Physiology of Muscle - 2

Question 1

Actions of muscle

Answer 1

Contraction or shorting of muscle fibers, convert chemical energy onto mechanical energy

Question 2

Relaxation

Answer 2

Passive process of a muscle contraction

Question 3

Structure of skeletal muscle

Answer 3

Bundles or sheets of tissue (fascia), fascia composed of many fibers, individual fibers composed of myofibrils, myofibrils are made of up end to end sarcomeres, sarcomers - the smallest repetitive subunit of contractile unit, sarcomeres are composed of thin and thick filaments

Question 4

Thin filaments

Answer 4

Actin

Question 5

Thick filaments

Answer 5

Myosin

Question 6

Largest to smallest

Answer 6

Muscle, fascia, fibers, myofibrils, sarcomeres, filaments, thin actin / thick myosin

Question 7

Myofibrils

Answer 7

Specialized contractile organelle that can constitute up to 90% the volume of muscle fiber, total volume in a fiber dictates potential force

Question 8

Sarcomeres

Answer 8

Functional unit of muscle, smallest component of muscle, give the striated appearance

Question 9

Thin filaments three proteins

Answer 9

Actin, tropmyosin, tropnin

Question 10

Actin proteins

Answer 10

Connected end to end into two long thin filaments, twisted to create double helical form, binding site for myosin

Question 11

Tropomyosin

Answer 11

Thread like proteins that lie end to end, two polypeptide chain, positioned along actin filaments to facilitate the binding of the myosin cross bridge for contraction to occur

Question 12

Troponin

Answer 12

Protein complex that consists three polypeptide units

Question 13

Three troponin units

Answer 13

T, I, C

Question 14

Troponin T

Answer 14

Binds tightly to tropmyosin

Question 15

Troponin I

Answer 15

Binds tightly to actin, inhibiting the actin/myosin interaction durning the relaxed state

Question 16

Troponin C

Answer 16

Binds to Ca to expose the myosin binding site on the actin molecule, initiating muscle contraction

Question 17

Myosin

Answer 17

Make up large thick filaments of the sarcomere, consitis of hundreds of proteins in a specific arrangement, Tesoro heavy chains and two light chains , composed of two identical subunits, both shaped like a golf club with heads on opposite ends

Question 18

Myosin head

Answer 18

Two globular heads projected at one end, represents binding site to actin during contraction, each head has two binding sites

Question 19

Two types of binding sites

Answer 19

Actin binding site, ATPase binding site

Question 20

Actin binding site

Answer 20

Binds the globular head to the actin molecule

Question 21

ATPase binding site

Answer 21

Bound ATP is hydrolyzed, yielding energy for contraction

Question 22

Sarcoplasmic Reticulum

Answer 22

Supplies Ca needed for contractions, interconnected tables surrounding each myofibrils like sleeve, end of each expands called lateral sacs

Question 23

Transverse tubules

Answer 23

Finger like invaginations of the sarcolemma, run perpendicular from surface, transferring actin potential, releases Ca to bind with troponin C

Question 24

Steps of contractions

Answer 24

Action potential is sent, causes nerve ending to release ACH, binds to receptor, causes action to be spread, T Tubules transfer actin uniformly, spread of actin to the SR causes immediate release of Ca, Ca binds to Troponin C, ATP cleaved to yield energy for contractions, causes shortlist of muscle

Question 25

Steps for relaxation

Answer 25

Ca is pumped back in SR, Ca is released from Troponin C, breakdown of myosin/actin linkage, filaments expand back to relaxed state

Question 26

What are the 5 lines and bands of sacromere

Answer 26

I-band, A-band, Z-line, M-line, H-zone

Question 27

I-band

Answer 27

Acting filaments, light bands

Question 28

A-band

Answer 28

Myosin filaments, dark bands

Question 29

Z-line

Answer 29

Defines the outer edges of the sarcomere

Question 30

M-line

Answer 30

Cross connections of myosin filaments that hold myosin filaments

Question 31

H-zone

Answer 31

Short section where actin does not overlap myosin filaments

Question 32

Two type of muscle contraction

Answer 32

Isometric, isotonic

Question 33

Isometric contractions

Answer 33

Muscle re sins the same, length when held stationary against equal resistance or tension

Question 34

Isotonic contractions

Answer 34

Tension in the muscle stays the same but the length changes

Question 35

Types of isotonic contractions

Answer 35

Concentratic, eccentric

Question 36

Concentric contractions

Answer 36

Common form, where the force generated by the muscle moves a bone or segment by shortening

Question 37

Eccentric contractions

Answer 37

The force generated by the muscle is nit sufficient and the external force (or gravity) causes the fibers to lengthen

Question 38

Types of smooth muscle

Answer 38

Single unit/ unitary, multi-unit

Question 39

Single- unit

Answer 39

Hundreds of millions fibers the contraction together, make up 99% of smooth muscle, fibers are joined with gap junctions

Question 40

Gap junctions

Answer 40

Transmit action potential from fiber to fiber

Question 41

Multi-unit

Answer 41

Consist of distinct single fibers, gap joints are not prevalent, each fiber operates independently,

Question 42

Smooth muscle contractions — than skeletal muscle

Answer 42

Slower

Question 43

How much more force does smooth muscle generate compared to skeletal muscle

Answer 43

4-6x greater