anatomy test muscles Flashcards
List the major functions of the muscular system.
Produce movement of skeleton
Maintain posture and body position
Support soft tissues
Guard entrances and exits
Maintain body temperature
contracted sarcomere vs. relaxed sarcomere
Contracted:
Smaller H zone
Bigger zone of overlap
Smaller I band
Relaxed
Bigger H zone
Smaller zone of overlap
Bigger I band
the relationship between the endomysium, perimysium and epimysium.
Each myofibril is surrounded by a connective tissue layer called the endomysium.
Each fascicle is surrounded by a connective tissue layer called the perimysium.
The muscle is surrounded by the epimysium connective tissue which is composed of collagen.
Describe how the actin and myosin allow contraction using the sliding filament theory. Include troponin, tropomyosin, and calcium in your explanation.
The actin active sites are blocked by troponin and tropomyosin
When the t-tubule receives the action potential and activates the sarcoplasmic reticulum to release calcium.
The calcium moves the troponin and tropomyosin exposing the active site.
The myosin heads grab onto the actin active site and pivot pulling the filaments over each other.
The myosin heads release and attach again, pivoting to pull the filaments over each other again.
allows the action potential to get into the muscle cell
t-tubules
releases the calcium to move the troponin and tropomyosin
sarcoplasmic reticulum
the site of contraction
sarcomere
provides longer term energy storage in muscle cells
creatine phosphate
provide immediate energy to muscle cells
ATP
gets the signal to contract across the synaptic cleft
ACh (acetylcholine)
What 2 things make up a motor unit?
One neuron and muscle cells stimulated by that neuron
Compare a twitch with repeated stimulation of the muscle during complete tetanus.
Muscle twitch—A brief contraction-relaxation response to a single action potential
Complete tetanus—Tension is steady (no relaxation phase) and largest if stimuli arrive at very high rates. Maximum tension
compare and contrast aerobic and anaerobic respiration
Anaerobic:
Less efficient at making ATP
No oxygen requirement
Uses glycogen reserves in SR when ATP & CP run low
Aerobic:
Very efficient at making ATP ; At rest provides all ATP needed
Reliant on oxygen availability
Only provides 1/3 of ATP during peak contraction
How do resting muscles generate ATP? What does it do with excess ATP created during rest?
Aerobic respiration makes ATP at rest - Storage of excess ATP as Creatine phosphate
How are isometric and isotonic contractions different?
Isotonic:
tension stays same, muscle length changes
doing a pushup
Isometric
tension varies, muscle length stays constant
holding a plank
What 3 factors affect muscle performance?
Type of fibers (fast versus slow)
Distribution of fibers (amount of fast versus slow)
Physical conditioning
How does your muscular system change with age?
Age-Related Reductions
Muscle size – fibers decrease in diameter, # of myofibrils decreases
Muscle elasticity – increases in connective tissue (fibrosis)
Muscle strength – due to #1+2
Exercise tolerance – rapid fatigue and decreased ability to regulate heat created
Injury recovery ability – less repair and more scar tissue formation with age
skeletal vs. cardiac vs. smooth
skeletal:
striations
many nuclei
cell=entire length of muscle
voluntary contraction
Cardiac:
Striations
one nuclei
small and branched
involuntary
Smooth:
no striations
one nuclei
very small
involuntary contraction
