Biology 1112

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Lecture 14

• Biology 1112
• Feb. 26, 2002
• Test Review

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Counter-Current Exchange Defined

• Exchange transfer of energy or materials
• Counter-current two fluids moving in opposite
  directions
• Water one way
• Blood, the other way

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Why Counter Current?

• Very, very effective
• Remember diffusion from high to low
  concentration
• Counter-current ensures gradient exists
  continually
• Exchange of gases can theoretically approach 100

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Question

• If fishes didnt have counter current exchange,
  what would be maximum possible transfer
  efficiency?

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Bird Lungs

• Have counter-current exchange
• Can extract oxygen from air thin enough to kill a
  human!
• One-way flow of air through lung
• No dead air space left after exhaling

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Smoking is Bad

• Kills 350,000 American annually
• Overwhelms, then destroys lung defense systems
• Emphysema hardening of alveoli
• Eventually rupture, reducing lung capacity
• Causes heart to work harder all the time

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Fetal Gas Exchange

• Gas exchange occurs in placenta
• Mom babys circulatory systems come close to
  each other
• Fetal hemoglobin attracts oxygen better than
  moms can hold onto it

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Open Circulation

• Blood vessels end in openings
• Organs bathed in blood
• Diffusion of wastes/materials happens by direct
  contact with blood
• Example insects, lobsters have open circulation

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Closed Circulation in Vertebrate Animals

• Two basic types
• Single circuit system
• Dual circuit system

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Single Circuit System

• Example fish
• Fish heart has 2 chambers
• Atrium (passively receives blood)
• Ventricle (actively pumps blood)
• Circuit repeated is heart to gills to body

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Disadvantage to Single Circuit

• Body gets only low pressure blood
• Why? Must pass through capillary bed in gills
• Small capillaries restrict pressure!

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Dual Circuit Circulation

• Example mammals
• Heart has 4 chambers
• 2 atria
• 2 ventricles
• Circuits are
• Pulmonary circuit heart to lungs
• Systemic heart to body

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Advantage to Dual Circuit

• Body cells can receive blood under high pressure
• Greater performance in burst activities

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Sample Questions

• Which veins carry oxygenated blood?

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Sample Questions

• Which veins carry oxygenated blood?

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Sample Questions

• Which arteries carry deoxygenated blood?

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Sample Questions

• Which arteries carry deoxygenated blood?

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Sample Questions

• Which side of the heart carries deoxygenated
  blood?

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Sample Questions

• Which side of the heart carries deoxygenated
  blood?
• Dont be confused by this picture!

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Sample Questions

• In passing from the atrium to ventricle, which
  valve must the blood go through?

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Sample Questions

• In passing from the atrium to ventricle, which
  valve must the blood go through?

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Sample Questions

• What is this structure?

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Sample Questions

• The aorta

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More on Murmurs

• Occur when heart valves wont close properly
• Apparently, fairly common (especially in
  children), most are harmless
• Websites
• To read more about murmurs, go to Plainsense
  website
• To hear a murmur, go to www.openheartsurgery.com
  website

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Heart Attack

• Occurs due to blockage of coronary arteries
• Death of cardiac muscle tissue
• Scar tissue forms during recovery
• This is not muscle
• Does not contract
• Loss of function

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Pressure Throughout System
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Platelets

• These are tiny membrane bound bits of cytoplasm
• Float through circulatory system
• Stick together when broken vessel detected
• Sufficient for small clots

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7th Inning Stretch
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Question for Discussion

• What is an animal?
• How do we define it?

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Characteristics of All Animals

• Eukaryotic
• Multicellular
• Heterotrophic
• No cell walls
• Blastula

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Animal Origins

• Probably evolved from single-celled protists
• May have arisen when dividing cells didnt
  separate

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The Blastula

• This is a hollow ball of cells
• Develops from animal zygote (fertilized egg)
• Occurs in all animals, and no other groups
• Later, one side folds in to form gastrula

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Hypothetical Proto-animals

• Probably formed a hollow ball of cells (similar
  to blastula)
• Later, the ball folded in, forming a double layer
• Eventually, cells began to specialize, forming
  different tissues

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Bilateral Symmetry

• Only 1 cut can divide animal equally
• Example
• Crawfish must be cut down middle, front to back
• Interesting body plan
• Allows head tail to differ
• Dorsal, ventral surfaces can differ
• Left and right are similar

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Psuedocoelom and Coelom

• These are body cavities
• A body cavity allows for
• Flexibility
• Organ protection
• Improved movement (muscles can work against
  hydroskeleton)
• Fluid can move nutrients, O2, metabollic wastes

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Comparison
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Roundworm Life History

• Most are free-living
• A few are parasitic
• Heartworms in dogs
• Trichinella spiralis in humans
• Causes trichinosis!
• Worms find way into muscles
• Very painful, can be fatal
• From undercooked pork!

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Arthropods

• Phylum Arthropoda
• All have
• Jointed appendages
• An exoskeleton
• Made of chitin (polysaccharide w/proteins)

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Ex Horseshoe Crabs are Arthropods

• Very, very ancient!
• Have some medical applications

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Ex Arachnids are Arthropods

• Include spiders, scorpions, ticks, dust mites
• Dust mites do not carry disease, but many people
  allergic to them!
• Without spiders, fly population would be largely
  unchecked

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Ex Crustaceans

• Lobsters, crayfish, crabs, shrimps, barnacles
• Interesting notes on barnacles
• They use jointed appendages to gather food
  particles
• Like other crustaceans, they can be eaten!

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Insects

• Easily the most diverse of the arthropods!
• 1 million species currently knownplenty left to
  be discovered
• There are more insect species than ALL other
  species combined!

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Shared Insect Characteristics

• Most have 3 body parts
• Head
• Thorax
• Abdomen
• Often have antennae
• Many have specialized mouth parts
• Ex mosquitos have mouth for piercing skin,
  sucking blood

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Ex Orthoptera and Hemiptera are Insects

• Order Orthoptera
• The grasshoppers and friends
• Hemiptera
• The true bugs

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Ex Odonata are Insects

• The dragonflies and damselflies
• 2 similar pairs of wings
• Larvae can be quite large
• Can eat small fish tadpoles!

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Ex Coleoptera are Insects

• The Beetles! The most popular (by number of
  species) order in the animal kingdom!
• Live in wide range of habitats forests, ponds,
  streams, soil, dung, carrion, plants
• Wide range of sizes 1mm to 12 cm
• 2 pairs of wings (dissimilar)
• Forewings form hard covering
• Hindwings used for flight

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Ex Lepidotperans are Insects

• The butterflies and moths
• Long, tube-like mouth parts for nectar-eating

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Ex Hymenoptera are Insects

• Ants, bees, wasps
• 2 pairs of wings
• Thorax and abdomen separated by very thin waist

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Ex Dipterans are Insects

• All have
• Single pair of wings
• A pair of halteres
• Like little gyroscopes
• Used for balance in flight

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Questions

• Is this an animal?
• Yes
• Is this an arthropod?
• Yes
• If so, is it an insect?
• No

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Questions

• Are arthropods all insects?
• No
• Are all insects arthropods?
• Yes

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Phylum Echinodermata

• The sea stars, sea urchins
• Radial symmetry
• Lack segmentation

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Phylum Chordata

• The chordates
• All share in common
• Dorsal hollow nerve cord
• Notochord
• The flexible rod between the digestive tract and
  nerve cord
• Post anal tail
• Gill structures

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Major Chordate Groups

• Tunicates
• Lancelets
• Vertebrates

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Bird Evolution

• Believed to have evolved from small, carnivorous
  dinosaurs
• Dino hand bones similar to bird wing bones
• When given certain hormones, chicken embryos will
  develop teeth!

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Archaeopteryx

• A very early bird!
• Reptilian characteristics
• Long tail
• Wing claws
• Teeth
• Scales on feet

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Class Mammalia

• All mammals
• Have fur (yes, even whales)
• Feed their offspring milk
• Are endothermic

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Three Basic Kinds of Mammals

• Monotremes
• They lay eggs!
• Include platypus
• Marsupials
• Carry young in pouch
• Ex kangaroos, opposums
• Eutherians (placentals)
• Longer pregnancy
• More developed young

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Another Question

• Are birds animals?
• Are fish animals?

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Worlds Biggest Plant

• The General Sherman Tree
• Species is Sequoiadendron gigantea
• Central California
• 2500 years old!!!
• National Park Service site
• US Geological Survey site

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Angiosperms

• These are flowering plants
• Two basic types
• Monocots
• Dicots

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Monocots

• Have one seed leaf
• Root network very fibrous
• Leaves have parallel veins
• Examples orchids, bamboos, palms, grasses
  (including rice, other grains)

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Dicots

• Have two seed leaves
• One main taproot plus root hairs
• Leaves have multiply branched veins
• Ex trees, shrubs, carrots

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Question

• Where would we classify pine trees?

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Answer

• Trick question they arent angiosperms
• Theyre gymnosperms (no flowers!)

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Xylem

• Contains water-conducting cells
• Carries water and nutrients toward the leaves

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Phloem

• Contains food conducting cells
• Transports sugars to tissues, roots