Animal Kingdom Evolution5 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 phylogeny5• *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 (rasp-like 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

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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

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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)

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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 energy-requiring 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

The Nervous System

• Neurons• Glial cells • Axon• Dendrite• Synapse• Neurotransmitters• Action potential

• Motor neurons• Interneurons• Sensory neurons

• Myelin sheath• Schwann cells• Reflex arc

http://outreach.mcb.harvard.edu/animations/synaptic.swf

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

• 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

http://msjensen.cehd.umn.edu/1135/Links/Animations/Flash/0016-swf_reflex_arc.swf

Neural signaling

• 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/chp44/4403s.swf

http://outreach.mcb.harvard.edu/animations/actionpotential.swf

Neural signaling• 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

http://www.mind.ilstu.edu/curriculum/neurons_intro/flash_electrical.php?modGUI=232&compGUI=1827&itemGUI=3158

http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf

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

• Acetylcholine (most common) •skeletal muscle

• Biogenic amines (derived from amino acids)

•norepinephrine •dopamine •serotonin

• Amino acids• Neuropeptides (short chains of amino acids)

•endorphin

http://www.blackwellpublishing.com/matthews/neurotrans.html

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 myosinhttp://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

• 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.

Know that there are different lobes for different purposes. You do not need to memorize this information.

Pitu

itary Glan

d

Corpus Callosum