Meeting Tissue Needs

Transcription

1 Meeting Tissue Needs Chapter 41 (41.1 4) Chapter 42 (42.1,5 7) Winter 2009 Lectures Cellular Work Cellular work Source of energy Cellular currency Cellular respiration Reactants Products 1

2 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 A Matter of Size Diffusion Bulk flow Size matters No circulatory system Gastrovascular cavity Open circulatory system Closed circulatory system 2

3 Gastrovascular Cavity GVC and body shape Cnidarians i 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 3

4 Closed Circulatory Systems 1. Heart pumps blood 2. Arteries to tissues 3. Capillaries 4. Veins to heart Portal veins Advantages Pressure Flow Two separate fluids Blood Interstitial fluid (lymph) Seen in: Annelids, Cephalopods, Echinoderms, Vertebrates Collection Sites Intestine Facilitated diffusion Respiratory surface Diffusion 4

5 Vertebrate Circulatory Systems Evolution of complexity Fish A simple 2 chamber heart 1 Atrium 1 Ventricle One circulatory loop Vertebrate Circulatory Systems Amphibians Three chambered heart 2 At i 2 Atria 1 Ventricle Double circulation Pulmocutaneous circuit Systemic circuit Advantages 5

6 Vertebrate Circulatory Systems Reptiles Double circulation Pulmonary circuit it Systemic circuit Three chambered heart Ventricle has a partial septum Advantages Vertebrate Circulatory Systems Birds and Mammals Double circulation Pulmonary circuit it Systemic circuit Four chambered heart Complete septum Advantages 6

7 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 7

8 Essential Nutrients Osteophagia Getting Nutrients Ingestion Suspension or Filter feeding Substrate feeding Fluid feeding Bulk feeding 8

9 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 9

10 Fluid Feeding Parasitizing a living host Specialized mouthparts Thin, sharp, hollow stylets Aphid Mosquito Fluid Feeding Aphids Photosynthates as food Aphid exploitation 10

11 Blood Feeding Specialized fluid feeders Anticoagulants Vampires 11

12 Bulk Feeding Ingestion of entire prey Adaptations of jaws Ingestion of smaller bits Adaptations of teeth Bulk Feeding SA 64 = 6 64 = SA = = SA 1 = = The derived behaviour is to tear off pieces Adaptations evolved Teeth, claws, etc. Advantages? 12

13 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 13

14 Teeth & Mastication Herbivores Grinding & pulverizing molars Cutting incisors Teeth & Mastication Carnivores Capture & killing canines Shearing premolars Molars? 14

15 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 15

16 Alimentary Canals Regional Specialization Crop Gizzard Esophagus Intestine Mouth Esophagus Stomach Gizzard Intestine Pharynx Anus Crop Anus Mouth Foregut Midgut Hindgut Esophagus Rectum Anus Crop Mouth Gastric cecae Digesting Carbohydrates The average human diet The major dietary carbohydrates are: Starch & glycogen Sucrose Lactose Maltose 16

17 Digesting Carbohydrates Absorption is limitted Amylase Maltase Sucrase Lactase Facilitated diffusion Digesting Proteins NH 3 COOH NH 3 COOH NH 3 COOH NH 3 COOH Acid hydrolysis 1. Endopeptidases Pepsin, trypsin, chymotrypsin 17

18 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 18

19 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 19

20 Adaptation to Diet Eating meat Small intestine Eating plants Small intestine Stomach Cecum Colon Carnivore Herbivore No Digestion? Cestodes Habitat Absorption of predigested material Integument 20

21 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 21

22 Other Alternatives A second precessing Absorption in the small intestine Microorganisms i live in the large intestine ti & cecum Therefore many animals practice coprophagy Cellular Respiration vs. Respiration One is the reason for the other 22

23 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 Gas Exchange Requirements Requirements for gas exchange: 1. Moist surface 2. Adequate surface area Larger animals have more cells 23

24 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 24

25 Cutaneous Respiration When does this work? Dependent on water Aquatic or damp terrestrial Thin skin Cutaneous Respiration Amphibians Not completely aquatic Rely on water 25

26 Water Breathing Large aquatic organisms Evaginations (outgrowths) Thin-walled structures Why not cutaneous respiration? External Gills Internal Gills Water Breathing The Polychaetes Parapodia N Numerous Relatively thin Rich blood supply Palps Multitasking structures Ventilation 26

27 Ventilation Internal gills Water current Gill bailers Cilia Ventilation Ram-jet ventilation Buccal pump 27

28 Gas Exchange Aquatic Water Blood 1. Concurrent exchange Equilibrium i Gas Exchange Aquatic 2. Countercurrent exchange Very efficient! i 28

29 Air Breathing Lungs Invaginations Moist Large surface area Water loss Ventilation Essential Inhalation 1. Active contraction 2. Lungs expand Negative pressure 29

30 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 30

31 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 i 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 INHALATION Air sacs fill Birds Air sacs expand Breath 1 Fresh air to posterior sacs Stale air to anterior sacs Lungs Air tubes (parabronchi) in lung EXHALATION Air sacs empty; lungs fill 31

32 Air Breathing Tracheae Spiracle The Insects Tracheal system Spiracles Tracheae & tracheoles Direct air supply Body cell Air sac Tracheole Trachea Body wall Air 2.5 µm Gas Transport Oxygen Metalloproteins Hemocyanin Hemoglobin Iron Heme 32

33 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 33