Respiratory system U.4 L.4

  • The purpose of the respiratory system : bring in oxygen, remove carbon dioxide

  • 4 stages of respiratory system ⮕

    breathing (inhalation / expiration)

    external respiration (exchange of gases between lungs & blood)

    internal respiration (exchange of gases between blood and cells)

    cellular respiration (energy-releasing reactions in cells)

    C6H12O6 + 6O2 --> 6CO2 + 6H2O + Chemical Energy (in ATP)

  • respiratory surfaces (lung/gill)

    1. must be large enough for gas exchange to occur quickly (high surface area)

    2. they must be moist so gases can dissolve

  • various types of respiratory surfaces and systems have evolved in different animals ⮕ ventilation : pumping oxygen medium (air, water/ whatever is being breathed in) over respiratory surface

  • types of resp. surfaces ⮕

    1. outer skin (worms breathing)

      • process of diffusion transports O2 and CO2 in and out of cells from blood

      • organisms must live in moist environments

      • adv. : large surface area / dis adv. need to contain moisture

    2. gills (fish breathing)

      • extensions of folds in the body surface that increase surface area

      • process of diffusion transports gases to blood and cells

      • all gill breathers live in aquatic environments

      • adv. : has specialized body part (gill) for breathing / dis adv. : must stay in an aquatic environment

    3. tracheal system (insects breathing)

      • internal system of branching respiratory tracheae (tubes)

      • tracheae connect cells directly to the environment through spiracles (opening) for gas exchange (blood not required)

    4. lungs

      • lungs ⮕ more gas exchange = can allow for larger body

      • sacs lined with a moist surface ⮕ these sacs increase surface area

      • blood transports gases to cells by diffusion

  • Aquatic gas exchange ⮕

    aquatic gas exchange occurs with gills : water in mouth, then ventilated over gills

    dissolved in O2 but the water diffuses into the blood in the gills

    CO2 diffuses out of blood, across gills, into the water. counter current exchange system where O2 & CO2 flow down diffusion gradients (high to low), since water and blood flow in opposite directions

  • blood and water flow in opposite directions because it maintains the concentration gradient to maintain diffusion

  • blood wants to go down and when they are cocurrent the blood goes into the air and they end up mixing to become the same level of concentration

  • terrestrial gas exchange ⮕

    tidal gas exchange : moves air in and out of the lungs, the brain regulates the breathing rate and monitors (the volume of air in lungs)

  • the muscular diaphragm and the intercostal muscles control air pressure inside the lungs and that is inhalation and exhalation

  • humans don’t use this because the water is what is causing them to be cocurrent, air doesn’t push in one direction

  • types of gas exchange ⮕

    fish : counter-current

    mammals : tidal exchange

    birds : cross current

  • inhalation is when the intercostal muscles and diaphragm contract ⮕rib cage moves out ⮕ volume increases ⮕ pressure decreases in lungs = air from external environment rushes in to balance low pressure

  • exhalation is the opposite, the diaphragm and intercostal muscles relax ⮕ volume decreases ⮕ pressure increases in lungs = air rushing out

  • spirograph : represents volume of air inhaled/exhaled ⮕ measured by spirometer

  • tidal volume : air inhaled/exhaled in a normal breath

  • inspiratory reserve volume : additional volume of air beyond tidal inhalation

  • expiratory reserve volume : additional volume of air beyond tidal exhalation

  • vital capacity (total lung volume) : total volume of gas that can be moved in/out of the lungs

  • residual volume : the amount of air that remains in the lungs and passageways

  • Upper respiratory system

    1. air enters through the nose/mouth then turbinate bones increase the surface area ⮕ warms the air with a dense network of capillaries, and cleanse it with mucus

    2. next, pharynx ⮕ glottis (opening closed by epiglottis) ⮕ larynx ⮕ trachea

    3. larynx is made of cartilage and used for sound production

    4. trachea is strengthened and kept open by semi-cirular loops of cartilage

  • lower respiratory system

    1. trachea ⮕ bronchi ⮕ bronchioles ⮕ alveoli

    2. each lung is surrounded by pleural membrane (decreases friction between lung/chest cavity and separates the lungs)

    3. ciliated epithelial cells line the trachea which helps move particles out of the body

  • surrounding both alveoli is capillaries

  • the walls of the capillaries and alveoli are only one cell thick so that gas exchange can occur quickly by diffusion

  • gas exchange has two different forms

    1. inhaled air has a higher concentration of O2 than the capillary blood ⮕ O2 diffuses out of the alveoli and into the blood

    2. CO2 will diffuses out of the blood into the alveoli where it is released into air in the lungs

  • O2 is carried by hemoglobin

  • RESPIRATORY DISORDER : PNEUMONIA ⮕

    inflammation and fluid build up in the alveoli caused by bacteria or viruses

    treatments : antibiotics, anti-virals and vaccines