Muscle Tissue, Case study 5

Question 1

duchenne’s muscular dystrophy

Answer 1

caused by a genetic mutation, resulting in the absence or insufficient amounts of the dystrophin protein to be present in the sarcomere
- X chromosome linked bc more common in males (ie if they have the gene, they have DMD bc they can’t pass it on unless they have it)

Question 2

lordosis

Answer 2

excessive convex curvature of the lumbar vertebrae

Question 3

kyphosis

Answer 3

excessive concave curvature in spine of cervical, thoracic and sacral regions

Question 4

dystrophin

Answer 4

a protein that attaches onto actin filaments and connects them to the sarcolemma

Question 5

how does muscular dystrophy cause muscle weakness?

Answer 5

• tears in muscles from poor structure, then always trying to repair muscles and so they are weak when used bc not enough myosin and actin are present
  OR
• muscle fibers are not connected all the way to the CT surrounding structures (tendons, bone) and so when H band shortens, there is no pull on surrounding tissues

Question 6

skeletal muscles system functions

Answer 6

heat production
body movement
posture maintenance
communication
respiration

Question 7

mnemonic for remembering functions of skeletal muscle

Answer 7

holy == heat prod.
billy's === body movement
puppy == posture
can === communication
run == respiration

Question 8

properties of skeletal muscle

Answer 8

contractility
excitability
extensibility
elasticity

Question 9

contractility

Answer 9

muscles can contract, generating force or tension

Question 10

excitability

Answer 10

muscles can respond to a stimulus by producing action potentials
- they are electrically excitable

Question 11

extensibility

Answer 11

muscle can be stretched beyond its resting length and still be able to contract bc of overlapping proteins

Question 12

elasticity

Answer 12

muscles can recoil to their original resting length after it’s been stretched

Question 13

skeletal muscle cells are (one word)

Answer 13

fibers

Question 14

skeletal muscle cells

Answer 14

• highly organized structure
• long (run length of muscle)
• multinucleated bc they come from myoblasts merged together during embryology
• nuclei loc just below plasma membrane

Question 15

order of layers of CT surrounding muscle tissue

Answer 15

fascia - muscle groups
epimysium - around whole muscle
perimysium - surrounds fascicle
endomysium - loose areolar/reticular CT b/w cells in a fascicle

Question 16

tendon

Answer 16

dense regular CT

- layers of periosteum (dense irregular) become dense regular

Question 17

fascia

Answer 17

surrounds groups of muscle

- dense irregular CT

Question 18

epimysium

Answer 18

dense irregular CT

- surrounds whole muscle

Question 19

fascicle

Answer 19

multiple muscle fibers grouped together

surrounded by perimysium

Question 20

perimysium

Answer 20

surrounds fascicle

Question 21

endomysium

Answer 21

loose areolar/reticular CT b/w muscle fibers

Question 22

myofibril

Answer 22

proteins bundled inside muscle fiber/cell

- run length of muscle fiber and create striped appearance of muscle

Question 23

sarcolemma

Answer 23

muscle cell membrane

Question 24

sarcoplasm

Answer 24

cytoplasm of muscle cell

Question 25

myofilaments

Answer 25

muscle filaments: protein strands inside myofibril

Question 26

each muscle fiber has its own _ and _.

Answer 26

• capillary beds

- branch of a somatic motor neuron

Question 27

how are mitochondria dispersed around a muscle fiber?

Answer 27

they are everywhere bc they are where ATP is being generated

- can acquire more mitochondria through more endurance training

Question 28

myofibrils are surrounded by what

Answer 28

triad

consists of 1 T-tubule with a terminal cistern on either side

Question 29

T-tubule

Answer 29

transverse tubule

• evaginations in the sarcolemma that run around each myofibril
• how AP get to each part of muscle cell
• 2 wrap around each sarcomere

Question 30

sarcoplasmic reticulum

Answer 30

smooth endoplasmic reticulum, wrap around myofibrils to be kind of network like
- store calcium

Question 31

terminal cisterns

Answer 31

one found on either side of T-tubules, makes up a part of the triad

Question 32

z-disk

Answer 32

runs across proteins and helps hold myofibrils together

- forms contractile unit called a sarcomere

Question 33

dystrophin

Answer 33

connects actin filaments on “free” side of z-disk to sarcomere and can also extend to endomysium

Question 34

myoglobin

Answer 34

makes muscles red

- picks up and carries oxygen

Question 35

titin

Answer 35

large coiled protein, gives skeletal muscle its elastic ability
attaches z-disk to m-line

Question 36

what are the types of proteins present in an actin myofilament

Answer 36

actin proteins
tropomyosin
troponin

Question 37

actin protein

Answer 37

ball shaped

lined up and twisted on 2 strands of tropomyosin to make a helix shape

Question 38

tropomyosin

Answer 38

2 long strands of protein that wrap around and cover all myosin-binding sites

Question 39

troponin

Answer 39

3 parts:

• 1 attaches to actin
• 1 attaches to tropomyosin
• 1 binds to calcium when avail from SR; when binds causes troponin to change shape and tropomyosin moves away from binding sites

Question 40

myosin myofilament

Answer 40

myosin protein is composed of 2 protein strands twisted together
- a filament is composed of 300 molecules all stuck together, held at the m-line

Question 41

myosin ATPase

Answer 41

located on myosin head

- ATP allows head to bend upward, grab actin and pull towards m-line