Ch11 Muscular Tissue Flashcards
1
Q
Skeletal Muscle
- attached to…
- _____ - _____ control
- _____ - alternating ____ & _____ bands (results from overlapping internal ______)
A
Skeletal Muscle
- attached to BONE(S)
- VOLUNTARY - CONSCIOUS control
- STRIATIONS - alternating LIGHT & DARK bands (results from overlapping internal CONTRACTILE PROTEINS)
2
Q
Muscle cell =
- as long as…
A
Muscle cell = muscle fiber (myofiber)
- as long as 30cm
3
Q
What are the universal characteristics of muscle?
A
- Responsiveness (excitability)
- Conductivity
- Extensibility
- Elasticity
- Contractility
4
Q
How is muscle responsive/excitable?
A
Reponsive/excitable to chemical signals, stretch, and electrical changes across plasma membrane
5
Q
How is muscle conductive?
A
Local electrical change triggers excitation wave that travels along muscle fiber
6
Q
How is muscle extensible?
A
Capable of being stretched between contractions
7
Q
How is muscle elastic?
A
Returns to original resting length after being stretched
8
Q
How is muscle contractable?
A
Shortens when stimulated
9
Q
Connective Tissue Elements
- perimysium surrounds…
- epimysium surrounds…
- endomysium surrounds…
A
Connective Tissue Elements
- perimysium surrounds MUSCLE FASCICLES
- epimysium surrounds ENTIRE MUSCLE
- endomysium surrounds MUSCLE CELLS
10
Q
Connective Tissue Elements
Tendons attach ____ to ____; lots of ____
- _____ slightly under ____, ____ when ____
- resists _______, protects ____ from ___
- returns ____ to its _____
A
Connective Tissue Elements
Tendons attach MUSCLE to BONE; lots of COLLAGEN
- STRETCHES slightly under TENSION, RECOILS when RELEASED
- resists EXCESSIVE STRETCHING, protects MUSCLE from INJURY
- returns MUSCLE to its RESTING LENGTH
11
Q
Muscle Fiber (Cell)
- Sarcolemma =
- Sarcoplasm =
- Glycogen =
- Myoglobin =
- Multiple Nuclei = (due to ___ of several ___)
- Myofibrils =
A
Muscle Fiber (Cell)
- Sarcolemma = PLASMA MEMBRANE
- Sarcoplasm = CYTOPLASM
- Glycogen = STORED TO PROVIDE ENERGY
- Myoglobin = RED PIGMENT, STORES O₂ FOR MUSCLE ACTIVITY
- Multiple Nuclei = FLATTENED, PRESSED AGAINST INSIDE OF SARCOLEMMA (due to FUSION of several MYOBLASTS)
- Myofibrils = LONG PROTEIN BUNDLES WITHIN A SARCOPLASM
12
Q
Muscle Fiber
- Sarcoplasmic Reticulum (SR) - __ ER, network ___ each ____: ____ reservoir
- Terminal Cisternae - ______ of SR
- T Tubules - tubular ____ of ____, penetrate through ____, emerge _____
- Triad - _____ + _____
A
Muscle Fiber
- Sarcoplasmic Reticulum (SR) - SMOOTH ER, network AROUND each MYOFIBRIL: CALCIUM reservoir
- Terminal Cisternae - DILATED END-SACS of SR
- T Tubules - tubular INFOLDINGS of SARCOLEMMA, penetrate through CELL, emerge ON OTHER SIDE
- Triad - T TUBULE + 2 TERMINAL CISTERNS
13
Q
Myofilaments
- thick filaments: ___ - 500____ molecules
- ______ (like golf clubs) ____
- ___ directed ____ in ___ array around ___
- ___ zone with no ____ in ____
A
Myofilaments
- thick filaments: 200 - 500 MYOSIN molecules
- 2 CHAINS (like golf clubs) INTERTWINED
- HEADS directed OUTWARD in HELICAL array around BUNDLE
- BARE zone with no HEADS in MIDDLE
14
Q
Myofilaments
- Thin filaments - ____ strands of _____
- string of _____ subunits; have ____ to bind ___ of ___
- tropomyosin molecules - ____ active sites on ____
- troponin molecule - ____, Ca+2 _____ on each _____ molecule
A
Myofilaments
- Thin filaments - 2 INTERTWINED strands of FIBROUS (F) ACTIN
- string of GLOBULAR (G) ACTIN subunits; have ACTIVE SITE to bind HEAD of MYOSIN
- tropomyosin molecules - BLOCK active sites on G ACTIN
- troponin molecule - SMALL, Ca+2 BINDING PROTEIN on each TROPOMYOSIN molecule
15
Q
A
16
Q
Myofilaments
Elastin filaments
- titin (____): ___ springy ____
- ___ each ____ filament, ___ it to ____
- ____ thick filament, ____ it betweeen ____
- prevent ____
A
Myofilaments
Elastin filaments
- titin (CONNECTIN): HUGE, springy PROTEIN
- FLANK each THICK filament, ANCHOR it to Z DISC
- STABILIZES thick filament, CENTERS it betweeen THIN FILAMENTS
- prevent OVERSTRETCHING
17
Q
Myofilament
- contractile proteins- ___ & ____
- regulatory proteins - ___ & ____
- determine ___ and ___ of ____
- _____ released from _____ binds to ____
- ___ moves ____ off _____ on ___
- accessory proteins
- anchor ____
- regulate _____
A
Myofilaments
- contractile proteins- MYOSIN & ACTIN
- regulatory proteins - TROPOMYOSIN & TROPONIN
- determine START and STOP of CONTRACTION
- CA+2 released from SARCOPLASM binds to TROPONIN
- TROPONIN moves TROPOMYOSIN off ACTIVE SITES on ACTIN
accessory proteins
- anchor MYOFILAMENTS
- regulate LENGTH
18
Q
Myofilaments
- dystrophin - most ____ important ______
- genetic defect =
A
Myofilaments
- dystrophin - most CLINICALLY important ACCESSORY PROTEIN
- genetic defect = MUSCULAR DYSTROPHY
19
Q
Striations
- A band =
- H band =
- M line =
- I band =
- Z disc = and ___
A
Striations
- A band = DARK, ANISOTROPIC
- H band = MIDDLE OF A BAND; THICK FILAMENTS ONLY
- M line = BISECTS H BAND
- I band = ALTERNATING LIGHTER BAND; ISOTROPIC
- Z disc = PROVIDES ACHORAGE FOR THIN FILAMENTS AND ELASTIC FILAMENTS and BISECTS I BAND
20
Q
A
21
Q
Striations
- sacromere - segment from ____ to ___
- _____ shorten because individual ____ shorten
- _____ ( _ lines) pulled ____, ____ and ___ filaments ___ past each other
- neither ___ nor ___ change ___ during ___
- only ____ of ___ changes
A
Striations
- sacromere - segment from Z DISC to Z DISC
- MUSCLE CELLS shorten because individual SACROMERES shorten
- Z DISC ( Z lines) pulled CLOSER TOGETHER, THICK and THIN filaments SLIDE past each other
- neither THICK nor THIN change LENGTH during SHORTENING
- only AMOUNT of OVERLAP changes
22
Q
NERVE - MUSCLE RELATIONSHIP
- somatic motor neurons - serve ____
- ____ of _____ = somatic ___ fibers; lead to ____
- motor unit = one nerve fiber + _____
A
NERVE - MUSCLE RELATIONSHIP
- somatic motor neurons - serve SKELETAL MUSCLE
- AXONS of MOTOR NEURONS = somatic MOTOR fibers; lead to SKELETAL MUSCLE
- motor unit = one nerve fiber + ALL MUSCLE FIBERS IT INNERVATES
23
Q
Motor Units
- average motor unit = ____ for each motor unit
- small motor units = ___degree of ____ ( __ - ___ muscle ___ per ___; ___ & ___ muscle)
- large motor units = more ____ than ___ (gastrocnemius has 1,000 ____ per ___)
A
Motor Units
- average motor unit = 200 MUSCLE FIBERS for each motor unit
- small motor units = FINE degree of CONTROL ( 3 - 6 muscle FIBERS per NEURON; EYE & HAND muscle)
- large motor units = more STRENGTH than CONTROL (gastrocnemius has 1,000 MUSCLE FIBERS per NEURON)
24
Q
Neuromuscular Junction (NMJ)
- NMJ = _____ between ____ and ____ (cell)
- Acetylcholine (ACh) is ____ from _____
*
A
Neuromuscular Junction (NMJ)
- NMJ = FUNCTIONAL CONNECTION between NERVE FIBER and MUSCLE FIBER (cell)
- Acetylcholine (ACh) is RELEASED from NERVE FIBER
25
Q
Components of NMJ
- synaptic knob = __ end of ___
- synaptic cleft = tiny ___ between ___ and ___
- basal lamina = thin ____ + ____ layer over all _____
- junctional folds = region of ____ (increases ___ and has ____)
*
A
Components of NMJ
- synaptic knob = SWOLLEN end of NERVE FIBER
- synaptic cleft = tiny GAP between NERVE and MUSCLE
- basal lamina = thin COLLAGENOUS + GLYCOPROTEIN layer over all MUSCLE FIBER
- junctional folds = region of SARCOLEMMA (increases SURFACE AREA and has ACETYLCHOLINESTERASE)
26
Q
Electrically Excitable Cells
- ______ and neurons are _______ cells
- ____ membrane is ___ or ___ - high concentration NA+ ______, but K+ (other ___) ____
- ______ in ____ across ___ = ______ (RMP; __ mV cell)
A
Electrically Excitable Cells
- MUSCLE FIBERS and neurons are ELECTRICALLY EXCITABLE cells
- PLASMA membrane is POLARIZED or CHARGED - high concentration NA+ OUTSIDE CELL, but K+ (other ANIONS) INSIDE CELL
- DIFFERENCE in CHARGE across MEMBRANE = RESTING MEMBRANE POTENTIAL (RMP; -90 mV cell)
27
Q
Electrically Excitable Cells (Muscle and Neurons)
- _____ of _____ charge at ____ (thus it is ___ or _____)
A
Electrically Excitable Cells (Muscle and Neurons)
- IMBALANCE of ELECTRICAL charge at PLASMA MEMBRANE (thus it is CHARGED or ELECTRICALLY UNSTABLE)
28
Q
Muscle Contraction and Relaxation
- 4 actions involved in this process
- Excitation = ____ potentials lead to _____ potentials in ______
- Excitation-contraction coupling = ___ potentials on _____ activate ____
- Contraction = ____ of ____ fiber
- Relaxation = return to ___
A
Muscle Contraction and Relaxation
- 4 actions involved in this process
- Excitation = NERVE ACTION potentials lead to ACTION potentials in MUSCLE FIBER
- Excitation-contraction coupling = ACTION potentials on SARCOLEMMA activate MYOFILAMENTS
- Contraction = SHORTENING of MUSCLE fiber
- Relaxation = return to RESTING LENGTH
29
Q
Excitation Steps 1 & 2
- ____ signals opens voltage-gated ___ channels in ___ terminal
- ___ stimulates ____ of ACh from _____
- ACh released into ____
A
Excitation Steps 1 & 2
- NEURAL signals opens voltage-gated CA+2 channels in AXON terminal
- CA+2 stimulates EXOCYTOSIS of ACh from SYNAPTIC VESICLES
- ACh released into SYNAPTIC CLEFT
30
Q
Excitation Steps 3, 4
- ACh molecules bind to _____, open ___ & ___ channels
- ___ enters; shifting RMP from __mV to __mV, then __ exits, RMP returns to __mV; quick voltage shift = ______ (__)
A
Excitation Steps 3, 4
- ACh molecules bind to RECEPTOR PROTEIN, open NA+ & K+ channels
- NA+ enters; shifting RMP from -90mV to +75mV, then K+ exits, RMP returns to -90mV; quick voltage shift = END-PLATE POTENTIAL (EPP)
31
Q
Excitation Step 5
- ______ (EPP) in end-plate region ____ nearby ______ channels
- produces _____ (__) that spreads over ____
A
Excitation Step 5
- VOLTAGE CHANGE (EPP) in end-plate region OPENS nearby VOLTAGE-GATED channels
- produces ACTION POTENTIAL (AP) that spreads over MUSCLE SURFACE
32
Q
Excitation - Contraction Coupling steps 6, 7
- ___ spreads down into ___
- opens ____ ion channels in ____ and CA+2 channels in ___
- CA+2 enters ___
*
A
Excitation - Contraction Coupling steps 6, 7
- AP spreads down into T TUBULES
- opens VOLTAGE-GATED ion channels in T TUBULES and CA+2 channels in SR
- CA+2 enters CYTOSOL
33
Q
Excitation - Contraction Coupling Steps 8, 9
- CA+2 binds to ____ in thin ___
- ______ complex changes ____, exposes active sites on ___
A
Excitation - Contraction Coupling Steps 8, 9
- CA+2 binds to TROPONIN in thin FILAMENTS
- TROPONIN-TROPOMYOSIN complex changes SHAPE, exposes active sites on ACTIN
34
Q
Contraction Steps 10, 11
- ____ ATPase in ___ head ____ ATP
- activates head “___” it in ___ position (ADP + Pi remain ___)
- head binds to ____ active site forming a ____-actin ___ - bridge
A
Contraction Steps 10, 11
- MYOSIN ATPase in MYOSIN head HYDROLYZES ATP
- activates head “COCKING” it in EXTENDED position (ADP + Pi remain ATTACHED)
- head binds to ACTIN active site forming a MYOSIN-actin CROSS-bridge
35
Q
Contraction Steps 12, 13
- ___ head releases ADP & ___, flexes, pulls thin ____ past thick — ____
- upon binding more ATP, ____ releases ____; process _____ (each ___ performs # ____/second)
A
Contraction Steps 12, 13
- MYOSIN head releases ADP & Pi, flexes, pulls thin FILAMENT past thick — POWER STROKE
- upon binding more ATP, MYOSIN releases ACTIN; process REPEATS (each HEAD performs 5 STROKES/second)
36
Q
Relaxation Steps 14, 15
- ____ stimulation, ACh release ____
- AChE ___ down ACh, fragments _____ into _____ knob
*
A
Relaxation Steps 14, 15
- NEURAL stimulation, ACh release STOPS
- AChE BREAKS down ACh, fragments REABSORBED into SYNAPTIC knob
37
Q
Relaxation Step 16
- Ca+2 pumped back into ___ by _____
- Ca+2 binds to ____ while in storage in ___
- ATP for muscle ___ as well as muscle ____
A
Relaxation Step 16
- Ca+2 pumped back into SR by ACTIVE TRANSPORT
- Ca+2 binds to CALSEQUESTRIN while in storage in SR
- ATP for muscle RELAXATION as well as muscle CONTRACTION
38
Q
Relaxation Steps 17, 18
- Ca+2 removed from _____, pumped back into ____
- _____ reblocks active sites
- ____ ceases to produce or maintain _____
- _____ returns to its ______ (recoil of ___ components and contraction of _____ muscles)
A
Relaxation Steps 17, 18
- Ca+2 removed from TROPONIN, pumped back into SR
- TROPOMYOSIN reblocks active sites
- MUSCLE FIBER ceases to produce or maintain TENSION
- MUSCLE FIBER returns to its RESTING LENGTH (recoil of ELASTIC components and contraction of ANTAGONISTIC muscles)
39
Q
Length - Tension Relationship & Muscle Tone
- amount of _____ generated by ____ depends on ___ before it was ____
- overly contracted = ____ contraction results (____ too close to ___, cannot slide)
- too stretched = ___ contraction results (___ overlap of ___ and ___ does not allow many ____ to form)
- optum resting length produces ___ when muscle ___
(____ maintains optimal ___ to produce ___ or partial ___)
A
Length - Tension Relationship & Muscle Tone
- amount of TENSION generated by MUSCLE depends on LENGTH before it was STIMULATED
- overly contracted = WEAK contraction results (THICK FILAMENT too close to Z DISCS, cannot slide)
- too stretched = WEAK contraction results (LITTLE overlap of THICK and THIN does not allow many CROSS-BRIDGES to form)
- optum resting length produces GREATEST FORCE when muscle CONTRACTS
(CNS maintains optimal LENGTH to produce MUSCLE TONE or partial CONTRACTION)
40
Q
Muscle Twitch (Frog)
- threshold -___ voltage necessary to generate ______ and produce ___
- twitch - quick cycle of ____/____ when stimulus at ____ or ____ (
A
Muscle Twitch (Frog)
- threshold - MINIMUM voltage necessary to generate ACTION POTENTIAL and produce CONTRACTION
- twitch - quick cycle of CONTRACTION/RELAXATION when stimulus at THRESHOLD or HIGHER (<0.1 sec)
41
Q
Muscle Twitch Phases
- latent period = ___ms delay between onset of ____ and onset of ___ response
- contraction phase = ____ slide, muscle ___
- relaxation phase - __ quickly reabsorbs Ca2+, ___ releases thin ____, ____ declines (muscle returns to ___)
A
Muscle Twitch Phases
- latent period = 2ms delay between onset of STIMULUS and onset of TWITCH response
- contraction phase = FILAMENT slide, muscle SHORTENS
- relaxation phase - SR quickly reabsorbs Ca2+, MYOSIN releases thin FILAMENTS, TENSION declines (muscle returns to RESTING LENGTH)
42
Q
Contraction Strength of Twitches
- _____ stimuli produces ___
old quote: “muscle fiber obeys an all-or none law” meaning they contract to maximum or not at all … true?
- no… ___ vary in __
- depends on: Ca2+ ____, previous stretch of ____, temperature, __, hydration
- closer ____ produces stronger ____
A
Contraction Strength of Twitches
- THRESHOLD stimuli produces TWITCHES
old quote: “muscle fiber obeys an all-or none law” meaning they contract to maximum or not at all … true?
- no… TWITCHES vary in STRENGTH
- depends on: Ca2+ CONCENTRATION, previous stretch of MUSCLE, temperature, pH, hydration
- closer STIMULI produces stronger TWITCHES
43
Q
Contraction Strength of Twitches
- stimulating whole ___ with higher and higher voltages produces _____
- more motor units are recruited = _____ (__) summation (ex- lift glass of milk vs whole gallon)
A
Contraction Strength of Twitches
- stimulating whole NERVE with higher and higher voltages produces STRONGER CONTRACTIONS
- more motor units are recruited = MULTIPLE MOTOR UNIT (MMU) summation (ex- lift glass of milk vs whole gallon)
44
Q
Contraction of Twitches
- when stimulus ____ (voltage) is ___, twitch strength can ___ with stimulus ____
- low frequency (up to ___ stim/sec) - each stimulus produces ___ twitches, full ___ follows
- moderate frequency (__-__ stim/sec) - each twitch ___, but develops more ___ than previous = ___
- Ca+2 not completely back in __
- __ increases myosin ATPase ____ (___ twitches as ___ warms up)
A
Contraction of Twitches
- when stimulus INTENSITY (voltage) is CONSTANT, twitch strength can VARY with stimulus FREQUENCY
- low frequency (up to 10 stim/sec) - each stimulus produces IDENTICAL twitches, full RECOVERY follows
- moderate frequency (10-20 stim/sec) - each twitch RECOVERS, but develops more TENSION than previous = TREPPE
- Ca+2 not completely back in SR
- HEAT increases myosin ATPase EFFICIENCY (STRONGER twitches as MUSCLE warms up)
45
Q
Contraction Strength of Twitches
- higher freqency (__-__ stim/sec) - generates more strength of ____
- each stimulus arrives before last one ___, new twitch rides “piggy-back” on previous one, generates higher ___
- temporal (wave) summation - stimuli arriving ___
- incomplete tetanus = sustained ___ contractions
- maximum frequency (__-__ stim/sec) - __ has no time to ___ at all
- twitches ___ into smooth, prolonged ___ = ___ tetanus
- rarely occurs in the ___
A
Contraction Strength of Twitches
- higher freqency (20-40 stim/sec) - generates more strength of CONTRACTION
- each stimulus arrives before last one RECOVERS, new twitch rides “piggy-back” on previous one, generates higher TENSION
- temporal (wave) summation - stimuli arriving CLOSE TOGETHER
- incomplete tetanus = sustained FLUTTERING contractions
- maximum frequency (40-50 stim/sec) - MUSCLE has no time to RELAX at all
- twitches FUSES into smooth, prolonged CONTRACTION = COMPLETE tetanus
- rarely occurs in the BODY
46
Q
Isometric & Isotonic Contraction
- isometric muscle contraction
- develops ___ without changing ___
- important in ___ muscle function and ____ muscle joint ____
- isotonic muscle contraction
- changes in ___ with no change in ___
- concentric contraction = ___ while ___
- eccentric contraction = ___ while ___
A
Isometric & Isotonic Contraction
- isometric muscle contraction
- develops TENSION without changing LENGTH
- important in POSTURAL muscle function and ANTAGONISTIC muscle joint STABILIZATION
- isotonic muscle contraction
- changes in LENGTH with no change in TENSION
- concentric contraction = TENSION while SHORTENING
- eccentric contraction = TENSION while LENGTHENING
47
Q
Isometric and Isotonic Contraction
ISOMETRIC AND ISOTONIC PHASES OF LIFTING
- beginning - ___ phase (muscle tension ___ but muscles do not ___) ex, box not moving
- when ___ overcomes ____ of load (___ levels off)
- ___ beings to ___ - ___ phase (box being lifted)
A
Isometric and Isotonic Contraction
ISOMETRIC AND ISOTONIC PHASES OF LIFTING
- beginning - ISOMETRIC phase (muscle tension RISES but muscles do not SHORTEN) ex, box not moving
- when TENSION overcomes RESISTANCE of load (TENSION levels off)
- MUSCLE beings to SHORTEN - ISOTONIC phase (box being lifted)
48
Q
ATP Sources
- all _____ depends on ___
- pathways of ___ synthesis
- anaerobic formation (ATP production ___) - without ___, produces ___ lactic acid
- aerobic respiration (__ ATP produced) - requires continuous ___, produces ___ and CO2
A
ATP Sources
- all MUSCLE CONTRACTION depends on ATP
- pathways of ATP synthesis
- anaerobic formation (ATP production LIMITED) - without OXYGEN, produces TOXIC lactic acid
- aerobic respiration (MORE ATP produced) - requires continuous OXYGEN, produces H20 and CO2
49
Q
Immediate Energy
- short, intense exercise (100m dash) - O2 need supplied by ___
- phosphagen system
- _____: transfers Pi from one ___ to another forming ___
- creating kinase: transfers Pi from ____ (__) to make ___ (provides energy for 1 minute of brisk walking or 6 seconds of sprinting)
A
Immediate Energy
- short, intense exercise (100m dash) - O2 need supplied by MYOGLOBIN
- phosphagen system
- MYOKINASE: transfers Pi from one ADP to another forming ATP
- creating kinase: transfers Pi from CREATINE PHOSPHATE (CP) to make ATP (provides energy for 1 minute of brisk walking or 6 seconds of sprinting)
50
Q
Short Term Energy
- glycogen-lactic acid system = takes over when _____ exhausted, glycogen to lactic acid (_________)
- produces enough ATP for ___-__ sec of ___ activity
- muscle obtains ____ from ___ and stored ___
A
Short Term Energy
- glycogen-lactic acid system = takes over when PHOSPHAGEN SYSTEM exhausted, glycogen to lactic acid (ANEROBIC RESPIRATION)
- produces enough ATP for 30-40 sec of MAXIMUM activity
- muscle obtains GLUCOSE from BLOOD and stored GLYCOGEN
51
Q
Long-Term Energy
- ________ is needed for prolonged ____(36 ATP/glucose)
- after 40 sec, ___ and _____ systems “catch up”, deliver O2 to ____ fast enough for ______ to meet ___ demands
- O2 consumption rate rises for 3-4 minutes, then ____, ATP production keeps ____ with ___
- limits set by depletion of ____, blood glucose, loss of fluid and electrolytes, set limits on _____
A
Long-Term Energy
- AEROBIC RESPIRATION is needed for prolonged EXERCISE (36 ATP/glucose)
- after 40 sec, RESPIRATORY and CARDIOVASCULAR systems “catch up”, deliver O2 to MUSCLES fast enough for AEROBIC RESPIRATION to meet ATP demands
- O2 consumption rate rises for 3-4 minutes, then LEVELS OFF, ATP production keeps PACE with DEMAND
- limits set by depletion of GLYCOGEN, blood glucose, loss of fluid and electrolytes, set limits on ENDURANCE
52
Q
Fatigue
- Muscle fatigue = progressive _____ from ____ use
- Fatigue thought to result from:
- ATP synthesis declines as ______ consumed
- Na+ - K+ pumps fail to keep _____ potential and ____
- _____ inhibits enzyme function
- accumulation of extracellular K+ _____ cell; makes muscle fiber ____
- ______ fibers use up their acetylcholine
A
Fatigue
- Muscle fatigue = progressive WEAKNESS from PROLONGED use
- Fatigue thought to result from:
- ATP synthesis declines as GLYCOGEN consumed
- Na+ - K+ pumps fail to keep MEMBRANE potential and EXCITABILITY
- LACTIC ACID inhibits enzyme function
- accumulation of extracellular K+ HYPERPOLARIZES cell; makes muscle fiber LESS EXCITABLE
- MOTOR NEURON fibers use up their acetylcholine
53
Q
Endurance
- ability to maintain _____ exercise > 5 minutes
- Determined by:
- maximum O2 uptake = uptake ___ to body size, peaks at age __, best in well-conditioned ____
- nutrient availability = _____ packs extra ____ into muscle cells & extra adds 2.7g water / g glycogen
A
Endurance
- ability to maintain HIGH-INTENSITY exercise > 5 minutes
- Determined by:
- maximum O2 uptake = uptake PROPORTIONATE to body size, peaks at age 20, best in well-conditioned ATHLETES
- nutrient availability = CARB-LOADING packs extra GLYCOGEN into muscle cells & extra adds 2.7g water / g glycogen
54
Q
Oxygen Debt
- ______ continues after strenuous exercise
- _______ (EPOC): typically ~11L extra needed after strenuous exercise
- purpose for extra O2:
- replace oxygen ___ (myoglobin, blood hemoglobin, etc)
- replenishing ____ system
- oxidizing ___ back to ____ in liver and kidneys
- serving elevated _____
A
Oxygen Debt
- HEAVY BREATHING continues after strenuous exercise
- EXCESS POSTEXERCISE OXYGEN CONSUMPTION (EPOC): typically ~11L extra needed after strenuous exercise
- purpose for extra O2:
- replace oxygen RESERVES (myoglobin, blood hemoglobin, etc)
- replenishing PHOSPHAGEN system
- oxidizing LACTIC ACID back to GLUCOSE in liver and kidneys
- serving elevated METABOLIC RATE
55
Q
Slow Twitch, Fast Twitch
- slow oxidative (SO), ____
- abundant mitochondria, myoglobin, ____
- adapted for ____ respiration and ___ resistance
- relative ___ twitch lasting about 100ms/twitch
- ___ (jogging); postural muscles of ___
A
Slow Twitch, Fast Twitch
- slow oxidative (SO), SLOW-TWITCH
- abundant mitochondria, myoglobin, CAPILLARIES
- adapted for AEROBIC respiration and FATIGUE resistance
- relative LONG twitch lasting about 100ms/twitch
- SOLEUS (jogging); postural muscles of BACK
56
Q
Slow Twitch, Fast Twitch
- Fast glycolytic (FG), ____
- fibers well-adapted for ______ but not ____ resistance
- rich in enzymes of _____ and glycogen-______systems
- SR releases and reabsorbs CA2+ quickly so __________ quicker (7.5ms/twitch)
- eye muscles, gastrocnemius (____), biceps brachii
A
Slow Twitch, Fast Twitch
- Fast glycolytic (FG), FAST-TWITCH
- fibers well-adapted for QUICK RESPONSE but not FATIGUE resistance
- rich in enzymes of PHOSPHAGEN and glycogen-LACTIC ACID systems
- SR releases and reabsorbs CA2+ quickly so CONTRACTIONS quicker (7.5ms/twitch)
- eye muscles, gastrocnemius (JUMPING), biceps brachii
57
Q
Muscular Strength and Conditioning
- Strength of Contraction depends on:
- ___ size and fascicle arrangement (3 or 4 kg/cm2 of cross-sectional area)
- size of ______ units and _____ recruitment
- length of muscle at start of ____
- resistance training (weight lifting)
- stimulates cell _____ due to synthesis of more myofilaments
- endurance training (____ exercise)
- produces increase in _____, glycogen and density of capillaries
A
Muscular Strength and Conditioning
- Strength of Contraction depends on:
- MUSCLE size and fascicle arrangement (3 or 4 kg/cm2 of cross-sectional area)
- size of MOTOR units and MOTOR UNIT recruitment
- length of muscle at start of CONTRACTION
- resistance training (weight lifting)
- stimulates cell ENLARGEMENT due to synthesis of more myofilaments
- endurance training (AEROBIC exercise)
- produces increase in MITOCHONDRIA, glycogen and density of capillaries
58
Q
Cardiac Muscle
- ____, thick cells with ___, notched ends
- linked to each other at _____
- electrical ____ allow cells to stimulate neighbors
- ______ keep cells from pulling apart
SR less ____, but larger T tubules admit CA+2 from ___ fluid
A
Cardiac Muscle
- STRIATED, thick cells with UNEVEN, notched ends
- linked to each other at INTERCALATED DISCS
- electrical GAP JUNCTIONS allow cells to stimulate neighbors
- MECHANICAL JUNCTIONS keep cells from pulling apart
SR less DEVELOPED, but larger T tubules admit CA+2 from EC fluid
59
Q
Cardiac Muscle
- ____ due to pacemaker cells
- uses ______ respiration almost exclusively
- large mitochondria make it ____ resistant
- rich in ____ and ___
- very vulnerable to interruptions in _____ supply
- damaged cells repaired by ___ not mitosis
- autonomic nervous system sends nerve fibers to ___, regulates ___
A
Cardiac Muscle
- AUTORHYTHMIC due to pacemaker cells
- uses AEROBIC RESPIRATION respiration almost exclusively
- large mitochondria make it FATIGUE resistant
- rich in MYOGLOBIN and GLYCOGEN
- very vulnerable to interruptions in OXYGEN supply
- damaged cells repaired by FIBROSIS not mitosis
- autonomic nervous system sends nerve fibers to HEART, regulates RATE
60
Q
Smooth Muscle
- ____ shape, no striations, sacromeres, z-lines (replaced by ____ bodies)
A
Smooth Muscle
- FUSIFORM shape, no striations, sacromeres, z-lines (replaced by DENSE bodies)
61
Q
Smooth Muscle Contraction
- ____ filaments pull on ____ filaments attached to ____ bodies on plasma membrane
- shortens entire cell in ____ fashion
A
Smooth Muscle Contraction
- THIN filaments pull on INTERMEDIATE filaments attached to DENSE bodies on plasma membrane
- shortens entire cell in TWISTING fashion
62
Q
Smooth Muscle
- SR is scanty, no _____
- CA2+ triggering contraction comes from ___
- CA+2 channels triggered to open by voltage, hormones, neurotransmitters, or cell ____
- if present, nerve supply ____, not somatic (like skeletal)
- _____ and _____ slow in comparison
- uses 10-300 times less ___
- capable of mitosis and hyperplasia
- injured smooth muscle _____ well
A
Smooth Muscle
- SR is scanty, no T TUBULES
- CA2+ triggering contraction comes from ECF
- CA+2 channels triggered to open by voltage, hormones, neurotransmitters, or cell STRETCHING
- if present, nerve supply AUTONOMIC, not somatic (like skeletal)
- CONTRACTION and RELAXATION slow in comparison
- uses 10-300 times less ATP
- capable of mitosis and hyperplasia
- injured smooth muscle REGENERATES well
63
Q
Muscular Dystrophy
- group of _____ diseases, skeletal muscles ____ and weaken; replaced with fat and fibrous scar tissue
- Muchenne MD = self-linked ___ trait (1 of 3,500 live-born boys)
- most ___ form; diagnosed ages 2-10
- mutation in gene for muscle ____ (actin not linked to sarcolemma, cell membranes _____ during contraction, necrosis, and scar tissue result
- rarely live past 20
A
Muscular Dystrophy
- group of HEREDITARY diseases, skeletal muscles DEGENERATE and weaken; replaced with fat and fibrous scar tissue
- Muchenne MD = self-linked RECESSIVE trait (1 of 3,500 live-born boys)
- most COMMON form; diagnosed ages 2-10
- mutation in gene for muscle PROTEIN (actin not linked to sarcolemma, cell membranes DAMAGED during contraction, necrosis, and scar tissue result
- rarely live past 20
64
Q
Muscular Dystrophy
- facioscapulohumeral MD - autosomal ____ trait affecting both sexes equally
- facial and shoulder muscles more than ___ muscles
A
Muscular Dystrophy
- facioscapulohumeral MD - autosomal DOMINANT trait affecting both sexes equally
- facial and shoulder muscles more than PELVIC muscles
65
Q
Myasthenia Gravis
- autoimmune disease = antibies attack ___, bind ACh receptors together in clusters
- muscle fibers ___ receptor clusters from sarcolemma
- fiber becomes less ___ to ACh
- disease of ____ between 20-40
- effect usually first appear in ___ muscles (drooping eyelids, double vision, difficulty swallowing, limb weakness)
- strabismus = inability to ____ on same point with both ___
- treatments = cholinesterase ___ and _____ agents
A
Myasthenia Gravis
- autoimmune disease = antibies attack NMJs, bind ACh receptors together in clusters
- muscle fibers REMOVE receptor clusters from sarcolemma
- fiber becomes less SENSITIVE to ACh
- disease of WOMEN between 20-40
- effect usually first appear in FACIAL muscles (drooping eyelids, double vision, difficulty swallowing, limb weakness)
- strabismus = inability to FIXATE on same point with both EYES
- treatments = cholinesterase INHIBITORS and IMMUNOSUPPRESSIVE agents
66
Q
Neuromuscular Toxins and Paralysis
- flaccid paralysis - muscles ___cannot ___
- curare: complete with ACH for receptor sites but do not ___ muscles
- ___ poison used by South American natives to poison BLOWGUN DARTS
A
Neuromuscular Toxins and Paralysis
- flaccid paralysis - muscles LIMP cannot CONTRACT
- curare: complete with ACH for receptor sites but do not STIMULATE muscles
- PLANT poison used by South American natives to poison BLOWGUN DARTS
67
Q
Neuromuscular Toxins and Paralysis
- botulism - food poising caused by ______ secured by _____ clostridium botulinum
- ____ release of ACh causing flaccid ___
- ______ cosmetic injections for wrinkle removal
A
Neuromuscular Toxins and Paralysis
- botulism - food poising caused by NEUROMUSCULAR TOXIN secured by BACTERIUMclostridium botulinum
- BLOCKS release of ACh causing flaccid PARALYSIS
- BOTOX cosmetic injections for wrinkle removal
68
Q
Neuromuscular Toxins and Paralysis
- toxins that interfere with synaptic function can ____ muscle
- some ___ contain cholinesterase ____
- bind to acetylcholinesterase, prevent it from ___ ACh
- tetanus (lockjaw) - spastic ___ caused by ___ from clostridium tetani
- toxins blocks glycine (which normally inhibits spinal motor neurons); causes _____: spastic ___
A
Neuromuscular Toxins and Paralysis
- toxins that interfere with synaptic function can PARALYZE muscle
- some PESTICIDES contain cholinesterase INHIBITORS
- bind to acetylcholinesterase, prevent it from DEGRADING ACh
- tetanus (lockjaw) - spastic PARALYSIS caused by TOXIN from clostridium tetani
- toxins blocks glycine (which normally inhibits spinal motor neurons); causes OVERSTIMULATION: spastic PARALYSIS
