Muscular Physiology

Question 1

Organization of Skeletal Muscle

Answer 1

fascicles

Question 2

Myosin

Answer 2

Heads, Crossbridges, Light Chains, and

Heavy Chains

Question 3

Actin

Answer 3

Binding site for
attachment with myosin
cross bridge

Question 4

Thin Filament

Answer 4

a polymer of actin with tightly bound regulatory proteins troponin and tropomyosin

Question 5

Excitation Contraction Coupling

Answer 5

Excitation = AP

• Contraction = Start of Contraction

Question 6

Calcium Release

Answer 6

Calcium is released from intracellular stores. AP Travels Down T tubule

Question 7

The Triad

Answer 7

T tubule

• Terminal Cisternae of the SR

Question 8

Two Key Proteins of Calcium Release

Answer 8

Dihydropyridine receptor and ryanodine receptor

Question 9

What occurs when a muscle fiber is relaxed

Answer 9

no cross-
bridge binding because the cross-
bridge binding site on actin is 
physically covered by the troponin-
tropomyosin complex

Question 10

what occurs when a muscle fiber is excited

Answer 10

released Ca2+
binds with troponin, pulling troponin-
tropomyosin complex aside to 
expose cross-bridge binding site; 
cross-bridge binding occurs

Question 11

Cross-Bridge Cycling

Answer 11

Stops When Ca2+ Levels Drop. Muscle contraction based on muscle proteins that slide past each other to generate movement.

Question 12

Muscle Twitch in a Single Fiber

Answer 12

Stimulates early

Question 13

Effects of Multiple Stimuli

Answer 13

Treppe

Question 14

Why Treppe?

Answer 14

“Warm-Up” Ca2+ Levels?

Question 15

Why Wave Summation?

Answer 15

Ca2+ Levels Already Increased. Cross-Bridges Already Formed

Question 16

Tetanus

Answer 16

Same as wave summation but more

Question 17

Changing the Force of a

Contraction in a Whole Muscle

Answer 17

Motor Units and Recruitment

Question 18

Isometric Contraction

Answer 18

a muscle contraction without motion

Question 19

Isotonic Contraction

Answer 19

Concentric Contractions and Eccentric Contractions

Question 20

Series Elastic

Answer 20

acts as a spring to store elastic energy when a tensed muscle is stretched.

Question 21

Parallel Elastic

Answer 21

consist of the membranes surrounding the contractile components which includes the sarcolemma, sarcoplasmic retinaculum, the perimysium and the epimysium

Question 22

Why do you need energy?

Answer 22

Myosin ATPase, ATP need to break cross-bridge attachment. Movement of Ca2+ requires energy.

Question 23

ATP Production Methods

Answer 23

Creatine Phosphate, Glycolysis, Oxidative Phosphorylation

Question 24

Creatine Phosphate

Answer 24

Creatine Kinase Catalyzes the reaction

Question 25

Glycolysis

Answer 25

Lactic Acid Production

Question 26

Oxidative Phosphorylation

Answer 26

Very high energy, but must have O2 and Myoglobin – Storage

Question 27

Physiological Fatigue (Muscle Fatigue)

Answer 27

Muscle can not contract fully – no matter what | the stimulus.

Question 28

Psychological Fatigue (Central Fatigue)

Answer 28

Muscle able to contract – human unwilling

Question 29

Skeletal Muscle Fiber Types

Answer 29

Slow Twitch | Fast Twitch

Question 30

Slow Twitch

Answer 30

Type I, Oxidative

Question 31

Fast Twitch

Answer 31

Type IIa, Oxidative | Type IIb, Glycolytic

Question 32

Smooth Muscle

Answer 32

Lack Striations, Relatively Small, “Spindle Shaped”,

Question 33

actin, myosin, dense bodies, caveolae

Answer 33

Actin – Lacks troponin Myosin – Longer than Skeletal Muscle myosin Dense Bodies – analogous to Z-lines Caveolae – T-tubule Like???

Question 34

Smooth Muscle Contraction

Answer 34

Ca2+ dependent mechanism – but very | different than skeletal muscle.

Question 35

What regulates contraction

Answer 35

Myosin (Light Chain)

Question 36

EC Smooth

Answer 36

Increased intracellular calcium, Ca2+ binds to calmodulin, Ca2+ - Calmodulin complex activates myosin (light chain) kinase, MLCK phosphorylates myosin, Cross-bridge attachment and cycling occur

Question 37

Myogenic contraction

Answer 37

Muscle is able to generate contraction on it’s own and Single-unit

Question 38

Neurogenic contraction

Answer 38

Nervous input is needed to initiate contractions, For smooth muscle it is ANS innervation, Multi-unit

Question 39

Where are Multi-unit Smooth Muscles found

Answer 39

Ciliary muscles, Iris, Large Blood Vessels, Bronchioles

Question 40

Multi-unit Smooth Muscle

Answer 40

Cells are electrically isolated Varicosities on post-ganglionic neuron near cells

Question 41

Where are Single-unit Smooth Muscle found

Answer 41

Everywhere else – gut, the lining of glands and | hollow organs, uterus...

Question 42

Single-unit Smooth Muscle

Answer 42

Cells are electrically linked, | Pacemaker Potentials, Slow Wave Potentials

Question 43

Slow-wave potentials

Answer 43

undulating changes in the resting membrane potential in gastrointestinal smooth muscle responsible for triggering an action potential.

Question 44

Single-unit Smooth Muscle Tone

Answer 44

Helps keep the shape of organs, Tonic vs. Phasic, enough Ca2+ in the cytosol to maintain some cross-bridge attachment

Question 45

Single-Unit Rate of Contraction

Answer 45

Regulated by ANS

Question 46

How long are smooth muscle contractions

Answer 46

Up to 3 sec