Chapter 7 Muscular System

Question 1

Functions of skeletal muscle

Answer 1

• Move the skeleton
• Maintain posture and body position
• Support soft tissues
• Guard entrances and exits
• Maintain body temperature

Question 2

Tissues in Skeletal muscle

Answer 2

• Skeletal muscle tissue
• Connective tissue proper: tendons and ensheathments
• Smooth muscle tissue
• Epithelium
• Nervous tissue
• Blood

Question 3

Myofibrils

Answer 3

Actin and myosin are arranged in long fibers.

- these do the contraction, and there are lots of them in each muscle fiber

Question 4

T Tubules

Answer 4

• Surround the myofibrils
• are transverse passageways that run the length of the fiber
• carry information across the cell so the whole fiber contracts together.
• talks to the sarcoplasmic reticulum

Question 5

Sarcoplasmic reticulum

Answer 5

stores lots of calcium ions, which when released start a contraction

Question 6

Fascicles

Answer 6

-Bundles of skeletal Muscle fibers surrounded or enclosed with endomysium connective tissue.

Question 7

Endomysium

Answer 7

• part of a skeletal muscle
• surrounds/encloses fascicles
• help repair damaged tissue

Question 8

perimysium

Answer 8

Gaps around various fascicles are filled with perimysium

- divides muscles into compartments between the fascicles

Question 9

Epimysium

Answer 9

Collagen sheath/ barrier or membrane of the muscle

Question 10

Relation between endomysium, perimysium, and epimysium is. . .

Answer 10

The collagen fibers of all 3 connective tissue layers connect at the ends of the muscle to form one of tow structures:

• Tendon
• Aponeurosis

Question 11

Tendon

Answer 11

Bundle of collagen (dense Regular connective tissue) hooking muscle to bone

Question 12

Aponeurosis

Answer 12

Broad sheet of collagen fibers connecting a muscle to the next muscle

Question 13

sarcomere

Answer 13

• is the repeating unit that makes up the myofilaments of the myofibrils.
• These are why skeletal muscle has striations, and are made of thick and thin filaments

Question 14

Dark, Thick filaments are made of

Answer 14

Myosin

Question 15

Light, Thin filaments are made of

Answer 15

actin

Question 16

H band

Answer 16

is the part of the A band that has myosin but not actin in it

Question 17

M line

Answer 17

strands of protein arranged perpendicular to the rest of the sarcomere to keep all of the myosin aligned

Question 18

Z line

Answer 18

The boundary between sarcomeres is made of interconnecting proteins

Question 19

Steps of a muscle contraction

Answer 19

Step 0: Neurotransmitter Ach released
Step 1: Ach binds to muscle
Step 2: Ach changes membrane polarity start an action potential
Step 3: Action potential gets moved down the t tubules until it gets to the sarcoplasmic reticulum (stores calcium)
Step 4: calcium ion gets released into the cytoplasm
Step 5: Calcium binds to troponin which tells tropomyosin to move off of the actin
Step 6:Myosin head binds to actin (cross bridging)
Step 7: Myosin head releases ADP and phosphate to swivel its head around
Step 8: Contraction of myosin head
Step 9: Need Another ATP to release from actin and relax muscle
Step 10: Myosin breaks down new ATP into ADP and phosphate to release from actin and swivel back to it’s starting position
Step 11: resetting or builds towards tetanus

Question 20

Contraction: latent period

Answer 20

the time it takes for the action potential to result in calcium release from the sarcoplasmic reticulum

Question 21

Contraction: Contraction phase

Answer 21

Tension from the contraction of the muscle fibers peaks as myosin binds to actin and pivots

Question 22

Contraction: Relaxation phase

Answer 22

the cell resets. Calcium is pumped back into the sarcoplasmic reticulum, myosin releases, and active sites are covered back up with tropomyosin.

Question 23

Tetanus (physiologic)

Answer 23

Maximum amount of muscle tension

• Most muscles operate at incomplete tetanus where the cell is nearly at peak tension
• complete tetanus (ex: charley horse), where the cell doesn’t have enough time to get rid of cytoplasmic calcium and allow relaxation

Question 24

Tetanus (the disease)

Answer 24

• also called “lockjaw”
• A bacterium enters the nervous system that causes motor neurons to be on full blast
• This leaves your muscle in complete tetanus, so every muscle is contracting at maximum power
• This lasts for week, if you don’t die first.

Question 25

Rigor mortis

Answer 25

- When someone dies their cells quickly run out of ATP. -- This leaves myosin stuck in the swiveled position on an actin, because it needs a new ATP to release and go back to start position. - Cells run out of ATP so the muscle are unable to relax

Question 26

Isotonic contraction

Answer 26

- The muscle keeps constant tension. - This is what happens when you flex your forearm or lift something. - The muscle changes LENGTH, tension stays the same - requires MOVEMENT

Question 27

Isometric contraction

Answer 27

- Tenses enough to maintain the same shape but no more. NO MOVEMENT - length stays the same, tension changes - Sitting up and holding a yoga pose are to examples.

Question 28

origin of a muscle

Answer 28

Point of attachment of a muscle which does not change position when the muscle contracts

Question 29

insertion of a muscle

Answer 29

- part that is being pulled toward the muscle

Question 30

Angle of the joint gets smaller

Answer 30

Flexion

Question 31

Angle of the joint gets bigger

Answer 31

Extension

Question 32

movement in a circle

Answer 32

rotation

Question 33

raising movement

Answer 33

elevation

Question 34

lowering movement

Answer 34

depression

Question 35

appendage moving away form the midline

Answer 35

Abduction

Question 36

appendage moving towards the midline

Answer 36

adduction

Question 37

protraction

Answer 37

moving anteriorly

Question 38

retraction

Answer 38

moving posteriorly

Question 39

tensors

Answer 39

muscles whose goal is to tense something up

Question 40

Agonist

Answer 40

prime mover whose contraction is chiefly responsible for movement

Question 41

antagonist

Answer 41

the muscle that would pull in the opposite direction

Question 42

Synergist

Answer 42

Help the agonist do it's job

Question 43

List the two main groups of muscles and their sub groups (7)

Answer 43

``` Axial Muscles - Head and neck - spine - trunk and pelvic floor Appendicular muscles - shoulders - upper limbs - pelvic girdle - lower limbs ```

Question 44

Muscle fatigue definition and two types

Answer 44

- When the muscle can't perform at the required level despite continued stimulation - Endurance fatigue - Burst fatigue

Question 45

Endurance fatigue

Answer 45

- When muscles break down all of the energy resources they have and don't have anything else to break down - occurs in marathoners and endurance athletes

Question 46

Burst fatigue

Answer 46

The muscle is used so hard that glycolysis happens creating lots of lactic acid which changes the pH so quickly that the muscle can't do it's job. - occurs in sprinters