Anatomy Exam 2, Muscles pt 1

What muscles are involuntary?

cardiac, smooth

What muscles are striated?

skeletal, cardiac

What are the three layers of connective tissues in Skeletal Muscles?

Epimysium, Perimysium, Endomysium

What does Epimysium surround?

The entire muscle

What does Perimysium surround?

Bundles of fiber, fascicles

What does endomysium surround?

Individual fibers

What is the organizational level of Skeletal Muscle?

Muscles —> Fascicles —> Muscle fibers —> Myofibrils —> Myofilaments

How are fibers produced?

fusion of myoblasts

What is the sarcolemma?

The cell membrane of a muscle fiber, propagate AP

What is the sarcoplasm?

Cytoplasm of fiber

What is the sarcoplasmic reticulum?

The membranous structure of a myofibril

What is transverse tubules, or T tubules?

transmits AP through fiber

What is terminal cisternae?

Attaches sarcoplasmic reticulum to T tubules, concentrates calcium

What is in thin filaments?

actin

What is in thick filaments?

myosin

What does tropomyosin do?

Blocks the active site

What does troponin do?

Binds to tropomyosin to remove it and expose the F-actin active site

What is the synaptic knob?

expanded tip of neuron axon

What is the synaptic vesicles?

Membrane sacs in synaptic knob, filled with Acetylcholine

What is the synaptic cleft?

The space between the synaptic knob and the motor end plate

What are ACh receptors?

Binds to Acetylcholine

What is Acetylcholinesterase?

Enzyme that breaks down Acetylcholine, preventing stimulation

What is incomplete tetanus?

stimulate fiber even though it is partially relaxed

What is complete tetanus?

Stimulate fiber continously, doesn’t enter relaxation phase

What are motor units?

Multiple fibers controlled by a single motor neuron

What is muscle hypertrophy?

increases diameter of muscle fibers, increased myofibrils

What is muscle atrophy?

lack of muscle activity, reduces muscle size, smaller fibers, less elasticity

What is muscle fatigue?

when it can no longer perform a required activity

What is force?

tension produced during contraction

What is endurance?

how long an activity can be sustained

What are the three types of skeletal muscle fibers?

Slow oxidative, Fast oxidative, Fast glycolytic

What type is Slow oxidative fibers?

Type I

What type is Fast oxidative fibers?

Type IIa

What type is Fast glycolytic fibers?

Type IIb

Features of slow oxidative fibers?

Small, aerobic, fatigue resistant

Features of fast oxidative fibers?

intermediate, not as fast but not as slow

Features of fast glycolytic fibers?

Large, produces huge tensions, but fatigue quickly

What are sarcomeres?

The contractile units of muscle

What is the color and band of thick filaments?

Dark, A bands

What is the color and band of light filaments?

Thin, I bands

What is in the A band?

Thick and thin filaments

What is in the I band?

Thin filaments and connectin

What is the M line?

The middle, with thick filaments and accessory proteins

What is the H zone?

Thick filaments

What is the Z disc?

Where the thin filaments are interconnected

Where does the calcium ions go at the relaxation phase?

transported into the sarcoplasmic reticulum

What does ATP binding on myosin head cause?

detach from the actin

What does ATP hydrolysis on myosin cause?

causes the myosin head to reload into a high-energy state, ready to bind to actin

What does ADP release on myosin cause?

causes power stroke, pulls actin towards the middle, remain tightly bound to actin in a low-energy state

What is muscle tone?

The normal tension of a muscle at rest

What color are slow oxidative fibers and why?

red, abundance of myoglobin and mitochondria

What color are fast glycolytic fibers and why?

pale, low myoglobin and mitochondria, large storage of glycogen