josh musces -

Question 1

what are the three muscle types and list if the are volantary and striated.

Answer 1

skeletal - striated, volantary
smooth - not striated, involantary
cardiac - striated, involantary

Question 2

decribe the flow of wraping of the muscle, begining with the mucle body and finishing at the protein fillaments (skeletal)

Answer 2

muscle body
->connective tissue wraps fascicle
-> groups of fibers
-> sarcolemma wraps muscle fiber
-> groups of myofibril
-> groups of protein filaments

Question 3

what is the cytoplasm of the muscle fibre?

Answer 3

sarcoplasm

Question 4

what is the sarcopasmic reticulum?

Answer 4

Specialized type of smooth ER that regulates the calcium ion concentration in the cytoplasm of skeletal muscle fibre

Question 5

what are the transverse T tubules

Answer 5

The extensions of the cell membrane that penetrate into the centre of skeletal muscle fibres

Question 6

a single sarcomere run from two lines, what are they

Answer 6

from Z line to Z line

Question 7

what are the names of the thick and thin fillament

Answer 7

thick - myosin
thin - actin

Question 8

describe the structure of the myosin

Answer 8

a thich band which have branches of myosin on the sides, these mysoin will bind to the actin fillament and cause contrations of the muscle.

Question 9

describe the structure of the actin

Answer 9

actin is suronded by bands of tropomyosin (reguatory protein which overlaps the binding sites when rested) and troponin (regulatory protein which bind to myosin and actin using reverse binding to calcium.)

Question 10

what are the three types of muscle twitchs and describe their diffrence of fuction

Answer 10

Slow twitch oxidative - Degrades glycogen in the Krebs cycle. This has high mitochondria count and high myoglobin.
Fast twitch oxidative - Degrades glycogen in the Krebs cycle. This has moderatly high mitochondria count and moderate myoglobin. as it can use glycolosis when needed.
Fast twitch glycolytic - Converts glycogen to lactic acid. Does not require oxygen, therefor it has low mitochondria and low myoglobin

Question 11

describe the colour of the meat from the three twich types in muscles

Answer 11

slow oxidative - high myoglobin means it is very dark read, consider rumps and ‘bloody’ meats
fast oxidative - moderate myoglobin means it will have a dark tone, condier thigh and leg meat from chicken
fast glycolic - no myoglobin produces white meat, high in chicken breast

Question 12

desrcibe the histology of the three muslce twitch types

Answer 12

slow oxidative - smallest diameter, which high enzymes activity, areobic
fast oxidative - share characteristic from both
fast glycolic - largest diameter, aneraobic.
the enzyme/ oxidative states will indicate how it will stain.

Question 13

for each type of muscle twitch describe the real uses they have

Answer 13

slow oxidative - endurence based (long distance running), it has a slower fatuige
fast oxidative - mix of long term but still highly rapid action
fast glycolic -high burst of energy, (sprinting) focuses on rapid contractions/ relaxations, has poor fatiuge. short term

Question 14

what are the two catergories of MRFs and they subfamilies

Answer 14

primary - MyoD and MYf5
secondary - myogenin, MRF4

Question 15

what are MRF responsible for

Answer 15

Muscle regulatory factors
- induce commitment of myogenic lineage and myofiber differentiation
- postnatal myogenesis

Question 16

list some growth factors important to muscles

Answer 16

insuin
Myostatin
TGF - Beta
FGF
Hepatocyte grief factor

Question 17

describe insulins role in muscle growth

Answer 17

Central role in development, differentiation & maintenance of skeletal muscle
Produced by liver, myoblasts, satellite cells, myofibres & fibroblasts
its direct effects are:
Increases glucose & AA uptake
Decreased Proteolysis
Increases Protein synthesis

Question 18

describe myostatin effect on muscle growth

Answer 18

Plays a central role in physiological processes as a NEGATIVE regulator of muscle growth
Inhibits myogenic differentiation by inhibiting expression of myogenic transcription factors MyoD & myogenin
Naturally occurring mutation -> muscle hypertrophy “double muscling”

Question 19

describe FGF role in muscle growth

Answer 19

Fey role in early myoblast development
Proliferating myogenic cells, suppresses expression of MRFs, MyoD & myogenin
(if blocked we will have premature differentiation and decreased muscle weight)

Question 20

describe TGF- beta effect on muscle growth

Answer 20

Slows the proliferation of myoblasts & satellite cells
Inhibits expression of MyoD & myogenin

Question 21

describe the effects of hepatocyte growth factor

Answer 21

Autocrine and paracrine effects on myogenic cell lineage
Induces the initial conversion of mesenchymal cells to establish the somitic pool of myogenic precursors
Stimulate activation and early division of satellite cells

Question 22

what growth factor are involved in stem cells determination into myoblasts

Answer 22

HGF, IGF

Question 23

what growth factor transform myoblasts into myotubes. (inorder and labeled)

Answer 23

dermination - HGF
proliferation - TGF-Beta, IGF
differentiation IGF, myogenin/MFR4
fusion: IGF, HGF

Question 24

what growth factors are involved in myotubes formation into myofibers

Answer 24

Fusion and hypertrophy is controled by:
IGF, FGF, HGF

Question 25

what regulative horomones are involved in muscle growth

Answer 25

Steroid and catecholamine derived Beta-agonists

Question 26

what permissive hormones are involved in muscle growth

Answer 26

insulin, thyroid and glucocorticoids

Question 27

what is insulins role and effect on muscle growth

Answer 27

regulate cellular glucose uptake (glycogen deposition). stimulates AA transport, protein synthesis and inhibits protein degrations during tissue growth. post nataly it will have an anabolic effect

Question 28

if there is a defficency in insulin what occurs?

Answer 28

muscle wastage

Question 29

what is thyroid horomes role and effect on muscle growth

Answer 29

muscle sythesis and sketetal muscle regulation. stimulate energy usage, oxidative metabolism and metabolic rate

Question 30

what is adrenal glucocorticoids role and effect on muscle growth

Answer 30

inhibit growth Reduce glucose use by tissues Increases gluconeogenesis Induces hyperglycaemia Increases protein catabolism Inhibit secretion of GH and IGF, slowing growth

Question 31

what happen if thyroid hormone is in excess and deficient

Answer 31

deficient - growth retardation excess - Protein degradation and muscle atrophy

Question 32

what happens if there is a high dosage of adrenal glucocorticoids

Answer 32

muscle atrophy

Question 33

when do most muscle fibres from?

Answer 33

during feotal development

Question 34

postnatal hypertrophy of muscles are controlled by what

Answer 34

satellite cell proliferation

Question 35

where are the muscle satellite cells kept post nataly

Answer 35

found at the basal lamina of mature myofibers, there are very samll amounts

Question 36

what do satellite cells do any how

Answer 36

- muscle regeneration Satellite cells proliferate into myogenic cells that fuse & form new muscle fibres. They have the ability to replicate DNA, divide and fuse with adjacent fibres.

Question 37

describe the proccess of muscle atrophy

Answer 37

when the rate of breakdown is higher than the rate of synthesis. Degradation of muscle protein results in decrease of myofibre cross sectional area Muscle nuclei are also lost during muscle atrophy degration is by: Calpain system Lysosomal system Proteasome pathway

Question 38

where is muscle atrophy the most common

Answer 38

fast glycotic fibers

Question 39

describe the process of muscle hypertrophy

Answer 39

Protein synthesis & degradation constantly occurring Rate of synthesis >> rate of breakdown = increased protein Rate of breakdown >> rate of synthesis = decreased protein Role of intracellular enzymes in maintaining balance between protein degradation & synthesis

Question 40

what is the callipyge gene and how does it effect muscle

Answer 40

Callipyge gene: the presence of this gene in sheep results in skeletal muscle enlargement, most prominent in hindquarters. The callipyge gene results in overexpression of delta-like homologue 1 (Dlk1).

Question 41

what id Dk1 and how does it cause mucle enlargment

Answer 41

Dlk1 is a cell membrane protein which activates pathways for satillite cells in tissues. overexression caused by the callipyge gene means that there will be an abnormal increase of satellite cells differention, increasing muscle mass.

Question 42

what is Nutritional muscular dystrophy

Answer 42

known as white muscle disease / ridgid limb syndrome, the muscle exhibits white or grey areas of degeneration. This is due to the lipid oxidation (free radicals) induced damage to sarcoplasmic reticulum, this means the calcium is not separated anymore. This is caused by a selenium deficiency (Se), possibly combined with vitamin E. Se is crucial for the synthesis of glutathione peroxidase, which protects cells from free radicals.