Muscular system Flashcards
what are the two types of muscles
smooth and striated
what type of muscle are skeletal and cardiac
striated
what is the reason for the striation
sarcomere
what is the order of organization of skeletal muscle
tendon –> muscle –> fascicles –> myofibers –> myofibrils –> filaments
what is the outermost layer of the muscle
epimysium
what is the outermost layer of the fascicles
perimysium
what is the outermost layer of the muscle fiber/lays in between fibers
endomysium
what is the distinct feature of the skeletal muscle
it it multi-nucleated
why does the skeletal muscle cell have multiple nuclei
the myoblasts - which each have a nucleus fuse together to form the muscle cell
why is the myofibril super long
the muscle cells fusing together
what is the outermost contractile layer of the muscle fiber
sarcolemma
what does the sarcolemma enclose
sarcoplasm
what are T-tubules integrated through
sarcoplasm
what travels through the T-tubules
action potentials
what is the sarcoplasmic reticulum filled with
Calcium
which receptors in the sarcoplasm are voltage gated
dihydropyridine
what do ryanodine receptors do
they let Ca2+ pass through the sarcoplasmic reticulum (SR)
what are myofibrils made of
sarcomeres
what is the structural and functional unit of the striated muscle
sarcomere
what makes the muscle contract (in the simplest term)
thin filaments sliding over the thick filaments
what band causes dark bands
A bands
what band causes light bands
I bands
what is the A band
thick and thin filaments overlap
what is the I band
thin filaments only
what is the M line
where all the thick filaments stem from/connect
what makes up the thick filament
myosin molecules
what characteristics does the myosin contain
2 heads and a tail
which way does the myosin tail face
toward the A band
how does the myosin “power stroke” forward
ATP binds and gives myosin head energy to move forward
when does myosin go forward
when it binds to actin
what are the thin filaments composed of
actin
what controls actin and myosin interactions
regulatory proteins
what is tropomyosin
a long protein that spans actin
what is it called when tropomyosin overlaps
head to tail overlap region
what protein is at the overlap region of the actin and myosin
troponin
what are the subunits of troponin
TnC, TnI, TnT
what does TnC do
binds calcium
TnI
inhibits by binding to actin to prevent myosin from binding
TnT
teathers TnC and TnI to tropomyosin
how will actin and myosin interact
there has to be changes in complex
What happens when calcium binds to TnC
hydrophobic pocket is revealed; TnI moves away and interacts with TnC instead of actin
what happens during structural changes of troponin complex
tropomyosin moves along actin which allows for actin and myosin to interact
what causes the cross bridge to move from blocked to just closed
Ca2+ binds to TnC
what causes tropomyosin to be pushed away
cross-bridges binding
what causes troponin complex to be moved to open state
cross bridges pushing tropomyosin further away
what causes weakly bound cross bridge to go to strongly bound
inorganic phosphate is released
what happens when myosin pulls back on actin (thin filament)
sarcomere contracts
what causes myosin and actin to detach
ATP kicks out ADP
where does an efferent neuron carry signals to and from
carries them from CNS to neuromuscular junction
what does the signal being carried to neuromuscular junction result in
depolarization
in excitation-contraction coupling what causes threshold to be reached
Na channels open
what do the vesicles contain in excitation contraction coupling
acetylcholine
in excitation-contraction coupling what causes the vesicle to release Ash
SNARE complex
what does the ACh travel through in excitation and relax. coupling
ligand-gated channels
in excitation-contraction coupling what does the binding of ACh cause
sodium enters muscle cell
in excitation-contraction coupling what does the influx of Na+ lead to in the cell
depolarization
in excitation-contraction coupling what causes Na+ channel to close
inactivation gate closes
in excitation-contraction coupling what channels open after Na+ channels close
K+ channels
in excitation-contraction coupling what is the result of K+ channels opening
K+ flows out which leads to rapid depolarization
in excitation-contraction coupling what causes hyperpolarization
K+ channels closing slowly
what activates the dihydropyridine receptors
action potential traveling down T-tubule
what do dihydropyridine receptor interacts with
ryanodine
what is the result of dihydropyridine receptors interacting with ryanodine receptors
Calcium is released from S.R.
What happens to calcium after it is released from S.R.
it binds to TnC in the troponin complex
what are the three things that cause sarcomere/muscle relaxation
ACh isn’t present because it is broken down, myosin detaches from actin via ATP, calcium is moved back into SR via SERCA pump
main feature of smooth muscle
involuntary control
where is smooth muscle found
body cavities and blood vessels
what is the shape and size of smooth muscle
spindle and small
what is the difference in nuclei between smooth and striated
striated has multiple, smooth has one
what is the main difference in strained and smooth muscle
smooth doesn’t have sarcomeres, t-tubules, myofibrils, etc.
how are thick filaments organized in smooth muscle
they’re scattered
where do thin and thick filament overlap
dense bodies
how does smooth muscle contract without sarcomeres
thick and thin filaments slide over each other
how does the entire tissue contract
one muscle cell pulls on the neighboring one
what are bulges in smooth muscle called
varocosities
where are the bulges in smooth muscle found
in axons that innervate smooth muscle cells
what do ligand gated channels in smooth muscle activate
voltage gated calcium channels
what do the neurotransmitters from the varicosities bind to
ligand gates ion channels
what does the opening of voltage gates Ca2+ channels in smooth muscle result in
Calcium moves in to smooth muscle cells –> contraction
two types of smooth muscle cells
multiunit and visceral (single unit)
how do multiunit smooth muscle cells work
each motor neuron innervates its own smooth muscle cell
how does a single unit smooth muscle cell work
motor neuron innervates just one cell
how are multiunit smooth m. cells regulated
by hormones ex) fight or flight
where are single unit smooth m. cells found
digestive/urinary tract
what are single unit smooth m. cells activated by
stretch
main similarity of cardiac muscle and skeletal muscle
myofibrils causing striation
differences of cardiac and skeletal muscle
cardiac muscle is smaller
what is the purpose of the cardiac muscle being small and branched
allows heart to contract and relax as a single unit
how are cardiomyocytes linked
intercalated discs
what are the types of cell junctions in intercalated discs
gap junctions and desmosomes
types of cells in the heart
contractile cells and autorhythmic cells
what is the purpose of desmosomes
mechanical support (destiny wants to be a mechanical engineer)
how does an AP move down heart
through contractile cells to gap junctions which results in contraction
what ion has a higher concentration inside the cell
K+ - which is why it leaves the cell during depolarization
types of metabolism
catabolism and anabolism
what is it called when molecules are broken down to extract energy
catabolism
what is it called when metabolic reactions synthesize building blocks to make new molecules
anabolism
what is the stored energy in muscles called
glycogen
what is the equation for photosynthesis
CO2 + water + energy from sun –> carbs + O2
where is chemical energy contained in photosynthesis
between bonds of atoms
what is the main idea of how our bodies get energy
they extract it from the carbon bonds to make ATP
what phosphate does ATP come from
The third/last phosphate
4 main pathways our body gets energy
glycolysis, pyruvate to acetyl coa, citric acid cycle, electron transport chain
what is glucose splitting
6-carbon glucose splits into two 3-carbon pyruvate molecules
what is the end products of glycolysis
2 pyruvate molecules and 4 ATP molecules
how many carbon atoms does pyruvate have
3
where does glycolysis take place
cytosol
what are the anaerobic pathways
glycolysis and pyruvate to acetyl coa or lactate
what does glycolysis require to take place
2 ATP molecules
what picks up electrons in glycolysis
NADH+
what can pyruvate convert to
acetyl CoA or lactate
what determines what pyruvate is converted into
amount of O2 available
where is lactate taken
liver
what happens to lactate in the liver
it’s converted back into glucose
how much net ATP is generated when glucose converts to pyruvate
2 ATP
what does pyruvate convert to when oxygen is available
acetyl CoA
how many acetyl coa molecules are produced from the 2 pyruvate from glycolysis
2 molecules
What happens to the 3 carbons in pyruvate
1 goes towards CO2 and the other 2 are linked to co-enzyme A to form acetyl CoA
what do the carbons from pyruvate bind with to make acetyl CoA
enzyme A
what is the substrate and also an end product of the citric acid cycle
oxaloacetate
what happens to the carbons in the citric acid cycle
the two from acetyl CoA bind with 4 from oxaloacetate to form 6 in citric acid
what happens to the 2 carbons that moved from acetyl CoA to citric acid
the convert to CO2
what does the citric acid cycle produce
GTP, 1 ATP, 1 NADH, 2 FADH, oxaloacetate (regenerated)
how many times does the critic acid cycle occur
2 times
why does the critic acid cycle occur twice
because it starts with ONE acetyl CoA but glycolysis makes two pyruvate which makes TWO acetyl CoA
what depletes the electrons of energy in the ETC
oxygen baskets
What does oxygen do in the ETC
picks up E- and combines with H+ to make water
what would happen if there wasn’t O2 in the ETC
ATP production would stop
how many complexes does the ETC have
4
where does NADH give its electrons to
complex 1
where does FADH2 give its electrons to
complex 2
how do electrons move energy levels when being passed down the ETC
they move from higher to lower energy levels as they release energy
how does H+ move into inter membrane space
as e- move from one complex to another, they pump H+ through
how does the electrochemical gradient occur
H+ being moved into intermembrane space means higher concentration of H+
what does the electrochemical gradient do to H+ ions
it moves it back into matrix
how do the H+ ions get back into matrix
atp synthase
what happens once H+ ions move back into matrix
they bond with O2 to make H2O
what is happening to the ATP synthase as H+ ions move through it
it rotates
what does the rotation of ATP synthase cause to happen
creates binding sites for ADP to bind to Pi to make ATP
what is the structure of lipids
glycerol backbone (3 carbon), each carbon is linked to a fatty acid
what is the function of lipase
breaks down glycerol backbone in to the 3 carbons
what happens to the 3 carbons that were broken down by lipase
they can enter glycolysis
what happens to the fatty acids that were broken down by lipase
they can be converted into acetyl-CoA
what is it called when acetyl CoA is made from fatty acids
beta oxidation
where does beta oxidation take place
mitochondria
what happens to the two end carbons that are cut off in beta oxidation
they link with CoA to make acetyl CoA
how does beta oxidation fuel ATP synthesis
acetyl-CoA enters critic acid cycle which goes to ETC
what is the function of carnitine
transports FFA across mitochondrial membrane to beta oxidation
when does the body make energy from proteins
starvation
what are proteins broken down into
amino acids
what happens to the amino group
deamination - strips off amino acid
what is left after deamination
carbon skeleton
what does the carbon skeleton enter
catabolic pathway
what determines how much ATP is created by the carbon skeleton
what pathway it enters
what does the breakdown of amino acids yield
urea, CO2, water, and ATP
How do we know what nutrient is being used to generate ATP
respiratory quotient
what is the equation for RQ
CO2 exhaled / O2 being used
what are the RQ values for the nutrients
carbs - 1, pro - 0.8, fat - 0.7
why does pro and fat have a smaller RQ
they require more O2 to make CO2 and water = denominator is smaller
how is creatine phosphate made
via amino acids
where is creatine phosphate created, stored, and excreted
made in the liver, stored in the muscles, excreted in the kidneys
what do the kidneys excrete in the creatine phosphate system
creatinine
what fuel are you using during rest
carbs and fat
what fuel are you using during an initial burst
creatine phosphate
what fuel are you using during anaerobic
carbs
what are you doing if your RQ level is at 0.8
resting
what type of muscle fiber for long distance
slow fibers
what type of muscle fiber for a sprint
fast fibers
what differentiates muscle fibers
size, blood vessels, how fuel is used, contraction speed, fatigue resistance
where does myoglobin mostly store O2
slow fibers
how to change muscle fibers
conditioning or genetics
what muscle fibers are in white meat
fast fibers to flee predators
what muscle fibers are in red meat
slow fibers to stand around
what is it called when the muscle can’t perform any longer
muscle fatigue
what is the main reason for muscle fatigue
metabolic reserves are depleted
what are some characteristics of muscle fatigue
increase in lactic acid, decrease in enzyme activity (acetyl coa binding), decreases in Ca2+ binding to TnC
what are the 3 reasons for DOMS
- tears in muscle tissue = loss of enzymes
- muscle spasms
- CT and tendon tears
what helps doms
stretching
what happens to muscle fibers as we age
decrease in size, elasticity, ability to recover
two main types of muscle contraction
isotonic and isometric
what are the two types of isotonic muscle contraction
concentric and and eccentric
how can we change the force produced by muscle
recruitment of motor units, twitch summation, force-length relationship
what is a motor unit
a motor neuron and all the fibers it innervates
characteristics of small motor units
few myofibers, slow twitch, fatigue resistant
characteristics of large motor units
few myofibers, fast twitch, fatigues quickly
why does force go back down in between twitches
Ca2+ goes back in to S.R.
what happens when the cardiac muscle is first stimulated
Na+ channels open causing depolarization
what causes plateau in cardiac muscle action potential
Ca2+ influx balanced by K+ efflux
what leads to repolarization of cardiac muscle action potential
K+ efflux and Ca2+ channels close
which muscle experiences summation
skeletal, not cardiac
what is force generated proportional to
of actin and myosin interactions
what limb does cardiac muscle experience force
ascending
what limb does skeletal muscle experience force
plateau
what type of muscle experiences a more dramatic increase in force with a sarcomere length change
cardiac - because the muscle is smaller
