Meat Flashcards
What is the definition of meat?
Animal tissue used for food
What types of meat are there?
- Red meat (beef, pork, veal, lamb/mutton, horse)
- poultry (chicken, turkey, duck)
- fish/seafood
- other types (deer, bears, dog, cats, worms, grubs)
What is the world’s leading meat?
Pork with 106,103 metric tons produced
What is the leading meat in the U.S.?
Poultry at 20,130 metric tons
What is smooth muscle?
Smooth muscle is muscle tissue where the muscle fibers are not highly ordered. They comprise the walls of the digestive tract, capillaries, etc.
What is involuntary striated muscle?
This is cardiac muscle that makes up the heart.
Striated means this muscle is “striped” and layered.
What is voluntary striated muscle?
This is skeletal muscle that have alternating dark and white bands.
What are myofibers?
Myofibers are muscle fibers. They are the structural unit of muscle.
What is the sarcolemma?
the excitable outer cell membrane of muscle fibers
Describe the nuclei in muscles.
Voluntary striated muscles have multiple nuclei, while smooth and involuntary striated muscle have just one nuclei.
What are myofibrils?
long fibers of contractile filaments in myofibers
the basic rod-like unit of a muscle fiber
They permit each cell to do work
What is the sarcoplasm?
The liquid portion of the cell.
What is the endomysium?
The thin layer than surrounds each muscle cell/fiber.
What is the perimysium?
The perimysium is the connective tissue layer that wraps around several muscle cells and forms a bundle (both primary and secondary).
What is the epimysium?
The layer that surrounds the entire muscle.
What is a sarcomere?
The smallest functional contractile unit.
It contains several hundred filaments, and is located between z-lines.
It can also be defined as the distance between two z-lines.
What’s the function of the myofibrils and what are they composed of?
Myofibrils permit each cell to do work. They are composed of actin and myosin.
What is actin?
Actin is the thin filaments of myofibrils. They appear as light bands.
What is myosin?
Myosin is the thick filaments of the myofibrils. They appear as dark bands.
Describe the sliding-filament theory.
When muscles contract, the actin and myosin filaments slide together and the sarcomere decreases in length. However, the actin and myosin filaments do not change length during contraction, they slide together. Contraction is regulated by the calcium ion concentration in the sarcoplasmic reticulum.
What is the sarcoplasmic reticulum?
This is the layer that surrounds the myofibrils.
What is the role of ATP in muscle contraction?
- keeps actin and myosin separated
- provides energy for contraction
Describe the anaerobic reactions of muscle contraction.
ATP <–> ADP + Energy
Phosphocreatine <–> Creatine + Energy
Glycogen (glucose) <–> lactic acid + energy
Anaerobic reactions produce less energy than aerobic reactions.
Describe the aerobic reactions of muscle contraction.
Glycogen + o2 –> h2o + co2 + energy
Lactic acid + o2 –> h20 + co2 + energy
fatty acid + o2 –> h20 + co2 + energy
Produces more energy than anaerobic reactions.
What is rigor mortis?
The stiffening of the carcass by intense shortening of the muscle fibers (no longer have enough energy to relax).
What is the resolution of rigor?
When the carcass relaxes due to autolysis (self breakdown). The muscle is more tender here due to the enzymatic breakdown of muscle protein.
The muscle becomes as tender as pre-rigor muscle.
What is rigor completion?
This is the point where the muscle is at its maximum toughness and maximum contraction.
What enzymes are involved in rigor mortis?
Calpains and cathepsins are the enzymes involved in autolysis
At what pH does resolution of rigor occur and calpains and cathepsins become active?
pH=5.6
What happens to the water binding capacity of muscle as the pH drops?
Water binding capacity drops. This explains why packaged meat sometime has free water at the bottom of the packaging.