Muscles

Question 1

Skeletal muscle function

Answer 1

Movement, support, heat production

Question 2

Muscle components

Answer 2

Myofilament - muscle fiber - fascicle - muscle

Question 3

Outer surface of muscle

Answer 3

Endomysium, perimysium, epimysium

Question 4

Muscle fiber characteristics

Answer 4

Multinucleated, post-mitotic

Question 5

Actin

Answer 5

Associated with tropomyosin and troponin

Question 6

Troponin

Answer 6

A - actin
C - calcium
T - tropomyosin

Question 7

Tropomyosin

Answer 7

Block myosin binding site on actin

Question 8

Myosin

Answer 8

Motor, 2 heads bind to actin & ATP

Question 9

Titin

Answer 9

Spring, maintains myosin & sarcomere

Question 10

Nebulin

Answer 10

Maintains actin

Question 11

Desmin

Answer 11

Anchors to ECM

Question 12

Dystrophin

Answer 12

Packages myofibrils

Question 13

Transmission of force

Answer 13

Longitudinal @ myotendinous junctions
Lateral @ network of muscle fibers

Question 14

Defect in dystrophin

Answer 14

Duchenne’s muscular dystrophy

Question 15

Sliding filament moodel

Answer 15

Sarcomere shortens
Filaments slide on each other but don’t shorten

Question 16

Cross bridge cycling initiation

Answer 16

@ rest, cb energized by ATP going to ADP + Pi = strained
Ca enters and binds troponin, tropomyosin moved from actin

Question 17

Cross bridge cycling steps

Answer 17

1. cross bridge attaches to actin
2. power stroke, Pi released, actin moves, ADP released
   rigor - myosin bound to actin
3. new ATP binds myosin, myosin released actin
4. reenergized when ATP splits

Question 18

Termination of cross bridge cycling

Answer 18

No action potential, no calcium released, actin is blockede

Question 19

Neuromuscular junction

Answer 19

Muscle fiber innervated by 1 motor neuron
ACh released

Question 20

Recruitment

Answer 20

More motor units, more force

Question 21

Propogation

Answer 21

1. Action potential depolarizes membrane
2. Calcium channels open and calcium enters
3. Ca activated ACh vesicles
4. ACh released and binds to nicotinic ACh-R @ motor end plated
5. Sodium enters causing EPP
6. Depolarization and action potential
7. Action potential propagates down membrane, into T-tubules
8. DHP-R in T-tubules activated
9. RyR activated
10. More calcium release and cross bridge cycling begins

Question 22

Excitation-contraction coupling

Answer 22

Calcium is essential
DHP-R sense depolarization, activated RyR, calcium released from SR

Question 23

Tension & Load

Answer 23

tension moves load

Question 24

Isotonic contraction

Answer 24

Change in muscle length, can be eccentric or concentric

Question 25

Concentric contraction

Answer 25

Muscle shortens, force > load

Question 26

Eccentric contraction

Answer 26

Muscle lengthens, force < load Can disrupt sarcomere

Question 27

Isometric contraction

Answer 27

No change in muscle length

Question 28

Muscle twitch

Answer 28

1 action potential, latency between act pot and twitch

Question 29

Contraction time

Answer 29

Depends on fiber type

Question 30

Heavier load

Answer 30

Increased latency, decreased velocity, duration and distance

Question 31

Summation

Answer 31

Successive action potential

Question 32

Unfused tetanus

Answer 32

Oscillate between partial relaxation and contraction

Question 33

Fused tetanus

Answer 33

Maximum tensions

Question 34

Power

Answer 34

load x velocity

Question 35

Muscle metabolism

Answer 35

Depends on ATP production

Question 36

Formation of ATP

Answer 36

Phosphorylation of ADP by creatinine Phosphorylation of glycolytic pathway Oxidative phosphorylation

Question 37

Glycolytic

Answer 37

Fast, inefficient Anerobic

Question 38

Oxidative phosphorylation

Answer 38

Slow, efficient Aerobic

Question 39

Fast glycolytic fibers (2B)

Answer 39

Fatigue quick, larger, stronger

Question 40

Fast oxidative fibers (2A)

Answer 40

Intermediate

Question 41

Slow oxidative (1)

Answer 41

Don't fatigue quick, smaller, weaker

Question 42

Muscle fatigue

Answer 42

Decreased tension and velocity

Question 43

Excitation-contraction coupling failure

Answer 43

No depolarization

Question 44

Lactic acid build up

Answer 44

Excess H+, inhibits Ca-ATPase

Question 45

Inhibition of cross bridge cycling

Answer 45

No Pi

Question 46

Central command fatigue

Answer 46

Brain related i.e. motivation

Question 47

Whole muscle contraction

Answer 47

Depends on fibers (type and #), action potential frequency, length, diameter, fatigue, motor units

Question 48

One motor unit

Answer 48

ALWAYS same types of fibers

Question 49

Slow motor unit

Answer 49

Long twitch, lo force and lo fatigue Slow oxidative, recruited first Preserved for postural

Question 50

Fast motor unit

Answer 50

Short twitch, hi force, hi fatigue Fast glycolytic

Question 51

Strength training

Answer 51

Hypertrophy, increased force, more sarcomeres in parallel

Question 52

Endurance training

Answer 52

Little hypertrophy

Question 53

Atrophy

Answer 53

Decreased diameter, decreased sarcomeres Fast fibers lost first

Question 54

Myogenesis

Answer 54

1. Induction 2. Migration 3. Aggregation 4. Proliferation 5. Differentiation

Question 55

Repair

Answer 55

Satellite cells divide asymmetrically

Question 56

Myostatin

Answer 56

Knockout leads to early hypertrophy

Question 57

Types of atrophy

Answer 57

Disuse Denervation Microgravity

Question 58

Aging

Answer 58

Decreased motor units and reinnervation

Question 59

Smooth muscle characteristics

Answer 59

Unstriated, spindle cell, one nucleus, involuntary No sarcomeres No troponin or tropomyosin

Question 60

Smooth muscle structure

Answer 60

Anchored to plasma membrane, connected by adherence junctions

Question 61

Smooth muscle signaling

Answer 61

Travels thru gap junctions, slow ATP use, no fatigue

Question 62

Smooth muscle contraction

Answer 62

Myosin light chain kinase activates and phosphorylates myosin Use caveolae Extracellular calcium and SR calcium Calcium plays active role

Question 63

Latch state

Answer 63

Continuous tension in smooth muscle

Question 64

Basal state

Answer 64

Smooth muscle tone