Chapter 42 Respiration

Basics Respiratory medium – air or water Get oxygen into the body; diffusion across a moist membrane Need oxygen for cellular respiration (end of ETC) Respiratory surfaces- gills, lungs Have to be moist Have to be large (surface area) Way to get oxygen to cells Need protection

Gills Water goes in one direction, blood goes in the opposite direction. Partial pressure gradient (moves from high to low) Maximizes diffusion Without this, you would reach equilibrium and you wouldn’t get a lot of oxygen. Concurrent (NOT efficient) Countercurrent (Efficient)

Tracheal systems Similar to the AC system in your house Oxygen goes directly to your cells Blood does not carry oxygen Limits size of the animal Bigger insects fly because flight muscles have lots of mitochondria and help bring in air

Lungs Land snails, primitive fish, most amphibians, all reptiles, all birds, all mammals Types of Respiration: 1. Breathing – inhaling and exhaling 2. External respiration – getting oxygen from the air and getting it into your blood 3. Internal respiration – getting oxygen from your blood to your tissues and organs 4. Cellular respiration – making ATP using oxygen

structures External nares (nostrils) Pharynx Larynx (voicebox) Glottis Sensory receptors Hair/cilia help filter the air Blood vessels help warm the air Mucus helps moisten the air Pharynx Larynx (voicebox) Vocal cord – vibrate when air moves over it; the length, thickness, and elasticity influence the sound of your voice Glottis Trachea Cartilaginous rings – keep trachea from collapsing Cilia beat up to remove any debris from going down Splits off into two bronchi Bronchus Splits into bonchioles

Alveoli Simple diffusion Surfactant (phospholipids and proteins that reduce surface tension) keep alveoli open made during the very end of embryonic development, so if babies are born prematurely, they may have lung problems. You can blow surfactant into the lungs to fix this.

Pleural Membrane Two membranes- one bound to lungs, one bound to ribcage Contains fluid Can cause lungs to collapse if air gets in

Just Breathe  As H+ and CO2 increases, pH decreases (not good!) The hindbrain (pons, medulla oblongata) contains breathing control centers Backup system- chemoreceptors (which check for low oxygen levels) in the aorta (should be highly oxygenated) and carotid arteries (go to brain so should have a lot of oxygen)

Negative Pressure Breathing Inhalation Diaphragm contracts (moves down), expands, pressure decreases so air comes into the lungs (since there is higher pressure outside the lungs), ribcage and alveoli expand Exhalation Diaphragm relaxes (moves up)

Terms Tidal air – normal volume of air Vital capacity – max volume you can force yourself to inhale Residual volume – air left after you try to exhale as much as you can

Birds are the true MVP More efficient breathing Have air sacs (keep the oxygen when they exhale and sends the oxygen to the lungs) and parabronchi (NOT alveoli)