Exam 2: Muscle

Question 1

Myocyte

Answer 1

muscle cell = myofiber = muscle fiber

Question 2

Myofilaments

Answer 2

filaments in muscle cells

Question 3

Sarcoplasm

Answer 3

cytoplasm of muscle cells

Question 4

What are muscle cells specialized for?

Answer 4

forceful contraction

Question 5

What is muscle derived from? (embryonic tissue)

Answer 5

mesoderm

Question 6

3 types of muscle

Answer 6

smooth
skeletal
cardiac

Question 7

Which type of muscle is not striated?

Answer 7

smooth

Question 8

Smooth muscle characteristics

Answer 8

central nuclei
long/tapered ends (for contraction)
innervated by ANS (involuntary contraction)

Question 9

What kind of tissue is smooth muscle surrounded by?

Answer 9

Reticular fibers in loose connective tissue w/ myelinated axons (to transmit contractions)

Question 10

Fusiform / Dense Bodies

Answer 10

attachment points for actin in smooth muscle
coil/contract cells

Question 11

What structures allow the contraction mechanism of muscle?

Answer 11

actin & myosin

Question 12

What shape does smooth muscle cell nuclei take during contraction?

Answer 12

elongated –> spiral/coil

Question 13

Caveolae

Answer 13

invaginations of plasma membrane in smooth muscle

involved in Ca2+ entry/exit during contraction

Question 14

Smooth muscle contraction

Answer 14

Ca2+ binds to calmodulin
Activates MLCK –> phosphorylates myosin –> cleave ATP = contraction
not rapid | sustained, tonic contraction of organs

Question 15

Two types of smooth muscle contraction

Answer 15

unitary/visceral
multiunit

Question 16

Unitary/visceral contraction

Answer 16

smooth muscle contraction
peristaltic waves trigger other cells via gap junctions

Question 17

Multiunit contraction

Answer 17

fine control (ex. iris)
sheets of cells contract at same time because all innervated individually (not gap junctions)

Question 18

Skeletal muscle characteristics

Answer 18

striated
multi-nuclei at periphery
reticular fibers important for contraction

Question 19

Cardiac muscle characteristics

Answer 19

striated
1 nuclei per cell at center | rectangular nuclei
branches | intercalated disks
HIGHLY vascular

Question 20

Myofibrils

Answer 20

columns of sarcomeres

Question 21

Explain the mechanical disadvantage of contraction in skeletal muscle

Answer 21

power traded for leverage & speed

Question 22

Desmin

Answer 22

intermediate filament of skeletal muscle
keeps sarcomeres in register & maintain structural integrity of myofibrils

Question 23

alpha-actinin

Answer 23

anchors actin filaments at Z-line in skeletal muscle & dense bodies of smooth

Question 24

Titin

Answer 24

protein that anchors and keeps sarcomere from over-extending (elastic!)

Question 25

Desminopathies

Answer 25

mutated desmin breaks up sarcomeres which leads to separation cardiomyopathy is one result of desminopathy

Question 26

I band

Answer 26

actin filaments not yet overlapping with myosin transected by Z line

Question 27

T tubule

Answer 27

invaginations of muscle cell which increases contraction/Ca2+ sequestering

Question 28

Triad in skeletal muscle

Answer 28

T tubule + SR on both sides allows for more efficient contraction

Question 29

Contraction of Skeletal Muscle

Answer 29

Ca2+ binds to troponin (conform change) | moves tropomyosin so myosin can bind to actin | myosin flexes & actin moves along it as long as ATP / Ca2+ bound

Question 30

Smooth muscle contraction controlled by activation of...

Answer 30

myosin

Question 31

Striated muscle contraction controlled by access to...

Answer 31

actin

Question 32

Type I skeletal muscle fiber

Answer 32

Slow, oxidative Long, sustained contraction

Question 33

Type IIa skeletal muscle fiber type

Answer 33

oxidative phosphorylation for relatively fast contraction

Question 34

Type IIb skeletal muscle fiber type

Answer 34

Rapid contraction, susceptible to fatigue

Question 35

Epimysium

Answer 35

DICCT sheath around whole muscle

Question 36

Perimysium

Answer 36

loose CT around fascicles

Question 37

Endomysium

Answer 37

connective tissue of reticular fibers around each myocyte highly vascular

Question 38

Intercalated Disks

Answer 38

cardiac muscle only junctions that transmit force of contraction between cells

Question 39

Parts of Intercalated disks

Answer 39

transverse portion lateral portion

Question 40

Transverse portion of intercalated disk

Answer 40

transmits force of contraction from one cardiac cell to another

Question 41

Lateral portion of intercalated disk

Answer 41

communicating junctions from one cell to another (gap junctions) to transmit trigger for contraction

Question 42

What structures are within intercalated disk?

Answer 42

Fascia adherens Macula adherens (desmosomes) Gap Junctions

Question 43

Fascia adherens

Answer 43

anchors actin filaments in intercalated disk

Question 44

Diad

Answer 44

structure in cardiac muscle made of T tubule, SR on one side Z line around it

Question 45

How does smooth muscle grow in response to physiological demand?

Answer 45

Hypertrophy AND hyperplasia

Question 46

Hypertrophy

Answer 46

individual cells get larger

Question 47

Hyperplasia

Answer 47

division of cells / increase in reproduction rate

Question 48

How does smooth muscle repair after injury?

Answer 48

cell replacement by connective tissue/scar tissue (DICCT) some new myocytes from pericytes

Question 49

How does skeletal muscle grow in response to physiological demand?

Answer 49

Hypertrophy only

Question 50

How does skeletal mucsle repair after injury?

Answer 50

substantial cell replacement new myofibers from satellite cells

Question 51

How does cardiac muscle grow in response to physiological demand?

Answer 51

Hypertrophy only

Question 52

I band

Answer 52

light band made of actin filaments in skeletal muscle

Question 53

A band

Answer 53

dark band containing myosin filaments in skeletal muscle

Question 54

Z disk/line

Answer 54

within I band where actin filaments attach in skeletal muscle

Question 55

H band

Answer 55

light zone at center of A band, gap between actin filaments in skeletal muscle

Question 56

M line

Answer 56

fine threads connecting central part of myosin filaments in skeletal muscle