Skeletal MuscleVocabularyTwo things Muscle can doSmooth MuscleMuscle Fiber TypesCardiac muscleCardiovascular InformationShockBlood flow has gotten low enough, so you are not adequately providing tissues with nutrientsHeart AttackControl of RespirationShallow Water BlackoutPHIS 206 1st EditionExam # 2 Study GuideMuscle- 3 Major categories: o 1.) Skeletal- Voluntary- Striated Muscleo 2.) Smooth- Involuntary- Visceral, non-striatedo 3.) Cardiac- Heart Muscle- All Muscles contract- Muscle is a mechanical deviceo Requires energy- Real device; efficiency is NOT perfect; doing work generates heat- Examples: Shivering when cold. & Exercise rises body temperature- Voluntary muscles can be consciously controlledSkeletal Muscle- Known since mid-19th Century that it has striations.- Striations are made from the arrangement of proteins.Vocabulary- Cell Membrane = Sarcolemma- Smooth covering of the cell that dips into the cytoplasm (t-tubules)- Endoplasmic Reticulum = Sacrcoplasmic Reticulum- Releases calcium into the cytoplasm- This release of calcium causes muscle contraction- Muscle Cell = Muscle Fiber- Muscle fibers bind together to form a muscle- Within it are Myofibrils- Visible manisfestations of proteins, long, cylindrical- Proteins1.) Actin- Thinner- known as thin filaments2.) Myosin- Thicker- known as thick filaments.-- Overlap one another-- They are attached to one another--“acto-myosin” fibers** Gives rigidity- makes muscles hard to pull apart**--regular, repeating array--lengthwise along the muscle- Cross bridges: molecular connections between thick and thin filaments near the tip of the filamentso Give muscle cell its longitudinal rigidity- Sarcomere length: about 2mm- Sarcolemma: smooth coveringSliding- Filament Mechanism-When Muscle fiber contracts, the thick and thin filaments stay the same size, they just get closer to one another-The ends of the thin and thick filaments become closer- Energy source is ADP-Provides energy for contraction-shortens muscle-Gets energy from mitochondria;* Muscle cells have lots of Mitochondria.*Two things Muscle can do- Isometric Contraction- Can generate force without - Cells shorten but muscles don’t- Force low, velocity high1.) Isotonic Contraction- Can shorten without generating force (At same tension)- Rarely happens in pure form, mostly approximation.- Generate motion at a constant force- Movement of limbs- Example: Piano player starts with isometric, then turns to isotonic.- Force high, velocity lowPhysical Definition of Work- Move Force through a distance.- By definition, Isometric does no work.Power- Rate at which you do work.- By definition, Isometric doesn’t generate power.** Maximum Ability to do work at high rate- 1/3 of 0 velocity and max velocity. **Length-tensions DiagramsTensionLength - Passive Tensiono As you increase length, you increase tensionso Not active, no energy requiredo Elasticity: stretchability of musclesTensionActive TensionI = electricityI I I ILength- Tension will increase, reach a maximum, then decline- With the little tension, the ends of the thick and thin filaments are far apart- At maximum tension, the ends of thick and thin filaments are completely aligned Muscle- Tetany: if you stimulate a muscle again, before it’s relaxed, it can stay contracted o Muscle contracts and stays contracted- Tetanic Stimulation -sensation that leads to tetanyo Average: 50-55 stimulations per second in human skeletal muscle- Incandescent light flickers, but we can’t see ito Electric current in US-60 stimuli per sec.(cycle current)o Most of the rest of the world-50 stimuli per sec. Reason US does this-Historical Meaning-it was believed that anything less than 60 cycles, then the lights would flicker- Truth is that you can see no flickering with cycles all the way down to around 40 cycles.Twitch- either it contracts or it doesn’t- NO halfway!Neural Control- Helps to make fine movementso Brain sends out instructions to how many Motor Units to send out.Motor neuron- Fire tetanic stimuli to cause muscle contraction- Releases Ach onto the motor endplate- Ach binds cholergenic receptors onto the endplate- Generates action potential in muscle- Vary strength of contraction: by increasing or decreaseing the number of motor neurons firing Motor Unit = 1 Motor Neuron & all the muscle cells it stimulates- 1 Motor Unit innervates more than one cell-Muscle cells are innervated by only 1 neuron-small motor units allow for finer, graded contractions -Motor Nerves that make fingers work have small motor units^^^^- In thigh, the motor units include several hundred cells-generate great power. ** Reason we play piano with fingers, not heels! **Smooth Muscle- Can shorten in every direction- Different from striated muscle:- Doesn’t have striations- Actin & Myosin present, but elements are not lined up in registered order,so do not see the visible manifestations of striations.- Smooth Muscle cells are electrically connected to one another- Transmit depolarization to cells- Immediately around it, which sends a wave propagated out.- Transmit action potentials from one to the next.- Strength are controlled by hormones and Neurotransmitters- Does contract Spontaneously (Skeletal Muscle doesn’t)- Smooth have membranes that are leaky, so when a smooth muscle cell rests, it never has a stable action potential, so it drifts up until cell depolarizes.* Reoccur at regular intervals * The rate of leakiness can be modified by neuron or hormone.- Muscle use energy to do worko Uses ATP for energyo Source for ATP come from Mitochondriao Aerobic Respiration (Continue to do for long time) -use oxygen in Mitochondria to produce ATP; can generate 2/3 of oxygen amount If me need more than 2/3, use anaerobic pathway-use ATP that comesfrom glucose- By-product- Lactic AcidLactic Acid- causes muscle fatigue; muscle refuses to contract anymore- When we reduce level of activity, anaerobic comes in and replaces oxygen & gets rid of lactic acid- If we lack oxygen, metabolites do not have enough substrates to metabolize all the way to carbon dioxide- Instead, it only metabolizes to lactic acid, which is more acidic and causes pain in sustained useMuscle Fiber Types- Red Muscle- Looks dark Lots of Myoglobin- Red protein- Related to hemoglobin- Also binds to oxygen- Carry around a reservoir of oxygeno Allows for oxygen to be used even when oxygen intake is decreasedo When you work to the point where you do too much, you can go a