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Comparative Physiology Aquatic and Aerial Respiration Part II Terrestrial respiration Terrestrial Gas Exchange • Some air breathing adaptations in – Platyhelmintheyes, annelida, arthropoda, gastropoda, vertebrata – Flatworms, earthworms, leeches have no special respiratory structures – Gasses exchanged across the body wall – Skin must remain moist – limited to moist habitats Terrestrial Gas Exchange • Gastropods, terrestrial arthropods, and vertebrates have specialized respiratory structures – Can inhabit dry and moist habitats – Arthropods have a tracheal system – Gastropods and arthropods also have lungs Gas Exchange in Terrestrial Animals • Three types of Lungs – Ventilation lungs • Move air in and out by a pumping mechanism – Diffusion lungs • Snails and slugs have a pneumostome which opens to a mantle well supplied with circulatory fluid – Book lungs • Diffusion lung found in spiders shaped like pages of a book. Found in abdomen and open to the atmosphere on the ventral surface. Ventilated by body movements and general activity Book lungs Gastropod Respiration Gas Exchange in Terrestrial Animals • Invertebrates – Insects • • • • • Large surface area to volume ratio Highly susceptible to drying Covered by cuticle with waxy layer Tracheal system accounts for most gas exchange Spiracles, tracheae, tracheoles Gas Exchange in Terrestrial Animals • Tracheal system accounts for most gas exchange • Air enters through spiracles – Hydrophobic hairs prevent dust and water entry • Spiracles open into the tracheae • The largest tubes in the system, cuticle lining holds them open • Trachea divide into tracheoles which end in blind, liquid filled tubules – As metabolites fill the fluid, water and gasses are drawn deeper into the tracheoles, increasing gas exchange in active tissues Gas Exchange in Terrestrial Animals • In small insects, diffusion is sufficient • In large insects, Air sacs located near large muscles achieve pumping in the system Gas Exchange in Terrestrial Animals – Aquatic insects • Tracheal system can extract oxygen from water or air – Tracheal gills- dense networks of fine trachea in featherlike extensions from the body Insect Tracheal System Gas Exchange in Terrestrial Animals • Amphibians Gas Exchange in Terrestrial Animals Gas Exchange in Terrestrial Animals • Vertebrates – Amphibians • Buccal pumping • Trachea, glottis, bronchus • Cutaneous gas exchange Gas Exchange - Buccal pumping 1 Gas Exchange - Buccal pumping 2 Gas Exchange - Buccal pumping 3 Gas Exchange - Buccal pumping 4 Gas Exchange in Terrestrial Animals • Vertebrates – Mammals • Higher metabolism requires more oxygen per unit of body weight to maintain homeostasis • Lungs provide efficient ventilation and greater surface area Terrestrial vertebrates: Lungs Terrestrial vertebrates: Lungs • Nostrils filter air • Nasal passages adjust temp • Larynx • • • • • Trachea and bronchi supported by cartilage rings Broncus divide into bronchioles which end in clusters of alveoli 30,000,000 alveoli per 75 KG person! 15x more area than frog Ciliary escalator to clean system Gas Exchange in Terrestrial Animals • Vertebrates – – – – – Birds Parabronchi Air capillaries Air sacs Crosscurrent exchange Breathing Breathing ventilates the lungs • Inhalation – Ribcage expands, diaphragm contracts, chest expands - lungs increase in size - air flows into the alveoli from higher pressure outside. • Exhalation – Rib and diaphragm muscles relax- chest contracts, lungs decrease in size -air forced out. Birds have highly efficient, flow through lungs Birds have highly efficient, flow through lungs • One - way air flow through the lungs • Air sacs ventilate respiratory surface in the lungs • Inhalation- posterior sacs fill with fresh air- anterior sacs fill with stale air • Exhalation - both sacs deflate forcing air into the lungs and out of the system • No alveoli, parallel tubes, crosscurrent exchanger, more efficient than mammalian lung Control over breathing Control over breathing Gas Transport and Body Fluids • Respiratory pigments – Functions • Hemacyanins – Mollusca and arthropoda, based ion Copper • Hemoglobins • Myoglobin Gas Transport and Body Fluids • Respiratory pigments – O2 binding to Hemoglobin – Cooperativity – Bohr effect Quiz • Read Withers 608-645 • Make a chart that compares the respiratory systems of the terrestrial organisms found in this chapter • Be thorough! Adaptations in Diving Mammals • Weddell seal – 300-500M dives for up to 15 minutes • Whales – 500M dives for up to 1 hour • Problems: – Oxygen demand and the bends Adaptations in Diving Mammals • Bends – – – – N2 from air dissolves in blood Surface too quickly N2 bubbles in blood like carbonated soda Capillaries blocked and ruptured, pain, brain seizures possible • Divers must ascend slowly! • Whales and seals come up fast? Adaptations in Diving Mammals • Whales and seals come up fast? – – – – Prevent high pressure air from contacting blood Exhale before dive Pressure collapses trachea and lungs, air removed Store oxygen! • 2x blood per unit of body weight • Myoglobin storage – Diving response • Slow heart rate to ½ to 1/10 normal rate • Anaerobic metabolism