Muscles Part 2 Fitz Flashcards
Isotonic twitch contractions
Generate force by changing the length of the muscle.
Tension differences are based on
The recruitment of more muscle fibers (more sarcomeres). With each sarcomere recruited, tension is increased.
Unfused tetanus
Spastic muscle movement. Action potentials causing a lot of contractions. Ex: working out in reps. Taking breaks.
Fused tetanus
Fully contracted muscle and stays contracted. This is what happens when a muscle cramps.
Why we get tetanus shots.
Optimal length of a fiber
The length at which the fiber develops the greatest isometric active tension.
Passive vs active tension
Passive (elastic) is due to titan elastic filament. Can be stretched and springs back into place.As you stretch it, passive tension increases.
Active tension of a muscle fibers develops during contraction and can be altered by changing the muscle length. As you stretch it, it reaches isometric, then decreases in tension due to too much overlap.
Fatigue resistant fibers vs fatigue prone
Fatigue resistant- oxidative fibers
Fatigue prone- glycolytic.
Three ways a muscle fiber can form ATP
- Create ATP from creatine phosphate (reserve ATP source)
- Oxidative phosphorylation of ADP in mitochondria
- Substrate level phosphorylation of ADP in the cytosol via glycolysis
Fast twitch fibers
Rapid contraction but short lived. Extra ocular muscles.
Slow twitch fibers
Very slow to reach max tension, but doesn’t fatigue as quickly.
Diameters to determine slow oxidative, fast oxidative and fast glycolytic
Slow oxidative- small and dark
Fast oxidative- medium size and lighter
Fast glycolytic- largest and lightest
Larger diameter= faster signal
Rates of fatigue for slow oxidative, fast oxidative and fast glycolytic
Rates of fatigue from fastest fatigue to slowest fatigue
Fastest- fast glycolytic
Fast oxidative
Slowest- Slow glycolytic
What gives oxidative fibers its red color
Myoglobin, which is only seen in lives muscles. Due to a higher need for blood supply.
4 parts of twitch contraction
- Latent period (2m sec when ca2+ is being released froM SR)
- Contraction period. Filaments slide past each other.
- Relaxation period. Active transport of Ca2+ back in SR
- Refractory period. Muscles cannot respond until it can reset.
Isotonic contraction
A load is moved by changing the length of a muscle.
Two types of isotonic contraction
Concentric- a muscle shortens to produce force and movement. Lifting book towards chest.
Eccentric- a muscle lengthens while maintaining force and movement. Lowering book towards legs with arms extended.
Isometric
No movement occurs. Tension is generated without muscle shortening. Holding a book out straight. Arms not bent.
Myogram measures
Muscle fibers
Summation
When a new contraction occurs before the muscle had fully relaxed, tension will add which is called summation.
Sensory feedback from the muscle is by
Muscle spindles (Activated by stretch) and golgi tendon organ (activated by tension)
A muscle spindle consists of ___
of a collection of specialized fibers that lie within a connective tissue capsule.
The muscle spindle is innervated by
Its own gamma motor neuron and is supplied by 2 afferent sensory terminals- primary and secondary. Both are activated by stretch.
The golgi tendon organ
Monitors change in muscle tension.
Located where muscle attaches to bone.
Patellar tendon reflex (stretch reflex)
Tapping on the tendon causes extension response from the golgi tendon and muscle spindles.
Atrophy
Happens primarily from not using a msuscle.
Which virus destroys motor neurons
Polio
ALS
Excitotixic disease- too much calcium in the cytoplasm results in the cell killing itself. In ALS, the neurons that have paravalbumin die last. Makes sense since paravalbumin is a calcium regulator.
Stephen hawking
Muscular dystrophy is more present in males or females
Males.
Muscular dystrophy is a disorder in which
Costamers (which hold the myofibrils to the sarcomere) rip and no longer support the muscle. Death usually occurs because the diaphragm can’t contract.
Dystrophin
A type of costumer, which is a protein that holds the myofibrils to the sarcomere.
Myasthenia graves
Body attacks ach receptors in muscles. Patient has diplopia- should use neostigmine to increase muscle contractions.
Muscular sclerosis is related to which polyneuropathy syndrome?
Guillaian barre- body attacks nerves. weakness and tingly.
Myofibrils of smooth muscles interact with ___, instead of Z, M lines
Dense bodies.
Is there a solid NMJ in smooth muscle
No
Receptors on smooth muscles
Variscocities. Little beads. Chemicals from nervous system can bind anywhere on the varicosities.
They are attached to the axon of the postganglionic autonomic neuron.
In smooth muscle, calcium binds to ___
In skeletal muscle, calcium binds to ___
Calmodulin
Troponin
What type of cell communication occurs in smooth muscle
Gap junctions/connexons. Wave of contractions. Systolic Ca2+ from extracellular fluid stimulates the smooth muscles.
Gap junctions are found in which two muscles
Cardiac and smooth
action potentials in cardiac muscles have a long plateau period due to which channel
The L calcium channel
