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Three types of muscle
- Smooth - involuntary
- Striated - Involuntary
- Striated - voluntary
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Muscle that makes up arteries, veins, GI tract
Smooth involuntary
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Muscle making up cardiac muscle
Striated involuntary
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Skeletal muscle
striated voluntary
-
true cell of the muscle
muscle fiber
-
muscle bundles contain _____ which contain ______
fibers, microfilaments
-
membrance surrounding the muscle fiber
sarcolemma
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sarcolemma is composed of
proteins and lipids
-
Tubules that form around the circumference of the sarcolemma are called
transverse tubules (t-tubules)
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Motor nerve fibers terminate on the sarcolemma at the
myoneural junction
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raised structures at the myoneural junction are called the
motor end plates
-
cytoplasm of muscle cells is called
sarcoplasm
-
the sarcoplasm is composed of
75 - 80% water, lipids, glycogen, ribosomes, proteins, non-protein nitrogenous compounds, and inorganic constituents
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Located at the periphery of the fiber and beneath the sarcolemma
Number not consistent
Nuclei
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Myofibrils compare to
organelles of a regular cell
-
extend entire length of fiber, composed of myofilaments
myofibrils
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composed of thick and thin filaments
myofilaments
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This gives muscle its striated appearance
where thick and thin filaments overlap forming dark bands
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Proteins in a muscle cell
- Actin
- Myosin
- Tropomyosin
- Tropin
- nebulin
- titin
-
Actin is (thick/thin)
thin
-
Myosin is (thick/thin)
thick
-
actin to myosin ratio
6:1
-
Light band is called the
I band
-
Dark band is called the
A band
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The I band is bisected by a thin dark band called
the Z disk (line)
-
The unit of the myofibril between 2 Z disks is
a sarcomere
-
Saromere contains ___ A band(s) and _____ I band(s)
1, two 1/2
-
____ and ____ are constant
M line and A band
-
____ filaments make up the A band
myosin
-
____ filaments make up the I band
actin
-
6 ___ filaments surround 1 ____ filament
actin, myosin
-
There are only ____ filaments in the H zone
myosin
-
There are only ____ filaments in the I band
actin
-
Actin filaments attach at the
z disk
-
____z filaments attach to one actin filament
four
-
actin and myosin are classified as
contractile
-
troponin and tropomyosin are classified as
regulatory proteins
-
titin and nebulin are classified as
cytoskeletal proteins
-
Actin is composed of _____ and ______ proteins
Globular and Fibrous
-
_______ polymerize to make a helix which is called ________
G-actin, F-actin
-
Tropomyosin has sub units of
troponin
-
Actin is ___% of myofibrillar protein
20
-
Myosin is ___% of myofibrillar protein
45
-
myosin is ____ shaped
rod
-
area that contains the rod portion only and no bands is called
the pseudo H zone
-
This protein functions as a molecular spring and is responsible for passive elasticity. It connects the Z line to the M line
Titin
-
actin-binding protein which is localized to the I band
Nebulin
-
Membranous system of tubules and cisternae
Sarcoplasmic Reticulum
-
site of calcium storage
SR
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run parallel to the myofibril
L-tubules
-
L-tubules converge in the H zone to form the
fenestrated collar
-
L-tubules converge at the A & I band junction with transversely oriented tubular elements called
terminal cisternae
-
Most abundant protein in the body
connective tissue
-
_____ tissue has a limited number of extracellular fibers
Adipose
-
CT surrounding muscles is known as
connective tissue proper
-
CT associated with bones and cartilage is known as
supportive CT
-
harnesses energy of the muscle
connective tissue
-
influences meat tenderness
collagen
-
principal structural component of CT
collagen
-
most abundant amino acid in collagen
glycine
-
_____ amount is consistent and unique to collagen
Hydroxyproline
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Insolubility and strength of collagen is the result of
intermolecular cross linkages
-
A mature carcass has more
cross linkages
-
enlargement of existing cells is called
hypertrophy
-
multiplication or production of new cells is called
hyperplasia
-
process by which cells and organs acquire individual characteristics
Differentiation
-
organization of dividing cells into specific organs
morphogenesis
-
It is hard to determine when maturation occurs because
because tissues and body parts grow and develop at different rates
-
when organs begin to degenerate without complete repair or replacement
senescence
-
Ovum phase lasts up to ___ days
14
-
tissue, organs, and systems are differentiated in the
Embryonic phase
-
embryonic phase lasts
25 to 45 days
-
myogenic cells undergo mitosis to form
myoblasts
-
myoblasts fuse and donate nuclei to a single immature muscle fiber known as
a myotube
-
Hyperplasia occurs during the first ____ of prenatal period, and hypertrophy occurs during the last ____
2/3, 1/3
-
proliferation of myfibrils occurs through
longitudinal splitting of large myofibrils into 2 daughter cells
-
growth in length occurs by
addition of sarcomeres
-
new nuclei are created by
satellite cells
-
satellite cells provide fibers with added ____ which increases muscle's ability to synthesize protein and grown
DNA
-
BCTRC
boneless closely trimmed retail cuts
-
larger diameter fibers are called
white fibers
-
Currently there are ___ growth promotants on market in US
30
-
Somatotropin is produced by the
anterior pituitary
-
Somatotropin responsible for ____ tissue growth
lean
-
Somatotropin promotes the release of ____ from the liver
IGF
-
HGH is produced by
recombinant DNA technology
-
rBST is known as
recombinant bovine somatotropin
-
rBST was developed by Monsanto and called
Posilac
-
Posilac is used to increase
milk production
-
Epinephrine and norepinepherine are from the
adrenal medulla
-
epinephrine and norepinephrine activate tissue receptors called
beta - receptors
-
-
some synthetic estrogens are:
- estradiol 17-beta
- zeronol
- estradiol benzoate
-
a synthetic androgen is
trenbolone acetate
-
synthetic androgens increase
feed efficiency and carcass leanness
-
Hormone like substances with chemical structures similar to epinephrine and norepinephrine are called
beta adrenergic agonists
-
______ shift nutrient utilization away form fat deposition toward muscle accretion
beta agonists
-
Paylean, Optaflex, Zilmax
beta agonists
-
Use of hormones averages ___% improvement in rate of gain, and ___% improvement in feed efficiency
10, 6-8
-
hormone fed to heifers to supress estrus
MGA (melengestrol acetate)
-
hormone approved in the 50's and then found to cause cancer
DES
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initial homeostatic control mechanisms that result from exsanguination
loss in blood pressure causes increased heart rate and constriction of blood vessels which forces blood to vital organs
-
Why is blood removal necessary
it is an excellent medium for bacterial growth
-
What happens to the pH post mortem
- aerobic metabolism fails which causes metabolism to switch to the anaerobic pathway.
- Lactic acid accumulates until stored glycogen is depleted
-
How do you prevent rapid denaturation of proteins as pH decreases
Chill the carcass
-
_______ is required for muscle to remain in a relaxed state
ATP Mg2+
-
Why is rigor postponed?
Creatine phosphate is stored postmortem and used to convert ADP back to ATP
-
What causes rigor
creatine phosphate and glycogen stores are used up and ATP becomes limiting. Actomyosin bridges are formed and these bonds cannot be broken without ATP
-
Decreased tension after rigor is due to
proteolytic degradation of specific myofibrillar proteins
-
Rigor involves 100% of binding sites, unlike normal contraction which involves ___%
20
-
______ and ______ are closely correlated because both involve energy metabolism
Rigor mortis and pH decline
-
Steps of protein degradation during aging
- Degradation of the Z disks
- As z disk degrade, tension from rigor causes myofibrils to rupture at the z disk/I band junction
- Calcium released post mortem activates the calpain system
-
Proteins which undergo degradation during aging
- desmin
- troponin - T
- titin
- nebulin
-
______ inhibits calpain activitiy
calpastatin
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First meat packer
William Pynchon - salted pigs
-
first meat scientist
Benjamin Franklin
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first meat packing plant
cincinnati - porkopolis
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