Exam 2: Myology

Question 1

Myology

Answer 1

-Study of muscles

Question 2

Functions of skeletal muscle tissue

Answer 2

• Body movement
• Maintenance of posture: muscle tone (continual contraction) keeps body from collapsing/falling
• Temperature regulation: heat produced when muscles contract
• Storage and movement of materials: sphincters (circular muscles around openings) open and close
• Support: helps hold organs in place ex: abdominal and pelvic floor muscles

Question 3

Gross Anatomy

Answer 3

• made up of muscle fibers=muscle cells
• each skeletal muscle is an organ
• many skeletal muscles work in groups

Question 4

Tendons/Aponeuroses

Answer 4

• tendons attach many skeletal muscles to bones (dense regualr CT)
• aponeuroses: flattened sheetlike tendon

Question 5

Endomysium

Answer 5

-surrounds muscle fiber

Question 6

Fasicles

Answer 6

-groups of muscle fibers

Question 7

Perimysium

Answer 7

-surrounds fasicles

Question 8

Epimysium

Answer 8

-surround sentire muscle

Question 9

Deep Fascia

Answer 9

-surrounds all the CT wrappings

Question 10

Superficial Fascia

Answer 10

-subcutanious layer is superficial to deep fascia

Question 11

Sarcolemma

Answer 11

-muscle cell membrane

Question 12

Sarcoplasm

Answer 12

-cytoplasm of skeletal fibers

Question 13

Internal characterists of muscle cell (sarcoplasmic reticulum)

Answer 13

• has organelles like lysosomes, ribosomes, and ER called sarcoplasmic reticulm
• SR function: store calcuim ions Ca²⁺ and releases them when muscle contracts

Question 14

Transverse Tubules (T-tubules)

Answer 14

-conduct nerve impulses quickly from sarcolema through muscle fiber

Question 15

Compositon of Muscle Fibers

Answer 15

• mainly made of myofibrils
• run length of muscle-as long as muscle fiber
• no nuclear or cellular wrapping

Question 16

Myofilaments

Answer 16

• compose myofibrils
• many needed to run length of muscle
• protein filaments
• each thick myofilament surrounded by 6 thin myofilaments
• arrangement of thick and thin filaments gives muscle its striations

Question 17

Myosin

Answer 17

• thick myofilaments
• fixed length

Question 18

Actin

Answer 18

-thin myofilaments

Question 19

I Bands

Answer 19

• light bands (I-LIGHT)
• thin myofilaments only

Question 20

A Bands

Answer 20

• dark bands (A=DARK)
• overlapping thick and thin myofilaments

Question 21

Z disc (Z Line)

Answer 21

• dark structure in the middle of an I band
• thick myofilaments only

Question 22

H Zone (H Band)

Answer 22

-a lighter central region in the middle of an A band

Question 23

M Line

Answer 23

• dark line in the middle of H zone
• thick myofilaments attach here

Question 24

Sarcomere

Answer 24

• run from Z disc to Z disc
• functional contractile unit
• many along length of muscle fiber
• shorten and narrow when muscle contracts

Question 25

Sliding Filament Model of Contraction

Answer 25

When Muscle Contracts:

• thick and thin myofilaments slide over one another
• length of each sarcomere shortens and narrows, muscle contracts
• H zones narrow and I bands narrow

**Z disc, M line, A band, thick and thin myofilaments stay the same size (do not shorten or narrow)