Short repsopnse question number 2

longer discprtion

What embryonic cells give rise to muscle fibers?

Mesodermal myoblasts

Are mature muscles able to divide and give rise to more muscle cells? Why or why not?

No

mature muscle fibers are amitotic and have a very small population of stem cells

What connective tissue covering bundles and supports muscle fibers and what does it cover?

Epimysium

dense irregular connective tissue that covers the entire muscle

What type of transmembrane receptor is present at the neuromuscular junction?

Acetylcholine (ACh) receptors

What molecule binds to receptors at the neuromuscular junction?

Acetylcholine

What drug alters acetylcholine signaling and what effect does it have on skeletal muscle contraction?

Botox

blocks acetylcholine release causing muscle paralysis

What happens across the sarcolemma when acetylcholine binds?

Ligand-gated sodium channels open causing Na⁺ influx

What other cell type besides muscle fibers is electrically excitable?

Neurons

Which organelle within the muscle fiber stores calcium?

Sarcoplasmic reticulum

What molecule provides ATP for the first 15 seconds of muscle activity?

Creatine phosphate

Which organelle produces most ATP for muscle contraction?

Mitochondria

What two cytoskeletal fibers form cross-bridges in muscle fibers?

Actin and myosin

What two proteins regulate cross-bridge formation based on calcium levels?

Troponin and tropomyosin

Which protein inhibits cross-bridge formation?

Tropomyosin

Which protein allows cross-bridge formation?

Troponin

What molecule in the sarcoplasm stores glycogen?

Glycosomes

What molecule in the sarcoplasm stores oxygen?

Myoglobin

With resistance training

which storage molecule and muscle fiber type become dominant?

With aerobic training

which storage molecule and muscle fiber type become dominant?

What is the function of dystrophin?

Anchors muscle filaments to the sarcolemma and extracellular matrix

What happens when dystrophin is mutated?

Muscular dystrophy causing sarcolemma tearing

What neurological disorder impairs muscle control and what are its characteristics?

Dystonia

involuntary sustained muscle contractions

tremors