Exam #3 chapter 9 (Histology & physiology) Part 3 Flashcards
Types of skeletal muscle fibers
1) slow-twitch oxidative (SO) (Type I)
2) Fast twitch Oxidative Glycolytic (FOG) (Type IIa)
3) Fast twitch Glycolytic (FG) (Type IIb)
what type of myoglobin content does slow-twitch oxidative (Type I) have?
high
what type of myoglobin content does FOG (type IIa) have?
high
what type of myoglobin content does FG (type IIb) have?
low
does SO (type I) have many or few mitochondria?
many
does FOG (type IIa) have many or few mitochondria?
many
does FG (type IIb) have many or few mitochondria?
few
what type of metabolism does type I fibers have?
high aerobic capacity, low anaerobic capacity
what type of metabolism does type IIa fibers have?
intermediate aerobic capacity, high anaerobic capacity
what type of metabolism does type IIb fibers have?
low aerobic capacity, highest anaerobic capacity
what type of fatigue resistance does type I fibers have?
high
what type of fatigue resistance does type IIa fibers have?
intermediate
what type of fatigue resistance does type IIb fibers have?
low
what type of myosin ATPase activity do all three skeletal muscles have?
type I is slow and type II a and b are fast
what type of glycogen concentration do all three skeletal muscle fibers have?
type I is low and type II a and b are high
what location are type I fibers most abundant?
generally in postural muscles and more in lower limbs than upper limbs
what location are type IIa fibers most abundant?
generally in lower limbs
what location are type IIb fibers most abundant in?
generally in upper limbs
what is the function of type I fibers?
maintenance of posture and performance of endurance activities
what is the function of type IIa fibers?
endurance activities in endurance-trained muscles
what is the function of type IIb fibers?
rapid, intense movements of short duration
what are some characteristics of slow-twitch muscle fibers (type I)?
contract slowly but fatigue resistant.
since the myosin ATP kinase in Type I fibers are slow, what happens to the myosin heads?
they pivot slowly
what is ATP generated by in type I fibers?
aerobic metabolism
what are type I fibers surrounded by?
abundant capillaries
what are some characteristics of fast-twitch (type II) fibers?
they contract quickly and fatigue quickly
what does type IIa use for ATP generation?
both anaerobic and aerobic respiration
what does type IIb use for ATP generation?
anaerobic metabolism
what does the distribution of muscle fiber types vary between?
different muscles in an individual and between individuals
what can exercise cause for different muscle fibers?
hypertrophy and some type IIa and type IIb to convert to the other
what do skeletal muscles require a huge amount of for contraction?
ATP
what type of muscle fibers would be used for sprinting?
type IIa
what type of muscle fibers would a marathoner use?
type I
what type of muscle fiber would weight lifting use?
type IIb
since a muscle can hypertrophy in strength and endurance what can happen if a muscle is not used?
it can decrease or atrophy
what type of respiration does slow-twitch fibers generally use and for what?
aerobic respiration to generate ATP
what type of respiration does fast-twitch fibers generally use?
anaerobic respiration
what type of fibers and methods does any muscle contraction use?
both fiber types and both methods of ATP generation
what does anaerobic respiration do? (2) (QW)
1) quickly generate 2 ATP per glucose by glycolysis
2) will generate some lactic acid (lactate) with little oxygen available
what can lactate be metabolized to?
pyruvate or glucose
how is lactate metabolized to pyruvate or glucose?
by certain cells such as liver, heart, kidney, adipose tissue and skeletal muscle
where is most of the lactate metabolized?
in the liver
what does aerobic respiration do?
slowly generate 36 ATP per glucose
what does aerobic respiration require?
oxygen
what else can aerobic respiration use?
fats, amino acids or carbohydrates
which type of respiration is more efficient?
aerobic respiration
even though aerobic respiration is more efficient what is it not?
quicker, it takes longer
at rest what do skeletal muscles use?
fatty acids and aerobic respiration
at maximal contraction what do skeletal muscles use?
more anaerobic respiration
what do cells not store large amounts of?
ATP
what is creatine phosphate?
an energy storage molecule
what does creatine phosphate do?
quickly generate an ATP when needed for muscle contraction (8-10 seconds)
when is creatine phophsate created?
when a muscle is at rest from ATP
at rest what is ATP produced by?
aerobic respiration
what are small amounts of ATP used for during rest?
in muscle contractions that maintain muscle tone and posutre
what is excess ATP used for during rest?
to produce creatine phosphate
during exercise what is supplying the ATP
the ATP that’s already in the cell is used first but during moderate exercise aerobic respiration provides most of the ATP necessary for molecule contraction
during times of extreme exercise what provides small amounts of ATP that can sustain muscle contraction for brief periods?
anaerobic respiration
what can energy stores in creatine phosphate during exercise also be used to do?
produce ATP
throughout times of exercise what provides energy for active muscle contraction?
ATP from all of these sources (4-6)
when does muscle fatigue occur?
when muscles DON’T contract properly
what can muscle fatigue occur from?
from a lowered pH (acidosis)
what is a lowered pH in muscles due to?
lactic acid or ATP depeletion or decreased ATP production
what is the biggest cause of lactic acid or ATP depletion?
Type II fibers
besides lowered pH what are other causes for muscle fatigue?
1) oxidative stress
2) inflammation in heavily used muscles
3) psychological fatigue
what is oxidative stress characterized by?
build-up of excess reactive oxygen species (ROS; free radicals)
when muscle contraction beings what happens to respiration?
there is a small increase but less than required
what does the small increase of respiration during contraction cause?
oxygen deficit
after exercise is completed what happens to respiration?
there is an oxygen debt to be paid that requires increased respiration to restore pre-contraction conditions (recovery oxygen consumption)
what is recovery oxygen consumption?
the elevated oxygen consumption that occurs after exercise has ended
what the recovery oxygen consumption used for?
a portion is used to “repay” the oxygen deficit but most of it is used to support metabolic processes that restore homeostasis after it was disturbed.
how long does recovery oxygen consumption generally last?
minutes to hours
what does the time that recovery oxygen consumption lasts depend on?
on the individual’s physical conditioning and on the length and intensity of the exercise session.
in smooth muscle what are thin filaments attached to?
dense bodies
what are dense bodies in smooth muscle anchored in?
the plasma membrane
what are dense bodies in smooth muscle interconnected by?
intermediate filaments
how are the actin and myosin filaments arranged in smooth muscle?
they overlap
how are the actin and myosin filaments organized?
as loose bundles instead of sarcomeres
what happens with thin and thick filaments during contraction?
they slide
what is different about smooth muscle vs. skeletal muscle? (4) (NLSC)
1) no T tubules
2) less developed sarcoplasmic reticulum
3) stores calcium
4) calcium comes from the sarcroplasmic retiuculum and across sarcolemma to cause contraction
what type of contraction does smooth muscle have?
slow
why is contraction slower in smooth muscle?
it’s a longer process
what must calcium do first during smooth muscle contraction?
calcium must diffuse in the cell and out of the sarcoplasmic reticulum
after calcium is diffused out of the sarcoplasmic reticulum what must it bind to?
calmodulin
what does the binding of calcium and calmodulin have to active?
myosin kinase
what does the activation of myosin kinase during smooth muscle contraction have to do?
attach a phosphate group to the myosin head before it can bind to actin
what does smooth muscle no contain during muscle contraction that skeletal muscle does?
troponin and tropomyosin
what is relaxation in smooth muscle?
prolonged or sustained
during muscle relaxation in smooth muscle what must myosin phosphatase do?
remove a posphate from the myosin head
what does removing a phosphate while the cross bridge is formed do in smooth muscle?
sustain a contraction in the latch state and relaxation occurs more rapidly
what is the most common type of smooth muscle?
visceral smooth muscle
where does visceral smooth muscle occur?
in the digestive, urinary and reproductive tracts
what does the visceral smooth muscle that occur in the digestive, urinary and reproductive tracts appear as?
sheets in the walls of the hollow organs
in visceral smooth muscle what is true of the fibers?
only a few are innervated and most are connected by gap junctions
what does the gap junctions that connect most visceral smooth muscle allow?
the tissue to function as a unit
what do some tissues have in visceral smooth muscle?
pacemaker cells
what does pacemaker cells in some visceral smooth muscle do?
cause the tissue to contract periodically (autorhythmicity)
what does stimulation by any signal cause in visceral smooth muscle?
causes entire tissue to contract
what does contraction of a muscle depend on?
where the muscle is
where does the other less common type of smooth muscle, multiunit smooth muscle found?
in the muscles inside the eye, the arrector pilli muscles and blood vessel walls
what are some characteristics of multiunit smooth muscle? (4) (AINA)
1) arranged into motor units
2) innervated
3) no connected by gap junctions
4) allows for precise control of the smooth muscle
what are some functional properties of smooth muscle that are not seen in skeletal?
1) some smooth muscle is autorhythmic
2) when smooth muscle is stretched quickly it tends to contract
3) when smooth muscle is stretched slowly it maintains a constant tension (smooth muscle tone)
4) the tension generated is constant over a large range of length
why is the tension generated of smooth muscle constant over a large range of length?
there no sarcomeres
what innervates smooth muscle?
the autonomic nervous system (ANS)
what does the ANS neurotransmitters acetylcholien and norepinephrine cause in smooth muscle?
contraction or relaxation depending on the neurotransmitter receptor
what do certain hormones stimulate during smooth muscle contraction?
oxytocin
what is oxytocin used for?
stimulates contraction of uterine smooth muscle especially during childbirth
what affects smooth muscle contraction?
many local chemical substances
what are cardiac muscle cells connected by?
intercalated disks with gap junctions
how is calcium moved in cardiac muscle?
it comes across the sarcolemma and out of the sarcoplasmic reticulum
compared to skeletal muscle, what is true of cardiac muscle?
it contracts much longer than a skeletal muscle twitch
unlike skeletal muscle what is true or contractions?
not every depolorization of the sarcolemma produces a contraction
what can certain signals do in smooth muscle?
open calcium channels in the sarcolemma and cause a contraction without depolorizing the sarcolemma
