BL1004 Respiration Oct 2024 PDF

BL1004-Respiration Prof. Sarah Culloty, School of Biological Earth and Environmental Sciences & College of Science, Engineering and Food Science. [email protected] Gas exchange – Supplies oxygen for cellular respiration and disposes of carbon dioxide Cellular respiration...

BL1004-Respiration Prof. Sarah Culloty, School of Biological Earth and Environmental Sciences & College of Science, Engineering and Food Science. [email protected] Gas exchange – Supplies oxygen for cellular respiration and disposes of carbon dioxide Cellular respiration is a set of metabolic reactions and processes that take place in the cells of organisms to Respiratory O2 CO2 medium Respiratory convert biochemical energy surface (air of water) from nutrients into ATP Organismal (chemical energy), and then level release waste products. Circulatory system Cellular level Energy-rich molecules Cellular respiration ATP from food General function of respiration  Gets O2 to cells  Gets rid of CO2  Different groups of organisms employ different strategies – depending on the environment Respiratory organs  Protozoa-e.g. Amoeba, Paramecium (Single celled organisms)  Gas transfer occurs across the plasma membrane by simple diffusion Small invertebrates e.g. Flatworm  Diffusion is adequate for the needs of the animal due to its size  General concepts  In specialized organs for respiration, there are normally extensive patterns of invagination and evagination to increase the membrane surface area  Gills are evaginated structures, lungs invaginated structures  Different organ types: Lungs, external gills and internal gills  Adjectives and how we describe: branchial for gills, pulmonary for lungs Respiratory organs Starfish breathe with their tube feet as well as their gills (branchial papulae) Fish - Gills  Gasexchange – water has low oxygen levels but gills can remove > 80% by countercurrent flow of bloodOxygen-poor and water blood Gill arch Oxygen-rich Lamella blood Blood vessel Gill arch % % 15 40 % 5% 70 % 30 Water 0% % 60 10 flow Operculum % 90 O2 Blood flow Water flow through capillaries over lamellae in lamellae showing % O2 showing % O2 Figure 42.21 Gill filaments Countercurrent exchange Tracheal Systems in Insects  Thetracheal system of insects consists of tiny branching tubes that penetrate the body Air sacs are reservoirs for Air sacs organs Tracheae Spiracle Air enters the tracheae through openings called spiracles on the insect’s body surface and passes into smaller tubes called tracheoles. The tracheoles are closed and contain fluid. When the animal is active and is using more O 2, most of the fluid is withdrawn into the body. This increases the surface area of air in contact with cells. Larger insects use bellow like movements to pump air into tracheal system.  Tracheal Systems in Insects  Gas-exchange surface is close to all cells Body  Circulatory system plays little or cell Air Tracheole sac no role in O2 transport Trachea Air Body wall Tracheoles Myofibrils Mitochondria Figure 42.22b 2.5 µm  Amphibians  Larval amphibians  Gills and skin  Most adult amphibians  Lungs and skin  Gills remain in some adult species, e.g. mudpuppies (Necturus) and axolotl  Some salamanders, lacking lungs, breathe only with their skin, which is highly vascularised (lots of blood vessels)  Some frogs hibernate in water and only use skin Birds  Lungs are rigid structures and undergo little change in volume  Air sacs expand and contract  Air flows unidirectionally  Gas-exchange system is cross-current  Mammals - lungs  Lungs of mammals are densely filled with branching airways:-23 levels of branching and 300 million alveoli in humans  The surface area of the gas- exchange membrane is great relative to the size  Mammals - lungs  The thickness of the barrier between the blood and the air is only 2 layers of cells:  Blood vessel  Alveoli (Air sac) Mammals  Movement of air  Buccal pressure in air- breathing fish and amphibians  Suction or aspiration in nonavian reptiles, and also in mammals and birds, using thoracic and abdominal muscles  Tidal volume~500ml  Vital capacity-3.4-4.8 L  Residual volume~1.5L Respiratory pigments Respiratory pigments are needed to bind and transport gases because O2 has a low solubility in water.  The respiratory pigment of almost all vertebrates is the protein haemoglobin (Fe), contained in the erythrocytes (red blood cells). The pigment in arthropods and most molluscs is haemocyanin (Cu) Oxygen transport Haemoglobin reversibly binds O2, loading O2 in the lungs and unloading it in other parts of the body with lower partial pressure (PO ) 2 Heme group Iron atom O2 loaded O2 in lungs O2 unloaded In tissues O2 Polypeptide chain  Acknowledgements  Majority of text and Powerpoint slides from Campbell’s Biology. Revision questions 1. What are the principals of countercurrent exchange? 2. Name two respiratory pigments 3. What is the tidal volume, residual volume, tidal capacity in humans? 4. What does the O2 molecule bind to in the haemoglobin molecule?