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Muscular Tissue C10

Bio 40A Muscular Tissue Chapter 10

Types of muscular tissue and their characteristics. 1)Skeletal- voluntary, striated, for body mvmnt. 2)Smooth- involuntary, nonstriated 3)Cardiac- involuntary, striated, heart.
Where is smooth muscle found? In walls of hollow internal structures, such as blood vessels, airways, and most organs in the abdominopelvic cavity. Also in skin (attached to hair follicles).
What is the function of muscular tissue? MOVEMENT. STABILIZATION of body posture. THERMOGENESIS (generating heat, includes shivering). STORAGE of substances.
What are the properties of muscle? All muscles contract, extend, are elastic, and are excitable (with electricity).
Synonymous with "muscle cell." Synoymous with "muscle fiber."
Standard shape of muscle cell. Extends string-like the whole length of a muscle.
What surrounds and protects muscular tissue? Connective tissue.
Large connective tissue sheet that wraps around groups of muscles. Fascia (=bandage)
"3 layers of fascia" (book says they extend FROM fascia) Epimysium- outermost layer that encircles the entire muscle. Perimysium- surrounds grps of 10 to 100+ muscle fibers. Endomysium- separates individual muscle fibers.
Bundles of muscle fibers surrounded by perimysium. Fascicles.
What gives meat it's grainy appearence. Fascicles.
What forms a tendon? Epimysium + perimysium + endomysium at end of muscle.
Broad, flat layer of tendon. 2 examples. Aponeurosis (apo=from, neur=sinew). Between rectus abdominis. Between frontal and occipital bellies of the occipitofrontalis muscle.
Bonus: define a tendon. A cord of dense regular connective tissue composed of parallel bundles of collagen fibers that attach a muscle to the periosteum of a bone.
Enclose certain tendons, especially those of the hands and feet. Contain what fluid that does what? Tendon (synovial) sheaths. Contains synovial fluid that reduces friction.
Inflammation of a tendon. Treat how? Tendonitis. Ice and rest.
When does muscle tissue begin to form? Forms from what cells? During embryonic development many myoblasts fuse to form each muscle fiber.
How often can muscle fibers undergo cell division? NEVER
Cells in muscles that retain the ability to undergo cell division. What do they do? Satellite cells. Fuse with one another or damaged muscle fibers to regenerate functional muscle fibers, but amount is not enough to compensate for significant muscle damage or degenration. "Rare"
Myoblasts become what? Muscle fibers and satellite cells.
What happens when there is significant muscle damage? Scarring/Fibrosis
Why do muscle cells have 100+ nuclei? Formed from the fusion of 100+ myoblasts, each with a nucleus.
What does exercise do? Builds the size (NOT #) of muscle cells.
Increase in the size of muscle fibers. Hypertrophy
Increase in the number of muscle fibers. Hyperplasia
Decrease in the size of muscle fibers. Atrophy. a=without, trophy=nourishment
"sarc"= = "flesh"
The plasma membrane of a muscle cell. Sarcolemma (sarc=flesh, lemma=sheath).
Name of the thousands of tiny invaginations of the sarcolemma. Function. Transverse (T) Tubules (bonus:filled with interstitial fluid) and muscle ACTION POTENTIALS travel along the sarcolemma and through the T tubules and spread quickly and evenly throughout the muscle.
Name of the cytoplasm of a muscle fiber. Contains a lot of what molecules? SARCOPLASM contains a lot of GLYCOGEN (chains of glucose) and MYOGLOBIN "transfers oxygen in cell (bonus: protein that binds to oxygen and releases it when needed by the mitochondria for ATP production)
Name of contractile organelles of muscle cells. Myofibrils extend the entire length of the cell (giving cell it's striated appearance).
Fluid-filled system of membranous sacs. Function. Similar to what organelle in nonmuscular cells? Sarcoplasmic Reticulum (SR)encircles each myofibril and stores Ca2+, releasing it for muscle contraction. Similar to the smooth ER.
Dilated end sacs of the SR. Butt against what other structures? Terminal Cisterns butt against T Tubules (Ca stored in the SR is released from these terminal cisterns)
Where are the nuclei of muscle cells located? Just beneath the sarcolemma.
Contractile portion (funtional unit) of a myofibril. Sarcomere. mere=part
Smaller structures within a myofibril. Thin and thick filaments.
Separate functional portions of myofibrils? Sarcomeres are separated by Z-DISCS (dense protein).
A sarcomere extends from where to where. Z-disk to z-disk.
A z-disk and M-line would be made of what kind of muscle protein? Structural (Bonus: Z-disc = actinin, M-line = myomesin)
Myofibrils are built from what 3 kinds of proteins? Structural(keep thin and thick filaments in alignment and help overall structure of cell), regulatory (switch contraction process on and off), and contractile (generate force during contraction).
Contractile protein of muscle anchored to M-lines. Myosin molecules (each in the shape of two golf clubs twisted together) make up each thick filament (bonus: about 300 molecules/thick filament. Converts chemical ATP energy to mechanical motion energy = motor protein)
Contractile protein of muscle anchored to Z-discs. Actin molecules make up each thin filament in the shape of a helix.
Regulatory proteins attached to the thin filament. Tropomyosin (cover the myosin-binding sites on actin in relaxed muscle) and Troponin (hold tropomyosin in place).
What causes active sites on actin to be exposed? Ca2+ (released by SR into cytosol) binds to troponin, which undergoes a change in shape and moves tropomyosin away from myosin-binding sites on actin.
Bonus: how many thin filaments surround each thick filament? 6
What happens with the onset of contraction? Calcium ion (CA2+) is released by the SR into the cytosol.
What proteins begin the contraction process? Troponin moves tropomyosin off active site of actin.
The model describing the process of muscle contraction? Sliding filament mechanism/theory.
What happens to muscle during contraction (short story). The thin and thick filaments slide past one another, shortening the sarcomeres, shortening the muscle.
First step of the contraction cycle. ATP HYDROLYSIS (ATP becomes ADP and phosphate group and myosin head is energized)
Second step of the contraction cycle. ATTACHMENT OF MYOSIN TO ACTIN (Phosphate group is released)(bonus: each attachment called a crossbridge)
Third step of the contraction cycle. POWER STROKE (ADP is released, Myosin head rotates toward center of sarcomere, moving thin filaments toward M-line)
Last step of the contraction cycle. DETACHMENT of myosin from actin (ATP binds to myosin head and myosin head detaches from actin)
What is needed to end the contraction cycle? ATP
The contraction cycle will continue as long as what is available? ATP and a high enough Ca2+ level near the thin filament.
bonus: How many times do each crossbridge attach and detach per second? All at once? Each of the 600/thick filament attach and detach about 5 times per second, randomly.
What energizes the myosin head? ATP becoming ADP + P
What happens when the myosin head attaches to actin? The phosphate group is released.
When is the ADP released from the myosin head? When the myosin head rotates.
What happens in muscle contraction (short story)? The sarcomeres/muscle fibers/muscles shorten.
A higher concentration of this ion will cause a greater muscle contraction. Calcium
How does the body get Ca out of the cytosol? What process does this cause? Active transport of Ca back into the SR for storage. Muscle relaxation.
NM Junction/? Neuromuscular junction/synapse
Name for space between muscle fiber and neuron. Synaptic cleft.
What carries the message from neuron to muscle? Acetylcholine (ACh)
Name of neuron that gives muscle cells messages. How does it do this? Motor Neurons have a synaptic end bulb from which ACh in vesicles is dispersed and received by muscle fiber ACh receptors.
Part of muscle fiber that receives ACh from neuron. Motor End Plate with ACh receptors/ligand gated channels (lock and key.
ACh is a what? Neurotransmitter.
What process releases ACh from the neuron? Exocytosis
ACh does what on the muscle fiber? What ions are involved? It activates ACh receptors and opens Ligand gated channels for Na ions.
What cause the SR to release calcium? The influx of Na into muscle cell makes it more positively charged and SR releases Ca.
What stops ACh? Enzymes degrade ACh in synaptic cleft.
How do muscles get the ATP needed to contract in the first 15 seconds of movement? Creatine Phosphate
How do muscles get ATP for contraction between 15 and 40 seconds of movement? Anaerobic Cellular Respiration
How do muscles get ATP for contraction for movement longer than 40 seconds? Aerobic Cellular Respiration
Muscles during basket ball and rennis use mainly what method of obtaining ATP? Anaerobic Cellular Respiration
What stage of getting ATP for contraction uses the most energy, thus is the best for exercise? Aerobic Cellular Respiration
How long an activity do the 3 ways of getting ATP support? Creatine Phosphate:short outburst, max output 15 seconds. Anaerobic:30-40sec. Aerobic >40sec.
Why do muscles fatigue? Run out of nutrients, such as O and Ca,and ACh.
negative biproduct of muscle metabolism and what it does lactic acid slows down muscle healing and light aerobic activity
What causes muscle pain? Microtearing of muscle fibers.
Why do we breath heavily after exercise? What does this do to affect that negative biproduct of muscle metabolism? Body is introducing more O2 into system. O2 + lactic acid = glycogen
Why should we do light aerobic exercise after more strenuous exercise? Flush out lactic acid and combine it with O2 to get glycogen.
What is a motor unit? The motor end plate of the neuron and the muscle it activates.
What configuration of motor units does the upper leg have? Why? Large movement means there are more muscle cells for each neuron. Sciatic nerve controls quad muscles.
What configuration of motor units does the hand have? Why? The precise movement means there are fewer muscle fibers per motor neuron.
What causes a twitch? A single action potential causes a brief contraction of a muscle fiber.
4 Phases of Muscle Contraction (wave on graph) 1)Latent P. (appl. of stimulus to pnt of contraction?) 2)Contraction P. 3)Relaxation P. (Peak on down) 4)Refractory P. (when muscle can't fire)
Why don't all myosin heads activate at once? Fancy term for this: Motor Unit Recruitment so we don't tire as easily since all parts of muscle have time to rest.
In what order do muscle fibers get used? How does weight training affect this? Weakest used first. Meanwhile strongest atrophy until they get used. Weight training and other activity "raises the bar" for muscle fibers.
How tense muscles are at rest is called what? How is it increased? Muscle tone. Train your brain (low wt. lots of reps. causes brain to trickle ACh in amts just below contraction levels).
No muscle tone. Causes. Flaccid (from trauma, stroke, injury) muscles can NOT activate.
Types of muscle contraction/tension. Concentric isotonic (muscle shortening w/movement), eccentric isotonic (muscle lengthening w/mvmt), isometric (tension with NO mvmt)
2 types of meat (muscle). Which has more nutrition? Which has more fat? Red (lots of mitochondria, blood, and myoglobin) has better nutrition but more fat than White (low in mitochondria, blood, and myoglobin)
Darkest red muscle fibers. Slow Oxidative (SO) Smallest, least powerful, most capillaries, slow contraction speed, great endurance, used in aerobic activity, "slow O2 use"
Muscle fibers used in fast walking. Fast Oxidative (FOG) In the middle for size, power, and amt of mitochondria and blood. Larger and less red than SO. Contract quickly. Fatigue quickly. Used in aerobic (fast walk)and anaerobic (sprint) activity.
Muscle fibers used in weight lifting. Fast Glycolytic (FG) Largest, most powerful, and fastest. Lowest in blood and mitochondria. Used only in anaerobic activity.
Why does our endurance improve with age, but not speed and lifting ability? FG turn to SO over time possibly from increase in posture muscles.
Created by: 741879016