Three types of muscles:
Skeletal, smooth, cardiac
Functions of skeletal muscle:
- support body
- faciliate movement by interacting with skeleton
- help maintain a contact body temp
- assist in movement in the cardiovascular and lymphatic vessels
- protect internal organs and stabilize joints
Origin:
muscle attachment on a stationary bone
Insertion:
muscle attachment on bone that moves
Examples on how skeletal muscles can be named:
- size: gluteus maximus is the largest.
- shape: deltoid (triangular)
- location
- direction of muscle fiber: rectus abdomens (rectus means straight)
- attachment
- number of attachments: biceps branchii (two attachments)
- action
Name the parts and functions of a muscle fiber:
- Plasma membrane= sarcolemma
- Cytoplasm= sarcoplasm
- Sarcoplasmic reticulum (stores calcium)
- Myofibrils
- Myofilaments
- sarcomeres
Myofibrils:
uncle of myofilaments that run the length of a fiber
Myofilaments:
actin and myosin arranged in repeating units
sarcomeres
repeating units of actin and myosin on a myofibril
actin:
thin protein filaments
Myosin:
thick protein filaments
Sliding filament theory
explains muscle contraction. myosin binds to actin. myosin pulls on the actin filament which causes it to slide across myosin filament.
Rigor mortis:
after death, muscle cells continue to produce some ATP, but when the ATP runs out, some myosin heads stay that way.
What are some possible sources of ATP for muscle contraction?
Glycogen and fat in muscle. Glucose and fatty acids in blood.
Three ways to produce more ATP:
creatine phosphate pathway, fermentation, and aerobic cellular respiration.
What are the characteristics of fast-twitch fibers?
Fast twitch:
- rely on CP and fermentation
- designed for strength
- light in color
- few mitochondria
- little or no myoglobin
- fewer blood vessels
Characteristics of slow twitch fibers:
- rely on aerobic respiration
- designed for endurance
- dark in color
- many mitochondria
- myoglobin
- more blood vessels
Muscle disorders:
spasms, seizure, cramps, strain, sprain
Muscular diseases:
fibromyaglia: achy muscles
muscular dystrophy
myastenia graves: Ach receptor is attacked, weakening muscles.
Amyotrophic lateral sclerosis: motor neurons degenerate ans die leading to loss of voluntary muscle movement.
Impulses that move down the T tubules of a muscle fiber initially cause:
release of calcium from the sarcoplasmic reticulum
The ___ is the plasma membrane of a muscle fiber:
sarcolemma
which pathway provides the quickest means for a muscle fiber to produce ATP?
creatine phosphate pathway
Which represents the maximal amount of muscle contraction?
tetanus
Cancers that occur in soft tissues, such as muscles, are referred to as:
sarcomas
