Anatomy and Physiology Muscular System
How much of the body is made up of muscle?
About 40%
antagonists and synergists?
Antagonists: directly oppose prime movers Synergists: muscles that contract at the same time as the prime mover
Thin filaments and thick filaments are the?
actin; myosin
What is the role of calcium ions (Ca++) in muscle contraction
binds troponin molecules in the thin filaments; initiates the chemical reactions that produce a contraction
Identify the *connective tissue membrane that covers individual muscle fibers, *the membrane that surrounds groups of skeletal muscle fibers (fascicles), and *the membrane that covers the muscle as a whole
endomysium; perimysium; epimysium
Name the type of muscles that generally function as joint stabilizers
fixator muscles
What muscle type helps maintain overall body posture when prime movers produce motion in the extremities
fixator muscles
what is the action of the sternocleidomastoid muscle
flexes the head
Name some features of the muscle cell that are not found in other types of cells
increase of mitochondria, presence of T tubules (brings the nerve impulse go all the way through the muscle fiber), contains myofibrils (has sarcomeres), several nuclei
Name the skeletal muscles that produce respiratory movements
internal (exhale) intercostal muscles, external (inhale) intercostal muscles and diaphragm
What is the difference between isotonic and isometric contractions? Concentric and eccentric?
isotonic- "the same" "tension" changing the length of the muscle isometric- "the same" "length" contracting the muscle not changing the length concentric- when the muscle shortens during the movement eccentric-occurs when the contracting muscle lengthens
Why is the traid relationship between T tubules and the SR important
it is important because it allows an electrical impulse traveling along a T tubule to stimulate the membranes of adjacent sacs of the SR
What are the three major functions of the skeletal muscles
movement, heat production (produce heat through respiration of cells; large part in homeostasis), posture (the continued partial contraction of many muscles makes this possible)
What group of muscles facilitates chewing movements
muscles of mastication
What is the perineum?
muscles of the pelvic floor in the anal triangle
Which muscle of facial expression has two parts, one lying over the forehead and the other covering the back of the skull
occipitofrontalis
Identify the point of attachment of a muscle to a bone that *does not move when the muscle contracts and one that *does move when the muscle contracts
origin; insertion
What causes the striations observed in the skeletal muscle fibers
overlapping thick and thin filaments
Name three types of fiber arrangements seen in skeletal muscle
parallel, convergent (coverage to narrow attachment), pennate (oblique [single father]), bipennate (double feather), sphincter (circular)
What name is used to describe a muscle that directly performs a specific movement
prime mover
Name the tough connective tissue cord that serves to attach a muscle to a bone
tendon sheaths
Describe the structure of thin and thick myofilaments, and name the kinds of proteins that compose them
thin filament- actin: troponin and tropomyosin thick filament- myosin: "doubled" heads
What is the neuromuscular junction (NMJ) and how does it work
type of connection called a synapse and is characterized by a narrow gap (synaptic claft) across which neurotransmitter molecules transmit signals
