Skeletal Muscle

Question 1

where is visceral/smooth muscle found?

Answer 1

• arterial wall
• wall of intestine
• airways of lungs

Question 2

where is voluntary/skeletal muscle found?

Answer 2

• skeletal muscles
• larynx
• diaphragm

Question 3

where is cardiac muscle found?

Answer 3

• heart

* base of great vessels

Question 4

name 3 other contractile cells

Answer 4

• pericytes
• myo-fibroblasts
• myo-epithelial cells

Question 5

what are the layers of connective tissue in skeletal muscle?

Answer 5

• endomycium
• perimycium
• epimycium

Question 6

what does skeletal muscle start as in embryonic life?

Answer 6

myoblasts

Question 7

describe the embryonic development of skeletal muscle

Answer 7

• individual precursor myoblasts fuse together to form muscle fibres
• a single muscle fibre will form from the fusion of hundreds of myoblasts
  ⇒ individual muscle fibres are multinucleated

Question 8

where are nuclei in skeletal muscles?

Answer 8

pressed towards the cell membrane

• unlike in smooth & cardiac muscle

Question 9

what are the components of skeletal muscle?

Answer 9

• sarcolemma
• multiple nuclei
• contractile proteins
• mitochondria
• sarcoplasmic reticulum
• glycogen-rich sarcoplasm
• T-tubular system

Question 10

what is the t-tubular system?

Answer 10

specialised network of tubules that convey calcium into the cytoplasm of the cell

Question 11

describe the histological appearance of skeletal muscle

Answer 11

• elongated fibres
• striated cytoplasm
• multinucleate
  
  • nuclei at edges
• non-branching

Question 12

why is skeletal muscle striated?

Answer 12

myofibrils in register

Question 13

what is a myofibril

Answer 13

arrangement of contractile proteins within a muscle fibre

Question 14

how many sarcomeres does each myofibril contain?

Answer 14

multiple

Question 15

what is a sarcomere?

Answer 15

functional units of the myofibril

- material between two Z lines

Question 16

what does each sarcomere contain?

Answer 16

• actin
• myosin
• accessory proteins

Question 17

what is the appearance of actin?

Answer 17

• thin

- light

Question 18

what is the appearance of myosin?

Answer 18

• thick

- dark

Question 19

what does actin give rise to?

Answer 19

isotropic (I) bands

Question 20

what does myosin give rise to?

Answer 20

anisotropic (A) bands

Question 21

what are the types of skeletal muscle fibre?

Answer 21

• type 1

- type 2

Question 22

what are the similarities between type 1 and type 2 skeletal muscle fibres?

Answer 22

rich in fibrillar ATPase

Question 23

how do type 1 skeletal muscle fibres obtain energy?

Answer 23

oxidative phosphorylation

Question 24

where are type 1 skeletal muscle fibres found?

Answer 24

muscles that maintain posture

Question 25

what are slow twitch muscle fibres?

Answer 25

type 1 | - fatigue resistant

Question 26

what are fast twitch muscle fibres?

Answer 26

type 2

Question 27

how do type 2a muscle fibres obtain energy?

Answer 27

oxidative & glycolytic metabolism | - some fatigue resistance

Question 28

how do type 2b muscle fibres obtain energy?

Answer 28

glycolysis | - fatigue sensitive

Question 29

how would you distinguish the types of skeletal muscle fibre histologically?

Answer 29

histochemical stain looking for ATPase

Question 30

what is the function of muscle spindles?

Answer 30

Detect stretch and tension

Question 31

describe the structure of muscle spindles

Answer 31

- fibrocollagenous capsule | - intrafusal muscle fibres wrapped around gamma efferent nerve fibres

Question 32

where is the endomysium?

Answer 32

between individual muscle fibres

Question 33

what is the function of the perimysium?

Answer 33

binds groups of muscles together to form fascicles

Question 34

what is the function of the epimysium?

Answer 34

binds fascicles together

Question 35

what is the function fo sharpey's fibres?

Answer 35

connect muscle to bone (and penetrate bone)

Question 36

describe the structure of sharpey's fibres

Answer 36

bundles of collagen linking epimysium to periosteum

Question 37

what is the function of tendons?

Answer 37

connect muscle to bone

Question 38

describe the structure of tendons

Answer 38

- parallel bundles of collagen | - intervening fibroblasts