Bio major 3

• Respiratory system


  1. Breathing/Ventilation - the movement of air into and out of the lungs - mechanical motion

  2. External respiration - the exchange of O2 and CO2 within the lungs

  3. Internal respiration - the exchange of O2 and CO2 within the blood and body tissue

  4. Cellular respiration - the oxidation of glucose for energy creating CO2 and H2O
• Respiratory system involves a 4-stage process
• Hiveoli


  Tiny sacs where air moves from the bronchiques
• Alveolus


  • Surrounded by capillaries
  • Diffusion of gases between air and blood occurs here
• Gas exchange in alveoli

  1. O2 moves from air in alveoli into capillaries

  2. CO2 moves from capillaries into air of alveoli
• Alveoli


  • Bulb-shaped during inhalation
  • Collapse during exhalation
• Nasal cavity


  Air enters via the nasal cavity and mouth
• Nasal cavity


  • Contains hairs and mucus that trap particles and keep air moist
  • Many blood vessels inside warm the incoming air
• Air flow


  1. Air travels through pharynx

  2. Branches into trachea (windpipe) or esophagus
• Epiglottis


  Enlarged flap of cartilage that covers the entrance to the trachea to prevent food from entering
• Cilia in respiratory tract

  1. Stimulated by food/debris

  2. Produce a cough
• Larynx


  • Composed of thin sheets of elastic ligaments (vocal cords)
  • Vibrate to produce sounds
• Vocal cords


  • Thicker in males, resulting in a lower voice
  • Inflammation can cause laryngitis
• Trachea


  • Lined with ciliated cells that produce mucus
  • Mucus traps debris filtered from nasal passages
  • Supported by cartilage rings that keep it open
• Branching of trachea


  1. Trachea branches into two bronchi

  2. Bronchi continue to branch into bronchioles
• Bronchioles


  • Lack cartilage rings
  • Composed of smooth muscle that can change their diameter
• Alveoli and capillaries


  • Very thin walls (one cell thick) for rapid gas exchange
  • Fluid secreted to prevent alveoli from sticking together
• Lungs


  • Surrounded by pleural membrane that attaches lungs to thoracic cavity
  • Pleural membrane reduces friction during breathing
• Pleurisy


  Inflammation of pleural membranes and buildup of fluid in chest cavity
• Expiration


  Easier than inspiration
• Respiratory volumes


  • Tidal volume
  • Inspiratory reserve volume
  • Expiratory reserve volume
  • Vital capacity
• Residual volume


  Amount of air remaining in lungs after forceful expiration
• Breathing movements


  1. Determined by action of muscles on size of thoracic cavity

  2. Pressure differences between chest cavity and atmosphere drive gas flow
• Hemoglobin


  Carries 99% of O2 in blood (as oxyhemoglobin)
• CO2 transport


  • 7% dissolved in blood plasma
  • 23% bound to hemoglobin (as carbaminohemoglobin)
  • 70% as bicarbonate ions
• Gas exchange and transport

  1. Gases diffuse down concentration gradients between alveoli and capillaries

  2. O2 leaves capillaries and diffuses into cells

  3. CO2 diffuses out of cells into blood
• Regulation of breathing


  1. Chemoreceptors detect CO2 and O2 levels

  2. Medulla oblongata controls breathing rate via nerves to intercostal muscles and diaphragm
• High altitude


  Air has less O2, immediate response is increased breathing rate, long-term is increased RBC production
• Exercise


  Increased CO2, decreased O2, and signals from brain increase ventilation of alveoli
• Upper respiratory infections


  • Tonsillitis
  • Laryngitis
• Lower respiratory tract disorders (LRTD)

  • Bronchitis
  • Pneumonia
  • Emphysema
  • Asthma
  • Lung cancer
• Bronchitis


  Inflammation of bronchi, can be acute (bacterial) or chronic (often from smoking)
• Pneumonia


  Fluid fills alveoli, can affect an entire lobe (lobar) or be in patches (viral)
• Emphysema


  Loss of elasticity in alveolar walls, reduces surface area for gas exchange
• Asthma


  Chronic obstructive disease that reduces bronchi and bronchiole diameter, environmental triggers cause attacks
• Lung cancer


  Tumors reduce available lung surface area for gas exchange, often caused by carcinogens in cigarette smoke
• Tissues


  • Respira
  • Digestive
  • Muscles
  • Musculoskeletal
• Bones and exoskeletons


  • Frame and create movement (act as levers)
  • Ligaments: Connect bone to bone
  • Tendons: Connect muscles to bone
  • Cartilage: Connective tissue
• Skeletal muscle


  Composed of numerous bundles of muscle fibres, each cell contains many nuclei
• Actin and myosin


  Thin and thick myofilaments bundled together within the muscle fibres