AnSci 171 M3 Flashcards
Three types of muscle tissue
- skeletal muscle
- smooth muscle
- cardiac muscle
providing elasticity elasticity to the walls of arteries, linings of the gastrointestinal, reproductive, urinary and respiratory tracts and lymphatic system.
smooth muscle
is located only in the heart where it provides rhythmic contractions throughout an animal’s life.
cardiac muscle tissue
cardiac muscle tissue is controlled involuntarily by the ____ nervous system.
autonomic
skeletal muscle contraction is directly stimulated by ____ efferent nerves
somatic
Comprised of the thin Actin filaments. Outer edge of the xadjacent sarcomeres.
I band (light bands)
Marks the junction of actin filaments in adjacent sarcomeres. Also anchors the actin filaments.
Z line
Thick myosin filaments, which overlap thin actin filaments.
A band (thick bands)
Centrl region zone. Consists of thick filaments
H band
In the center of A band
M band
it is the functional unit of skeletal muscle.
sarcomere
thick filaments are also known as
myosin
thin filaments are also known as
actin
is a fibrous protein chain that lies in the groove between the two strands of actin
tropomyosin
covers the myosin binding site, preventing cross-bridges forming between actin and myosin
tropomyosin
is the protein complex located at regularly spaced intervals along the tropomyosin protein chain. The troponin complex is made up of three subunits.
troponin
binds the troponin complex to tropomyosin (hence ‘T’).
troponin T
has an uncertain role
troponin I
contains the Ca2+ binding site (hence ‘C ’for Ca2+). Binding of Ca2+ to troponin C causes tropomyosin to roll deeper into the actin groove, which uncovers the myosin binding site, allowing cross- bridges to form between actin and myosin
troponin C
bind to troponin (on actin) and cause tropomyosin to move, exposing
binding sites for the myosin heads
calcium ions
causes the myosin heads to swivel and change orientation
ATP hydrolosis
sliding of actin along myosin therefore (shortens/elongates) the sarcomere, causing muscle contraction
shortens
bind to the actin filament before returning to their original conformation (releasing ADP + Pi)
Swivelled myosin heads
Distinctive connective tissue layers
- epimysium
- primysium
- endomysium
Highest mass fractions or most abundant proteins in the Intramuscular Connective Tissue (IMCT)
Collagens
Protein molecules made up of amino acids. It provides structural support to the extracellular space of connective tissues.
Collagens
comprised of the protein elastin and associated microfilaments.
Elastic fibers
minor component of IMCT and typically represents much less than 1% of the fatfree dry weight of muscle.
Elastin
These molecules contain both protein and carbohydrate units.
Glycoproteins and Proteoglycans
have more protein and short glycan chains with no repeating unit.
Glycoproteins
confer stability to the proteins.
Glycans
are commonly transmembrane proteins that take part in cell communication and signaling.
Glycoproteins
have much more carbohydrate units attached to the central protein backbone.
Proteoglycans
stored in the form of triglycerides in adipose cells
Lipids
consists of adipocytes bound together by thin collagenous networks
Adipose tissue
white fat is aggregated in meat animals into four main sections:
- subcutaneous fat
- visceral fat
- intermuscular fat
- intramuscular fat (marbling)
chemical composition of meat:
- water
- protein
- lipid
- carbohydate
- miscellanous soluble nonprotein substances
- vitamins
Muscle becomes inextensible: this is the stiffening reffered to as
Rigor Mortis
what is called a postmortem rigidity is a definite sign of death.
rigor mortis
Two of the major quality defects facing the meat industry
Pale, Soft, Exudative (PSE)
Dark Firm and Dry (DFD)
predisposing factors contributing to pse and dfd in meats
- breed
- sex
- species
- pre-slaughter handling and post handling of animals
pH of PSE meat is ____ at ____ minutes after slaugter
<6; 45 minutes
pH of DFD meat is ____ at ____ hours after slaugter
≥6; 12-48 hours
causes of PSE meat
- stress in ante-mortem
- acute stress
causes of DFD meat
- chronic or long-term stress
