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Animal Kingdom Evolution 5 Defining characteristics of the animal kingdom: 1) Heterotrophic eukaryotes; ingestion 2) Lack cell walls; collagen 3) Nervous & muscular tissue 4) Sexual; diploid; cleavage; blastula; gastrulation; larvae; metamorphosis 5) Regulatory genes: Hox genes Animal phylogeny • • *Monophyletic; colonial flagellated protist ancestor First split • 1- Parazoa vs. Eumetazoa dichotomy: • *(Parazoa)~ no true tissues example sponges • • *(Eumetazoa)~ true tissues all other animals Parazoa *Parazoa: No true tissues • Invertebrates • No true tissues, unspecialized cells: *Sponges Closest lineage to protists • Phylum Porifera Phylum: Porifera (“pore bearer”) • • • • • *Sessile (attached to bottom) Spongocoel (central cavity) *Osculum (large opening) Choanocytes (flagellated collar cells) *Hermaphroditic (produce both sperm and eggs) • Eumetazoa: True Tissues: Everything but sponges • 2nd split – Body Symmetry • Radiata vs.Bilateria dichotomy: 1) *radial body symmetry *Cnidaria (hydra; ‘jellyfish’; sea anemones) & *Ctenophora (comb jellies) 2) *bilateral body symmetry (also: **cephalization) • all other animals Eumetazoa The Radiata, Diploblastic • Radial symmetry • Phy: Cnidaria (hydra, jellies, sea anemones, corals) • *No mesoderm; gastrovascular cavity (GVC)(sac with a central digestive cavity) • Hydrostatic skeleton (fluid held under pressure) • Polyps and medusa • Cnidocytes (cells used for defense and prey capture) • Nematocysts (stinging capsule) • Phy: Ctenophora (comb jellies) 3. Gasturlation: diploblastic vs. triploblastic • 3- Gastrulation: germ layer development; ectoderm (outer), mesoderm (middle), endoderm (inner) • diploblastic-2 layers; no mesoderm; – Radiata – Phy: Cnidaria (hydra, jellies, sea anemones, corals) • triploblastic-all 3 layers – *bilateria symmetry – All others 4- Acoelomate, Pseudocoelomate, and Coelomate • All are triploblastic animals • *acoelomates solid body, no body cavity – (Platyhelminthes-flatworms) – mesoderm but, GVC with only one opening – *Some cephalization • *pseudocoelomates body cavity, but not lined with mesoderm called – (Rotifers); *1st with a complete digestive track – Parthenogenesis: type of reproduction in which females produce offspring from unfertilized eggs • Coelomate: true coelom (body cavity) lined with mesoderm called – Phy: Nematoda (roundworms) – Complete digestive track; no circulatory system Animal phylogeny 5 • *Protostomes • Phylogenetics debated…. 1)Phy: Nemertea (proboscis and ribbon worms) • *Complete digestion and closed circulatory system (blood) 2) Phy: the lophophorates (sea mats, tube worms, lamp shells) The Coelomates: Protostomes, II 3) Phy: Mollusca (snails, slugs, squid, octopus, clams, oysters, chiton) • Soft body protected by a hard shell of calcium carbonate • Foot (movement), visceral mass (internal organs); mantle (secretes shell); radula (rasplike scraping organ) • Ciliated trochophore larvae (related to Annelida?) The Coelomates: Protostomes, III 4) Phy: Annelida (earthworms, leeches, marine worms) • True body segmentation (specialization of body regions) • Closed circulatory system • Metanephridia: excretory tubes • “Brainlike” cerebral ganglia • *Hermaphrodites, but cross- fertilize QuickTime™ and a Cinepak decompressor are needed to see this picture. The Coelomates: Protostomes, IV 5) Phy: Arthropoda trilobites (extinct); crustaceans (crabs, lobsters, shrimps); spiders, scorpions, ticks (arachnids); insects (entomology) • *2 out of every 3 organisms (most successful of all phyla) • *Segmentation, • *hard exoskeleton (cuticle)~ molting, • *jointed appendages; open circulatory system (hemolymph); • *extensive cephalization Insect characteristics • • • • • • Outnumber all other forms of life combined Malpighian tubules: outpocketings of the digestive tract (excretion) Tracheal system: branched tubes that infiltrate the body (gas exchange) *Metamorphosis…... *•incomplete: young resemble adults, then molt into adulthood (grasshoppers) *•complete: larval stages (looks different than adult); larva to adult through pupal stage QuickTime™ and a Cinepak decompressor are needed to see this picture. The Coelomates: *Deuterostomes, I • • • • 1) Phy: Echinodermata (sea stars, sea urchins, sand dollars, sea lilies, sea cucumbers, sea daisies) Spiny skin; sessile or slow moving Often pentaradial Water vascular system by hydraulic canals (tube feet) QuickTime™ and a Cinepak decompressor are needed to see this picture. Deuterostomes • Next branch • Chordates • *Notochord: longitudinal, flexible rod located between the digestive and the nerve cord • *Dorsal, hollow nerve cord; eventually develops into the brain and spinal cord • *Pharyngeal slits; become modified for gas exchange, jaw support, and/or hearing • *Muscular, postanal tail Invertebrate chordates • • • • Both suspension feeders….. Subphy: Urochordata (tunicates; sea squirt); mostly sessile & marine Subphy: Cephalochordata (lancelets); marine, sand dwellers *Importance: vertebrates closest relatives; in the fossil record, appear 50 million years before first vertebrate • *Paedogenesis: development of sexual maturity in a larva (link with vertebrates?) Subphylum: Vertebrata • Retain chordate characteristics with specializations…. • *Neural crest: group of embryonic cells near dorsal margins of closing neural tube • *Pronounced cephalization: concentration of sensory and neural equipment in the head • *Cranium and vertebral column • *Closed circulatory system with a ventral chambered heart Vertebrate diversity • Phy: Chordata • Subphy: Vertebrata – Superclass: Agnatha jawless vertebrates (hagfish, lampreys) – *Most primitive, living vertebrates Vocabulary tetrapods (‘4-footed’) amniotes (shelled egg) Superclass Gnathostomata, I • Placoderms (extinct): first with hinged jaws and paired appendages • Class: Chondrichthyes~ *Sharks, skates, rays • *Cartilaginous fishes; well developed jaws and paired fins; continual water flow over gills (gas exchange); lateral line system (water pressure changes) • *Life cycles: • *Oviparous- eggs hatch outside mother’s body • *Ovoviviparous- retain fertilized eggs; nourished by egg yolk; young born live • *Viviparous- young develop within uterus; nourished by placenta Superclass Gnathostomata, III • • • • Class: Amphibia *1st tetrapods on land Frogs, toads, salamanders, caecilians Metamorphosis; lack shelled egg; moist skin for gas exchange Superclass Gnathostomata, IV • Class: Reptilia • Lizards, snakes, turtles, and crocodilians • *Amniote (shelled) egg with extraembryonic membranes (gas exchange, waste storage, nutrient transfer); • absence of feathers, hair, and mammary glands; *ectothermic; scales with protein keratin (waterproof); lungs; ectothermic (dinosaurs endothermic?) Superclass Gnathostomata, V • Class: Aves • Birds • *Flight adaptations: wings (honeycombed bone); feathers (keratin); toothless; one ovary • *Evolved from reptiles (amniote egg and leg scales); endothermic *(4-chambered heart) •Archaeopteryx (stemmed from an ancestor that gave rise to birds) Superclass Gnathostomata, VI • Class: Mammalia • *Mammary glands; hair (keratin); endothermic; 4-chambered heart; large brains; teeth differentiation • *Evolved from reptilian stock before birds • *Monotremes (egg-laying): platypus; echidna • *Marsupials (pouch): opossums, kangaroos, koalas • *Eutherian (placenta): all other mammals Order: Primates (evolution) • *Characteristics: hands & feet for grasping; large brains, short jaws, flat face; parental care and complex social behaviors • Suborder: Prosimii •lemurs, tarsiers • Suborder: Anthropoidea •monkeys, apes, humans (opposable thumb) • *45-50 million years ago • *Paleoanthropology: study of human origins • *Hominoid: great apes & humans • Hominid (narrower classification): √ australopithecines (all extinct) *√ genus Homo (only 1 exant, sapiens) Human evolution • • • • Misconceptions: 1- Chimp ancestor (2 divergent branches) 2- Step-wise series (coexistence of human species) 3- Trait unison(all traits at once) vs. mosaic evolution(over time) (*bipedalism, upright, enlarged brain) The first humans • Ape-human split (5-7 mya) • Australopithecus; “Lucy” (4.0 mya) • Homo habilis; “Handy Man” (2.5 mya) • Homo erectus; first to migrate (1.8 mya) • Neanderthals (200,000 ya) • Homo sapiens (100,000 ya?) • Multiregional model (parallel evolution) • “Out of Africa” (replacement evolution) Tissues: groups of cells with a common structure and function (4 types) • Anatomy: structure • Physiology: function • Type 1- Epithelial: outside of body and lines organs and cavities; held together by tight junctions • basement membrane: dense mat of extracellular matrix • Simple: single layer of cells • Stratified: multiple tiers of cells • Cuboidal (like dice) • Columnar (like bricks on end) • Squamous (like floor tiles) • Glandular (can secrete) mucous membrane Connective Tissue (6 kinds) • Type 2- Connective Tissue: bind and support other tissues; scattered cells through matrix 3 kinds of fibers: – A-Collagenous fibers (collagen protein) non elastic B-Elastic fibers (elastin protein) C-Reticular fibers (thin branched collagen fibers) • Loose connective tissue: binds epithelia to underlying tissue; holds organs (has all 3 fiber types) – Two types of cells dominate • 1-Fibroblasts- secretes the protein for extracellular fibers • 2-Macrophages- amoeboid WBC’s; phagocytosis • Adipose tissue (specialized form)- fat storage; insulation Connective Tissue, Type II • Fibrous connective tissue: parallel bundles of cells – 1-Tendons- muscles to bones – 2-Ligaments- bones to bones; joints (BOBOLI) • Cartilage: collagen in a rubbery matrix (chondroitin); flexible support • Bone: mineralized tissue by osteoblast cells • Blood: liquid plasma matrix; erythrocytes (RBC’s) carry O2; leukocytes (WBC’s) immunity Nervous Tissue, Type III • 3-Nervous: senses stimuli and transmits signals from 1 part of the animal to another • *Neuron: functional unit that transmits impulses • *Cell body (contains nucleus) • *Dendrites: transmit impulses from tips to rest of neuron • *Axons: transmit impulses toward another neuron or effector Muscle Tissue (3 kinds) • 4- Muscle: capable of contracting when stimulated by nerve impulses; myofibrils composed of proteins actin and myosin; 3 types: • A- Skeletal: voluntary movement (striated) • B- Cardiac: contractile wall of heart (branched striated) • C- Smooth: involuntary activities (no striations) Internal regulation • Interstitial fluid: internal fluid environment of vertebrates; exchanges nutrients and wastes • *Homeostasis: “steady state” or internal balance • *Negative feedback: change in a physiological variable that is being monitored triggers a response that counteracts the initial fluctuation; i.e., body temperature • *Positive feedback: physiological control mechanism in which a change in some variable triggers mechanisms that amplify the change; i.e., uterine contractions at childbirth Metabolism: sum of all energyrequiring biochemical reactions • *Catabolic processes of cellular respiration • Calorie; kilocalorie/C • *Endotherms: bodies warmed by metabolic heat • *Ectotherms: bodies warmed by environment • Basal Metabolic Rate (BMR): minimal rate powering basic functions of life (endotherms) • Standard Metabolic Rate (SMR): minimal rate powering basic functions of life (ectotherms) Chapter 48 ~ Nervous System http://outreach.mcb.harvard.edu/animations/synaptic.swf The Nervous System • • • • • • • Neurons Glial cells Axon Dendrite Synapse Neurotransmitters Action potential • Motor neurons • Interneurons • Sensory neurons • Myelin sheath • Schwann cells • Reflex arc Nervous systems • Effector cells~ muscle or gland cells • Nerves~ bundles of neurons wrapped in connective tissue • Central nervous system (CNS)~ brain and spinal cord • Peripheral nervous system (PNS)~ sensory and motor neurons Structural Unit of Nervous System • • • • • • • • Neuron~ structural and functional unit Cell body~ nucelus and organelles Dendrites~ impulses from tips to neuron Axons~ impulses toward tips Myelin sheath~ supporting, insulating layer Schwann cells~ PNS support cells Synaptic terminals~ neurotransmitter releaser Synapse~ neuron junction Simple Nerve Circuit http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0016-swf_reflex_arc.swf • • • • • • Sensory neuron: convey information to spinal cord Interneurons: information integration Motor neurons: convey signals to effector cell (muscle or gland) Reflex: simple response; sensory to motor neurons Ganglion (ganglia): cluster of nerve cell bodies in the PNS Supporting cells/glia: nonconductiong cell that provides support, insulation, and protection Neural signaling http://bcs.whfreeman.com/thelifewire/content/chp44/4403s.swf http://outreach.mcb.harvard.edu/animations/actionpotential.swf • Membrane potential (voltage differences across the plasma membrane) • *Intracellular/extracellular ionic concentration difference • K+ diffuses out (Na+ in); large anions cannot follow….selective permeability of the plasma membrane • Net negative charge of about -70mV http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf Neural signaling http://www.mind.ilstu.edu/curriculum/neurons_intro/flash_electrical.php?modGUI=232&compGUI=1827&itemGUI=3158 • • • • • • Excitable cells~ cells that can change membrane potentials (neurons, muscle) Resting potential~ the unexcited state of excitable cells Gated ion channels (open/close response to stimuli): photoreceptors; vibrations in air (sound receptors); chemical (neurotransmitters) & voltage (membrane potential changes) Graded Potentials (depend on strength of stimulus): 1- Hyperpolarization (outflow of K+); increase in electrical gradient; cell becomes more negative 2- Depolarization (inflow of Na+); reduction in electrical gradient; cell becomes less negative Neural signaling • • • • • • • • • Threshold potential: if stimulus reaches a certain voltage (-50 to -55 mV)…. The action potential is triggered…. Voltage-gated ion channels (Na+; K+) 1-Resting state •both channels closed 2-Threshold •a stimulus opens some Na+ channels 3-Depolarization •action potential generated •Na+ channels open; cell becomes positive (K+ channels closed) 4-Repolarization •Na+ channels close, K+ channels open; K+ leaves •cell becomes negative 5-Undershoot •both gates close, but K+ channel is slow; resting state restored Refractory period~ insensitive to depolarization due to closing of Na+ gates Neural signaling • • • • • • “Travel” of the action potential is self-propagating Regeneration of “new” action potentials only after refractory period Forward direction only Action potential speed: 1-Axon diameter (larger = faster; 100m/sec) 2-Nodes of Ranvier (concentration of ion channels); saltatory conduction; 150m/sec Synaptic communication • • • • • • Presynaptic cell: transmitting cell Postsynaptic cell: receiving cell Synaptic cleft: separation gap Synaptic vesicles: neurotransmitter releasers Ca+ influx: caused by action potential; vesicles fuse with presynaptic membrane and release…. Neurotransmitter http://www.bayareapainmedical.com/neurtrns.html Neurotransmitters http://www.blackwellpublishing.com/matthews/neurotrans.html • Acetylcholine (most common) •skeletal muscle • Biogenic amines (derived from amino acids) •norepinephrine •dopamine •serotonin • Amino acids • Neuropeptides (short chains of amino acids) •endorphin Nervous System (know this slide) • Central Nervous System – Crainial Nerves – Spinal Nerves • Peripheral Nervous System – Sensory (afferent) Division • Sensing external environment • Sensing internal environment – Motor (Efferent) Division • Autonomic Nervous System – Sympathetic Nervous System » increase energy consumption – Parasympathetic Nervous System » conservation of energy • Somatic Nervous System – voluntary, conscious control, muscles Vertebrate PNS Vertebrate Skeletal Muscle • *Contract/relax: antagonistic pairs w/skeleton • *Muscles: bundle of…. – Muscle fibers: single cell w/ many nuclei consisting of…. • *Myofibrils: longitudinal bundles composed of…. – *Myofilaments: » Thin~ 2 strands of actin protein and one strand of a regulatory protein » Thick~ staggerd arrays of myosin protein http://entochem.tamu.edu/MuscleStrucContractswf/index.html Vertebrate Skeletal Muscle • Sarcomere: repeating unit of muscle tissue, composed of…. • • • • Z lines~sarcomere border I band~only actin protein A band~actin & myosin protein overlap H zone~central sarcomere; only myosin http://www.sumanasinc.com/webcontent/animations/content/muscle.html • • • • **Sliding-filament model Theory of muscle contraction Sarcomere length reduced Z line length becomes shorter Actin and myosin slide past each other (overlap increases) http://www.blackwellpublishing.com/matthews/myosin.html **Actin-myosin interaction • 1- Myosin head hydrolyzes ATP to ADP and inorganic phosphate (Pi); termed the “high energy configuration” • 2- Myosin head binds to actin; termed a “cross bridge” • 3- Releasing ADP and (Pi), myosin relaxes sliding actin; “low energy configuration” • 4- Binding of new ATP releases myosin head • Creatine phosphate~ supplier of phosphate to ADP **Muscle contraction regulation • Relaxation: tropomyosin blocks myosin binding sites on actin • Contraction: calcium binds to toponin complex; tropomyosin changes shape, exposing myosin binding sites http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter10/animation__action_potentials_and_muscle_contraction.html **Muscle contraction regulation • Calcium (Ca+)~ concentration regulated by the…. • Sarcoplasmic reticulum~ a specialized endoplasmic reticulum • Stimulated by action potential in a motor neuron • T (transverse) tubules~ travel channels in plasma membrane for action potential • Ca+ then binds to troponin The Vertebrate Brain (know this slide) • Forebrain – •*cerebrum~ memory, learning, emotion – •*cerebral cortex~ sensory and motor nerve cell bodies – •*corpus callosum~ connects left (analytical) and right (creative) hemispheres – •*thalamus (main input/output from cerebrum); *hypothalamus (hormone production) – Midbrain – •inferior (auditory) and superior (visual) colliculi • Hindbrain •*cerebellum~coordination of movement •*medulla oblongata/ pons~ autonomic, homeostatic functions Emotion Cerebrum Know that there are different lobes for different purposes. You do not need to memorize this information. • Cerebral hemispheres • Cerebral cortex— ”gray matter” • Convolutions • Cerebral lobes • Frontal lobe— conscious thought and muscle control. • Parietal Lobes— receive information from skin receptors. • Occipital Lobe— receives visual input. • Temporal Lobe—has areas for hearing and smelling. Pituitary Gland Corpus Callosum