultimately, energy to resynthesize ATP and CP synthesis comes from catabolism of food.	If cell runs out of ATP and can’t synthesize more, contraction stops. Possibly results in stiffness caused by inability of myosin heads to disengage from actin.
The roles of glucose and oxygen in muscle contraction	Both required for continued, efficient nutrient catabolism by muscle fibers.
Glucose in muscle contraction	nutrient molecule with many chemical bonds. Potential energy stored in bonds released during catabolism and transferred to ATP and CP.	All glucose needed by muscle fibers comes from blood. Skeletal muscles surrounded by network of blood capillaries. Allow molecules to enter or leave blood. Some muscle fibers ensure uninterrupted supply of glucose by storing it in glycogen.
Oxygen in muscle contraction	Needed for aerobic respiration. Also comes from blood. Most is temporarily bound to hemoglobin molecules. Reddish pigment inside RBCs.	Can be stored to ensure uninterrupted supply. During rest, oxygen in sarcoplasm attracted to myoglobin. Also reddish pigment with iron groups that attract oxygen to hold it temporarily
• Know difference between aerobic and anaerobic respiration	1.Aerobic respiration: Catabolic process that requires oxygen. Produces maximum amount of energy from each glucose molecule.	When oxygen supply is low, muscle fibers shift toward another catabolic process called anaerobic respiration.	2.Anaerobic respiration: Does not require the immediate use of oxygen. Can produce ATP without it. Very rapid. Muscles may rely on this method to resynthesize ATP. If they have a hard time getting oxygen or that generate a great deal of force very quickly
Cardiac muscle	striated involuntary muscle
Smooth muscle	nonstriated involuntary muscle
Define myopathy	Muscle disorders. Disrupt normal movement. Can be mild to very severe.
Define strain	Strain: Injuries to skeletal muscle by overexertion or trauma. Can result in a tear. Characterized by muscle pain
Sprain	Injury at area of joint. Ligament is damaged
Define myalgia	muscle pain.
Define myositis	Myositis: Muscle inflammation. Can occur during a sprain
Fibromyositis	Tendon inflammation with myositis. Inflammations can subside after a few hours. Injuries take weeks to repair. Scars in muscle tissue can form
Define poliomyelitis	Poliomyelitis: Viral infection of nerves that control skeletal muscle. Can be symptomless but also can cause paralysis that could eventually lead to death. Practically eliminated in US due to vaccines.
Define duchenne muscular dystrophy	Duchenne muscular dystrophy (DMD): Most common type. Muscle atrophy is hidden by replacement with fat and fibrous tissue. “false muscle growth”. Starts with mild leg muscle weakness that eventually affects the shoulder muscles as well.
Define hernia	Protrusion of abdominal organ through opening in the abdominal wall. Commonly is small intestine or stomach. Caused by weakness of abdominal muscles. There are many types of hernias.
Describe the 3 general functions of skeletal muscle	1. Movement: Contractions produce movement of entire body (locomotion) and its parts. 2.Heat Production: Muscle cells produce heat by catabolism. Muscle cells are highly active and numerous. Produce a major share of total body heat.	Contraction is one of most important parts of maintaining body temperature. 3.Posture: Continued partial contraction of many skeletal muscles makes standing	and sitting possible. Helps maintain relatively stable body position while performing other movements.
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A&P Chap 10