APHY Ch 9 Muscles

Name 3 types of muscle tissue and describe where each is located and whether it is voluntary or involuntary

Skeletal (attached to bones, voluntary), Cardiac (heart, involuntary), Smooth (walls of organs, involuntary)

What are organs of the muscular system

Skeletal muscles, tendons, and fascia

Define fascia, tendon, and aponeurosis

Fascia = connective tissue surrounding muscles, Tendon = connects muscle to bone, Aponeurosis = broad, flat tendon

Define epimysium, perimysium, and endomysium

Epimysium surrounds whole muscle, Perimysium surrounds fascicles, Endomysium surrounds individual fibers

What is a skeletal muscle called? Do these cells have one nucleus or many

Muscle fiber, multinucleated

What is the cell membrane of a muscle fiber/cell called

Sarcolemma

What is the cytoplasm of a muscle fiber/cell called

Sarcoplasm

What do myofibrils consist of

Actin (thin) and myosin (thick) filament

What is the endoplasmic reticulum of muscle fiber/cells called? What is stored in it

Sarcoplasmic reticulum, stores calcium ions (Ca²⁺)

What is the function of a transverse/T tubule

Carries electrical impulses deep into the muscle fiber

What makes the striation pattern in a skeletal muscle

Arrangement of actin and myosin filaments

What is the functional unit of contraction in a muscle fiber

Sarcomere

Name and describe each of the structures that make up a sarcomere (I band, A band, etc.)

Z line = boundary, I band = thin filaments only, A band = length of thick filaments, H zone = thick filaments only, M line = center

Thin filaments are made of what? Thick filaments are made of what

Thin = actin, Thick = myosin

Which filament forms the cross bridges

myosin

What are the actions of troponin and tropomyosin

Troponin binds Ca²⁺, tropomyosin blocks or exposes binding sites on actin

What is a neuromuscular junction?

Site where a motor neuron meets a muscle fiber

What is a motor neuron? What is a motor end plate

Motor neuron = nerve that stimulates muscle, Motor end plate = specialized region of sarcolemma at NMJ

What is a synaptic cleft? What are synaptic vesicles

Synaptic cleft = gap between neuron and muscle, Synaptic vesicles = sacs that store neurotransmitter

Name the neurotransmitter that stimulates muscle contraction. What is the action of this neurotransmitter

Acetylcholine (ACh), triggers muscle impulse and contraction

A muscle impulse/action potential triggers the release of what from the sarcoplasmic reticulum, leading to muscle contraction

Calcium ions (Ca²⁺)

What is the sliding filament model of muscle contraction

Actin filaments slide over myosin, shortening the muscle

List the steps involved in muscle contraction, in order

ACh released → muscle impulse → Ca²⁺ released → troponin binds Ca²⁺ → tropomyosin shifts → cross-bridge forms → power stroke → ATP detaches myosin → cycle repeats

What enzyme decomposes acetylcholine

Acetylcholinesterase

Describe the role of creatine phosphate

Rapidly regenerates ATP

What is myoglobin? What is its color

Oxygen-binding protein, red

Define oxygen debt

Oxygen deficiency after exercise requiring recovery

Define muscle fatigue

Decreased ability of muscle to contract due to prolonged activity

How do skeletal muscles help maintain body temperature

Produce heat during contraction

Define threshold stimulus

Minimum stimulus needed to cause a muscle contraction

Define twitch

A single contraction and relaxation cycle

Define summation

Increased force of contraction from repeated stimuli

Define tetany

Sustained contraction without relaxation

Define motor unit and recruitment

Motor unit = one neuron and its muscle fibers, Recruitment = activation of more motor units

Define isotonic, concentric, eccentric and isometric and give examples

Isotonic = muscle changes length, Concentric = shortens (lifting weight), Eccentric = lengthens (lowering weight), Isometric = no length change (holding weight)

Explain differences between slow-twitch fibers, fast-twitch fatigue-resistant fibers, and fast-twitch glycolytic fibers

Slow-twitch = endurance, fatigue-resistant, Fast fatigue-resistant = moderate endurance, Fast glycolytic = powerful, fatigue quickly

How are red fibers and white fibers different

Red = high myoglobin, endurance, White = low myoglobin, quick bursts

Explain how smooth muscle differs from skeletal muscle

Smooth = involuntary, non-striated, Skeletal = voluntary, striated

Explain how cardiac muscle differs from skeletal muscle

Cardiac = involuntary, branching cells, intercalated discs, Skeletal = voluntary, long cylindrical cells

Explain a lever in terms of muscles and bones

Bones act as levers, joints as fulcrums, muscles provide force

Define agonist, prime mover, synergist, and antagonist in terms of muscles

Agonist/prime mover = main muscle, Synergist = assists, Antagonist = opposes movement

Define origin and insertion

Origin = fixed attachment, Insertion = moves during contraction