Muscle Tissue- Ch 10 and 11

What supplies each skeletal muscle?

- 1 nerve - 1 artery - 2 veins

What are main power factors for muscle?

- 1/2 length of contraction max power - more fibers involved means more power (more motor units or more fibers/motor unit) - more frequent stimulation in tetanus or wave summation increases power

What are ACh receptors and how do they work to transmit the action potential?

- AP from nerve causes their release at synaptic bulb -Gated Na+ channels - ACh from synaptic bulb fits into them perfectly, this opens the Na+ gate, allowing depolarization and transmission of the action potential to the muscle membrane surface

How do anabolic steroids affect muscles? What are the side effects?

- Act similar to testosterone (analog), increase muscle size, strength and endurance Side effects: Liver cancer Kidney damage Heart disease Mood swings Facial hair and voice deepening of females Atrophy of testicles and baldness in males

Describe the thin filaments.

- Actin, troponin and tropomyosin -Myosin binding sites on actin - Thin filaments held in place by Z lines (border of sarcomere)

How does aging affect muscle tissue?

- Age 30 fat starts to replace muscle tissue: "use it or lose it" - Slowing of reflexes (nerve reactivity) and decrease in max strength - Formation of more slow twitch fibers from fast twitch: may be due to aging or lack of use

What is the molecular cause of both wave summation and tetanus?

- Ca2+ remaining in sarcoplasm - Force of second contraction is easily added to the first, elastic elements remain partially contracted and do not delay beginning of next contraction

What must be present for sliding filament mechanism to occur? How far does the fiber move with the action of each myosin head movement?

- Ca2+ to uncover binding sites -ATP to move myosin head - 10 nm

What protein binds to Ca2+ ions in the cytosol of smooth muscle? What does this cause? Do smooth muscles have sarcomeres? Does smooth muscle contract more quickly or more slowly than skeletal muscle?

- Calmodulin instead of troponin - Activated myosin-light-chain-kinase: enzyme that allows for myosin actin binding and allows contraction at slow rate - No sarcomeres - Smooth muscle contracts more slowly and lasts longer

What is gangrene?

- Destruction of living tissue due to obstruction of blood and oxygen supply: disruption caused by bacteria (clostridium streptococci and staphylococci)--> these live in dead tissue and release toxins which seep into blood and cause septicemia

What is myopathy?

- Disease or disorder of skeletal muscle tissue

Describe third class levers and give a body example.

- Effort is between resistance and fulcrum (tweezers) - always produces mechanical disadvantage- effort always closer to fulcrum - favors ROM and speed to force increase - most common body lever Flexor muscles at elbow: Fulcrum: elbow joint (ulna and humerus/radius) Effort: Bicep contraction Resistance/Load: weight in hand

What is EC coupling?

- Excitation contraction coupling (action potential/depolarization--> contraction) -Putting everything together - thought process sending impulse - AP arriving at neuromuscular junction - Regeneration of AP at muscle membrane - Release of Ca2+ from sarcoplasmic reticulum - Sliding of thin filaments over thick in sarcomeres - generation of work of muscle fibers - motor neuron and skeletal muscle fiber (junction)

Describe a first class lever and give a body example.

- Fulcrum is between resistance and effort (seesaw) -Produces mechanical advantage (force wise) is effort is farther from fulcrum than resistance Head resting on vertebral column (atlas vertebra C1): Effort: posterior neck muscles Fulcrum/pivot: atlas muscle and skull joint Resistance: Weight of face

Which changes length during muscle contraction?

- I band and H zone

What is myotonia?

- Increased excitability and contractility of muscle -decreases power of muscle -tonic spasm: more contracted in muscle tone

How can exercise induce muscle damage?

- Intense exercise: -torn sarcolemmas, damaged myofibrils and disrupted Z-discs -results in blood level increase of myoglobin and creatine phosphate which are normally only in muscle cells Delayed onset muscle soreness: - occurs 12-48 hours after strenuous exercise - stiffness, tenderness and swelling due to microscopic cell damage (repair with increasing myofibrils, sarcoplasmic reticulum and mitochondria to avoid this in future - increases strength

What is the H zone and what does it have to do with muscle contraction.

- It is an area in the A band where only myosin is present in relaxed muscle (non overlap), when muscle contracts and the actin filaments slide past the myosin, the region of overlap is increased and the length of the H zone decreases (in center of sarcomere)

Describe the latent, contraction and relaxation period of a twitch contraction. What is the time of the action potential sent? How long does the actual contraction take

- Latent period: there has been a decision to contract and ACh is released (flat on graph) and Ca2+ released, slack released from elastic componants - Contraction: filaments slide past each other -Relaxation: Ca2+ actively transported into sarcoplasmic reticulum, Muscle returns to resting length AP= 1-2 mseconds Twitch= 20-200 mseconds (reaction to depolarization)

What is oxygen debt? What does EPOC mean? Why do we have these?

- Oxygen debt=EPOC= excess post exercise oxygen consumption - is the required amount of O2 to restore homeostatic conditions in muscle cells: when cells have been operating at O2 deficit O2 is needed to : 1. replenish ATP stores for use (lots used in exercise)--> used in Krebs cycle 2. Replenish creatine phosphate (used at beg. of exercise) 3. Replenish myoglobin stores of O2 in muscle (O2 source of muscle) 4. Convert lactic acid to pyruvate which is used for aerobic respiration

What is the role of the M line, titin and the Z discs in the sarcomere? Describe each.

- Proteins help anchor the thick and thin filaments in place M line: Center line of sarcomere, holds myosin in place Titin: spring like protein near actin filaments that help make contractile and extensile motion possible (how sarcomeres lessen in length when actin fibers slide towards M line) Z disc: end points of sarcomere, anchor actin filaments--> UNITS OF CONTRACTION

What causes fatigue?

- Reduction in Ca2+ levels, ATP levels used up, CO2 levels high (not able to produce glucose), lactic acid build up

Describe repair of smooth muscle tissue.

- Regeneration possible---> stem cells in BV walls - cells grow in size (hypertrophy) - uterus cells can divide (hyperplasia)

Why are skeletal muscles multinucleate?

- Stem cells fuse

What are large muscle groups encased in?

- Superficial and deep fascia: keeps muscles enclosed in compartments by function.

Describe tetanus. What are the types? Describe the types.

- Tetanus= sustained contraction of muscle, summation of muscle contractions resulting in increased force of contraction, due to multiple stimuli one after another Incomplete/unfused: permits partial relaxation between contractions Fused/complete: no relaxation between stimuli Both eventually reach a plateau where no more force can be produced even with more stimuli (finite number of motor units to stimulate)

What and when is the refractory period of a muscle cell? What is the difference in refractory period between skeletal and cardiac muscle?

- The time when a muscle has lost its excitability= after relaxation Skeletal muscle has a short refractory period and becomes fatigued more easily= 5 msec Cardiac muscle has a long refractory period and thus does not fatigue even when worked hard (thus heart problems come from lack of O2 and glucose, not fatigue)= 300 msec

What is a charley horse?

- Torn muscle that is the result of an impact: it involves bleeding within muscle and inflammation - Rest, ice, wrap and elevate

Skeletal muscle characteristics and functions

- attached thru tendons to skeleton - functions: movement and posture - appearance: striated, nuclei elongated and to the side of fiber (eccentric), parallel fibers - control: voluntary

How many muscle fibers are generally controlled by one somatic motor neuron? How does it control the contraction?

10-2000 (smaller for detailed movements, larger for strength muscles) 150 average Stimulus from one neuron causes all fibers to contract in unison- scattered throughout muscle belly

Describe aerobic respiration. When is it used for muscle contraction ATP production? What are the sources of O2? How many ATP produced per glucose?

Aerobic respiration: 1. Complete oxidation of glucose via cell respiration: pyruvic acid--> krebs cycle and--> ETC 2. Produces heat, ATP, CO2 (given off as waste) and H2O (metabolic water) Used when muscular activity lasts more than 30 s (kicks in when lactic acid cycle can't keep up)--> 90% of ATP provided when activity is more than 10 minutes Uses O2 (aerobic) --> from myoglobin (O2 holder in muscle cells) and hemoglobin Active in endurance muscles--> can provide energy for several minutes to hours 36-38 ATP produced

How do multiple muscles work together to achieve a certain motion?

Agonist/Prime mover: contracts to cause desired action (can only pull) Antagonist: resists action of prime mover/agonist, must be at rest during agonist contraction to allow movement (stretches): Contracts to undo motion of agonist because muscles can only pull Synergist: contract during motion to stabilize nearby and used joints Fixator: specialized type of synergist- stabilizes origin of prime mover (can't move insertion if origin is moving)- scapula held steady so deltoid can raise arm

Name the important contractile, regulatory and structural muscle proteins.

Contractile: myosin and actin Regulatory: Troponin and Tropomyosin Structural: Titin, Nebulin, Alpha-actin, Myomesin, Dystrophan

What is the epicranial aponeurosis?

Connects muscle bellies of occipitalis and frontalis to form "one muscle" the occipitofrontalis--> functions like flat tendon, covers surface of flat bone

How does fascia arrangement change with groups of muscles involved?

Epimysium grows and gets thicker, eventually forming fascia that covers many vicinal muscles--> e.g. fascia lata enveloping quadriceps and hamstrings

Where are nerve fibers and capillaries found in the muscle?

In the endomysium between individual cells

What is tenosynovitis?

Inflammation of tendon and its sheath at certain joints--> wrist, elbow and shoulder common Pain is associated with motion Causes: trauma, strain on muscle/tendon, excessive exercise (wear from friction)

How are skeletal muscles organized?

Into compartments according to functions, encased in deep CT

What is leverage? What two types of mechanical advantage can be gained by levers?

Leverage is the mechanical advantage gained by a lever. 1. A small effort force can produce a large force with use of the lever, but sacrifices range of motion of that force 2. A effort force is not magnified, but the range of motion is increased

What is range of motion?

Max ability to move the bones of a joint through an arc

Each motor neuron supplies...

Multiple muscle cells (neuromuscular junction)

What is the difference between red and white muscle fibers? What are other differences that can occur between fiber types?

Red: -more myoglobin (red oxygen storing pigment) - more capillaries and mitochondria - smaller diameter White: - less myoglobin, capillaries and mitochondria - can grow in diameter, larger diameter to begin with - Contraction and relaxation speeds vary: depend on enzyme regulation: faster in white - Resistance to fatigue: different metabolic processes to produce ATP (lactic acid fermentation, creatine phosphate, aerobic): better in red b/c aerobic respiration

What are stress fractures?

Repetitive jarring stress causes fractures in bone (low force, chronic repetition)--> common in tibia from running

What is a tremor?

Rhythmic, involuntary contraction of opposing muscle groups that cause shaking (agonist than antagonist)

Describe the motor end plate.

Rich in ligand/chemical gated channels that respond to Acetylcholine, open to allow sodium to rush into cell--> receptors for Acetylcholine are here and are gated sodium channels

What is the arrangement of filaments in a muscle fiber?

Sarcomeres: - Z discs are the borders and the contractile units - Overlapping region (A band) sandwiched between two I bands that contain Z discs - In overlapping region (A band, there are 6 actin filaments around every myosin filament)

What are they types of skeletal muscle fibers based on structure and function? What are the characteristics of each? Give an example of each.

Slow oxidative: -Slow twitch (time of contraction is longer) - small diameter - red in color (dark meat)- myoglobin, BV, mitochondria (aerobic pathways) - prolonged, sustained contractions--> postural, marathon running (soleus) - 1/3-1/5 second contractions Oxidative-glycolytic: - mix of fast and slow twitch--> fast twitch A type- anaerobic and aerobic pathways - medium diameter - red/pink in color (high myoglobin, medium mitochondria, medium capillaries- boys have more_ - split ATP quickly, used for walking and sprinting -1/15 s muscle contraction time Fast glycolytic: - Fast twitch B type - Large diameter--> largest and strongest fiber, can increase in diameter up to 50% with training - white color (few mitochondria, few BV, low myoglobin) (white meat) - anaerobic movements of short duration (short contractions) (anaerobic pathways) - weight lifting muscle--> arms muscles, extrinsic eye muscles (blinking) - Contraction 1/40th of a second

How does muscle tissue work homeostatically to control body temperature?

Smooth muscle: -releases heat by dilating arteries in peripheral BV and increasing blood flow at body surface -conserves heat by contracting peripheral BV and keeping blood flow closer to core, preventing release of heat at body surface Skeletal muscle: -allows actions to release heat by motion: panting (by evaporation), fanning self (produces more heat, though) - conserves/produces heat by shivering

What is myomalacia?

Softening of muscle/loss of tone (stiffness even when at rest due to motor unit activity)

When is speed or ROM favored? When is force favored? (in levers)

Speed/ROM: when resistance is further from fulcrum Force: when effort is further from fulcrum

What is a lever arm?

The distance between the fulcrum and furthest force (load or effort)

Where are circular fascicle arrangements found? Example.

The surround openings that move Ex. Orbicularis oculi (eye) and Orbicularis oris (mouth)

What are synaptic end bulbs? How do they function in muscle contraction?

They are the enlarged ends of axons, AKA the axon terminal, extensions of Golgi bodies, (which carry nerve impulse or action potential) and fit into the motor end plate of the muscle cell- they house synaptic vesicles which release acetyl choline across the synaptic cleft to the receptors in the motor end plate, transmitting the action potential from the nerve to the muscle

What is compartmental syndrome?

When swelling of muscle tissue presses on CT, causing necrosis of muscle tissue

What are the possible actions of muscles.

flexor extensor abductor/adductor levator depressor pronator supinator sphincter (open and close openings like a door) rotator tensor (stabilizer)

What is a fasciculation?

involuntary, brief twitch of a motor unit visible beneath the skin

What is a sarcolemma?

muscle cell membrane

What is the term for muscle cell cytoplasm?

sarcoplasm

What are x and y axis of myogram?

x= time in milliseconds (msec) y= force of contraction

How is a muscle organized? Smallest to largest components.

~4500 Filaments (3000 actin and 1500 myosin)--> Myofibril 100-1000 Myofibrils--> Muscle fiber (cell) Many muscle fibers--> Fascicle--> Many fascicles--> Muscle (organ)

Describe muscle cells in a state of homeostasis.

- balanced rate of O2 intake by production of CO2 and other waste--> no buildup of waste - not a lot of heat produced because ATP production is not too high--> 70-80% energy used by muscles lost as heat (muscle activity used to maintain correct body temp) - Lactic acid production is low (not much need for anaerobic respiration)

What factors affect ROM?

- can shorten by 30% of resting length, thus longer fascicles mean more ROM (parallel and fusiform muscles greatest ROM) - complex fibers balance power and ROM

What is the motion of smooth muscle contraction? How does it compare to skeletal and cardiac muscle?

- contracts and twists into a helix as it shortens, relaxes by untwisting - skeletal and cardiac muscle contract like a slinky linearly

Why don't you buy bulging or dented cans?

- crack could allow bacteria in - bulging indicates bacteria inside (anaerobic respiration gases)

How is the muscular system divided into organs?

- each muscle is an organ

What are the characteristics of muscle tissue?

- excitability - conductivity - contractibility - extensibility -elasticity

Describe fusiform fascicle arrangement with an example.

- fibers are almost parallel to the long axis of the muscle - tapers toward flat tendons (narrower at ends of tendons) - flat tendons Example: digit flexors

Describe parallel fascicle arrangement with an example.

- fibers are parallel to one another and the long axis of the muscle - flat tendons Examples: geniohyoid and sternohyoid

When does fibrosis occur in skeletal muscle repair?

- fibers are too few in number to enlarge and replace space of damaged cells--> stroma replaces parenchyma (CT)

What is the mitotic capacity (for repair) of skeletal muscle?

- fibers cannot divide after first year (very little in adults) - growth and repair does not occur from mitosis, but enlarging of existing cells (hypertrophy) - some new cells can occur from satellite cells and bone marrow

Describe Actin.

- has myosin binding site - covered in troponin and tropomyosin

What is myosclerosis?

- homeostatic imbalance that causes hardening of muscle caused by calcification to bony like tissue - from trauma and metabolic disorder

What is myofibrosis?

- homeostatic imbalance where CT replaces muscle fibers - from trauma or metabolic disorder

What is myositis?

- inflammation of muscle fibers with an unknown cause

What is plantar fasciitis?

- inflammation of the plantar fascia (CT=ligaments and tendons in bottom of foot) -ligaments and tendons (fascia) can begin to ossify to bone spurs if not well treated - most common cause of heel pain - takes months to resolve

What is muscle tone? What body needs is it responsible for?

- involuntary contraction of a small number of motor units when muscle is at rest -motor units are alternated in constantly shifting pattern - muscles are firm even though relaxed - does NOT produce movement- keeps muscles ready to produce movement - helps maintain: tone of smooth muscles in BV, posture

Percentage wise, what is the length of a muscle cell at rest compared with the optimum length? What is optimum length?

- it is 70-130 percent of the optimum (a little shorter or a little longer), optimum= length where tension generated is greatest (half contracted)

Visceral (smooth) muscle locations, characteristics, and functions

- located in gastrointestinal tract, uterus, eye, BV - functions: peristalsis, blood pressure (vasoconstriction and dilation), pupil size, erects hairs (arrector pilli) - appearance: no striations, one central nucleus - control: involuntary

Cardiac muscle characteristics and functions

- located only in heart - functions: pump blood continually - appearance: striated, one central (centered) nucleus per fiber - control: involuntary

What is muscle fatigue and what are its causes?

- loss of muscle strength (inability to contract) 1. Build up of lactic acid 2. insufficient release of ACh 3. inadequate ATP production 4. inadequate glucose stores 5. inadequate oxygen stores 6. inadequate Ca2+ release

Describe the composition of skeletal muscles with reference to the three types of skeletal muscle fibers. Describe motor units in reference to fiber types.

- mixture of all three fiber types (mostly) - proportions vary with action of the muscle Neck and back and leg: high proportion of postural SO muscle fibers (red) Shoulder and arm have higher proportion of FG fibers - One motor unit controls only one type of fiber (all fibers of a motor unit are the same type) - Different fibers are included by recruiting motor units of different types within a muscle

What are the functions of muscle tissue?

- motion - posture maintenance - organ volume (BV, bronchioles, smooth) - heat production (shivering--> increases body heat produced by 40-50%) - blood circulation (heart)

What is rigor mortis?

- muscle rigidity that begins 3- 4 hours after death, lasting 36-72 hours - Caused by Ca2+ leakage out of sarcoplasmic reticulum after death, allowing myosin heads to form cross bridges with actin--> ATP synthesis has ceased, crossbridges cannot detach from actin until proteolytic enzymes start digesting decomposing cells After 36-72 hours, muscles become flaccid again from the denaturation of proteins (myosin and actin)

How does fascicular arrangement of a muscle affect force and ROM?

- muscles with longer fibers (longer fascicles) have greater ROM - shorter fibers contract more forcefully than long, but don't move as much

What are the basic structures involved in causing a muscle contraction?

- neuromuscular junction, axon terminal, motor end plate, neurotransmitter, sarcolemma, stored Ca2+, ATP, muscle proteins

Describe a pulled groin.

- painful strain of thigh adductors - minor

How are muscles organized?

-In functional groups: different muscles with same functions in specific and complementary areas (quadriceps and hamstrings)

What is a Volkman's contracture?

- permanent shortening of the muscle - destroyed muscle is replaced by CT (losing function and ability to stretch and contract further) - caused by interference of circulation to muscle (like burn that gets a cast on it.

What is recruitment? How does it affect muscle physiology and movement?

- process of increasing the number of motor units involved in a contraction AKA motor unit summation Prevents fatigue by alternating which motor units are used and reducing stress on motor units that are being used Provides smoother contraction by spreading out force

What is fascia? Describe the two layers.

- protective connective tissue layers around muscles--> superficial and deep layers Superficial: attaches skin to muscle--> made of subcutaneous layer under skin (adipose and loose areolar tissue) Deep: dense irregular CT around and within muscle

What is a tendon? What is the difference in a tendon and an aponeurosis?

- rounded cord of dense CT - attaches muscle to PERIOSTEUM of bone -aponeurosis: a tendon, but more like thick fascia connecting two muscles bellies by a broad, flat layer instead of a rounded cord *Tendons are extensions of CT and attach muscle to bone or other muscle

What are t-tubules?

- run transverse through muscle fiber - internal extensions of sarcolemma - involved in transmission of nerve impulse across muscle fiber--> extends into cell near SR, change in voltage with AP opens Ca2+ channels on SR

Describe a torn calcaneal tendon.

- running injury= separation of muscle from tendon AKA Achilles tendon tear - serious (low blood supply)

Does the sarcomere get longer or shorter when muscle contracts? When it is stretched? At what point of contraction is the power of the muscle maximized and what does this mean for the sarcomere length?

- shorter when contracted - longer when stretched - When muscle is half way to max contraction, power is greatest- so when sarcomere is half of its shortest length, power is the greatest

How do motor units control strength of muscle contraction?

- the number of motor units, and thus muscle fibers stimulated (how many motor neurons send signal) - how large the motor units are- large motor units means more fibers involved means larger force of contraction from fewer motor units

How does use of muscle fibers affect composition of muscle of the different fiber types

- the proportion of the types of the different fibers doesn't change, but the characteristics of those that are present can be altered by certain types of activity: use of fast glycolytic (white) fibers can increase their diameter, making muscle larger--> tends to lessen strength of other types though (endurance muscles), vice versa for distance runners with slow oxidative (red)

What is the motor end plate? What role does it play in muscle contraction?

- the receiving end of the action potential from the nerve, holds the synaptic bulb, holds ACh receptors which allow for ACh to cross synaptic cleft and transmit impulse to muscle

What is treppe? How is it involved in athletes warming up?

- the staircase affect of muscle contraction strength 1. Inactive muscles experience a series of twitches 2. Ca2+ is pumped into inactive cells, allowing for stronger contractions with each subsequent stimulus They cause their muscles to twitch over and over, increasing the Ca2+ concentration in the myofibrils, priming their muscles to contract more forcefully after warming up.

What fills synaptic vesicles? How do they function in muscle contraction?

- they are filled with ACh (acetyl choline), they work by exocytosis at the end of the synaptic bulb, release ACh into the synaptic gap

Describe myosin.

- two golf clubs twisted together - heads (cross bridges) extend towards actin - held in place by M line proteins

What is important about tropomyosin in muscle contraction?

- uncovers myosin binding sites of actin, causes muscle contraction to take place

What is sarcoplasmic reticulum?

- unique to muscle cells - network of membrane enclosed tubules - form sleeve around each myofibril

Describe cardiac muscle repair.

- very, very little mitosis, though it is possible - most healing is done by fibrosis (stroma/scar tissue formation)--> why loss of function after heart attacks

When do muscles use a lot of ATP? How long does ATP formed in the sarcoplasm last?

- when active (lots of contraction)-> use glucose, need from storage-> break down fat to form glucose to make ATP - Only a few seconds

What is a lever?

-A rigid structure that moves around a fixed point (fulcrum/pivot) - two forces act on the lever in opposition to each other: Load opposes movement of lever, Effort causes movement

What are some pathological substances that affect function at the NMJ? How do they do so?

-Botulinum toxin: toxin released by botulinum bacteria in improperly canned food, causes botulism: blockage of release of ACh at NMJ, muscle contraction does not occur (no regeneration of AP in muscle cell)--> diaphragm cannot contract and no breathing - Curare: poisonous toxin from plants (used on arrows and darts), causes muscle paralysis by blocking ACh receptors--> relaxes muscles during surgery - Neostigmine: antiacetylcholinesterase agent--> prevents breakdown of ACh, causes increase in signal strength and increased strength of contraction--> antidote for curare after surgery

Describe a second class lever and give a body example.

-Resistance is between effort and fulcrum (wheelbarrow) - always produced mechanical advantage (resistance always closer to fulcrum) - lose speed/ROM for force Raising up on toes: Fulcrum: Balls of feet (metatarsals and phalanges) Resistance: body weight carried on heels Effort: contraction of calf muscles (pulling heel off floor)

What types of motion are muscles capable of?

-Shortening and pulling only

What are shin splints?

-Tendonitis of foot dorsiflexors -minor and responds to treatment

Describe pulled hamstrings.

-strain of lower leg flexors - minor

Each muscle CELL is supplied by...

1 motor neuron terminal branch, 1 or two capillaries

How does relaxation occur after a muscle contraction?

1. AChE breaks down ACh in synaptic cleft (prevents more AP from being sent) 2. Muscle AP ceases 3. Ca2+ channels in sarcoplasmic reticulum close 4. Active transport pumps in SR pump calcium from sarcoplasm back into SR storage 5. Calcium binding protein (calsequestrin) helps bind Ca2+ in SR 6. Troponin no longer bound to Ca2+, allows for tropomyosin to rotate back to position covering myosin binding sites 7. Titin allows for actin to slide back to original position

What are the two main functions of ATP in the contraction of muscle cells regarding the filaments?

1. ATP cocks myosin head 2. ATP cleaves myosin head from actin

What are three sources of ATP production in muscle cells?

1. Creatine phosphate system 2. Anaerobic respiration (AKA glycogen/lactic acid system) 3. Aerobic cellular respiration

What factors are used for muscle naming?

1. Fiber direction relative to midline: transverse (perpendicular), oblique (at angle), rectus (parallel) 2. Size: brevus, longus, maximus, minimus, magnus 3. Shape: deltoid (triangular), trapezius (trapezoid), rhomboid (rhombus, 4 sides with opposites parallel) serratus (like serrated knife) 4. Action: levator scapulae (elevates scapula), adductor magnus, tensor tympani 5. Number of origins: biceps, triceps, quadriceps (4 separate muscles with same functions) 6. Location: for bone it's near or whether lateral or medial (radialis, femoris, medialis) 7. Location of origin and insertion: sternocleidomastoid (origin- through- insertion)

What is the sliding filament mechanism of contraction?

1. Myosin cross bridges pull on thin filaments 2. Thin filaments slide inward towards M line 3. H zone shortens, Z lines move closer together 4. Manty sarcomeres shorten this way--> muscle fiber shortens--> muscle shortens THICK AND THIN FILAMENTS DO NOT CHANGE IN LENGTH

List the general steps of contraction up to Ca2+ release.

1. Nerve impulse reaches axon terminal (synaptic bulb) 2. Synaptic vesicles release ACh across synaptic cleft 3. ACh binds to ACh receptors on motor end plate, opening the sodium channels 4. Depolarization of the sarcolemma begins, transmitting action potential 5. Action potential crosses transverse tubule 6. Near transverse tubule, AP depolarization auses release of Ca2+ from sarcoplasmic reticulum by voltage gated Ca2+ channels 7. Increased Ca2+ concentration allows calcium to bind to troponin inside the myofibril, allowing for motion of tropomyosin to reveal myosin binding sites--> contraction cycle begins

What are the treatments in order or severity of injury?

1. RICE: Rest, ice, compress, elevate 2. NSAIDS: non-steroidal anti-inflammatories- ibuprofen and aspirin- analgesic and anti-inflammatory if used over time (needed for healing process) 3. Steroid injections

Describe the action of a muscle action potential and how it is generated in terms of membrane potential.

1. Resting membrane potential is -70 mV (+ outside, - inside) 2. AcCh stimulus at motor end plate allows influx of Na+, depolarizing slightly, if this depolarization reaches -55mV then the action potential will be propagated, if the depolarization does not reach -55 mV from the initial Na+ rush from AcCh (not strong enough stimulus) than there is no AP 3. Na+ rush rapidly increases in rate after reaching threshold potential to +30mV, happening across the cell membrane as more Na+ channels open down the line 4. After Na+ rush (peak occurs), K+ channels have opened and K+ rushes rapidly out to repolarize the cell membrane, it over shoots at first, but then membrane potential returns to normal. 5. End with higher concentration of Na+ inside and K+ outside (Na/K pumps correct this) but proper charge gradient

Ratio of actin to myosin in a myofibril

2:1

How many classes of levers are there?

3

How much can a muscle reduce its length by during contraction?

30%

What word should you associate with neurons?

Communication

What percent of a lean adult's body weight is muscle?

40-50

How much heat from ATP is transformed in ATP energy? How much is lost?

60% lost 40% made to ATP

How many skeletal muscles are there?

700

List the steps of the contraction cycle from Ca2+ release to the end.

8. 4 steps of contraction cycle a. ATP binds to myosin head, becoming hydrolyzed to ADP and PO4-, this cocks myosin head b. Myosin head binds to revealed actin, giving off PO4-, spontaneously from cocked position c. Myosin head releases ADP causing rotation towards center of sarcomere (power stroke of contraction) d. ATP binds to Myosin, becoming hydrolyzed, and releasing myosin from actin, repeat all 4 steps form here 9. Cycle continues as long as Ca2+ levels and ATP levels are high enough * This is what causes thin and thick filaments to slide past one another (actin moves)

What is a fascicle?

A bundle of muscle fibers: the stringiness of muscle is caused by fascicles

What is paralysis?

A nerve to muscle communication disruption, leads to muscle atrophy

What is a spasm?

A sudden involuntary contraction of a single muscle within a large group of muscles: usually painless, but causes immobility

What is Runner's knee?

AKA Patellofemoral stress syndrome - ligament or cartilage damage in knee - from repetitive overuse - most common serious injury

Describe the 3 types of CT associated with deep fascia of muscle and their structure.

AKA deep fascia Epimysium: surrounds whole muscle (organ) Perimysium: surrounds groups/bundles of muscle cells= Fasicle (10-100) within muscle Endomysium: separates individual muscle cells They all come together at end of muscle belly to form tendons

What is a muscle tic?

An abnormal contraction that causes involuntary twitching (brief, single contraction) of skeletal muscles normally under voluntary control - usually eyelid or facial muscles

How is the muscle AP propagated and where?

At the sarcolemma, done by voltage/electrical gated Na+ and K+ channels - Initial depolarization triggers opening of Na+ channels nearby, allowing more depolarization. - After depolarization has begun and Na+ channels have opened, this triggers triggers opening of K+ which allows K+ to flow out, repolarizing membrane

Compare and contrast atrophy and hypertrophy.

Atrophy: -wasting away of muscles (smaller in size) - caused by disuse (disuse atrophy) or severing of the nerve supply (denervation atrophy)--> causes disuse - transition to connective tissue cannot be reversed (caused by disuse) Hypertrophy: - increase in muscle fiber diameter - result from forceful, repetitive muscular activity and increase in myofibrils (which hold fiber proteins), sarcoplasmic reticulum and mitochondria (to allow for force to be more easily produced)

Basic description of pennate fascicle arrangement. Give example of each type with description.

Basic: Fibers are short compared to muscle length Central tendon extends into muscle Unipennate: Fibers attach to one side of tendon and end Ex. Digitorum longus Bipennate: Fibers attach to both sides of central tendon and end Ex. Rectus femorus Multipennate: Several tendons branch from central tendon, each branch holds a bipennate muscle Ex. Deltoid

What is an example of facial paralysis?

Bell's palsey--> Shows that muscles tend to be controlled by nerves according to side: can have one side paralyzed and the other normal Able to heal because it involves the PNS

What are the roles of bones and joints as levers in the human body?

Bone= lever Joint= fulcrum

What is a twitch contraction?

Brief contraction of all muscle cells in a motor unit responding to a SINGLE action potential - when threshold potential (depolarization) is reached, all cells will contract (all or nothing)

What is fibromyalgia?

Cause of FMS: widespread musculoskeletal pain and fatigue from an unknown cause - affects muscles, ligaments and tendons causing ache all over - muscles twitch and have burning sensation - affects women more than men, all ages

What is Myasthenia Gravis? Affected groups and treatments.

Common neuromuscular transmission disorder (homeostatic imbalance): - progressive autoimmune - block ACh receptors at NMJ - Muscle gets progressively weaker with more receptors damaged (can't regenerate AP across sarcolemma) - Starts with double vision and swallowing difficulties--> paralysis of respiratory muscles Most common in women 20-40 with link to thymus gland tumors Treatment of steroids that reduce antibodies that bind to ACh receptors (cause), give inhibitors of acetylcholinesterase to increase ACh in NMJ

Describe the creatine phosphate system and when this type of ATP production would be most helpful and why. Supplement information. When does creatine phosphate system come in handy?

Creatine phosphate system: 1. Anaerobic, produces few ATP--> phosphate from creatine phosphate adds a phosphate to ATP 2. Only happens in muscle fibers 3. Used for maximum contraction activities for short bursts Powers max muscle contraction for 15 seconds--> useful for 100 m dash OR to provide energy for the time in which it takes for O2 to diffuse from hemoglobin and myoglobin (for aerobic respiration) Creatine substances promote muscle mass increase, but are controversial

What is the name of a myosin/actin attachment?

Crossbridge

Which gates open during depolarization? During repolarization?

Depolarization: Na+ Repolarization: K+

What is compartment syndrome? Is it treatable?

External/internal pressure constricts structures in a compartment-->Results in damaged BV which reduces blood flow to structures in compartment--> without intervention nerves are damaged, scar tissue develops which can cause contracture (permanent contraction of muscle)

Describe the characteristics of cardiac muscle fibers and their contractions.

Fibers: branched, involuntary, striated Myoglobin: high Mitochondria: many Capillaries: many (similar in composition to red fibers/slow oxidative of skeletal muscle) Contractions: - prolonged, constant contractions and long refractory period (don't get fatigued because can't be forced to contract too much) - Ca2+ comes from SR and ECF, troponin and tropomyosin act like in skeletal muscle - autorhythmic (unique to cardiac), sets its own rhythm- when supplied with blood it will keep beating, even without a brain to signal it

Describe the glycogen lactic acid system. Describe when it would be most useful for muscle contraction ATP production.

Glycogen/Lactic acid system (anaerobic respiration): 1. Muscle glycogen is broken down to glucose, which undergoes glycolysis to produce 2 ATP 2. This forms the glucose into 2 pyruvic acids that break down into lactic acid 3. Lactic acid buildup increases fatigue 4. Small amount of ATP formed --> AKA fermentation--> partial breakdown of glucose and production of lactic acid Produces energy for 30-40 s of max muscle contraction: useful for 300 m dash

What is a myogram? What are its phases?

Graph- record of twitch muscle contraction Three phases: 1. Latent 2. Contraction 3. Relaxation

Describe muscular dystrophy, most affected and treatments.

Group of inherited diseases that destroy muscles: -progressive -Duchenne M D most common form - Little or no dystrophin to reinforce sarcolemma leading to tears in muscle - Loss of walking by age 12, death at 20-30 Boys most affected (sex linked gene) Research into genetic engineering to replace faulty dystrophin genes (failures)

Describe IM injections. When are they given? What are common sites?

Intramuscular injection (into muscle), below subcutaneous layer, faster absorption than oral (slower than IV) Given: rapid absorption needed, when drug irritates subcutaneous layer or IV is not well tolerated with medicine given Common sites: gluteus medius, vastus lateralis (thigh), deltoid

What is a cramp? And what might cause one to occur?

Involuntary and often painful muscle contractions caused by inadequate blood flow to muscles (as in dehydration), overuse and injury, and abnormal blood electrolyte levels (treat night cramps with electrolytes at night

Describe isometric and isotonic contractions.

Isotonic: movement of a load (resisting force) - concentric contraction: muscle shortens to produce force and movement (agonist in contraction) - eccentric contractions: muscle lengthens while maintaining force and movement - tension generated without muscle shortening - maintaining posture and supporting objects in fixed position

What is wave summation? How does it occur? Does the action potential change size?

It is increased strength of a contraction that occurs because a new stimulus is sent before the muscle has completely relaxed after a previous stimulus New action potential sent shorter after last, action potentials are the same size, but because they are causing contraction forces to sum together, the force of the contraction is greater

What moves more freely, Na+ or K+?

K+

What are the roles of structural proteins? Give examples.

Keep thick and thin filaments in proper alignment Give myofibril elasticity and flexibility Link myofibrils to sarcolemma and ECM Titin: helps a sarcomere return to its resting length after a muscle has been contracted- largest polypeptide known Myomesin: forms M line Nebulin: helps maintain alignment of thin filaments in the sarcomere Dystrophin: reinforces sarcolemma, helps transmit tension generated by the sarcomere to the tendons--> allows for wide distribution of force--> makes tougher cell membrane (sarcolemma)

What factors affect muscle tension? How do they do it?

Muscle tension is increased by stronger contractions of agonist muscles. 1. Fiber length, how much the protein fibers overlap (myosin and actin)--> sarcomere length 2. Motor unit size (how many fibers controlled in each motor unit) 3. Number of motor units stimulated (recruitment of more motor units increases force as needed because more fibers are contracting= more force produced) 4. Frequency of stimuli

What is muscle tension? What are its components? Describe them. Give examples.

Muscle tension= contractile force produced by muscles (contraction and extension) 1. Active: muscle filament contractions (actin and myosin sliding)--> prime mover shortens, producing pulling force (agonist)--> bicep forming bump when flexed 2. Passive: stretching of elastic components (titin, epimysium, endomysium, perimysium, tendons)-->antagonist is stretched in this way (puts potential in antagonist to do work)--> Kangaroo Achilles tendon acts like rubber band when stretched and can produce a great force (hopping) after being stretched by agonist muscle contraction, more efficient than running

What is a myoma? Where is it commonly found?

Muscle tumor- commonly found on uterus

How would you describe structure of myosin/actin?

Myosin= 2 golf clubs wound together, then wound together with others of same structure= thicker filament Actin= Spaghetti (actin and tropomyosin) and meatballs (troponin) wound together--> thinner filament

Can muscles push?

No, they can only pull: pushing may seem to appear by pulling action of antagonist muscle

Describe smooth muscle and its two types.

Nonstriated Involuntary Thick, thin and intermediate filaments (to dense bodies) but NO sarcomeres Taper at ends Single, oval and central nucleus No t tubules, little sarcoplasmic reticulum for Ca2+ storage Visceral: -single unit - increases or decreases diameter - found in walls of hollow organs (stomach, intestines) and small BV - fibers are in a network and function as a single unit controlled by 1 neuron= gross control Multiunit: -found in large BV and large airways, arrector pili, iris of the eye - high detail contraction= 1 neuron controls few fibers, many neurons control one area of muscle - fiber operate singly, not in a unit (needed for detail and variety)

What is a motor unit?

One somatic motor neuron and all the skeletal muscle fibers (cells) it stimulates

What is a muscle origin? An insertion? A belly?

Origin: bone that does not move when the muscle shortens (usually proximal) and the tendon attached to it Insertion: The movable bone when a muscle contracts and the tendon attached to it (usually distal) Belly: fleshy part of muscle between the attachment sites, does the shortening and produces force through contraction

Give an example of triangle fascicle arrangement.

Pectoralis major

What are the most common causes of running injuries?

Poor training: overuse, too much too quickly Poor equipment Biomechanical problems: joint abnormalities (double jointed people)

What forms striations in skeletal muscle?

The overlap of thick and thin filaments - I bands= light= thin filaments (actin only) - A bands= dark= thick filaments and thin filaments overlap (myosin and actin)

How does fascia affect origin/insertion point of muscle?

Three layers of deep fascia: epimysium, perimysium, endomysium come together at ends of muscles to form origin and insertion points of tendons

What happens at NMJ, in general?

Transmission of neuron electrical signal to muscle electrical signal

When would a muscle cell go into oxygen debt?

When glucose enters the cell and needs to be used to produce ATP, but adequate oxygen is not present to undergo aerobic respiration--> anaerobic respiration of creatine phosphate cycle and glycogen/lactic (fermentation) acid cycle

What is the presynaptic membrane at the neuromuscular junction, the post?

presynaptic membrane= neuron postsynaptic membrane= motor end plate