Muscle Architecture & Contraction Flashcards Preview

PTRS 825 Final Exam > Muscle Architecture & Contraction > Flashcards

Flashcards in Muscle Architecture & Contraction Deck (32)
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1

Epimysium (Fascia)

Surrounds entire muscle

2

Perimysium

Surrounds fasciculi

3

Endomysium

Surround myocytes

4

Sarcolemma

Muscle cell membrane
Underlies endomysium
Contains sarcoplasm, cellular proteins, organelles and myofibrils

5

Transverse Tubules

Invagination of sarcolemma that transmit action potential into interior muscle cell
Closely apposed to SR

6

Sarcoplasmic Reticulum

Membranous sac underlying sarcolemma
Responsible for calcium storage, release and reuptake
Integral to muscle contraction

7

Terminal Cisternae

Store and release calcium

8

Myofibrils

Divided into individual contractile units - sarcomere

9

Myosin

Thick filament

10

Actin

Thin filament
Troponin and tropomyosin located on actin protein

11

Titin/Connectin (Molecular blueprint)

Coordinate assembly of structural/regulator/contractile proteins

12

Titin/Connectin (Molecular spring)

Links z-disk to m-line
Maintains position of actin and myosin

13

Nebulin

Precisely regulates actin length

14

Obscurin

Assembly and organization of SR with myofilaments

15

Myosin - Heavy Chain Polypeptides

Light meromyosin - form molecular backbone
Heavy meromyosin - form globular head (S1) and neck (S2)
Isoforms determined by ATPase activity and contribute to contraction velocity

16

Myosin - Light Chain Polypeptides

Each S1/2 contains essential and regulatory chains
Isoforms fine tune contraction velocity

17

Tropomyosin

Blocks myosin binding sites at rest

18

Troponin

Regulates tropomyosin position

19

Low M-ATPase

Lower max contraction velocity and longer time to peak tension
"Slow twitch"

20

High M-ATPase

Higher max contraction velocity and shorter time to peak tension
"Fast twitch"

21

Type I

Slow oxidative

22

Type IIa

Fast oxidative-glycolytic

23

Type IIb

Fast glycolytic

24

Myosin Isoforms

Genetically determined
Can't override intrinsic qualities (I II, can't do)
Can alter depending on training type (IIa IIb)

25

Myoplasticity

Changes in use/environment generating alterations in structural/enzymatic protein content

26

Gene expression influenced by

Loading conditions
Nutrition
Hormones
Environment
Contractile activity

27

Myoplastic adaptation can occur at level of:

Structure (CSA)
Type
Metabolism
Energy storage
Capillary density
Function

28

Endurance Adaptations

Increased oxidative capacity, mitochondrial density and expression of Type I
Reduced expression of Type IIb fibers (days)
Reduced expression of Type IIa fibers (years)

29

Endurance Adaptions result in

Delayed metabolic acidosis
Increased fatigue resistance and oxygen consumption

30

Resistance Adaptations

Increased CSA and number of nuclei/cell
Reduced mitochondrial density and expression of Type I and IIb fibers
Increased expression of Type IIa