Respiration

Gas exchange (O 2 and CO 2 ) Diffusion down concentration gradient Specialized epithelial surfaces Moist Thin Large surface area

Respiration Fick’s Law—The larger the surface area and the steeper the partial pressure gradient, the faster diffusion will proceed. Ventilation Active movement of air Necessary in larger animals Enhances gas exchange rates

Respiratory Pigments Metal ions that bind to and carry O2 Hemoglobin All vertebrates; some mollusks, annelids, crustaceans Iron ion Oxygenated—red, deoxygenated—dark red In all Kingdoms, but not all organisms Structure of molecule varies by species

Respiratory Pigments Hemocyanin Most mollusks, some arthropods Copper ion Oxygenated—blue, deoxygenated—colorless Second most common pigment Myoglobin Found in muscle tissue Can store O 2 for later use Amounts vary between species

Invertebrate Respiration Integumentary Exchange Some aquatic animals Small, simple organisms Protozoans Poriferans, Cnidarians, Platyhelminthes, Annelids, etc. Short distance between O 2 and tissues

Invertebrate Respiration Gills Aquatic mollusks, arthropods Different than fish Outgrowth of body wall Highly folded Gas exchange to water

Invertebrate Respiration Book Lungs Most arachnids 1-4 pairs Folded appearance Direct opening outside of body

Invertebrate Respiration Tracheal System Insects, millipedes, centipedes, some arachnids Spiracles in integument Tubes branch several times Tips of finest branches end at body cells in all tissues

Vertebrate Respiration Gills Aquatic vertebrates Most internal External in some fish larvae & amphibians Finely branched Attached to firm supports

Vertebrate Respiration Countercurrent Flow Blood flows in opposite direction to water Maximizes O 2 exchange

Vertebrate Respiration Lungs All terrestrial vertebrates, some fish Saclike internal organ Airways connect to external environment Variable complexity

Vertebrate Respiration Amphibian respiration Larvae gills, adults lungs Some integumentary exchange Frogs/toads take O 2 through lungs, eliminate CO 2 through skin Small, simple lungs Positive pressure “Gulps” air into mouth Pushes air into lungs Body wall muscles contract, forcing air out of lungs

Vertebrate Respiration Reptile respiration More developed lungs Negative pressure Draw air into lungs Expansion & contraction of ribs causes ventilation

Vertebrate Respiration Avian respiration Rigid lungs No alveoli Air sacs Air flow continuously through lungs Inhalation—air moves into posterior air sacs & lungs Exhalation—air moves from air sacs into lungs, also exits lungs Ventilate by expanding & contracting chest

Vertebrate Respiration Mammal respiration Diaphragm Contracts, pulling chest cavity down (negative pressure) Relaxes, allowing outward flow Ribcage can expand & contract Exhalation not complete O 2 -poor and O 2 -rich air mix

Mammal/Human Respiration Nasal & Oral CavitiesPharynxGlottisLarynxTrachea BronchiBronchiolesAlveoli

Mammal/Human Respiration Alveous (pl. alveoli) Only in mammals Spherical sacs Surrounded by capillaries Simple squamous epithelium

Respiratory Cycle Inhalation Ribs move out, diaphragm (if present) moves down Increases thoracic volume Draws air into lungs Active, requires energy Gas exchange Exhalation Intercostal muscles & diaphragm relax Thoracic volume returns to normal Reduction in volume forces air out Passive, no energy required

Special Situations High altitude Air pressure decreases w/ altitude This decreases O 2 transport Hypoxia Low blood O 2 Heart & respiratory muscles work harder Hyperventilate Animals Hemoglobin has better affinity for oxygen Carry more O 2 at low pressure

Special Situations Humans born at high altitude Lungs have more alveoli & blood vessels Heart has larger ventricles to pump more blood Muscles have more mitochondria Humans born at low altitude Can acclimate Eventually produce more RBCs Better oxygenation, but thicker blood

Special Situations Deep Sea High pressure due to water volume Forces nitrogen to be dissolved in tissues Passes through cell membranes If in neurons, disrupts signals Nitrogen narcosis When ascend, N2 moves into blood If too rapid, bubbles form in blood “The Bends” Pain in joints, obstructed blood flow to organs

Special Situations Well-trained humans hold breath 3 min Human records Free-diving length: 9 min 8 sec Free-diving depth: 244m (800’) Deep-diving depth: 330m (1,082’) 10m to reach depth 8 hr 49 min to return to surface

Special Situations Animals Sperm whale: 2500m (8,200’, 1.5mi), hr Leatherback sea turtle: 1,000m (3,280’), 30 min Bottlenose dolphin: 550m (1,804’), 10 min

Special Situations How???? Fill lungs fully before dive 85-90% air exchange Humans 15% As dive lengthens, blood directed away from most organs Preferentially to brain & heart Myoglobin up to 10 times humans 41% of O 2 stored in muscles (humans 13%) High lactic acid tolerance Can operate in anaerobic metabolism longer Mechanisms to avoid “bends” Air w/ N 2 taken at surface (lower pressure) W/ depth, air moved to nonabsorptive areas, reducing gas exchange