Muscular system Flashcards

Question

myosin head

Answer 1

binds to actin molecule to form cross-bridges to contract the muscle break down ATP to release energy bend hinge region pivot - so they can bind to actin to produce force - collectively adds to muscle production

Answer 2

each muscle fiber is innervated by a branch of a motor neuron at the neuromuscular junction. this point of contact between axon terminal & Sarcolemma results in Ap in a muscle fiber. stimulus for this(AP) is the release of acetylcholine from the NM

Answer 3

Motor neuron signal transmitted to muscle cell through a specialized synapse( Neuromuscular junction) 1. electrical component 2 . mechanical component muscle fibers are electrically excitable · Aps travel from brain or spinal cord along axons to muscle fibers and cause them to contract · electrically excitable cells , like other cells are polarized. inside of most cell membranes is negatively case · voltage/electrical charge difference , exists across each cell membrane - this charge difference across cell membrane of an unstimulated cell is called RMP.

Answer 4

1. When an Ap reaches the terminal of a motorneuron, It causes Ca2+ channels in cell membrane of an axon to open. Ca2+ diffuses into axon terminal 2. Once inside cell , the Ca2+ causes the contents of a few synaptic vesicles to be secreted by exocytosis from the presynaptic terminal into the synaptic cleft. 3. ach molecules are released from Synaptic Vesicles. I. ach diffuse across cleft & bind to ligand-gated Na+ channels in Sarcolemma causing them to open 5. Na+ ions then diffuse into muscle fiber , causing depolarization In skeletal muscle, each AP in motor neuron causes depolarization in muscle fiber that exceeds threshold. This produces an AP in muscle fiber. 6.Ach then unbinds from gate Na+ channels, which then close. 7. Enzyme acetylcholinerase rapidly breaks down ach in synaptic cleft into acetic acid and choline. Enzyme keeps ach from accumulating within the synaptic cleft, where it would act as a constant stimulus at the mototr end-plate, producing continuous contraction in muscle fiber. 8..8 motor neurons actively absorb choline molecules into axon terminal. The choline molecules then combine with acetic acid within the neuron to produce Ach. 9. recycling choline molecules requires less NRG and is more rapid than continuously synthesizing new Ach molecules. The Ach molecules are then taken up by synaptic vesicles.

Answer 5

AP occurs when the excitable cell is stimulated reversal of RMP --> inside of cell becomes more pos, compared to outside charge reversal occurs because ion channels open when cell is stimulated. diffusion of ions through these channels changes the charge across the cell membrane and produces an AP lasts 1ms - a few ms two phases: 1.depolarization 2.repolarization before a neuron or a muscle fiber is stimulated, the gated Na+ and K+ ion channels are closed. when cell is stimulated, llgand-gated Na+ channels open & Na+ diffuses into the cell Na+ will make the inside of the cell membrane depolarized (more +) if depolarization causes the membrane potential to reach threshold, an AP triggered. A s the inside of a cell becomes more + , this voltage causes additional permeability changes in the cell membrane · this stops depolarization & starts repolarization. repolarization phase is the return of membrane potential to its resting value . occurs when when ligand-gated Nat+ channels close and gated K+ channels open K+ moves out of the cell the inside of the cell becomes more (-) AP ends and rmp is restored by Na+ K+ pump

Answer 6

· Phospholipid bilayer is a hydrophobic environment inhibiting the movement decrease of charged particles, particularly, across the cell membrane Ion can move across membrane through ion channels 1.leak -main ones, slow leak of ions down [ ] gradient. 2.gated - most important in stimulated cells. governs production of AP

Answer 7

AP made in sarcolemma of skeletal muscle fiber can lead to contraction of the fiber. AP is propagated along motor neuron. AP in motor neuron stimulates opening of voltage-gated Ca2+ channels The influx of Ca2+ into motor neuron causes secretion of ach. ach opens ligand-gated Na+ channels in sacrolemma AP in muscle fiber travels along entire sarcolemma. AP also moves down T-tubles.

Answer 8

sodium potassium pump maintains the uneven distribution of Na+ & K+ across the cell membrane. · transports K+ from outside the cell to Inside & transports Na+ from inside the cell to the outside . negative inside compared to the outside. need electrical chemical gradient. electrical charge difference in an unstimulated cell. · still ready to respond in a moments notice. RMP results DC of 3 factors: 1. [] K+ inside cell>than outside 2 . 5 ) Na+ outside cell >than inside 3.Membrane more permeable to K+ than Na+ (-) charged molecules (more K+ leak channels than Na+), such as proteins are "trapped" inside the cell because cell membrane is impermeable. [ ] gradient for an ion determines if it will enter or leave a cell. K+ channels, K+ out - go towards lower [ ] of that ion Na+ channels, Na+ in - go towards lower [ ] of that ion.

Answer 9

mechanical component of muscle contraction many cycles occur per contraction ifCa+ is present this will continue 1.Exposure of active sites- Ca+ binding to troponin -myosin head stores NRG from ATP breakdown. 2.Cross bridge formation - free phosphate released - myosin head attached to actin - actin sites are exposed, myosin quickly binds. 3. Power stroke - cocking of myosin - stored NRG being used - forms cross-bridge to trigger rapid movement of myosin head called the power stroke. - Actin filament does the movement. 4. Cross-bridge release - triphosphate bind - binding of ATP to myosin head causes it to detach from myosin 5.Hydrolysis of ATP - Myosin head breaks down ATP unto ADP and P -- which remain attached to myosin head. Myosin return to their resting position

Answer 10

We regulate the amount of force a muscle produces by controlling how many muscle cells (fibers) are stimulated to contract we can modify force production to vary our movements.

Answer 11

includes a single motor neuron and all the muscle fibers it innervates. Motor units vary in their size and their sensitivity to stimulation Small motor units have a handful of muscle fibers, while large motor units can have hundreds of muscle fibers. The muscle fibers within a motor unit are the same fiber type A muscle will contain motor units of various sizes and types Muscles tend to have motor units of a certain size, depending on their function small muscles in the hand and eye have very small motor units that allow for the fine motor control required for delicate and precise movements. Large muscles in the legs have huge motor units and produce large forces with less fine control.

Answer 12

a motor unit is recruited when an action potential is sent down its motor neuron. As indicated above the motor neuron can stimulate a few or many muscle fibers -- to get certain cells to contract. We can produce smooth, fluid movements of varying force by regulating the number and size of motor units that we recruit.

Answer 13

Muscle fiber are classified into 3 specialized types based on their structural and functional characteristics. Slow oxidative to fatigue, use O2 well, have lots of mitochondria. SO – high capacity for aerobic metabolism (using oxygen) FOG – intermediate characteristics for aerobic and anaerobic metabolism FG - High capacity for anaerobic (without oxygen) force and power output Isometric and Isotonic contractions: Isometric- muscle does not shorten. - increase tension. - lifting something way to heavy. Isotonic - muscle shortens. concentric(muscle shortens) and ecccentric(increase muscle length).

Answer 14

Functions- low-twitch oxiadative (SO) (Type-I): Maintenance of posture and performance of endurance activities. Fast-twitch oxidative glycolytic (FOG) (Type IIa): Endurance activities in endurance-trained muscles. Fast-twitch glycolytic (FG) (Type IIb): Rapid, intense movements of short duration. Will recruit all to reach maximal muscle demand.

Answer 15

Location where fibers are most abundant- low-twitch oxiadative (SO) (Type-I): Generally in postural muscles and more in lower limbs than upper limbs. Fast-twitch oxidative glycolytic (FOG) (Type IIa): Generally in lower limbs. Fast-twitch glycolytic (FG) (Type IIb): Generally in upper limbs.

Answer 16

Glycogen concentration- low-twitch oxiadative (SO) (Type-I):Low. Fast-twitch oxidative glycolytic (FOG) (Type IIa):High Fast-twitch glycolytic (FG) (Type IIb):High.

Answer 17

Myoglobin content - Slow-twitch oxiadative (SO) (Type-I):High. Fast-twitch oxidative glycolytic (FOG) (Type IIa): High. Fast-twitch glycolytic (FG) (Type IIb): Low.

Answer 18

Mitochondria - Slow-twitch oxiadative (SO) (Type-I): Many. Fast-twitch oxidative glycolytic (FOG) (Type IIa): Many. Fast-twitch glycolytic (FG) (Type IIb): Few

Answer 19

Capillaries - Slow-twitch oxiadative (SO) (Type-I): Many. Fast-twitch oxidative glycolytic (FOG) (Type IIa):Many. Fast-twitch glycolytic (FG) (Type IIb): Few.

Answer 20

Metabolism - Slow-twitch oxiadative (SO) (Type-I): High aerobic capacity, low anaerobic capacity. Fast-twitch oxidative glycolytic (FOG) (Type IIa): Intermediate aerobic capacity, high anaerobic capacity. Fast-twitch glycolytic (FG) (Type IIb): Low aerobic capacity, highest anaerobic capacity.

Answer 21

Fatigue resistance - low-twitch oxiadative (SO) (Type-I):High. Fast-twitch oxidative glycolytic (FOG) (Type IIa):Intermediate. Fast-twitch glycolytic (FG) (Type IIb):Low, wear out quickly, cant maintain a sprint.

Answer 22

Myosin ATpose activity- low-twitch oxiadative (SO) (Type-I):Slow. Fast-twitch oxidative glycolytic (FOG) (Type IIa):Fast Fast-twitch glycolytic (FG) (Type IIb):Fast.

Answer 23

Glycogen concentration- low-twitch oxiadative (SO) (Type-I):Low. Fast-twitch oxidative glycolytic (FOG) (Type IIa):High Fast-twitch glycolytic (FG) (Type IIb):High.

Answer 24

- weight lifting – high force low duration exercise. Increases size and strength of recruited muscle fibers (all fiber types that are recruited). many different exercises are required to ensure all muscles in the body are stimulated to adapt to the training. Increase in fiber size is called hypertrophy Fiber growth requires more nuclei to be added to each muscle fiber. Resistance exercise stimulates Satellite cells to fuse with muscle fibers providing new nuclei New nuclei can sustain the higher level of protein synthesis that is needed to maintain the larger cell size. The additional protein includes: the myofilament proteins involved in force production (myosin, actin, titin). proteins needed to maintain physiological needs. enzymes for ATP re-synthesis and transporters to maintain membrane potential during relaxation. transporters to remove calcium during relaxation.

Answer 25

Training can increase the size and capacity of both types of muscle fibers so they can perform more efficiently. Aerobic based exercise - low force long duration exercise Increase aerobic enzymes (mitochondria) Increased capillary density (O2 uptake) Increased Cardiac Output from Heart (O2 delivery) Increased uptake and storage of fuel (carbohydrates and lipids) for aerobic metabolism Increased resistance to fatigue (reduced work capacity) Better protection against oxidative stress, inflammation and acidosis Endurance trained individuals can sustain a higher rate of aerobic metabolism, allowing them to maintain a faster running/cycling/swimming pace for much longer, improving performance in endurance events like a 10km run or triathlon. intense exercise that requires ATP production without )2 (weight + lifting, increases muscular strength and mass and cause fast - twitch muscle fibers to enlarge more than slow twitch fibers. exercise in with ATP is produced with )2 increaseing vascularity of muscle and causes slow-twitch muscles fibers to enlarge more. - throguh training with this we can run long distances. in response to exercise hypertrophy occurs --> muscle increases in size, muscle increases in strength and endurance atrophy (muscle decreases in size) --> both result from changes in size of individual muscle fibers New nuclei are added to muscle fibers because small satellite cells near skeletal muscle fibers increase in # in response to exercise and then fuse with skeletal muscle fibers, mitochondria, blood vessels and connective tissue also increase in #. athletic training increases muscle strength because in increase muscle size and # of motor units recruited simultaneous by nervous system. improved endurance is in part to increased metabolism, increased circulation to exercising muscles increase # of capillaries, more effecient respiration, and greater capacity of heart to pump blood.

Answer 26

a,b. Immediate – Adenylate Kinase and Creatine Kinase(fatigue fast) - very fast but very limited quantity(cant do it often) c. Anaerobic – Partial release of energy from Glucose – fast but limited quantity d. Aerobic - Complete energy release from Glucose and Fats – slow but very large quantity Different fiber types have higher capacity for different pathways for ATP re-synthesis Different muscles will have more of specific fiber types to support their functional roles transfers on phosphate from on ADP to a second ADP resulting in one ATP and one AMP transfer of phosphate produce ATP break all glucose. Harness NRG between bonds breaking glucose in half limited, but less high net gain of ATP

Answer 27

Epimysium; Perimysium; Endomysium;

Answer 28

forms connective tissue sheath that surrounds, each skeletal muscle. protein fibers gradually merge with a layer of connective tissue between adjacent muscles and connecting the skin to superficial muscles outer layers of connective tissue separate the muscles from nearby structures

Answer 29

subdivides each who muscle into many, visible bundles of muscle fibers (cells) called fascicles. is a loose connective tissue serving as passageways for blood vessels and neurons that supply each fascicle

Answer 30

delicate layer of connective tissue that separates the individual muscle fibers within each fascicle. serves as passageways for nerve fibers and blood vessels that supply each separate muscle fiber.

Answer 31

attach muscle to bone