Week 8

• Types of Muscles

  Smooth muscle

  Striated muscle

  -Cardiac muscle

  -Skeletal muscle
• a type of muscle named for its striped appearance; including cardiac and skeletal muscles.

  Striated muscle
• a type of striated muscle found in the heart.

  Cardiac muscle
• a type of striated muscle that is attached to bones and is responsible for the majority of body movements

  Skeletal muscle
• A long fiber strand running the length of a muscle fiber that is responsible for contraction

  Myofibrils
• A myofibril segment bound on either side by a Z line and spanned by thin filaments

  Sarcomere
• a boundary line for each sarcomere within a myofibril.

  Z line
• a protein that makes up the thin filaments of the myofibril.

  Actin
• A protein that makes up the thick filaments of the myofibril.

  Myosin
• The protein covering of an actin molecule that prevents the molecule from binding with myosin when a muscle is in the resting state

  Troponin
• In humans, the thick myosin filaments in muscle fibers come in three varieties. Type I fibers are known as slow-twitch fibers, and Types IIa and IIb are known as fast-twitch fibers.
• A muscle fiber containing Type I myosin filaments and large numbers of mitochondria that contracts slowly using aerobic metabolism.

  Slow-twitch fiber
• a chemical processes that requires oxygen

  Aerobic metabolism
• a chemical process that does not require oxygen

  anaerobic metabolism
• A spinal reflex, such as the patellar reflex, that requires the action of only one synapse between sensory and motor neurons.

  Monosynaptic Reflexes
• A spinal reflex that requires interaction at more than one synapse.

  Polysynaptic Reflexes
• Another familiar example of a polysynaptic reflex is the flexion reflex (A polysynaptic spinal reflex that produces withdrawal of a limb from a painful stimulus).
• We rely on flexion reflexes to protect us from further injury, such as when we jerk our hand away after touching a hot surface on the stove. It’s a good thing that the spinal cord, rather than the brain, manages this function. By the time the brain perceived the problem, generated solutions, evaluated solutions, and implemented solutions, your hand would be in bad shape
• Myasthenia Gravis


  An autoimmune condition caused by the degeneration of ACh receptors at the neuromuscular junction, resulting in muscle weakness and fatigue
• Muscular Dystrophy


  A group of diseases characterized by extreme muscle development followed by muscle wasting, due to abnormalities in the protein dystrophin
• Polio


  A contagious viral disease that attacks the spinal motor neurons, producing paralysis
• Amyotrophic Lateral Sclerosis (ALS)


  Also known as Lou Gehrig's disease, is a disease in which motor neurons of the spinal cord and brainstem progressively deteriorate, leading to death
• Parkinson's Disease


  A degenerative disease characterized by difficulty in moving, muscular tremors, and frozen facial expressions
• Huntington's disease


  A genetic disorder beginning in middle age that results in jerky, involuntary movements and progresses to psychosis and premature death
• Smooth muscle 


  a type of muscle found in the lining of the digestive tract, within arteries, and in the reproductive system
• smooth muscle 


  controlled by the autonomic nervous system.
• Slow-twitch fiber


  primarily responsible for movement requiring endurance.
• Fast-twitch fiber


  primarily responsible for movement requiring explosive strength.
• Accidental spinal cord damage

  • If the damage occurs in the cervical, or neck, region of the spinal cord, the person will experience quadriplegia, or the loss of movement in both arms and legs.
• Accidental spinal cord damage

  • If the damage occurs in the lumbar region of the lower back, the person will experience paraplegia, the loss of movement in the legs.
• Amyotrophic Lateral Sclerosis (ALS) - also known as Lou Gehrig’s disease
• patellar reflex 


  (knee-jerk reflex determines whether a basic spinal stretch reflex is in good working order)
• Accidental spinal cord damage



  The spinal cord can be accidentally damaged when the protective vertebrae surrounding the cord are broken and compress or sever the cord itself.
• Muscle fiber


  an individual muscle cell which are long and vey thin.
• (Human muscle fiber cells usually extend the length of the muscle and are up to 30 cm long and from 0.05 to 0.15 mm wide)
• The alpha motor neurons form highly efficient connections with muscle fibers at a location called the neuromuscular junction
• neuromuscular junction


  A synapse formed between an alpha motor neuron axon terminal and a muscle fiber
• A motor unit is made up of a single alpha motor neuron and all the muscle fibers it innervates.
• muscle spindles


  A sensory structure that provides feedback regarding muscle stretch
• intrafusal muscle fibers


  (One of the fibers that make up a muscle spindle)