Bio 10 Lecture Notes 8: Animal Diversity and Physiology SRJC

Transcription

1 1.) Animal Kingdom: Evolution and Diversity Characteristics of Animals Multicelled Aerobic heterotrophs Sexual reproduction Some also reproduce asexually Embryos produce primary tissues Motile at some stage Animal Lineages Vertebrates (single phylum: Chordata) Mammals Birds Reptiles Amphibians Fishes Invertebrates (many phyla) No backbone Animal Origins Monophyletic group Ediacarans Oldest date to 610 million years ago Animals probably arose from Ediacaran ancestors about 610 million years ago. Variety of forms Early animals were thin, flat-bodied, with a good surface-to-volume ratio for absorbing nutrients. Cambrian explosion of diversity During the Cambrian, animals underwent an enormous adaptive radiation resulting in all of the major groups of animals Animal Diversity Many characteristics are used to group animals and determine evolutionary links Body Plans Symmetry Segmentation and cephalization Body cavities Digestive systems (none, incomplete or complete) Embryonic Development (protostomes and deuterostomes) Body Plans Radial symmetry Parts arrayed around a central point Bilateral symmetry Two halves that mirror each other Cephalization Concentration of nerve and sensory cells at anterior end A Carranza Page 1 7/25/2015

2 Segmentation Repeating series of body units Units may or may not be similar to one another Earthworms: segments appear similar Insects: segments may be fused and/or have specialized functions Body Cavities Coelom- (lined with peritoneum) is a space between the gut and body wall that allows internal organs to expand and operate freely Acoelomate Some animals (flatworms) do not have a coelom but instead are packed solidly with tissue between the gut and body wall Pseudocoelomate Others, such as roundworms, have a false coelom (pseudocoel), not lined with peritoneum Coelomate Most animals are coelomates and have a true coelom, lined with peritoneum Digestive Systems- Region where food is digested and then absorbed No digestive system- intracellular (in cell) digestion (e.g. sponges) Incomplete digestive system ( saclike gut) One opening for taking in food and expelling waste (e.g. flatworms, sea anemones) Complete digestive system Opening at both ends, mouth and anus Sponges No symmetry, tissues, or organs Filter feeders with intra-cellular digestion, no digestive system Reproduce sexually Microscopic swimming larva Cnidarians Radial symmetry Only animals that produce nematocysts Epithelial tissues Nerve net Hydrostatic skeleton Saclike gut (incomplete digestive system) Medusa and polyp forms Jellyfish, corals, sea anemones, hydras Protostome vs Deuterostome Two animal lineages distinguished by embryonic development Protostome (first mouth)- blastopore develops into mouth (e.g.) insects, snails, worms A Carranza Page 2 7/25/2015

3 Deuterostome (second mouth) blastopore develops into anus (e.g.) seastars, vertebrates Flatworms Bilateral, cephalized, no body cavity Most are hermaphrodites Include Turbellarians (including planarians) Flukes (including schistosomes) Tapeworms Schistosomes Parasitic flatworms Complicated life cycles, infect multiple hosts at different stages Larval stage infects a mollusk Adult infects a vertebrate Annelids Segmented, coelomates Earthworms Leeches Marine polychaetes Some with rudimentary brains and nerve cords Setae Chitin-reinforced bristles for crawling Oligochaetes Few bristles per segment (earthworms) Polychaetes Many bristles per segment (marine worms) Leeches Mollusks Bilateral, soft-bodied, coelomate Many have a shell or reduced version of one Mantle drapes over body and secretes shell Molluscan Diversity Gastropods (snails) Chitons Bivalves (clams, etc) Cephalopods (squids, octopuses) Cephalopod Adaptations Closed circulatory system Increases oxygen Squids Fastest invertebrates Jet propulsion Octopuses A Carranza Page 3 7/25/2015

4 Smartest invertebrates Largest brains Most complex eye among inverts. Roundworms (Nematodes) Bilateral, cephalized Pseudocoelom Complete digestive system Most free-living Some parasitize plants, animals, or humans Trichinosis Elephantiasis Arthropods Invertebrate group with the greatest number of species Five lineages: Trilobites (extinct) Chelicerates (spiders, mites, ticks, scorpions) Crustaceans (crabs, shrimps, barnacles) Insects Myriopods (centipedes, millipedes) Adaptations for Success Hardened exoskeleton Jointed appendages Fused and modified segments Respiratory structures Specialized sensory structures Specialized developmental stages Exoskeleton Molting of the cuticle Metamorphosis Division of labor between different developmental stages Growth as embryo (caterpillar) Reproduction and dispersal as adult (butterfly) Chelicerates Marine chelicerates : horseshoe crabs, sea spiders Arachnids (terrestrial chelicerates); Spiders, Mites, Scorpions, Chiggers, Daddy longlegs, Ticks Crustaceans Most are marine, some freshwater, a few terrestrial Head has two pairs of antenna, three pairs of food-handling appendages Insects 3 Segments (head, thorax, abdomen) The only winged invertebrates More than 800,000 known species High reproductive capacity A Carranza Page 4 7/25/2015

5 The most successful animals in terms of Distribution Number of species Population size Competitive adaptations Exploitation of diverse foods Echinoderms Marine group Calcium carbonate spines or plates No brain Tube feet Adults radial with bilateral features, but considered bilateral Chordates Chordate Features Notochord supports body Nervous system develops from dorsal nerve cord Embryos have pharynx with slits Embryos have tail that extends past anus Tunicates Notochord, tail and nerve cord occur only in larval stage (tadpole larval) Neoteny (paedomorphosis): sexual maturity in larval stage Possible mechanism for rise of vertebrates from tunicate ancestor Lancelet: An invertebrate Chordate Craniates (vertebrates) A chamber of cartilage or bone holds the brain Fishes Amphibians Reptiles Birds Mammals Key Innovations Shift from notochord to vertebrae Nerve cord expanded into brain Evolution of jaws Paired fins evolved, gave rise to limbs Gills and eventually lungs Jawed Fishes Most diverse and numerous group of vertebrates Cartilaginous fishes Sharks and rays A Carranza Page 5 7/25/2015

6 Bony fishes Ray-finned fishes: Soft ray fishes Salmonids (salmon, trout) Cyprinids (carp, gold fish, Koy) Spiny ray fishes Perciform (perch, bass, blue gill) Scorpiniform (sculpin, rock fish, ling cod) Scrombiform (tuna, sword fish, etc) Lobe-finned fishes Lungfishes and coelocanths Very ancient, mostly extinct, group Likely gave rise to terrestrial vertebrates Early Amphibians Fishlike skull and tail Four limbs (tetrapods) Short neck Modern Amphibians Require water at some stage in life cycle; most lay eggs in water Lungs are less efficient than those of other vertebrates Skin serves as respiratory organ Frogs, toads, salamanders Rise of Amniotes Arose during Carboniferous Adaptations to life on land Tough, scaly skin Internal fertilization Amniote eggs Water-conserving kidneys Living Reptiles Not a monophyletic group, several ancestral groups Crocodilians Turtles Snakes and lizards Dinosaurs Descended from Triassic reptiles Several mass extinctions, ending with K-T asteroid impact Some are now considered early birds Birds Vertebrates with feathers Diverse Good learners Diverged from small dinosaurs during Mesozoic Amniote eggs fertilized internally Feathers and Flight Flight required full-body modification A Carranza Page 6 7/25/2015

7 Bone structure, respiration, circulation Wings, feathers, musculature Mammals Mammal Characteristics Hair Mammary glands Distinctive teeth Highly developed brain Extended care for young Three Mammalian Lineages Monotremes Egg-laying mammals Marsupials Pouched mammals Eutherians Placental mammals 2.) Animal Physiology Required Nutrients Water Carbohydrates Lipids Proteins Minerals Vitamins Water Makes up ~90% of some animals Makes up a major portion of many body parts Humans require at least 1 L / day Carbohydrates Main source of energy High in bulk fiber Refined carbohydrates do not supply need Obesity Americans consumption ~2 lb refined sugar/week Lipids Parts of membranes Energy reserves Essential fatty acids (olive oil, canola oil) Saturated fats Roughly 40% of American diet Proteins Consist of amino acids hooked together A Carranza Page 7 7/25/2015

8 20 amino acids 8 essential amino acids Animal protein contains all 20 amino acids Vegetables do not contain required balance of amino acids for humans A vegetable does not provide complete protein Complementarities can supply all essential amino acids. Beans supply lysine, corn supplies methionine Minerals 17 essential minerals Inorganic substances: Iron, iodine, zinc, calcium, sulfur, potassium, chloride, magnesium, etc. Required for growth, metabolism, survival Deficiencies stunted growth or weak Vitamins 13 essential vitamins Complex organic compounds Play metabolic role cofactors and coenzymes Animals cannot synthesize themselves Water Soluble vitamins Taken in excess eliminated in urine generally do no harm C, B complex (B1, B2, B6, B12, niacin) Fat Soluble vitamins Taken in excess stored in fatty tissues can cause serious health problems A, D, E, K Simple Digestive Processes Intracellular Digestion Phagocytosis Extracellular Digestion carbohydrates simple sugar proteins amino acids lipids glycerol & fatty acids Digestive Systems Incomplete Digestive System Mouth and gut, no anus Complete Digestive System Mouth, Pharynx, Esophagus, Crop/gizzard (birds and grass hoppers), Stomach, Intestine, Anus Digestive System Functions Mechanical Processing breakdown, mixing, and food movement Secretion release of digestive enzymes that aid digestion Digestion breakdown of food particles Absorption passage of digested nutrients and fluid from the tube (extracellular space) into the body s cells Elimination expulsion of undigested materials Vertebrate Mouth Specializations A Carranza Page 8 7/25/2015

9 Herbivores- have teeth for grinding (molars are well developed) Carnivores- have teeth for tearing and chewing flesh (canines well developed) Omnivores have combination of above Circulatory Systems Single-celled organisms, direct exchange with environment Circulatory Systems Rapidly transports substances to and from cells May carry gases, food, chemical messages, waste material and living cells Interstitial fluid bathes tissues Heart muscular blood vessel that acts as a pump Open Circulatory Systems Vessels empty into interstitial fluid, blood is re-collected Closed Circulatory System Vessels are continuous, but increasingly small Hearts Fish 2 chambered heart Amphibians 3-chambered heart Birds and Mammals 4-chambered heart 2 ventricles 2 atria Atrium thin-walled; receives blood from body; pumps to ventricle Ventricle muscular wall; forces blood into major arteries Cellular Respiration C6H12O6 + O2 CO2 + H2O + energy Respiration in Water and Air aquatic environments- involves gills terrestrial environments- involves lungs Gas Exchange Surface exchange- directly across epidermis, found in small animals with good SA/V ratio Vascular exchange- across gills or lungs, in larger animals, provide good SA/V ratios Gills- external structures Lungs- internal structures Trachea- only found in insects, like lungs Gills Gill Filament- has small branches for increased surface area Countercurrent Exchange- provides efficient gas exchange with water Lungs Amphibians have inefficient gas exchange system, augmented by exchange through skin Birds- need extra efficient system for flight, have air sacs that re-run air through lungs Human- air is driven into lungs by downward movement of diaphragm which expands lungs. Diaphragm contraction, expels air at exhalation A Carranza Page 9 7/25/2015

10 3.) Animal Organ Systems 3.1) Human Digestion Human Digestive System Complete system with many specialized accessory glands and organs About 10 meters long (30 ft) Lined with mucus-secreting epithelium Movement is one way, from mouth to anus Major Components Mouth (oral cavity) Pharynx (throat) Esophagus Gut Stomach Small intestine Large intestine Rectum Anus Accessory Organs Salivary glands Secrete saliva Liver Secretes bile Gallbladder Stores and concentrates bile Pancreas Secretes digestive enzymes Mechanical Processing Food is reduced down to its molecular components throughout the digestive process First it must be broken mechanically in the mouth Teeth break down food Saliva Produced by salivary glands at back of mouth and under tongue Saliva includes Salivary amylase (enzyme) Bicarbonate (buffer) Mucins (bind food into bolus) Water Swallowing Complex reflex Tongue forces food into pharynx Epiglottis and vocal cords close off trachea; breathing temporarily ceases Food moves into esophagus, then through esophageal sphincter into stomach A Carranza Page 10 7/25/2015

11 Structure of Stomach J-shaped organ lies below the diaphragm Sphincters at both ends Outer serosa covers smooth muscle layers Inner layer of glandular epithelium faces lumen Stomach Secretions Secreted into lumen (gastric fluid) Hydrochloric acid (HCl) Mucus (protective) Protein-digesting enzymes Stomach cells also secrete the hormone gastrin into the bloodstream Small Intestine Longest segment of digestive tract Receives chyme from stomach Receives secretions from liver, gallbladder, and pancreas Pancreas secretes enzymes to breakdown food, sodium bicarbonate to neutralize stomach acid Liver secretes bile salts to breakdown fats Digests food into absorbable subunits Pancreas secretes enzymes to breakdown food, sodium bicarbonate to neutralize stomach acid Liver secretes bile salts to breakdown fats Walls of Small Intestine Projections into the intestinal lumen increase the surface area available for absorption Nutrient Absorption Passage of molecules into internal environment Occurs mainly in small intestine Various methods of absorption Osmosis, transport proteins, diffusion Absorption Mechanisms Monosaccharides & amino acids are actively transported across plasma membrane of epithelial cells, then from cell into internal environment Fat Absorption Bile salts emulsify lipids Into the Blood Glucose and amino acids enter blood vessels directly Triglycerides enter lymph vessels, which eventually drain into blood vessels Large Intestine (Colon) Concentrates and stores feces Actively transports sodium ions out of lumen; water follows (by osmosis) Resident bacteria produce vitamins Rectum Final portion of large intestine Stores feces Anus A Carranza Page 11 7/25/2015

12 Final sphincter Controls Over Digestion Nervous system Secretion of acids and enzymes Smooth muscle contractions Endocrine system Appetite (leptin and grehlin) Digestion (gastrin, secretin, CCK) 3.2) Circulation and Respiration Blood Flow and Gas Exchange Rate of blood flow varies with diameter of blood vessels Slowest flow in smallest vessels, the capillaries Gases are exchanged between blood and interstitial fluid across capillary walls Vertebrate Circulatory Systems 4 chambered hearts in birds and mammals Heart is fully partitioned into two halves. Blood circulates in two circuits: from the heart s right half to lungs and back, then from the heart s left half to oxygenrequiring tissues and back Double Circuits In birds and mammals Right half of heart Pulmonary circuit Heart to lungs and return Left half of heart Systemic circuit Heart to body tissues and return Functions of Blood Transports oxygen and nutrients to cells Carries carbon dioxide and wastes away from cells Helps stabilize internal ph Carries infection-fighting cells Helps equalize temperature Components of Blood Plasma Water Proteins Dissolved materials Cells Red blood cells White blood cells Platelets A Carranza Page 12 7/25/2015

13 Blood Cell Development Stem cells in bone marrow produce blood cells and platelets Body continually replaces blood cells Erythrocytes (Red Cells) Most numerous cells in blood Transport oxygen and carbon dioxide Colored red by oxygen-binding pigment (hemoglobin) Have no nucleus when mature Leukocytes (White Cells) Function in housekeeping and defense Cell types Basophils Dendritic cells Eosinophils B cells Neutrophils T cells Macrophages Platelets Membrane-bound cell fragments Derived from megakaryocytes, which arise from stem cells Release substances that initiate blood clotting Clotting Mechanism Prothrombin is converted to thrombin Fibrinogen is converted to fibrin Fibrin forms net that entangles cells and platelets Human Heart Is a Double Pump Partition separates heart into left and right sides Each pumps blood through a different circuit Pulmonary Circuit Heart to lungs Oxygenates blood Systemic Circuit Starts at aorta Carries oxygenated blood to body tissues Four Chambers Each side has two chambers Upper atrium Lower ventricle Valves between atria and ventricles Cardiac Cycle Diastole-(early) both chambers relax, atria fill Diastole (mid-late) atria contract, ventricles fill Systole ventricles contract Conduction and Contraction SA node in right atrium is pacemaker Electrical signals cause contraction of atria Signal flows to AV node and down septum to ventricles A Carranza Page 13 7/25/2015

14 Blood Vessels Arteries: carry blood away from heart Arterioles: diameter is adjusted to regulate blood flow Capillaries: diffusion occurs across thin walls Blood Pressure Highest in arteries, lowest in veins Usually measured in the brachial artery Systolic pressure is peak pressure Ventricular contraction Diastolic pressure is the lowest pressure Ventricular relaxation Resistance Adjusted at arterioles Vasodilation Increases vessel diameter Lowers blood pressure Vasoconstriction Decreases vessel diameter Increases blood pressure Capillary Beds Diffusion zone; site of exchange between blood and interstitial fluid Capillary wall is one cell thick Flow is slow; allows gases to diffuse across membranes of blood cells and across endothelium Capillary Exchange Delivers to the interstitial fluid Sugar Amino acids Fatty acids Glycerol White blood cells Gases Bulk Flow in Capillary Bed Normally, ultrafiltration only slightly exceeds reabsorption Fluid enters interstitial fluid and returned to blood via the lymphatic system High blood pressure causes excessive ultrafiltration and results in edema The Venous System Blood flows from capillaries to venules to veins Veins are large-diameter vessels with some smooth muscle in wall Vein Function Valves in veins prevent blood from flowing backward A Carranza Page 14 7/25/2015

15 3.3) Respiration Respiration Physiological process by which oxygen moves into an animal s internal environment and carbon dioxide moves out Aerobic respiration Cellular process, produces ATP Oxygen is used Carbon dioxide is produced Respiratory System Works with the circulatory system to deliver oxygen and remove carbon dioxide Also helps regulate acid-base balance Pressure Gradients Concentration gradients for gases Gases diffuse down their pressure gradients Gases enter and leave the body by diffusing down pressure gradients across respiratory membranes Factors In Gas Exchange Surface-to-volume ratio Small, flat animals Ventilation Adaptations enhance exchange rate Respiratory pigments Hemoglobin and myoglobin Surface-to-Volume Ratio As animal size increases, surface-to-volume ratio decreases Small, flat animals can use the body surface as their respiratory surface Larger animals have special structures to increase respiratory surface, such as gills or lungs Vertebrate Lungs Originated in some fishes as outpouching from gut wall (swim bladder) Allow gas exchange in air and in oxygen-poor aquatic habitats 3.4) Human Respiratory System Breathing Moves air into and out of lungs Occurs in a cyclic pattern called the respiratory cycle One respiratory cycle consists of inhalation and exhalation Inhalation Diaphragm flattens External intercostal muscles contract Volume of thoracic cavity increases Lungs expand Air flows down pressure gradient into lungs Normal (Passive) Exhalation Muscles of inhalation relax Thoracic cavity recoils A Carranza Page 15 7/25/2015

16 Lung volume decreases Air flows down pressure gradient and out of lungs Active Exhalation Abdominal and internal intercostal muscles contract Contraction decreases thoracic cavity volume more than passive exhalation Greater volume of air flows out to equalize intrapulmonary pressure with atmospheric pressure Respiratory Membrane Area between an alveolus and a pulmonary capillary Oxygen and carbon dioxide diffuse across easily Oxygen Transport Most oxygen is bound to heme groups in hemoglobin in red blood cells Hemoglobin has higher affinity for oxygen when it is at high partial pressure (in pulmonary capillaries) Lower affinity for oxygen in tissues, where partial pressure is low Bicarbonate Formation Most carbon dioxide is transported as bicarbonate Some binds to hemoglobin Small amount dissolves in plasma Control of Breathing Nervous system controls rhythm and magnitude of breathing Breathing is adjusted as a result of changes in Carbon dioxide levels Oxygen levels Blood acidity A Carranza Page 16 7/25/2015