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1-Muscle Growth, Structure, and Contraction
Terms in this set (49)
What are the stats of beef in the US in 2016?
Total of 50.3 billion lbs in pork/beef
1% increase in growth at $1/pound= over 500 million dollars
Two types of muscle growth
An increase in muscle cell number
Occurs prior to birth (cell number does not change after birth)
Example: double muscled cattle
Increase in cell size
Occurs primarily after birth
Example: Callipyge Sheep
Comparing Hyperplasia and Hypertrophy
Double Muscled Cattle: first described in 1809, still find many double muscled breeds
Callipyge Sheep: first described in 1982 from one ram, found only in research flocks today, "Beautiful Buttocks:, terrible meat quality- mostly tough
Potential issues with growth
Speed of growth
Muscle can be classified as what two general fiber types?
Red (slow twitch)-dark
White (fast twitch)
What is the comparison between the red and white fibers in: Speed of contraction
Red is slower than white
What is the comparison between the red and white fibers in: Myoglobin Content (carries O2)
Red is higher than white
What is the comparison between the red and white fibers in: Fiber Diameter
Red is smaller than white
What is the comparison between the red and white fibers in: Fatigue Resistance
Red is better than white
What is the comparison between the red and white fibers in: Capillary Density
Red is denser than white
What is the comparison between the red and white fibers in: Lipid Content
Red has more than white
What is the comparison between the red and white fibers in: Glycogen content
Red is lower than white
What is the comparison between the red and white fibers in: Mitochondria Diameter (uses O2)
Red is bigger than white
What is the comparison between the red and white fibers in: Muscle Metabolism Type
Red: Oxidative (needs O2)
White: Glycolytic (can use only glycogen)
What are the two types of muscle metabolism?
Glycolytic or Anaerobic Metabolism
Produces ATP and lactic acid
Does not need oxygen
Oxydative or Aerobic Metabolism
Metabolizes lactic acid to produce ATP
Through the TCA cycle and electron transport in the mitochondria
How many types of muscle are there?
Where are the three types of muscles found?
Skeletal: on bones
Smooth: mostly in digestive tract and blood vessels
Cardiac: in the heart
How many nuclei does each type of muscle have?
Smooth: 1 centrally located
Cardiac: 1-2 centrally located
Are the different muscle types striated?
Are the types of muscle involuntary or voluntary?
What do nuclei do?
Nuclei produce DNA which produces RNA which produces Protein
Need more nuclei to produce more protein
Why is muscle structure important?
Important for contraction
Important for the postmortem conversion of muscle to meat
What are the layers of muscle?
Muscle --> Muscle Bundles --> Muscle Fibers (Cells) --> Myofibrils --> Sarcomere
What connective tissue surrounds the whole muscle?
What connective tissue surrounds the muscle bundles?
What connective tissue surrounds the muscle fibers?
What is a sarcomere?
The functional unit of muscle
What causes muscle contraction
Repeated unit of the myfibril
*See drawing in notes
I-Band and A-Band during contraction
I-Band shortens during contraction
A-Band does not change in length during contraction
What are the three types of protein in a sarcomere?
What are the Contractile Proteins in a sarcomere?
What are the Structural Proteins in a sarcomere?
Titin, Desmin, Nebulin
What are the Regulatory Proteins in a sarcomere?
What are the four proteins needed for contraction?
What role does actin play in contraction?
Makes up a majority of the thin filaments
Contains the binding site for myosin
What role does myosin play in contraction?
Makes up the thick filaments
Comprised of a "Rod" and "Head"
Head interacts with actin which causes contraction to occur
What role does tropomyosin play in contraction?
Located in the the thin filament
Covers the mysoin binding site on actin at rest which inhibits the interaction of actin and myosin
What role does troponin play in contraction?
Located with Tropomyosin in the thin filament
Binds Calcium and moves tropomyosin away from the myosin binding site on actin
What is needed for muscle contraction?
How do muscles get the energy needed for contraction?
TCA Cycle - aerobic
Electron Transport Chain - aerobic (in mitochondria)
Where does the stimulus come from for contraction?
What are the 7 steps of contraction?
1. Nerve Signal
2. Sarcoplasmic Reticulum releases Ca++
3. Ca++ binds to troponin --> troponin changes shape and moves tropomyosin away from the myosin binding site on actin
4. Myosin binds to actin
5. Myosin head undergoes the "Power Stroke"
6. Sarcoplasmic Reticulum pulls Ca++ out of the cell and back into itself
7. Actin and Myosin bond is broken using ATP
What is the Sarcoplasmic Reticulum?
a structure that surrounds the myofibril
What does Ca++ trigger in the steps of contraction?
the start of the actin/myosin bond
When Ca++ is released by the sarcoplasmic reticulum, how much of an increase is there?
100 fold increase in Ca++ concentration
What is used for the Power Stroke?
Uses ATP to ratchet the myosin head
This set is often in folders with...
1-Meat Science Introduction
1-Components and Composition of Meat
1-Conversion of Muscle to Meat
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