A&P Chapter 9

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A&P Chapter 9
2012-11-05 13:06:27

A&P Chapter 9 Muscles
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  1. What is the main function of all muscles?
  2. What is cardiac muscle?
    Found in the heart, involuntary rhythmic contraction, branched, striated fibre with single nucleus and intercalated discs
  3. What is smooth muscle?
    Found in walls of hollow internal organs, involuntary movement of internal organs, elongated, spindle shaped fibre with single nucleus.
  4. What is skeletal muscle?
    Spans joints and attached to skeleton, voluntary movement of skeletal parts, multi-nucleated, striated, cylindrical fibres.
  5. What are the four functions of skeletal muscle? Which one is homeostatic?
    Production of movement, Maintenance of posture, thermogenesis (homeostatic) and stabalization of joints.
  6. What are the four characteristics of muscle tissue?
    Excitability, contractility, extensibility and elasticity.
  7. What is excitability?
    The ability to receive and respond to a stimulus
  8. What is contractility?
    The ability to shorten forcibly when adequately stimulated
  9. What is extensibility?
    The ability to be stretched
  10. What is elasticity?
    The ability to recoil and resume original length after being stretched
  11. What is epimysium?
    A layer of CT that closely surrounds a muscle tissue. (epimysium > Perimysium > Endomysium > Muscle Fiber)
  12. What is a fascicle?
    A bundle of super-long skeletal muscle cells (fibers) surrounded by a layer of dense irregular CT called the Perimysium.(epimysium > Perimysium > Endomysium > Muscle Fiber)
  13. What is the perimysium?
    A layer of dense irregular CT that surrounds the fascicles.(epimysium > Perimysium > Endomysium > Muscle Fiber)
  14. What is the endomysium?
    A layer of loose CT that surrounds each muscle cell (fiber) which extends the length of the muscle organ. (epimysium > Perimysium > Endomysium > Muscle Fiber)
  15. What is a muscle cell?
    An individual fiber in the muscle that extends the length of the muscle organ. They are so large because they are a result of hundreds of myoblasts fusing together.
  16. What is sarcolemma?
    The cell membrane to muscle.
  17. What is sarcoplasm?'
    the muscle cytoplasm. It has lots of mitochondria, glycogen granules and myofibrils because it has to create a lot of engergy.
  18. What is the sarcoplasmic reticulum?
    Muscle cell version of the smooth endoplasmic reticulum. Functions as a calcium storage depot in muscle.
  19. What is a T-Tubule?
    Invaginations in the sarcolemma that penetrate through the cell
  20. What are myofibrils?
    Made up of long bundles of protein structures called myofilaments that make up muscle fibers and extend the lenth of the cell.
  21. What is a thin (Actin) filament?
    Each one is made up of three proteins: actin, tropomysoin and troponin. They along with thick filaments make up myofibrils which gives muscle the ability to contract.
  22. What is a thick (myosin) filament?
    A single myosin protien resembles two golf clubs whose shafts have been twisted together, 300 of these form a single thick filament. They along with thin filaments make up myofibrils which gives muscle the ability to contract.
  23. What is a sarcomere?
    An ordered arrangment of thick and thin filaments, a functional unit of skeletal muscle that makes it contract. It has regions of thin filaments, regions of thick and regions where thick and thin overlap.
  24. What is a neuromuscular junction?
    Synapse between a motor neuron and a skeletal muscle fiber. It has a motor end plate and synaptic cleft. Is where neurotransmitter, acetylcholine, is released to control skeletal muscle contraction.
  25. What are the four steps of muscle contraction?
    1. a skeletal muscle must be activated by a nerve, which releases acetylcholine 2. Nerve activation increases the concentration of calcium in the vicinity of actin and myosin, the contractile proteins 3. The presense of calcium permits muscle contraction 4. When a muscle cell is no longer stimulated by a nerve, contraction ends.
  26. What is membrane potential?
    Differences in concentration of ions on opposite sides of a cellular membrane. K+ have a higher concentration on the inside and Na+ has a higher concentration outside. This separation of charges is what causes the membrane potential
  27. What is the Sodium (Na+) Potassium (K+) pump?
    It is an active transport mechanism that keeps potassium inside the cell and sodium outside to maintain cell potential. It gets energy from ATP.
  28. What are the three types of ion channels?
    Voltage gated channels, Sodium/Potassium channels, Calcium channels. They are integral proteins found in the cell membrane.
  29. What is depolarization threshold, what happens if threshold is reached? What happens if its not?
    It is the threshold that must be met in order for voltage-gated ion channels to open. If it is not met no muscle contraction will occur. If it does reach threshold, the channels will open and the process of muscle contraction will occur.
  30. What is an action potential?
    Sequence of electical changes in the axon of a neuron exposed to a stimulus that exceeds threshold.
  31. How does depolarization result in ca2+ release? What cell structures are involved?
    The depolarization caused by sodium influx in one part of the sarcolemma causes voltage gated channels to open. This causes voltage gated channels to open in the next patch of membrane. It travels along the sarcolemma in both directions down the T tubules which contain voltage sensitive proteins connected to Ca+ channels which releases Ca+
  32. What is the role of calcium in muscle contraction?
    The calcium binds to the troponin of the thin filament so that the two contractile proteins can slide & the sarcomere can shorten.
  33. What is the role of ATP in muscle contraction and relaxation?
    ATP is needed for the attachment, power stroke and release of mysoin heads.
  34. What factors determine strength of muscle contraction?
    The number of crossbridges, the number of myofibrils per muscle fiber and the number of contracting muscle fibers. They all contract with the same intensity, so it depends on how many muscle fibers contract.
  35. What does a resting muscle use ATP for?
    It is used to create another energy storage compound called creatine phosphate (backup storage unit for energy) and it powers the combination of glucose monomers into the storage polymer glycogen.
  36. What is Glycolysis?
    The energy releasing breakdown of glucose to pyruvic acid during cellular respiration. The 6-carbon sugar glucose is broken down in the cytosol into two 3-carbon pyruvic acid molecules with a net gain of 2 ATP and the release of high-energy electrons
  37. What is the citric acid cycle (Krebs)?
    For each citric acid molecule 1 ATP is produced, 8 hydrogen atoms are transferred to NAD+ and FAD and 2 CO2 are produced.
  38. What is the electron transport chain?
    It occurs in the mitochondria. Energy from electrons transferred to ATP synthase which catalyzes the phophorylation of ADP to ATP. Water is formed.
  39. What are the end products of glycolysis?
    Glucose is consumed, Produces 6 CO2, 4 ATP and 12 electron carriers (10 NADH and 2 FADH2)
  40. How many ATP's are produced from one glucose in fermentation?
    2 ATP
  41. How many ATP's are produced from one glucose in aerobic metabolism via the transport chain?
    36 ATP
  42. Where does each of the three series of reactions take place?
    Glycolysis occurs in the cytoplasm, citric acid cycle occurs in the matrix of mitochrondria, the electron transport chain occurs in the mitochondrial membrane.
  43. What is the function of the phosphate system?
    It is a back up storage unit for energy, when the stored ATP is used up. It is the energy stored in creatine-phosphate
  44. What is the end product of fermentation?
    lactic acid which typically diffuses out of muscles into the blood stream and is taken to the liver, kidneys or heart which can use it as an energy source.
  45. Under what conditions does fermentation occur in muscle?
    It occurs withough the presense of oxygen (anaerobic)
  46. What is a motor unit and why is it important?
    It is a somatic motor neuron and all the skeletal muscle fibers it innervates. When stimulated, all the muscle fibers will contract as a unit. The smaller the motor unit the finer and more delicate the movements.
  47. Compare and contrast slow and fast muscle fibers?
    Slow fibers contract slowly and fast fibers are fast. Slow fibers have high endurance and fast are best suited for short term, power activies. Slow fibers have myoglobin so they are darker colored and fast have no myglobin so they are lighter. Slow has lots of mitochondria and even though fast fibers use tons of ATP it has very few mitochondria.
  48. Roles of NADH and FADH2
    NADH (potential ADP) and FADH2 are hydrogen and high energy electron carriers generated by glycolysis and the citric acid cycle. They transport the high energy electrons to the electron transport chain. Glucose is the highest yielder of energy anything else (ex: fatty lipids) produces less ATP