SLCC PHYSIOLOGY EXAM #3 (CH. 12-
16) QUESTIONS AND ANSWERS
Sarcolemma - Answer-surrounding cell membrane around muscle
Sarcoplasmic reticulum - Answer-The smooth ER of a muscle cell, Ca2+ reservoir,
around each myofibril in the muscle cell.
myofibrils - Answer-bundle of contractile proteins within muscle
sarcomere - Answer-functional unit of muscle within myofibrils
Z lines - Answer-dense set of proteins, has actin protein
M line - Answer-not quite as dense, myosin protein stays in the middle
A band - Answer-from one end to another of myosin, partial overlap of actin/myosin
H zone - Answer-only where myosin, no overlap of actin in M line
I band - Answer-one end of myosin in one sarcomere, only overlap of actin, no myosin
myosin - Answer-thick filaments. shortens both sides of myofibril, pulls actin toward M
line, decreases H zone, shortens I band
actin - Answer-thin filaments. made of subunits, has myosin binding sites
tropomyosin - Answer-controlled by actin, long filament, when muscle is relaxed, covers
binding sites of actin
troponin - Answer-changes shape when Ca binds to it. pulls tropomyosin from binding
sites and exposes actin binding sites. controlls tropomyosin
Ca controls ___________ - Answer-contraction
titin - Answer-acts like anchor to anchor myosin to z lines on both sides
sliding filament model - Answer-The idea that muscle contraction is based on the
movement of thin (actin) filaments along thick (myosin) filaments, shortening the
sarcomere
Cross-bridge cycle - Answer-myosin grabs actin, pulls actin toward cent of sarcomere
(towards m line), ATP provides energy to detach myosin head and cock it back to
original shape, process repeats.
, No calcium- no contraction
No ATP- no release
excitation-contraction coupling of skeletal muscle - Answer--depolarization of
sarcolemma (excitation)
-depolarization of T-tubule
-DHP receptors in membrane respond to voltage change
-release of calcium from sarcoplasmic reticulum
-calcium binds to troponin which moves topomyosin away from the binding sites
-cross bridge cycle (contraction of muscle)
Does skeletal muscle have pacemaker cells? - Answer-No
termination of contraction - Answer-calcium gets pumped quickly back into SR, stops
sending signal
isometric and isotonic twitches - Answer-...
summation and tetanus - Answer-1. summation is where muscle contractions combine
and become stronger and more prolonged
2. tetatnus is the continous sustained contraction where muscle cannot relax. will
release if maintained.
fiber diameter - Answer-increased diameter --> increased myofibrils in parallel -->
increased force production
length and tension - Answer-Max length that skeletal muscle can be stretched
(stretched too far it loses the ability to contract b/c actin and myosin heads are too far to
bind)
motor units - Answer-a single motor neuron and all muscle fibers innervated by it
muscle recruitment - Answer-increase in the # of motor units being used to increase
strength of contraction
What are the 3 muscle fiber types? - Answer-Slow oxidative, fast oxidative, fast
glycolytic
Slow oxidative - Answer-Makes a lot of ATP, fatiques slowly, has to have oxygen, small
diameter, little tension, darkest color. Lots of blood taking oxygen using myoglobin.
Fast oxidative - Answer-Makes a lot of ATP, fatigues slowly, pretty fast but not as fast
as fast glycolytic, carries myoglobin, medium diameter, medium color.
Fast glycolytic - Answer-Not making a lot of ATP, fatigues quickly, fast, doesnt use
oxygen- only glycolysis, light color, large diameter
16) QUESTIONS AND ANSWERS
Sarcolemma - Answer-surrounding cell membrane around muscle
Sarcoplasmic reticulum - Answer-The smooth ER of a muscle cell, Ca2+ reservoir,
around each myofibril in the muscle cell.
myofibrils - Answer-bundle of contractile proteins within muscle
sarcomere - Answer-functional unit of muscle within myofibrils
Z lines - Answer-dense set of proteins, has actin protein
M line - Answer-not quite as dense, myosin protein stays in the middle
A band - Answer-from one end to another of myosin, partial overlap of actin/myosin
H zone - Answer-only where myosin, no overlap of actin in M line
I band - Answer-one end of myosin in one sarcomere, only overlap of actin, no myosin
myosin - Answer-thick filaments. shortens both sides of myofibril, pulls actin toward M
line, decreases H zone, shortens I band
actin - Answer-thin filaments. made of subunits, has myosin binding sites
tropomyosin - Answer-controlled by actin, long filament, when muscle is relaxed, covers
binding sites of actin
troponin - Answer-changes shape when Ca binds to it. pulls tropomyosin from binding
sites and exposes actin binding sites. controlls tropomyosin
Ca controls ___________ - Answer-contraction
titin - Answer-acts like anchor to anchor myosin to z lines on both sides
sliding filament model - Answer-The idea that muscle contraction is based on the
movement of thin (actin) filaments along thick (myosin) filaments, shortening the
sarcomere
Cross-bridge cycle - Answer-myosin grabs actin, pulls actin toward cent of sarcomere
(towards m line), ATP provides energy to detach myosin head and cock it back to
original shape, process repeats.
, No calcium- no contraction
No ATP- no release
excitation-contraction coupling of skeletal muscle - Answer--depolarization of
sarcolemma (excitation)
-depolarization of T-tubule
-DHP receptors in membrane respond to voltage change
-release of calcium from sarcoplasmic reticulum
-calcium binds to troponin which moves topomyosin away from the binding sites
-cross bridge cycle (contraction of muscle)
Does skeletal muscle have pacemaker cells? - Answer-No
termination of contraction - Answer-calcium gets pumped quickly back into SR, stops
sending signal
isometric and isotonic twitches - Answer-...
summation and tetanus - Answer-1. summation is where muscle contractions combine
and become stronger and more prolonged
2. tetatnus is the continous sustained contraction where muscle cannot relax. will
release if maintained.
fiber diameter - Answer-increased diameter --> increased myofibrils in parallel -->
increased force production
length and tension - Answer-Max length that skeletal muscle can be stretched
(stretched too far it loses the ability to contract b/c actin and myosin heads are too far to
bind)
motor units - Answer-a single motor neuron and all muscle fibers innervated by it
muscle recruitment - Answer-increase in the # of motor units being used to increase
strength of contraction
What are the 3 muscle fiber types? - Answer-Slow oxidative, fast oxidative, fast
glycolytic
Slow oxidative - Answer-Makes a lot of ATP, fatiques slowly, has to have oxygen, small
diameter, little tension, darkest color. Lots of blood taking oxygen using myoglobin.
Fast oxidative - Answer-Makes a lot of ATP, fatigues slowly, pretty fast but not as fast
as fast glycolytic, carries myoglobin, medium diameter, medium color.
Fast glycolytic - Answer-Not making a lot of ATP, fatigues quickly, fast, doesnt use
oxygen- only glycolysis, light color, large diameter
