Muscle Mechanics

Question 1

Myofibrils

Answer 1

-threadlike structures
-lie parallel to eachother

Question 2

Sarcomere

Answer 2

-contractile unit of the muscle
-repeating unit of the myofibril between the stripes

Question 3

Myofilaments

Answer 3

-protein filaments that overlap within the sarcomere

Question 4

Thin filaments

Answer 4

-contain actin, troponin C, and tropomyosin proteins

Question 5

Thick filaments

Answer 5

-contain myosin proteins

Question 6

I band

Answer 6

-region that contains only actin and Z line
-appears as light band

Question 7

A band

Answer 7

-region that contains myosin, as well as overlapping actin, appears as dark band

Question 8

H zone

Answer 8

-region of the A band that contains only myosin and M-line

Question 9

M line

Answer 9

-transverse band that anchors myosin to eachother

Question 10

Z line

Answer 10

-transverse band that anchors actin to eachother

Question 11

Factors affecting muscle force development

Answer 11

-length
-velocity
-physiological cross-sectional area
-muscle geometry
-activation

Question 12

Muscle force length relationship

Answer 12

-there is an optimum sarcomere length for force generation

Question 13

Stretching theory

Answer 13

-stretch induced force enhancement

Question 14

Hill type muscle model

Answer 14

-contractile element
-series elastic element
-parallel elastic element

Question 15

Contractile element (Hill-type muscle model)

Answer 15

-represents forces development via cross-bridge attachments in the sarcomeres

Question 16

Series elastic element

Answer 16

-represents force-deflection properties of tendon

Question 17

Parallel elastic element

Answer 17

-represents force-deflection properties of sarcolemma, epimysium, perimysium, and endomysium

Question 18

Muscle force-velocity relationship

Answer 18

-the greater the shortening velocity of the muscle, the smaller the force that can be produced
-a muscle contracting eccentrically is capable of producing more force than a muscle contracting concentrically

Question 19

Physiological cross-sectional area

Answer 19

-adding sarcomeres in parallel makes a muscle stronger but not faster
-adding sarcomeres in series makes a muscle faster but not stronger

Question 20

Muscle geometry

Answer 20

-pennate muscles have more cross sectional area compared to longitudinal muscles and therefore can generate more force

Question 21

Activation

Answer 21

-electrical stimulation causes muscle to contract (through release of Ca+)

Question 22

Ways to increase activation of a muscle fibre

Answer 22

-increase firing frequency of a given motor unit
-recruit more motor units

Question 23

Hennemans size principle

Answer 23

-motor units are recruited from smallest (slow twitch) to largest (fast twitch)