Meeting Tissue Needs Chapter 41 (844 866) Chapter 42 (867 891) Winter 2009 Lectures 10-13 Cellular Work Cellular work Source of energy Cellular currency Cellular respiration Reactants Products Trafficking Each cell needs: A supply of each reactant Digestive system Respiratory system A waste removal system Respiratory system Renal system A mechanism to connect these systems 1
A Matter of Size Diffusion Bulk flow Size matters No circulatory system Gastrovascular cavity Open circulatory system Closed circulatory system Gastrovascular Cavity GVC and body shape Cnidarians Diploblastic Fairly big Platyhelminths Triploblastic Very thin Diffusion Open Circulatory Systems 1. Heart pumps hemolymph 2. Open-ended arteries 3. Sinuses, no veins 4. Openings in the heart One body fluid Seen in: Arthropods, Brachiopods, Mollusks, tunicates and lancelets Advantages 2
Closed Circulatory Systems 1. Heart pumps blood 2. Arteries to tissues 3. Capillaries 4. Veins to heart Portal veins Two separate fluids Blood Interstitial fluid (lymph) Advantages Pressure Flow Seen in: Annelids, Cephalopods, Echinoderms, Vertebrates Collection Sites Intestine Facilitated diffusion Respiratory surface Diffusion Vertebrate Circulatory Systems Evolution of complexity Fish A simple 2 chamber heart 1 Atrium 1 Ventricle One circulatory loop 3
Vertebrate Circulatory Systems Amphibians Three chambered heart 2 Atria 1 Ventricle Double circulation Pulmocutaneous circuit Systemic circuit Advantages Vertebrate Circulatory Systems Reptiles Double circulation Pulmonary circuit Systemic circuit Three chambered heart Ventricle has a partial septum Advantages Vertebrate Circulatory Systems Birds and Mammals Double circulation Pulmonary circuit Systemic circuit Four chambered heart Complete septum Advantages 4
Basic Nutrition Heterotrophy Carbon compounds Generation of ATP Generation of macromolecules Essential nutrients Some amino acids Some fatty acids Vitamins Minerals & Electrolytes Essential Nutrients 20 amino acids ~ ½ can be synthesized N source ~ ½ are essential Complete proteins Animal proteins Incomplete proteins Plant proteins Deficiency Salt licks Essential Nutrients Osteophagia 5
Getting Nutrients Ingestion Suspension or Filter feeding Substrate feeding Fluid feeding Bulk feeding Filter Feeding Evolution of specific structures Appendages, Pharynx, Teeth, Gills Secreted mucus sacs Is filter feeding restricted to small organisms? Substrate Feeding Eat your environment Earthworm Apple maggots Leaf miner insects 6
Fluid Feeding Parasitizing a living host Specialized mouthparts Thin, sharp, hollow stylets Aphid Mosquito Fluid Feeding Aphids Photosynthates as food Aphid exploitation Blood Feeding Specialized fluid feeders Anticoagulants 7
Vampires Bulk Feeding Ingestion of entire prey Adaptations of jaws Ingestion of smaller bits Adaptations of teeth Bulk Feeding SA 64 = 6 64 = SA = 4 4 6 = The derived behaviour is to tear off pieces Adaptations evolved Teeth, claws, etc. SA 1 = 1 1 6 = Advantages? 8
Food Processing 1. Ingestion Is this inside the body? 2. Digestion Mechanical Chemical 3. Absorption 4. Elimination Teeth & Mastication The mammalian mouth Incisors Canines Premolars Molars Modifications based on diet Teeth & Mastication Herbivores Grinding & pulverizing molars Cutting incisors 9
Teeth & Mastication Carnivores Capture & killing canines Shearing premolars Molars? Chemical Digestion Where Does Chemical Digestion Occur? Intracellular All protists Sponges Tripeptides Oral groove Cell mouth Food vacuoles Extracellular Chamber Digestion Gastrovascular cavity Cnidaria Platyhelminthes Alimentary canal Most other phyla Anus Mouth 10
Alimentary Canals Regional Specialization Stomach Gizzard Intestine Crop Gizzard Esophagus Intestine Pharynx Mouth Esophagus Crop Anus Anus Mouth Foregut Esophagus Midgut Hindgut Rectum Anus Crop Mouth Gastric cecae Digesting Carbohydrates The average human diet The major dietary carbohydrates are: Starch & glycogen Sucrose Lactose Maltose Digesting Carbohydrates Absorption is limitted Amylase Maltase Sucrase Lactase Facilitated diffusion 11
Digesting Proteins NH 3 COOH NH 3 COOH NH 3 COOH NH 3 COOH Acid hydrolysis 1. Endopeptidases Pepsin, trypsin, chymotrypsin Digesting Proteins NH 3 COOH NH 3 COOH NH 3 COOH NH 3 COOH 2. Exopeptidases Carboxypeptidases, aminopeptidases Facilitated diffusion Intracellular digestion Digesting Lipids Triglycerides Fats and oils Oil and water don t mix! Emulsification Bile salts from micelles Lipase Reassembled in cell Chilomicrons 12
Maximizing Surface Area Maximizes digestion and absorption Villi and Microvilli Maximizing Surface Area Typhlosole of earthworm (big fold) Gastric caeca of insects (branches of gut) Spiral valve of sharks Adaptation to Diet Eating meat Small intestine Eating plants Small intestine Stomach Cecum Colon Carnivore Herbivore 13
No Digestion? Cestodes Habitat Absorption of predigested material Integument Digesting Cellulose Complex glucose polymer Not digestible Microscopic organisms can Symbiotic relationships Fermentation chambers Multiple stomachs Reprocessing food Other Alternatives Symbiotic cellulases The termite Wood = cellulose Endosymbiotic protists Leafcutter & gardening ants Exosymbiotic fungi Compost piles 14
Other Alternatives A second precessing Absorption in the small intestine Microorganisms live in the large intestine & cecum Therefore many animals practice coprophagy Cellular Respiration vs. Respiration One is the reason for the other Movement of Gases Simple diffusion Concentration gradient Diffuse away Efficiency of diffusion Slow and short Maximum efficient distance All cells must be close to source 15
Gas Exchange Requirements Requirements for gas exchange: 1. Moist surface 2. Adequate surface area Larger animals have more cells Respiratory Surfaces 1. Body surface Cutaneous respiration Specific respiratory surfaces 2. Gills 3. Lungs Gas Exchange Size and Habitat Diffusion Porifera Cnidaria Platyhelminthes Diffusion + Circulation Highly vascularized Capillaries Pick up oxygen Drop off carbon dioxide Most of the other phyla 16
Cutaneous Respiration When does this work? Dependent on water Aquatic or damp terrestrial Thin skin Cutaneous Respiration Amphibians Not completely aquatic Rely on water Water Breathing Large aquatic organisms Evaginations (outgrowths) Thin-walled structures Why not cutaneous respiration? External Gills Internal Gills 17
Water Breathing The Polychaetes Parapodia Numerous Relatively thin Rich blood supply Palps Multitasking structures Ventilation Ventilation Internal gills Water current Gill bailers Cilia Ventilation Ram-jet ventilation Buccal pump 18
Gas Exchange Aquatic Water Blood 1. Concurrent exchange Equilibrium Gas Exchange Aquatic 2. Countercurrent exchange Very efficient! Air Breathing Lungs Invaginations Moist Large surface area Water loss 19
Ventilation Essential Inhalation 1. Active contraction 2. Lungs expand Negative pressure Ventilation Exhalation 3. Muscles relax 4. Lungs recoil Positive pressure Gas Exchange Terrestrial Variable efficiency Frogs have: Small lungs Parasitic flukes How is this possible? Need to keep moist Amphibious Mucus 20
Other Vertebrate Lungs Branch of pulmonary vein (oxygen-rich blood) Terminal bronchiole Branch of pulmonary artery (oxygen-poor blood) Alveoli air sacs Gas exchange Numerous capillaries Incredible surface area ~100 m 2 in humans Alveoli SEM Colorized 50 µm 50 µm SEM Other Vertebrate Lungs Posterior air sacs Anterior air sacs Lungs Trachea Air Breath 2 Fresh air to lungs Stale air out Air Birds Air sacs expand Breath 1 Fresh air to posterior sacs INHALATION Air sacs fill Stale air to anterior sacs Lungs Air tubes (parabronchi) in lung EXHALATION Air sacs empty; lungs fill Air Breathing Tracheae The Insects Tracheal system Spiracles Tracheae & tracheoles Spiracle Air sac Body cell Tracheole Direct air supply Trachea Body wall Air 2.5 µm 21
Gas Transport Oxygen Metalloproteins Hemocyanin Hemoglobin Iron Heme Gas Transport Body tissue CO 2 produced CO 2 transport from tissues Carbon dioxide Interstitial fluid CO 2 Carbonic anhydrase Plasma within capillary CO 2 Capillary wall Red blood cell Hb Hemoglobin picks up ~5% CO 2 + H + Waste Removal Ammonia Urea Uric acid Carbon dioxide Respiratory surface Nitrogenous waste Amino & nucleic acid metabolism 22