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Parents bring in their 8-year old son to the ER for a recent fall…

- - - - Appearance
        
        spindle-shaped cells, non-striated
      - Location
        
        walls of hollow, internal organs (GI tract, urinary tract, blood vessels)
      - Control
        
        involuntary
        
        contracts without being stimulated by the nervous system
        
        i.e. contractions slow and sustained
    - - Structures of Skeletal Muscle Fiber
        
        Fasciles
        
        groups of muscle fibers
        
        T tubules
        
        parts of the sarcolemma that fold into the muscle fiber
        
        Endomysium
        
        sheet of connective tissue that surrounds each muscle cell
        
        Sarcomere
        
        contractile unit of a muscle fiber made up of myofilaments
        
        Structures of the Sarcomere
        
        Z discs
        
        zig-zagging structures on either edge of the sarcomere
        
        M lines
        
        found in the middle of the sarcomere
        
        troponin
        
        regulatory protein that interacts with Calcium
        
        H zone
        
        middle region in the sarcomere where only thick filaments are present
        
        tropomyosin
        
        regulatory protein that runs the entire length of the the thin filament
        
        A band
        
        darker bands in the sarcomere
        
        myosin
        
        protein that makes up thick myofilaments within the sarcomere
        
        I band
        
        regions that contain thin filaments and are lighter in appearance
        
        actin
        
        protein that makes up thin myofilaments within the sarcomere
        
        Tendons
        
        composed of dense regular connective tissue
        
        Epimysium
        
        layer of connective tissue that surrounds the entire muscle
        
        Sarcolemma
        
        plasma membrane
        
        Myofibrils
        
        contractile fibers inside muscle cell
        
        Sarcoplasmic Reticulum
        
        smooth endoplasmic reticulum
      - Appearance
        
        striated "ants on a log"
      - 3 Types of Skeletal Muscle Fiber
        
        Fast Oxidative Fibers
        
        mitochondria
        
        many
        
        color
        
        red to pink
        
        fiber diameter
        
        large
        
        "I contract quickly and I build ATP from the Electron Transport Chain"
        
        Fast Glycolytic Fibers
        
        mitochondria
        
        few
        
        color
        
        white (pale)
        
        fiber diameter
        
        intermediate
        
        "I contract quickly and I build ATP from glycogen"
        
        Slow Oxidative Fibers
        
        color
        
        red
        
        mitochondria
        
        many
        
        fiber diameter
        
        small
        
        "I contract slowly and I build ATP from the Electron Transport Chain"
      - Location
        
        skeletal muscles
      - voluntary
        
        subject to conscious control
    - - Appearance
        
        striated with intercalated discs
      - Location
        
        wall of heart
      - Control
        
        involuntary
        
        contracts without being stimulated by the nervous system
        
        i.e. we have no conscious control over how fast our hearts beats
  - - - messenger RNA; type of RNA that carries instructions from DNA in the nucleus to the ribosomes
        
        transcription
    - - translation
    - - Deoxyribose Nucleic Acid
        
        transcription
    - - translation
    - - transcription
    - - translation
  - - - osteoblasts
        
        bone-building
      - osteoclasts
        
        bone-breaking
      - osteocytes
        
        mature
    - - lacuna
        
        cell location
      - chondroitin sulfate
        
        ground substance
      - chondrocytes
        
        cell
      - collagen
        
        extracellular proteins
    - - calcium phosphase
        
        ground substance
      - collagen
        
        extracellular proteins
      - osteocytes
        
        cell
      - lacuna
        
        cell location
  - - - as long as the binding sites on actin remain exposed, the cross-bridge cycle will repeat. As the cycle repeats, the thin myofilaments are pulled toward each other and the sarcomere shortens
  - - - lungs
      - diaphragm
    - - heart
    - - brain
    - - glands
    - - small intestine
      - liver
      - stomach
      - esophagus
      - gallbladder
    - - compact bone
      - hyaline cartilage
- - - - Indirect Cause #1
        
        Parents state that over the course of the last year, he has become much less physically active and has seemed more clumsy. His walking pattern has changed, especially in the last few months, with him walking on his tiptoes instead of the soles of his feet. He has recently complained of muscle aches and weakness, especially in the mornings when he sometimes struggles to get out of bed, and throughout the day he rarely engages in physical activities because he is "too tired".
  - - - Duchenne Muscle Dystrophy (DMD) genetic disorder characterized by progressive muscle degeneration and weakness due to the alterations of a protein called Dystrophin that help keep muscle fibers intact. Diagnosis confirmed when mutation of the DMD gene is identified.
        
        Indirect Cause #2
        
        Muscles are made up of bundles of fibers. A group of proteins along the membrane surrounding each fiber helps to keep muscle cells working properly. DMD is the result when one of the proteins, Dystrophin is absent.
- - - - weak muscles lead to a progressive decline in ability for gas exchange, leading to sleep disturbances, respiratory infections and failure
    - - cardiac dysfunction and disease
    - - vision and speech problems, seizures and structural changes in brain
    - - growth hormone deficiency, delayed pubertal develoment
    - - gastric dilation, chronic constipation, gastroesophageal reflux, delayed gastric emptying, swallowing impairment, heartburn
    - - weak bones, reduced mobility, vertebral fractures from use of steroids to treat DMD
- - - - Function
        
        movement of food, urine and blood
    - - Function
        
        produce movement, maintain body posture and position, stabilize joints and generate heat
      - Structures of Skeletal Muscle Fiber
        
        Endomysium
        
        provides an appropriate chemical environment for the exchange of Calcium, Sodium and Potassium
        
        Fasciles
        
        determine movement of muscle
        
        Tendons
        
        transmit the mechanical force of muscle contraction to bones
        
        T tubules
        
        allow membrane potential to reach all myofibrils inside the cell; stores Calcium
        
        Sarcolemma
        
        acts as a barrier between the extracellular and intracellular compartments; maintains membrane potential
        
        Sarcomere
        
        contracts muscle
        
        Structures of the Sarcomere
        
        Z discs
        
        act as an anchoring point of the thin filaments
        
        M lines
        
        helps to anchor the thick filaments together
        
        troponin
        
        binds tropomyosin and helps position it on actin
        
        H zone
        
        shortens the muscle due to increasing overlap of actin and myosin filaments
        
        tropomyosin
        
        in a relaxed muscle fiber, they block myosin-binding sites on actin so that myosin heads on the thick filaments cannot bind to the thin filaments
        
        A band
        
        maintain a constant length during contraction
        
        myosin
        
        acts as a ATPase and splits ATP and uses the released energy to drive movement
        
        I band
        
        shortens during muscle contraction
        
        actin
        
        support, divide and produce cells in order to enable cells to move spontaneously and actively, supportive framework for myosin proteins during muscle contraction
        
        Sarcoplasmic Reticulum
        
        stores Calcium in a resting muscle cell
        
        Epimysium
        
        protects muscles from friction against other muscles and bones
        
        Myofibrils
        
        perform muscle contraction via the sliding-filament model
      - 3 Types of Skeletal Muscle Fiber
        
        Fast Oxidative Fibers
        
        myoglobin content
        
        high
        
        glycogen stores
        
        intermediate
        
        myosin ATPase activity
        
        fast
        
        rate of fatigue
        
        intermediate (moderately fatigue-resistant)
        
        speed of contraction
        
        fast
        
        activities best suited for
        
        sprinting, walking
        
        Fast Glycolytic Fibers
        
        myoglobin content
        
        low
        
        glycogen stores
        
        high
        
        myosin ATPase activity
        
        fast
        
        rate of fatigue
        
        fast (fatigable)
        
        speed of contraction
        
        fast
        
        activities best suited for
        
        short-term intense or powerful movements i.e. hitting a baseball
        
        Slow Oxidative Fibers
        
        glycogen stores
        
        low
        
        myoglobin content
        
        high
        
        myosin ATPase activity
        
        slow
        
        rate of fatigue
        
        slow (fatigue-resistant)
        
        speed of contraction
        
        slow
        
        activities best suited for
        
        endurance-type activities i.e. running a marathon; maintaining posture (antigravity muscles)
    - - Function
        
        pumps blood to the rest of body
  - - - an mRNA strand is made based on the DNA sequence
    - - the mRNA strand is made based on the DNA sequence
    - - RNA polymerase attaches to the DNA strand in the promoter region
    - - the mRNA strand attaches to the ribosome
    - - tRNA molecule bring amino acids to the ribosome
    - - the complete amino acid chain is released from the ribosome and fold
  - - - pre-cursors to osteoblasts called stem cells, appear along the burrow or pit where they proliferate (increase in numbers) and differentiate (change) into pre-osteoblasts
    - - mature into osteoblasts at the surface of the burrow or pit
        
        release osteoid at the site, forming a new soft nonmineralized matrix
        
        new matrix is mineralized with Calcium and Phosphorus
    - - osteoclasts dig out a cavity, called a resorption pit, in spongy bone or burrow a tunnel in compact bone
        
        Calcium can be released into the blood for use in various body functions
        
        osteoclasts disappear
    - - site, with resting lining cells, remains dormant until next cycle
    - - pre-osteoclasts are attracted to the remodeling sites
        
        fuse to form osteoclasts
  - - - this causes depolarization of the T tubules and causes the release of Calcium from the terminal cisternae of the sarcoplasmic reticulum
    - - this movement of Calcium into the muscle cell causes Calcium to bind to troponin, which moves tropomyosin, exposing the myosin-binding active sites on G actin
    - - ACh then binds to receptors on the motor end plate (of muscle cell). If the end plate reaches the threshold, an action potential is propagated on the sarcolemma and down the T tubules
    - - the myosin head then form cross bridges to the G actin and immediately pivot toward the M line, causing chemically activated muscle contraction
    - - the influx of Calcium into the axon terminal causes the exocytosis of ACh ( a neurotransmitter: Acetylcholine) into the synaptic cleft
    - - ATP binds to myosin heads, causing them to release muscle contraction and recock
    - - an action potential arrives at the axon terminal (of neuron) and voltage-gated Calcium channels open, causing an influx of Calcium into the axon terminal
  - - - the Power Stroke
        
        ADP is released and the activated myosin head pivots, this slides the thin myofilament towards the center of the sarcomere
    - - Cross-Bridge Detachment
        
        a molecule of ATP binds to the myosin
    - - Cross-Bridge Formation
        
        the activated myosin head binds to actin, forming a cross bridge
    - - Reactivation of myosin head
        
        ATP is hydrolyzed, generating ADP and inorganic phosphate; myosin returns to the "cocked" position
  - - - heart
        
        pumps blood throughout the body, supplies oxygen and nutrients to the tissues and removes carbon dioxide
    - - lungs
        
        gas exchange
      - diaphragm
        
        main site of respiration
    - - glands
        
        thyroid
        
        produces thyroxine, which regulates metabolism
        
        testis
        
        produce testerone, responsible for sperm production
        
        pineal
        
        releases melatonin
        
        thymus
        
        during childhood, releases thymosin, which stimulates Tcell development
        
        pancreas
        
        produces insulin
        
        parathyroid
        
        regulate level of Calcium in the blood
        
        pituitary
        
        produces hormones that regulate other glands
    - - compact bone
        
        support the body structurally, protect vital organs, movement
      - hyaline cartilage
    - - small intestine
        
        main site of nutrient absorption and digestion
      - liver
        
        filter blood coming from digestive tract before passing it to the rest of the body
      - esophagus
      - gallbladder
        
        stores bile
      - large intestine
        
        absorbs water and vitamin d, stores feces for defecation
    - - brain