Muscle Review Question Answers
1) Layers of connective tissue enclose and separate all parts of a
skeletal muscle.
Facia – covering over individual skeletal muscles – may form tendon
Epimysium – layer that closely surrounds muscle tissue
Perimysium – extends inward from epimysium and separates muscle
tissue into small section (fasicles)
Endomysium – surrounds each muscle fiber in a fasiche.
2) A skeletal muscle fiber is a singe muscle cell. A muscle (cell) fiber
membrane *sarcolemma. *Cytoplasm – sacroplasm – contains many
nuclei and mitochondria. Also has myofibrils (contraction).
Myofibrils – thick filaments made of myocin and thin filaments made
of actin – give light and dark characteristic. Repeating units sacromeres. Also has sacroplasmic reticulum running parallel to
myofibrils.
3) Because of the alternating actin and myosin myofilaments.
4) Cross bridge cycling. Myosin and actin interact to shorten and extend
sacromere – uses ATP.
5) Motor neurons use the neurotransmitter Acetylcholine to control
skeletal muscle. Ach is released from axon and transmitted to
receptors on muscle fiber – this allows for the transfer of messages.
6) Creatine Phospate – Cellular Respiration
7) Blood carries oxygen from the lungs to body cells on hemoglobin.
Myoglobin – in muscles – stores oxygen temporarily.
8) When cells don’t have enough oxygen – they will shift from aerobic to
anaerobic respiration – This will lead to a build up of lactic acid. This
will cause fatigue in muscles. Acid prevents muscle fibers from
responding to stimulation. Oxygen debt is amount of oxygen needed
to convert lactic acid to glucose.
9) Heat is a by-product of cellular respiration. Half of the energy
produced by cellular respiration is used for metabolism. The other
half becomes heat. Muscle tissue represents a large portion of body
mass.
10) Threshold stimulus – minimal strength required to cause contraction.
Phenomenon in which a muscle fiber completely contracts.
11) Twitch – brief muscular contraction followed by relaxation. Sustained
contraction – increases strength
12) Isotonic – where muscles shorten when they contract (lifting and
object). Isometric – tension within muscle increases, but muscles
remain the same length (pushing against a wall).
13) Slower twitch – always oxidative (produce ATP by C.R.) – resistant to
fatigue (red fibers) many mitochondria. Fast twitch – primarily
glycolic or primarily oxidative (white fibers) – fatigue more easily.
14) Origin – immovable end of muscle. Insertion – movable end.
15) Muscle primarily responsible for producing a reaction.
16) Muscles that contract and assist a prime mover. Muscles that resist a
prime mover and cause movement in the opposite direction. If prime
mover and antagonist contract simultaneously – the structure remains
rigid.