Lecture 4: Muscle tissue and muscles

Question 1

Isometric contraction

Answer 1

length of muscles does not change

Question 2

Isotonic contraction

Answer 2

length of muscle changes

Question 3

Concentric contraction

Answer 3

muscle gets shorter

Question 4

Eccentric contraction

Answer 4

muscle gets longer

Question 5

How are muscles named

Answer 5

Shape
Origin-insertion
Function
Relative size
Fiber arrangement
Location

Question 6

Fiber arrangements

Answer 6

Straight
Fusiform (spindle)
Unipennate
Bipennate
Multipennate

Question 7

Agonist

Answer 7

Muscle doing the desired action

Question 8

Antagonist

Answer 8

Muscle that opposes the agonist

Question 9

Synergist

Answer 9

Muscle that eliminates unwanted action by the agonist

Question 10

Fixator

Answer 10

Muscle that stabilizes base of attachment of agonist (usually isometrically)

Question 11

Unijoint

Answer 11

Muscle that only crosses one joint

Question 12

Multijoint

Answer 12

Muscle that crosses multiple joints

Question 13

Insufficiency

Answer 13

Inability of a multijoint muscle to contract maximally over all joints crossed simultaneously

Question 14

Active insufficiency

Answer 14

The diminished ability of a muscle to produce or maintain active tension. Involves agonist.

Question 15

Passive insufficiency

Answer 15

Occurs when the inactive antagonist muscle is of insufficient length to allow a force to complete the full range of motion available.

Question 16

Muscles that pass anterior to the axis of a joint

Answer 16

Flexors

Question 17

Muscles that pass posterior to the axis of a joint

Answer 17

Extensors

Question 18

Muscles that pass lateral to the axis of a joint

Answer 18

Abductors

Question 19

Muscles are classified by:

Answer 19

Appearance
Arrangement of Nucleus
Function

Question 20

Muscle appearances

Answer 20

Smooth

Striated

Question 21

Muscle nuclei arrangements

Answer 21

Mononucleated

Multinucleated (Syncytium)

Question 22

Muscle function can be:

Answer 22

Voluntary or involuntary

Question 23

Types of muscle tissue

Answer 23

Skeletal (striated)
Smooth
Cardiac

Question 24

Smooth muscle appearance

Answer 24

Spindle-shaped mononucleated cells, centrally located nuclei

Question 25

Characteristics of cardiac muscle

Answer 25

Consists of chains of individual cells that are striated and mononucleated. Special intercellular junctions called intercalated discs.

Question 26

Skeletal muscle characteristics

Answer 26

Striated, peripheral nuclei, multinucleated, action potentials

Question 27

Origin (Proximal attachment)

Answer 27

Usually proximal, may be fixed with regard to movement

Question 28

Insertion (distal attachment)

Answer 28

Usually distal, usually more movable

Question 29

Tendons attach what

Answer 29

muscles and bone

Question 30

Tendon characteristics

Answer 30

Dense collagenous CT, surrounded by peritendineum, poorly vascularized

Question 31

Aponeuroses

Answer 31

Flat, fan-shaped tendons typically giving rise to other tendons

Question 32

Myofilament

Answer 32

Actin & Myosin organized into cylindrical unit called sarcomeres

Question 33

Myofibril

Answer 33

Chain of sarcomeres

Question 34

Myofiber

Answer 34

Bundle of myofibrils (often referred to as a muscle cell) each fiber formed from many fused myoblasts

Question 35

Fascicle

Answer 35

Bundle of myofibers

Question 36

Varying numbers of fascicles compose:

Answer 36

Muscle

Question 37

Endomysium

Answer 37

Surrounds each muscle fiber/myofiber

Question 38

Perimysium

Answer 38

Surrounds each fascicle

Question 39

Epimysium

Answer 39

Surrounds each muscle, continuous with tendons, attaches to periosteum

Question 40

Connective tissue provides:

Answer 40

physical support and a pathway for nerves and vessels

Question 41

Z-lines

Answer 41

Separate adjacent sarcomeres, composed of Z-actin

Question 42

I-bands

Answer 42

Make up ends of each sarcomere, composed of actin

Question 43

A-bands

Answer 43

Located in middle of sarcomere, composed of actin and myosin

Question 44

T or F: The number of myofibers cannot be increased after birth

Answer 44

True

Question 45

T or F: The number of myofibrils cannot be increased after birth

Answer 45

False, the number can be increased which will increase mass of myofiber and muscle

Question 46

Sarcoplasmic reticulum

Answer 46

Equivialent to ER of most cells

Question 47

T-tubules

Answer 47

Tubular extensions of muscle fiber membrane (sarcolemma) that extend into the cytoplasm (saracoplasm)

Question 48

T-tubule function

Answer 48

Conduct action potential from cell membrane surface to interior

Question 49

Cisternae

Answer 49

Saccular extensions of the sarcoplasmic reticulum that release calcium ions in response to action potential

Question 50

Release of Ca+ ions from cisternae does what

Answer 50

triggers sliding of myosin and actin filaments, resulting in contraction