Physio

• Vertebrate muscle types


  • Smooth muscles
  • Skeletal or Striated muscles
  • Cardiac muscles

  
• Smooth muscles


  • Control the digestive system and other organs
• Skeletal or Striated muscles


  • Control movement of the body in relation to the environment
• Cardiac muscles


  • Have properties intermediate between those of smooth and skeletal muscles

  
• Human muscle fiber types

  • Fast-twitch fibers
  • Slow-twitch fibers
• Fast-twitch fibers


  Use reactions that do not require oxygen (anaerobic) at the time but need oxygen for recovery
• Slow-twitch fibers


  Use oxygen during movements (aerobic), and are used for non-strenuous activities
• Bicycling activity


  1. Aerobic use of slow-twitch fibers

  2. Anaerobic use of fast-twitch fibers as glucose supplies dwindle

  3. Muscle fatigue
• Types of movements


  • Voluntary movements
  • Involuntary movements
  • Reflexes
• Reflexes


  • Consistent automatic responses to stimuli
  • Insensitive to reinforcements, punishments, and motivations
• Reflexes


  • Stretch reflex
  • Pupil constriction in bright light
• Even walking includes involuntary components
• It is difficult to make voluntary clockwise and counterclockwise movements on the same side of the body at the same time, but not difficult to move the left hand in one direction while moving the right foot in the opposite direction
• Infant reflexes


  • Grasp reflex
  • Babinski reflex
  • Rooting reflex
• Infant reflexes fade with age but the connections remain intact, not lost but suppressed by messages from the brain, especially the frontal cortex
• If the cerebral cortex is damaged, the infant reflexes are released from inhibition
• Infant reflexes sometimes return temporarily if alcohol, carbon dioxide, or other chemicals decrease the activity in the cerebral cortex
• Infants and children also show certain allied reflexes more strongly than adults, such as reflexively closing eyes and mouth and sneezing in response to dust or bright light
• Ballistic movement


  Executed as a whole, cannot be altered once initiated
• Most behaviors are subject to feedback correction
• Motor cortex


  • Involved in controlling voluntary movements
  • Divided into primary motor cortex (Area 4) and supplementary motor area (Area 6)

  
• To carry out goal-directed movements, the motor cortex must receive information from various brain lobes

  
• Electrical stimulation of the motor cortex in dogs revealed a motor map where different body parts have corresponding regions in the cortex, with more space devoted to parts that can make finer movements

  
• Basal ganglia


  • Involved in selecting and triggering well-coordinated voluntary movements
  • Damage to basal ganglia leads to difficulty starting movements and trembling/slowness
• Cerebellum


  • Acts as an internal "clock" to precisely regulate the sequence and duration of elementary movements
  • Receives information about intended movement from sensory and motor cortices, and sends information back to motor cortex about required direction, force, and duration

  
• Ataxia


  A degenerative disorder affecting the brain, brainstem or spinal cord, resulting in clumsiness, inaccuracy, instability, imbalance, tremor or lack of coordination in voluntary movements
• Cerebellum


  • Receives information about intended movement from sensory and motor cortexes
  • Sends information back to motor cortex about required direction, force, and duration of movement

  
• Cerebellum loop


  Operates in addition to basal ganglia loop to regulate details of motor control
• Ataxia


  • Degenerative disorder affecting the brain, brainstem or spinal cord
  • Can result in clumsiness, inaccuracy, instability, imbalance, tremor or lack of coordination in voluntary movements
  • Movements are not smooth and may appear disjointed or jerky
  • Patients may fall down frequently due to unsteady gait
  • Can also affect speech and eye movement
• Dystonia


  • Neurological muscle disorder characterized by involuntary muscle spasms
  • Results from abnormal functioning of basal ganglia
  • Can affect any part of the body, including arms, legs, trunk, eyelids and vocal cords
  • General dystonias involve the entire body, focal dystonias involve only one body location
• Huntington's Disease


  • Progressive, degenerative and fatal disease caused by deterioration of nerve cells in the brain
  • Onset most often occurs between ages 35 and 50, progressing over 10 to 25 years
  • Affects an estimated one in every 10,000 people in the U.S.
  • Juvenile form affects patients age 20 and younger, accounting for about 16 percent of cases
  • Symptoms include jerking, uncontrollable movements, progressive loss of mental abilities, and development of psychiatric problems
  • Hereditary - a child with one affected parent has a 50 percent chance of developing the disease
• Multiple System Atrophy (MSA)


  • Progressive, neurodegenerative disease affecting movement, blood pressure and other body functions
  • Symptoms include stiffness or rigidity, freezing or slowed movements, instability, loss of balance, loss of coordination, orthostatic hypotension, male impotence, urinary difficulties, constipation, and speech and swallowing difficulties
• Myoclonus


  • Twitching or intermittent spasm of a muscle or group of muscles
  • Classified into several major types and many subcategories
  • Most common type is cortical myoclonus, arising from the sensorimotor cortex
  • Jerky movements usually have a regular rhythm and may be focal or multifocal
  • Can be associated with various diseases including Celiac, Angelman, Huntington's, Rett, and Alzheimer's
• Parkinson's Disease


  • Progressive disorder caused by degeneration of nerve cells in the substantia nigra, which controls movement
  • Symptoms include tremor, muscle rigidity, gradual loss of spontaneous and automatic movement, stooped posture, unsteady walk or balance, and depression or dementia
  • Estimated 60,000 new cases diagnosed each year, with 7-10 million people affected worldwide
  • Risk increases with age, but 4% are diagnosed before age 50
• Rett Syndrome


  • Progressive neurological disorder causing reduced muscle tone, autistic-like behavior, repetitive hand movements, irregular breathing, decreased ability to express feelings, developmental delays, gait abnormalities, and seizures
  • First symptom is usually loss of muscle tone
  • Affects about 1 in 10,000 to 23,000 infant girls, but prevalence may be higher due to undiagnosed cases
  • Victims are profoundly disabled, requiring maximum assistance with daily living
• Tourette Syndrome


  • Hereditary neurological disorder characterized by repeated involuntary movements (tics) and uncontrollable vocal sounds
  • Evidences itself most often between ages 6 and 15, but may occur as early as 2 or as late as 20
  • First symptoms are often facial tics, followed by tics in arms, legs or trunk
  • Verbal tics (vocalizations) usually occur with movements, and may include grunting, throat clearing, shouting, barking, coprolalia, and copropraxia
  • In 70% of cases, tics disappear by early 20s
• Homeostasis


  The body's need to reach and maintain a certain state of equilibrium

  
• How Homeostasis is Maintained

  1. Stimulus

  2. Receptor

  3. Control unit

  4. Effector

  
• Negative feedback loop


  • Works to decrease the effect of the stimulus
• Positive feedback loop


  • Increases the effect of the stimulus