Muscular System

Question 1

characteristics of skeletal muscle

Answer 1

• long, cylindrical + multi-nucleated
• voluntary movement
• striated
• contraction = heat released

fibers > fascicles > muscle

Question 2

connective tissue: fascia

Answer 2

• encloses groups of muscles

epimysium: surrounds muscle
perimysium: wraps fascicles
endomysium: wraps each muscle fiber

Question 3

connective tissue: tendons

Answer 3

• attaches muscle to bone

- extensions of fascia coverings (epimysium, perimysium, endomysium)

Question 4

connective tissue: aponeurosis

Answer 4

• sheet like tendon

- encloses muscle to CT

Question 5

muscle fibers consist of…

Answer 5

sarcolemma
T-tubules
sarcoplasm
sarcoplasmic reticulum

Question 6

fibers: sarcolemma

Answer 6

specialized muscle cell plasma membrane

Question 7

fibers: T-tubules

Answer 7

continuation of sarcolemma deep in muscle fibers

Question 8

fibers: sarcoplasm

Answer 8

cytoplasm of muscle fibers

Question 9

fibers: sarcoplasmic reticulum

Answer 9

• smooth ER with terminal cisternae

- triads are T-tubules with 2 terminal cisternae

Question 10

myofibril characteristics

Answer 10

• organelles that form muscle fibers
• made of bundles of myofilaments
• formed by attached sarcomeres end to end
• consists of thin and thick myofibril

Question 11

thin myofibrils composed of…

Answer 11

1) actin: muscle contractions
2) tropomyosin: breaks binding sites until contraction
3) troponin: binds to calcium during contraction

Question 12

thick myofibrils are composed of…

Answer 12

• myosin: contains rod like tail + globular heads
• globular heads bind on actin
• titin: protein connecting globular heads to Z band

Question 13

characteristics of sarcomere

Answer 13

• myofibrils organized in groups on myofilaments
• dark + light bands (striated appearance)

dark: overlap
light: no overlap

Question 14

sarcomere consist of…

Answer 14

1) A bands
2) H band
3) I band
4) Z disk
5) M line
6) T tubules

Question 15

causes of movement

Answer 15

• muscles pulling on bone when contracting (origin & insertion)
• using group actin: (agonist, antagonist, synergist)
  **agonist: main muscle
  antagonist: oppose against
  synergist: extra force by preventing undesirable
  effects
• lever systems: bone + muscle interact at joint
• *lever: bone
  joint: fulcrum
  effort: contraction against

Question 16

naming: location

Answer 16

• tibialis anterior

- tibialis posterior

Question 17

naming: relative size

Answer 17

• maximus
• medius
• minumus

Question 18

naming: direction of muscle fibers

Answer 18

• rectus: straight
• transversus: 90 angle
• oblique: not 90 angle

Question 19

naming: num. of origins

Answer 19

• biceps brachii > 2 points on scapula
• triceps brachii > 3 points on scapula + humerus
• quadriceps femoris > 4 points on ilium + fermur

Question 20

naming: shape of muscle

Answer 20

• deltoid > triangular shape

- trapezius > trapezoid shape

Question 21

naming: action

Answer 21

• flexors: decrease angle b/w bones
• extensors: increase angle b/w bones
• abductors: move limb away from midline
• adductors: move limb toward midline

Question 22

naming: origin + insertion

Answer 22

origin: fixed point (does not move during contraction)
insertion: moving point

ex:
sternocleidomastoid
- origin: sternum + clavicle
- insertion: mastoid process of temporal bone