Unit 2 - Muscular System Flashcards
Function of muscular system
Support Stabilization Protection Movement Regulate body temp Contraction assists in movement within the lymphatic system
What are muscles made up of?
Cells called Fibers
Tissue, blood vessels and nerve fibers
What is the cytoplasm of the muscle cell called?
Sarcoplasm
What is myglobin
Stores oxygen in muscle fiber cells
What is stored in the sarcoplasmic reticulum?
Stores Ca++
Stored in the terminal cisternae
Myofibrils
Protein fibers within muscle cell
Sarcomere
Repeating structural and functional unit
Actin
Thin protein filament composing I band
Contains tropomyosin and troponin
Calcium binds to troponin and causes troponin to change shape
Myosin
Thick protein filament composing A band
Forms cross bridges
What is the sarcomere made up of?
Alternating light and dark bands called I and A bands
Muscle contraction
Muscles get shorter and pull on bone
H zone disappears when contracted
Describe contraction
- Action potential gets to axonal terminal
- Ca++ enters axonal
- Causes release of acetylcholine
- then binds to receptors
- Na+ channels open
- Action occurs on sarcolemma muscle
Twitch
Single stimulus and contraction
Summation
Increased muscle tension due to increased stimulus frequency
Recruitment
Increased muscle tension due to increased number of motor units
Tetanus
Maximum muscle tension due to large stimulation
Sustained contraction
Lag phase
Occurs just after the action potential reaches sarcolemma
Contraction phase
Occurs when the actin and myosin bind and the sarcomere shortens and pulls the Z discs toward the M line
Relaxation phase
The actin and myosin complex releases and the calcium is actively transported back into sarcoplasmic reticulum
Isometric contractions
The length of the muscle does not change but the amount of tension increases during contraction
Think holding a position under tension
Isotonic contraction
Length and tension during contraction does not change
Concentric phase
Tension increases as the muscle shortens
Bicep curl
Eccentric phase
Maintain tension but muscle lengthens
Lowering ten pound dumbbell
Type I muscle fibers
Slow twitch - more myoglobin
Oxidative/aerobic respiration
Type IIa muscle fibers
Fast twitch
Both aerobic and anaerobic
Mostly in lower limbs
Type IIb muscle fibers
Fast twitch - Respond quickly to stimulus
Mostly in upper limbs
Anaerobic
ATP
Cells form of energy and is needed for contraction to energize the cross bridges
Creatine phosphate
Can give a phosphate group to ADP to creat ATP
Cab only do it for a few secs at a time
Aerobic metabolism
Make ATP using oxygen
In mitochondria and yields 36 ATP per molecule of glucose
Anaerobic metabolism
Can make ATP quickly but is inefficient
Used during a 50 meter dash
Oxygen debt
Occurs during anaerobic metabolism
Need oxygen to oxidize lactic acid build up
Muscle fatigue
Eventually muscle cells run out of ATP
No sources of stored oxygen
Muscle returns to relaxed configuration