Physiology 208 Muscles PART 1

tasnimjaisee's version from 2017-11-30 22:48

Lecture 1

Question Answer
The primary function of all muscle is to generate?force responding to physiological stimulus
Generation of force in muscles depends on conversion of ____ energychemical (ATP)
Skeletal Muscles have which type of nuclei (multi/single)Multinucleated
Skeletal Muscles are primarily voluntary by?somatic motor neurons
Between skeletal and cardiac muscles which cells are non-branched?Skeletal
Cardiac Muscle are primarily involuntary by?spontaneous electrical activity
Cardiac Muscle can be altered by? (2)Autonomic NS - Hormones
Smooth Muscle are primarily involuntary by? (5)spontaneous, hormones, autonomic control, paracrine/autocrines
Smooth Muscle provides mechanical control of which tracts? (3)Digestive - Urinary - Reproductive
Skeletal Muscle attached to bones by?Tendons
Skeletal Muscle: Originclosest to trunk or stationary bone
Skeletal Muscle: Insertionmore distal/mobile attachment
Skeletal Muscle: Antagonistic muscle groupsflexor - extensor pairs
Flexorbrings bones together
Extensormoves bones away
Skeletal Muscle is how much of the body's weight?40%
Skeletal Muscle is how much of daily energy expenditure?15-60%
Muscle terminology: Muscle cellMuscle fiber
Muscle terminology: Cell membraneSacolemma
Muscle terminology: CytoplasmSacoplasm
Muscle terminology: Modified ERSacoplasmic reticulum
Breakdown of Skeletal Muscle (4)Skeletal Muscle→ Muscle Fasicle→Muscle fiber→Myofibril→Sarcomere
Thick filamentMyosin
Thin filamentActin
Explain the structural form of F-Actin (3)Double-stranded alpha helical polymer of G-actin molecules
What is a binding site for thick filaments?F-Actin
What is the thin filament backbone?F-Actin
Explain the structural form of Tropomyosin2 identical coiled alpha helices
What does Tropomyosin regulate?Myosin to actin binding
troponin T (TnT)binds single tropomyosin
troponin C (Tnc)Ca2+ binding site
What are the parts of Troponin complex?heterotrimer consisting of TnT, Tnc, TnI
troponin I (TnI)In resting conditions bound to actin inhibiting contraction
Troponin complex is situated in every ___ actin molecules7
What does F-Actin belong in? (Thick/Thin)Thin filaments
What does Tropomyosin belong in? (Thick/Thin)Thin filaments
What does Myosin molecules belong in? (Thick/Thin)Thick filaments
Explain the structure of Myosin molecule and what it's followed by (2)2 heavy chains heads; 2 light chains each - Followed by alpha-helical rods wrapped around each other
What are the light chains called on each heavy chain head?MLC-1 (Essential) and MLC-2 (Regulatory)
MLC-1Essential light chain
MLC-2Regulatory light chain
What does regulatory light chain maintain?ATPase activity of myosin
What does essential light chain maintain?stabilizes myosin head
Titin (3)Protein from M to Z - elastic recoil - Stabilization
Nebulin (3)Wraps around thin filament - regulates length & structure
Z disk (2)zigzag - attachment site for thin filaments
Lightest band of sarcomereI band
Which sarcomere controls region occupied only by thin filamentsI band
Darkest band of sarcomereA Band
Which sarcomere encompasses entire length of the thick filament?A band
Which sarcomere includes very dark area where thin and thick filaments overlap?A Band
Which sarcomere is the central region of A band H-Zone
Which sarcomere consists only of thick filaments?H-zone
Which sarcomere forms the attachment site for the thick filaments?M line
Which sarcomere is equivalent to z disk for thin filaments, for thickM line
Glucose is stored as ____ within the sarcoplasmglycogen
In the sliding filament model, what does the actin & myosin do? slide past each other without length change
In the sliding filament model, what does the sacromere do?shortens during contraction
During muscle contractions: Explain H zone, I band and A band's actionsH zone and I band shorten; A band stays the same
Force generated by a contracting skeletal muscle is?Tension
Neuromuscular junctionsomatic motor neuron & muscle fibre synapse
Excitation-contraction coupling results?Action potential increasing Ca2+
Contraction-Relaxation cycle comes from which signal?Ca2+
Contraction-Relaxation cycle froms which reactions?Muscle twitch - Sliding filament theory
A single muscle fibre contains ____+ myofibrils1000
Where does Tropomyosin sit in?In 2 groves formed by actin strands

Lecture 2

Question Answer
Parts of primary motor cortexpremotor cortex - Basal ganglia - Thalamus - Midbrain - Cerebellum
Corticospinal Tractdescending tract (ventral and interior lateral white matter)
Upper motor neuronbrain to spinal cord
Alpha (lower) motor neuronfrom spinal cord to muscle
A single motor neuron and all the muscle fibres alpha (lower) motor neurons innervates is known as?Motor unit
The area where the alpha motor neuron makes synaptic contact with the muscle fibre is known as?Neuromuscular junction
Describe alpha-motor neurons (length, myelination state, m/s)Large - Myelinated - 15-120m/s
Do all Alpha-motor neuron fibers respond simultaneously?Yes
Number of muscle fibers/motor units for alpha-motor neurons' delicate precise work<10
Number of muscle fibers/motor units for alpha-motor neurons' powerful less precise contractions>100
Which compartment degeneration causes ALS?Upper &/ lower motor neurons
Is genetically inherited ALS a dominant or recessive trait?Dominant
What percent of ALS cases are genetically inherrited?10%
25% of genetically inherited cases of ALS are due to a mutation in which genes?superoxide dismutase
Superoxide dismutase catalyzes the dismutation of superoxide into?oxygen and hydrogen peroxide
What is the chemical formula of superoxide?O2-
Superoxide dismutase is an important ____ defenseAntioxidant
Three components of neuromuscular junctionPresynaptic motor neuron - Synaptic cleft - Postsynaptic membrane
Sarcolemma at the neuromuscular junction is known as?Motor end plate
The neuromuscular junction consists of ____, motor end plates and ____Axons - Schwann
____ ____ on sarcolemma increase surface areaJunctional folds
Motor neuron vesicles contain which chemical?acetylcholine
Muscle sarcolemma contains which type of receptorsnicotinic acetylcholine
Acetylcholine receptors are members of which ligand gated ion channels family?Cys-loop receptor
Net Na+ influx _____ the muscle fibreDepolarizes
Open channels of nicotinic cholinergic receptors allows which chemicals to pass?Na+ and K+
Opening of ACh receptor requires how many acetylcholine molecules?2
Acethocholine is metabolized by?Acetylcholinesterase (AChE)
Post synaptic membranes are modified into?Motor end plates
Na+ entry through nACh generates which type of potential?excitatory end-plate potential
Nicotinic Acetylcholine Receptor is classified as a ____ cation channelmonovalent
What does an EPP spreading to adjacent voltage gated Na+ channels on the sarcolemma initiate?Action potential
excitatory end-plate potential spreads to which channels on the sarcolemma?Na+
Once AP’s stop firing in the alpha motor neuron, what must be done to the acetylcholine in the synaptic cleft? (2)Removed & diffused - Brake to acetate & choline by acetylcholinesterase
What does choline acetyltransferase do?Supplies Acetyl CoA to make acetylcholine with choline
Which cell part is Acetyl CoA made from?mitochondria of choline acetyltransferase (chat)
In the case of Myasthenia gravis, how does the autoimmune system react? (3)Antibodies bind AChR - Inactivates AChR - Postjunctional fold degeneration
Action potentials propagate from the sarcolemma to the interior of muscle fibres along the ____ ____ networkTransverse tubule
Specialized Ca2+ storage organelles known as ____ ____ are strategically organized with the T-tublulessarcoplasmic reticulum
The ultimate intracellular chemical signal that triggers contraction in all muscle types is a rise in?intracellular calcium [Ca2+]i
Ca2+ can enter the sarcoplasm from the extracellular space by? (2)Voltage gated Ca2+ channels - Intracellular Ca2+ storage reservoir
At how many points do T-tubules penetrate the muscle fibre and surround the myofibrils?2
At WHICH sacromeres do T-tubules penetrate the muscle fibre and surround myofibrils?A and I band
Along its length the tubules are associated with two ___ to form a "triad"cisternae
What do sarcoplasmic reticulum store?Ca2+

Lecture 3

Question Answer
Between RyR and DHP, which is considered a L-type Ca2+ channel?DHP
Between RyR and DHP, which is voltage sensitive?DHP
Between RyR and DHP, which is considered a Ca2+ release channel on SR?RyR
RyRRyanodine receptor
Initiation of muscle action potential (2)ACh release at junction & Na+ entry
Ca2+ can also enter the sarcoplasm through ____-type ____ channelsL / Ca2+
Explain the Excitation-Contracyion Coupling process (2)T-Tuble AP alters DHPR - DHPR opens RyR Ca2+ channels
Which ways can RyR can be activated? (2)Mechanically - Ca2+ induce
Is Ca2+ induced Ca2+ release vital for skeletal muscle?No
How does an increase in [Ca2+]i trigger contraction?Removing inhibition of cross-bridge cycling
Ca2+ binds ___ affinity sites on TnCLow
Which kind of change does Ca+ binding to TnC create?Myosin binding site on actin revealed; Troponin complex & tropomyosin move
Cross bridge cycleATP binding - ATP hydrolysis - Power Stroke - ADP release
Cross bridge cycle: ATP bindingMyosin for actin affinity reduced
Corss bridge cycle: ATP Hydrolysis (2)ATP breaks into ADP & Pi - Cocked state myosin binds new actin
Cross bridge cycle: Power stroke (3)Pi release creates higher affinity - Myosin returns to un-cocked state - Pulls actin motion
Cross bridge cycle: ADP releaseMyosin is bound until ATP initiates cycle
Termination of contraction requires removal of? and why?Ca2+ must be removed for myosin binding site on actin to be covered by tropomyosin
Ca2+ can be removed to the extracellular space by? (2)Na-Ca exchanger / Ca2+ pump
Ca2+ reuptake into the SR is mediated by?SERCA-type Ca2+ pump
_____ and _____ maximize Ca2+ uptake by the SRCalsequestrin - Calreticulin
Up to ___ Ca2+ binding sites per molecule50
Rigor mortisDevelopment of rigid muscle several hours after death
During rigor mortis, what does ATP production stopping cause? (2)Ca2+ cannot be removed (SERCA) - Myosins sticks to actin until deterioration
SERCAsarcoplasmic and endoplasmic reticulum Ca2+ ATPase
Motor neuron (axon) AP graph crest description (Sharp/Curved, Skinny/Wide, Potential, Time)Sharp - Skinny - (+30 to -70) - N/A
muscle fiber AP graph crest description (Sharp/Curved - Skinny/Wide - Potential - Time)Curved - Wide - (+20 to -80) - 2msec
Twitch fiber AP graph crest description (Sharp/Curved - Skinny/Wide - Potential - Time)Curved - Wide - N/A - 10-100msec
What are the stages of muscle twitch graphs?Latent - Contraction - Relaxation
Delay between muscle fibre AP and contraction (latent period) time is due to?Ca2+ released - Binding troponin
What do our sources of ATP for muscles come from? (2)Free intracellulars - Phosphocreatine
PhosphocreatineEnergy storage by resting muscles from ATP
Muscles at rest equationMetabolism ATP + Creatin → ADP + Phosphocreatine
Working muscles equationPhosphocreatine + ADP → Creatine + ATP
phosphocreatine ATP restores after how many seconds?10
For both working and at rest muscles, what enzyme binds wih creatine to continue the process of using ATPKinase
GlycogenesisGlucose stored in muscle cells as glycogen
GlycogenolysisGlycogen converted back to glucose for ATP usage
Glycolosis results in the production of how many ATP molecules?2
Glycolosis results glucose breaking down to which form?Pyruvate
Anaerobic metabolismprocess occurs in the absence of oxygen
Pyruvate is further broken down to ____lactate
If oxygen and mitochondria are present ____ metabolism takes placeoxidative (aerobic)
After glycolysis, what does pyruvate enter?citric acid cycle
What are the results of the citric acid cycle? (3)2 ATP - High Energy Electrons - H+
High energy electrons + (H+) + O2 = ?ATP26-28 ATP

Lecture 4

Question Answer
What is muscle fatigue ?Decrease in muscle tension as a result of previous contractile activity
How is muscle fatigue caused?Sarcoplasmic Ca2+ leaks
Central fatiguetiredness and a desire to cease activity
During ATP hydrolysis what could influence the sensation of fatigue perceived by the brain?Low pH from acid production
What recent experiments have revealed a connection between fuel status and central fatigue?CHO subjects exercise longer
Peripheral Fatigue ACh synthesis can’t keep up with neuron firing rate
Muscle fatigue most experimental evidence points to problems with?ECC
Explain the T-Tubules in Muscle fatigueAP firing causes K+ build; changing AP threshold
Explain the muscle fibres during Muscle fatigueBuild: Pi, ADP, H+ /// Reduce: ATP
Explain the sarcoplasmic reticulum during Muscle fatigueReduce Ca2+ uptake & release
Explain the Troponin C during Muscle fatigueReduce Ca2+ senstivity; less CBC
Explain the Myosin head during Muscle fatiguePi & ADP release during CBC by sarcoplasma buildup
Muscle classification is dependent upon?Max shortening velocity & ATP path
Slow fibres contain myosin with ____ ATPase activity (TYPE ___)slower & l
Fast fibres contain myosin with ____ ATPase activity (TYPE ___)rapid & II
Between glycolytic and oxidative fibres; which contain few mitochondria?Glycolytic
Determinants of Force/muscle cell developmentDiameter - Fatigability - Rest - Activation
Determinants of Force/entire muscle developmentNumber of muscle cells activated
Muscle length influences tension development by determining?the degree of overlap between actin and myosin filaments
Too much of too litle overlap of thick and thin filaments in resting muscle results in?decreased tension
The amount of tension developed is directly proportional to the number of ___ ___ formedcross bridges
A single action potential in a single muscle fibre results in an individual form of?muscle twitch
A single action potential in a muscle fibre lasts approximately?1-3ms
A muscle twitch lasts approximately?100ms
If a subsequent action potential occurs before the muscle fibre is allowed to relax a more forceful contraction occurs due to?summation of single twitches
Tetanusmaintained contractile response to repeated stimuli
Unfused tetanusreaches steady contraction; FIbre slightly relaxes between stimuli