muscular sys 10 and 11 bio 201
Acetylcholine receptors
(Ach) Neurotransmitter that is released from nerve fiber to stimulate muscles cells
How does endurance training prepare an athlete for an Ironman triathlon? Explain what is going on at the molecular and cellular level!
(Aerobic exercise) produces an increase in mitochondria, myoglobin, glycogen and density of capillaries. Less lactic acid production.
What protein is the thin filament made of?
(actin filaments) The protein actin
What protein is the thick filament made of?
(myosin filaments) The protein myosin
Describe on a molecular and cellular level what is occurring when a muscle becomes fatigued.
*ATP synthesis declines as glycogen is consumed *sodium-potassium pumps fail to maintain membrane potential and excitability *lactic acid inhibits enzyme function *accumulation of extracellular K+ hyperpolarizes the cell *motor nerve fibers use up their acetylcholine
Explain, in detail, why an individual becomes rigid soon after death, but then days later, becomes floppy. Make sure to include the roles of ATP and calcium in your explanation.
*Massive release of Calcium that promote myosin cross bridge bindings, yet no ATP, therefore no relaxation *Muscle proteins break down after several hours after death
What types of things would an endurance athlete be concerned with? Explain!
*Oxygen uptake *Nutrient availability (carbo-loading)
Explain what is meant by the statement that, "A muscle is never entirely relaxed." Yes, this question is asking you to talk about muscle tone.
*Some fibers are contracted even in a relaxed muscle
How exactly do strength workouts increase muscle size?
*stimulates cell enlargement due to synthesis of more myofilaments *Hypertrophy (increased muscle size) vs. increase in number of muscle cells
ATP and ADP during muscle contraction AND muscle relaxation
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Actin during muscle contraction AND muscle relaxation
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Calcium during muscle contraction AND muscle relaxation
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Compare and contrast, in detail, what is occurring on a molecular and cellular level for immediate, short term, and long term energy needs of a muscle.
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Diagram AND explain in words ALL of the steps involved in muscle contraction AND relaxation.
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Myosin during muscle contraction AND muscle relaxation
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Mysosin binding site during muscle contraction AND muscle relaxation
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Mysosin head during muscle contraction AND muscle relaxation
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Thick filament
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Thin filament
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Tropomysosin during muscle contraction AND muscle relaxation
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Troponin during muscle contraction AND muscle relaxation
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What is the function of a Titin protein? What two regions of the sarcomere does it connect?
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Which band of a sarcomere contains only actin?
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Which band of a sarcomere has actin and myosin?
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Which region of a myosin molecule attaches to actin? (Hint: it looks like a golf club head).
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Which zone of a sarcomere has only "bare" myosin?
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Compare and contrast isotonic and isometric muscle contraction. Give some examples of each.
1.) Isometric muscle contraction *develops tension without changing length *important in postural muscle function and antagonistic *muscle joint stabilization 2.) Isotonic muscle contraction *Same tension while shortening=concentric *Same tension while lengthening=eccentric
What is a "triad" referring to?
1 T tubule and 2 terminal cristerea
Steps of ECC
1. Action potential 2. Voltage gated calcium channels open 3. Synaptic vesicles release ACh via exoctosis 4. ACh diffuses across synaptic cleft and burning ligand gated channel 5. Nitcotin ACh receptor is activated to open ligand gate ikon channel 6. Sodium entered the cell and Potassium exits the cell 7. Depolarization end plate potential is created which protpates action potential to the T-tublue
What is the difference between a concentric and eccentric isotonic contraction?
1.) Concentric contraction: *Tension exceeds resistance & muscle shortens 2.) Eccentric contraction: *Resistance exceeds tension & muscle lengthens (gravity)
Label the connective tissue wrappings of a skeletal muscle.
1.) Endomysium - around single muscle fiber *Contains capillaries and nerve fibers contacting muscle cells *Contains satellite cells (stem cells) that repair damage 2.) Perimysium - around a fascicle (bundle) of fibers *Contains blood vessel and nerve supply to fascicles 3.)Epimysium - surrounds all the fasicles *Exterior collagen layer *Connected to deep fascia *Separates muscle from surrounding tissues
Briefly summarize the four actions necessary for muscle contraction and relaxation.
1.) Excitation = nerve action potentials lead to action potentials in muscle fiber 2.) Excitation-contraction coupling = action potentials on the sarcolemma activate myofilaments 3.) Contraction = shortening of muscle fiber 4.) Relaxation = return to resting length
What are the three phases of twitch AND what is happening on the molecular and cellular level during each of these phases?
1.) Latent period before contraction: *the action potential moves through sarcolemma causing Ca2+ release 2.) Contraction phase: *calcium ions bind *tension builds to peak 3.) Relaxation phase: *Ca2+ levels fall *active sites are covered *tension falls to resting levels
List AND describe the functions of skeletal muscles.
1.) Movement 2.) Posture 3.) Supports soft tissue 4.) Guards entrances and exits 5.) Provides heat/maintains body temperature 6.) Storage of minerals
Discuss HOW some of the neuromuscular toxins covered in class affect the NMJ.
1.) Pesticides (cholonesterase inhibitors) *binds to ACh-sterase and prevents it from degrading ACh (spastic paralysis) 2.)Flaccid paralysis (Clostridium "botulinum" bacteria) 3.) Flaccid paralysis (limp muscles) *curavra that competes with ACh (respiratory arrest)
List AND describe the characteristics of skeletal muscle.
1.) Responsiveness (excitability) *to chemical signals, stretch and electrical changes across the plasma membrane 2.) Conductivity *local electrical change triggers a wave of excitation that travels along the muscle fiber 3.) Contractility -- shortens when stimulated 4.)Extensibility -- capable of being stretched 5.)Elasticity -- returns to its original resting length after being stretched
Compare and contrast slow twitch and fast twitch muscle fibers.
1.) Slow- slow oxidative fiber (oxygen) smaller * more mitochondria, myoglobin and capillaries *apapted for aerobic respiration and resistant to fatigue * slow to contract * soles and postural muscles of the back 2.) Fast- "Fast glycolotic fibers" larger, large glycogen reserves, few mitochondria, fast glycotyic *rich in enzymes for phosphagen and glycogen-lactic acid systems* sarcoplasmic reticulum releases calcium quickly so contractions are quicker * extra ocular eye muscles, gastrocnemius and biceps brachii *fatigue faster
Compare and contrast unfused and fused tetanus. Make sure to mention "treppe" in your answer.
1.) Unfused: incomplete (bumpy) *Some relaxation occurs between contractions *Sustained, fluttering contractions of motor units *The results are summed into a smooth contraction 2.) Fused: complete (smooth *No evidence of relaxation before the following contractions *The result is an intense, sustained muscle contraction *Calcium is never reclaimed by the SR
Explain, in detail, the concept of a motor unit. How would the arrangement of a motor unit differ for fine control vs. strength control?
A motor neuron and the muscle fibers it innervates *dispersed throughout the muscle *when contract together causes weak contraction over wide area *provides ability to sustain long-term contraction as motor units take turns resting (postural control) 1.) Fine control *small motor units contain as few as 20 muscle fibers per *nerve fiber i.e. eye muscles 2.) Strength control *gastrocnemius muscle has 1000 fibers per nerve fiber (recruitment)
Dark band
A-line
Acetylcholine
ACh
Sketch the length tension curve and use it to describe the optimum length for a forceful muscle contraction.
Amount of tension generated depends on length of muscle before it was stimulated. See length tension curve
Review the processes of anaerobic and aerobic respiration. I briefly went over it in class this time around, but you may have to go back to your notes from several weeks ago.
Anaerobic- no oxygen required, produces lactic acid, little ATP produced Aerobic- oxygen required, produces H2O and CO2, more ATP produced
Discuss HOW myasthenia gravis leads to progressive weakness.
Antibodies attack NMJ and bind ACh receptors in clusters (Receptors removed and less sensitive to ACh)
What is creatine phosphate in terms of a supplement? Specifically, who is going to benefit from it? Why?
Creatine kinase transfers Pi groups from creatine phosphate to make ATP (short burst)
A-Band
Dark bands
What is DOMS? What exactly causes it?
Delayed Onset Muscle Soreness *Not sure (too many factors, including....
Describe what is occurring when a muscle goes into "oxygen debt." Make sure to explain EPOC in your response
Heavy breathing after strenuous exercise. (EPOC- excess postexercise oxygen consumption) *Replacing oxygen through the body *replenishing the phoshagen system *reconverting lactic acid to glucose in kidney and liver *serving the elected metabolic rate that occurs as long as the body temperature remains elevated by exercise
Light band
I-line
I-Band
Light bands
Describe the number and location of nuclei in a myofiber
Multi-nuclei, giant cells
What are two other names for a muscle fiber?
Myofiber and myocyte
Make sure you understand the difference between a myofiber and a myofibril!
Myofiber-a single muscle cell Myofubril- bundles of protein filaments (actin and myosin) that causes contraction
Muscle cells are packed full of which type of protein filament?
Myofibrils
What exactly is a cross bridge?
Myosin filaments that have heads (extensions)
Describe what twitch would look like on graph
One single curve, rather than multiple curves then lowers
What is another name for the plasma membrane of a myofiber?
Sarcolemma
What is the name given to the contractile unit of muscle?
Sarcomere
What is another name for the muscle cytoplasm?
Sarcoplasm (contains glycogen and mitochondria to provide engery for contraction and myogobin for binding oxygen)
What does recruitment mean in terms of muscle contraction?
Stimulating the whole nerve with higher and higher voltage produces stronger contractions
Major function?
Skeletal- Cardiac- Smooth-
What is the location of nucleus (central vs. peripheral)?
Skeletal- Cardiac- Smooth-
Where in the human body is it found?
Skeletal- Cardiac-Heart Smooth-
Intercalated discs?
Skeletal- Cardiac-Yes Smooth-No
Compare and contrast skeletal muscle, cardiac muscle, and smooth muscle
Skeletal- voluntary, controlled by somatic nervous system Cardiac- involuntary controlled by autonomic nervous system (log shaped, linked by intercalated disks) Smooth- involuntary controlled by autonomic nervous system
Does it have one nucleus or is it multinucleate?
Skeletal-1 Cardiac-Multi Smooth-1
Striated or non-striated?
Skeletal-Non Cardiac-Straited Smooth-Non
Voluntary or involuntary?
Skeletal-Voluntary Cardiac- Involuntary Smooth-Involuntary
Can it divide?
Skeletal-Yes Cardiac-No Smooth-Yes
Describe the location of the T tubules, sarcoplasmic reticulum, and terminal cisternae. What is the function of each of these structures?
T-tubles: circles around myofibrils SR: Network around each myofibril (spider webs) TC:
Z-Line
Thin filaments extended in each directions
Explain the phenomenon of "all or none" when describing muscle contraction.
Within a skeletal muscle, not all fibers may be stimulated during the same interval, therefore different combinations of muscle fiber contractions may give differing responses, such as graded responses
Acetylocolinensterase
breaks down ACh and causes relaxation
Junctional Folds
region of sarcolemma that increases surface area for ACh receptors and contains acetylcholinesterase
What is an aponeurosis? Where are some regions in the human body might you find one? How does an aponeurosis differ from a tendon?
sheet-like structure *Foot *shoulder *Jaw
Synaptic knob (bulb)
swollen end of nerve fiber (contains ACh)
H-band
that portion of the A band where the thick and thin filaments do not overlap.
M-Line
the middle of the dark band
Basal lamina
thin layer of collagen and glycoprotein over all of muscle fiber
Synaptic cleft
tiny gap between nerve and muscle cells