Really rough midterm review; it's all my notes from the fall term (thus far) squashed together with some diagrams thrown in. The diagrams and pictures aren't formatted nicely, so I recommend downloading the document and resizing them. I'll post a neater midterm review later, but most of the info I deem excessive will be deleted.
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W1 Intro 6 characteristics of living organisms Highly organized and complicated structure Metabolism – all chemical rxns that happen in an organism Growth Ability to maintain fairly stable internal environment (homeostasis) Ability to respond to stimuli Reproduction Cell theory 1. The cell is the fundamental unit of structure and function in living organisms. 2. All cells arise from pre-existing cells by division. 3. Energy flow (metabolism and biochemistry) occurs within cells. 4. Cells contain hereditary information (DNA) which is passed from cell to cell during cell division. 5. All cells are basically the same in chemical composition in organisms of similar species. 6. All known living things are made up of one or more cells. 7. Some organisms are made up of only one cell and are known as unicellular organisms. 8. Others are multicellular, composed of a number of cells. 9. The activity of an organism depends on the total activity of independent cells. Cell Smallest unit of an organism Has characteristics from above Cell membrane Regulate movement in/out cell Cytoplasm All the living part of cell inside cell mem & excluding nucleus DNA Genetic material
Transcript
W1
Intro
6 characteristics of living organismsHighly organized and complicated structureMetabolism – all chemical rxns that happen in an organismGrowthAbility to maintain fairly stable internal environment (homeostasis)Ability to respond to stimuliReproduction
Cell theory
1. The cell is the fundamental unit of structure and function in living organisms.2. All cells arise from pre-existing cells by division.3. Energy flow (metabolism and biochemistry) occurs within cells.4. Cells contain hereditary information (DNA) which is passed from cell to cell during cell
division.5. All cells are basically the same in chemical composition in organisms of similar species.6. All known living things are made up of one or more cells.7. Some organisms are made up of only one cell and are known as unicellular organisms.8. Others are multicellular, composed of a number of cells.9. The activity of an organism depends on the total activity of independent cells.
CellSmallest unit of an organismHas characteristics from above
Cell membraneRegulate movement in/out cell
CytoplasmAll the living part of cell inside cell mem & excluding nucleus
DNAGenetic material
RibosomesProtein synthesis
OrganelleSpecialized structure in cytoplasm of cell which carries out specific function
ProkaryoticBacteriaDoesn’t contain mem-bound organelles or nucleusSmaller than eukaryotes
Eukaryotic
All elseInternal mem systemsContains mem-bound organelles & nucleus
→Organelles (eukaryotic)Nucleus
Enclosed by nuclear envelope [double mem]; often containing visible nucleoli > produce ribosomes; contains genetic material
Endoplasmic reticulum-forms an interconnected network of tubules, vesicles, and cisternae within cells-Rough endoplasmic reticulums synthesize proteins, while smooth endoplasmic reticulums synthesize lipids and steroids, metabolize carbohydrates and steroids, and regulate calcium concentration, drug detoxification, and attachment of receptors on cell membrane proteins
Golgi apparatusProcess and package macromolecules, such as proteins and lipids, after their synthesis and before they make their way to their destination
LysosomesDigestive enzymes
mitochondriaATP, cellular respiration
ribosomesprotein synthesis
cytoskeletoninternal system of protein fibres & tubules that extends throughout cytoplasm of eukaryotic cell; composed of actin microfilaments, intermediate filaments & microtubules; gives shape to cell & provides support for cell extensions such as villi & axons of nerve cells
structural component
plant cells animal cells
cell wallsupport, protect, water limit; composed of polysaccharides (cellulose) or chitin or of peptidoglycans
Both have mem. (a→plasma, p→cell), cytoplasm, vacuole/vesicles, nucleus, ER, golgi ap, mitochondria, nucleolus, ribosome
VirusesComposed largely of nucleic acid (DNA or RNA) & proteinReproduce in living cellsTakes over host’s metabolic machineryHost cell then produces viral proteins & nucleic acidsLack metabolic machinery to reproduce their genetic material independently of host
Consists of a molecule of DNA or RNA – surrounded by a protein coat (sometimes coat surrounded by outer envelope of carbohydrate protein &/or lipid)No ribosomes or any of the enzymes needed for energy production
W2
Intro to Natural Selection
EvolutionChange, over time, in heritable characteristics of organisms, resulting in alteration of structure & fn, & leading to diversity of living forms
AdaptationsFeatures of structure & function which suit an
organism to environment
Natural Selection-Preference of traits which aid species in survival – individuals with these traits more likely to survive & produce offspring (less preferable traits which do not aid in survival are not carried on as the individuals die off & produce less offspring).-Doesn’t create adaptations, but screens heritable variations in each generation, increasing occurrence of beneficial traits & eliminating less successful ones.
1. Individuals in a population aren’t identical; they vary (sometimes only slightly) in structure, function, & behaviour
2. Some variation heritable, determined by organism’s genetics (passed parent > offspring)
3. All living things have tendency to overproduce (more produced than environment can support).
4. Despite overproduction populations remain relatively stable ( many individuals fail to ∴survive & reproduce)
5. Different individuals leave different #s of descendants – depends on chance of survival to reproductive age, # offspring produced, & survival & reproduction of offspring. Individuals with characteristics that successfully adapt them to environment more likely ∴to pass these traits on to next generation.
Descent with Modification-Changes arising via natural selection could lead to alteration of a population & eventually emergence of new species-Common ancient ancestor – as descendents dispersed into new habitats, they accumulated diverse adaptations fitting them to varying ways of life
Taxonomy & Systematics
TaxonomyThe analysis of an organism’s characteristics for the purpose of classificationBranch of bio concerned w/ naming/classifying organisms
Biological SpeciesPopulation of individuals that can interbreed
Practical purposes of biological classificationTo organize organisms into categories to allow examination of evolution and to provide a universal name to everything (vs. a common name) in order to make it easier to discuss and find records of.
Influence of Darwin’s work on biological classificationDescent from common ancestor altered structure of classification system; evolutionary links between tiersNatural selection
Phylogenyevolutionary history of species or group of related species & line of descent of a species or higher taxonomic group
SystematicsBranch of bio concerned w/ naming & classifying organisms in an attempt to reconstruct evolutionary historyTaxonomy which takes evolution into account
Phylogenetic treeDiagram that represents evolutionary relationships b/w diff taxa or b/w diff proteins
Artificial vs natural system of classificationIn a natural system of classification the members of a given taxon share a more recent
common ancestor with each other than they do with the members of any other taxonArtificial-classification that groups organisms or objects together on the basis of a few convenient characteristics rather than on the basis of evolutionary relationships-1 general fn: to serve as a practical aid in organizing & communicating info about organismsNatural-a taxonomic classification that groups organisms or objects together on the basis of the sum total of all their characteristics, & tries to indicate evolutionary relationships-has same fn as a but in addition expresses a theory of relationships among organisms
Explain why current system of biological classification doesn’t completely achieve the goal of being a natural system
1. ignorance – don’t know enough about organisms & their evolution2. tradition or inertiaNot everything is fully linked in respect to evolution and protists don’t fit very well (have attributes of other groups)
Dichotomous key (& practice)Device consistinbg of a series of paired contrasting choides that is used to identify unknown items (main use to identify organismsDichotomy – 1. Branching that results from division of growing point into two equal parts; 2. Repeated forking
Describe the 2-kingdom system of classification used by most biologists until 1960’s (text pg 551)
Taxon (plural taxa)Named level of classification in the taxonomic hierarchy
Eg taxon: ‘genus panthera’ level of classification: genusThe members of any particular taxonomic group
Binomial nomenclatureThe system of double Latin names given to plants & animals, consisting of a generic name followed by a specific name eg. Felis (genus) tigris (species)
Unicellular: organism consists of single free-living cell
Colonial: org consists of group of cells, tightly bound to each other, commonly forming sheets, balls, or threads; the cells aren’t specialized – they’re very similar to each other in form & fn; each cell potentially free living should colony be disturbed
Multicellular: org consists of numerous specialized cells eith distinct fns, acting together in coordinated fashion; individual cells not free living in nature & can only survive in context of rest of org
Inorganic cmpds: small, simple molecules found nonliving (abiotic)
Organic cmpds: large, complex; contain C backbone; produced by living cells; requires E to make them; E released when broken down into io cmpds (store E); living cells made up of them (proteins, starch, fat, etc)
Autotrophic: capable of producing complex organic materials, such as sugar, from simple chemicals such as water & CO2, most commonly via photosynthesis
Heterotrophic: unable to synth complex organic materials from simple inorganic chemicals; these organic materials must be obtained in the diet
Absorption: digestive enzymes released outside body & digested nutrients taken in via absorptionIngestion: other orgs consumed whole or in pieces then digested inside gut
Groups Cell Type (p or e) # Cells (uni…) Mode of NutritionArchaea
prokaryotic unicellular or colonialsome autotrophic,
some heterotrophicBacteria
Protists
eukaryotic
unicellular, or colonial, some
multicellular
heterotrophic or autotrophic
Animals
multicellular
heterotrophic by ingestion
Fungiheterotrophic by
absorptionPlants autotrophic
Archaea & Bacteria
Origin of prokaryotic cells – 3.5 billion years ago↓ developed ability to photosynthesize; initially unicellular, some colonies
Origin of eukaryotic cells – 2 billion years agoOrigin of multicellular organisms – 1.2 billion years ago
Specialized cells working co-ordinately w/1 single organism
CharacteristicDomain
Bacteria Archaea EukaryaNuclear Mem absent absent presentMem-bound Organelles
absent absent present
Peptidoglycan in Cell Wall
present absent absent
Mem Lipids unbranched branched unbranchedRibosomes 70s 70s 80s
1. Variety of nutrition, diff ways2. Asexual reproduction (quick)3. Respond quickly to external changes; rapid exchange of genetic material allows advantageous adaptations to spread quickly (eg resistance)4. endospores: special cells enclosed in hard wall; can survive harsh conditions (lack of nutrients/water, excessive heat/cold, poisons); open in favourable conditions5. existed long time → lot of time to adapt to diverse habitats
Structural characteristics used to distinguish among bacteriaCell shape
Cell wall compositionMotilityMode of nutrition
Mode of NutritionAble to Synth o.cmpds from io.materials
E source C source
Photoautotroph yes light CO2 (io)Chemoautotroph yes io cmpds CO2 (io)Photoheterotroph no light ocmds
Chemoheterotroph no io cmpds ocpmds
4 roles of bacteria in biosphere1. pathogens
Diseases in plants/animals; grow in host; release poison or endotoxin when bacteria dies or exotoxins as bacteria grow
2. decompositionBreak down waste/dead plants/animals → return elements such as C, O, N to envi in forms that can be used by other orgs
3. fixation of io elementsEg. N in atmosphere converted to ammonia nitrate needed by plants
ProtistsMany more closely related to plants, animals, or fungi than they are to each otherMostly water, freshwater lakes & streams, saltwater, & moist soil
Symbiosis: close association of 2 diff sp’s living in direct contact w/ each other
Mutualism: mutually beneficial relationship b/w 2 species whether or not the sp’s are in direct contact w/ each other
Eukaryotes acquiring internal mem systems1. Infolding of plasma mem. By this process nuclear envelope, ER, golgi ap, & certain other structures may have formed\2. Endosymbiosis. According to endosymbiotic theory, chloroplasts & mitochondria are remnants of ancient prokaryotic cells that took up residence in other, larger prokaryotic cells. Possibly were parasites or were captured.
a. some present-day orgs have endosymbiotic relationships in which participants haven’t lost their separate identities. These relationships may resemble earlier stages in the evolution of eukaryotic cellsb. chloroplasts & mitochondria are very similar to certain kinds of bacteria. They’re the same size, have mems w/ molecular components resembling those of prokaryotic plasma mems, they have own DNA in form of circular
molecule just as in prokaryotes, & they reproduce in the same way bacteria do (by a splitting process)
Ecologically they fall into 3 categories:1. Heterotrophs that feed by intracellular digestion2. Heterotrophs that feed by absorption3. Photoautotrophs
Green, brown, & red algae include some multicellular sp’s, mostly saltwaterColour due to variation in the photosynthetic pigmentsKelp (brown)
Holdfast: rootlike, anchors to rocksStipe: stemlikeBlades: leaflikeGas-filled float may be presentNo specialized cells or tissues for transport of water, minerals, & organic nutrients throughout the multicellular body (thus no true roots, stems, leaves)
Fungi3 ecological categories
1. Decomposers absorb nutrients from wastes or dead remains2. Mutualists absorb nutrients from living plant or animal organisms but benefit these organisms in some way3. Parasites or Pathogens absorb nutrients from living host, damaging or weakening it
Composed of tiny threads called hyphae (sing hypha) which pack tightly together to form a mycelium.
Have cell walls reinforced by chitin
Share more recent common ancestor (heterotrophic protest which lived in colonies) with animals than with plants
Lichens (symbiosis)One sp fungus, one sp photosynthetic green algae or a cyanobacteriumReferred to by the scientific name of its fungus
Human uses1. Antibiotics2. Baker’s yeast3. Alcoholic beverages4. Flavouring5. Food
W3
Vascular Plant Structure
Tissue: an aggregate of cells that are similar in structure & fnRoot vs. shoot system
Root system > root hairs> absorb water & minerals, store food, anchor plantShoot system in vasc plant > photosynthesis & reproduction (via flowers-angiosperms, cones-most gymnosperms, spores-ferns)
FIGURE 1
Primary cell wallAll plant cellsMaterials secreted by plasma
memThinStretches easily as cell growsProtectsHelps to maintain shapeCellulose: long chainlike
carbohydrate; major component in cell walls
Secondary cell wallSome plant cells
At maturityLocated b/w primary cell wall & plasma memUsually more cellulose than primaryContains lignin for strength & rigidity (next to cellulose most abundant large organic molecules in plants)
Middle lamellaThin layer of sticky substances that glue the cells togetherIn some plant tissues it is also lignified
ParenchymaLiving cells, unspecialized in structure & fn, w/ thin, stretchy primary wallsMost plant cells start out asSome mature into other cell typesSome remain parenchyma entire life & carry out fns like psynth & food storageSome parenchyma cells are Meristematic
Able to divide to produce new cellsElongation of shoots & roots under control of apical meristem (apic = tip)Concentrations of meristematic parenchyma at root ends & buds of shoots
Usually large central vacuole at maturity
CollenchymaAlive at maturityLack 2ndary wallsPrimary walls irregularly thickened – additional strength while still stretchy for growthOften arranged in supportive columns in young growing stems
SclerenchymaThick, lignified 2ndary wallsUsually dead at maturityMost common forms are fibers (ex. hemp, jute, flax)Support in plant parts no longer growing
Tracheids & vessel elementsWater-conducting cells of xylemDead & hollow at maturity2ndary wallsTracheids
Long, tapered cells similar to the fibers of sclerenchymaWater passes from one tracheid to next via pits that penetrate cell wallsLignified walls provide support to plant
Vessel elementsMore efficient than tracheidsLarger diameterLarger holes in walls b/w adjacent cellsThinner walls thus less support than tracheids
Sieve-tube membersConducting cells of the phloemTransport sugars & other organic materialsAlive at maturityOnly primary wallsSimilar to parenchyma but lack a nucleus & contain other certain organelles
Some plant tissues, ex. columns of collenchymas, only one cell type (collenchymas thus cell type and tissue type). Other plant tissues have several cell types; ex. angiosperms – xylem tissue has both tracheids & vessel elements & interspersed among the water-conducting cells other cell types like sclerenchyma fibers and parenchyma.
Nonwoody (herbaceous) eudicot
In middle of stem large region of parenchyma
In ring around parenchyma are vascular bundles, each having xylem on inside & phloem on outsideB/w xylem & phloem of each bundle & extending b/w adjacent bundles is narrow band of meristematic parenchyma called vascular cambium
In some eudicots cells of vascular cambium divide to produce additional xylem & phloem
Vascular bundles may also be capped by an aggregation of sclerenchyma
Cells on outside surface of stem, covered by waxy cuticle, from epidermis
Beneath epidermis are patches of collenchyma
FIGURE 5
Plan drawing. Generalized pattern of cell types & locations; in various eudicot species some types of cells such as collenchymas & sclerenchyma distributed in diff patterns or aren’t present at all
In monocot stem vasc bundles scattered; no vasc cambium. Thus monocots unable to enlarge their stems by 2ndary growth. Only few species (ex. bamboo & palms) become woody, & way in which they produce wood has little in common w/ eudicot way.
Xylem & phloem form continuous conducting systems throughout body of vasc plant. Arrangement diff b/w roots & stems. No vasc bundles in eudicot root, instead xylem & phloem located in central cylinder called stele. Xylem typically forms an X shaped (or + shaped) figure in very middle, & phloem lies b/w legs of the X or +. Separating xylem & phloem is vasc cambium. Change in arrangement of tissues occurs in short transition zone b/w roots & stems.
Support in Plants
Gen adaptations plants have evolved as result of competition for light
Shade-tolerance: ability to grow & reproduce in dm light
Ability to colonize disturbed habitats (*shade-intolerant)
Structures & mechanisms for support of plant body (xylem)
Parenchyma & other cell types w/ flexible cell walls provides mechanical support through turgor pressure (force exerted by the fluid contents of a cell against its
wall) by pushing adjacent cells tightly together. (Parenchyma contributes more support via TP than any other cell type b/c it makes up such a large part of the cell body)
Secondary growth: cells of cambium divide to produce 2ndary rings of xylem & phloem
Adaptations of plants for climbingTendrils: slender coiling structures- modified leaves or stems (ex grapes, garden peas)Twining stems: ex kiwis, scarlet runner beansAerial roots: above ground roots (ex English ivy)Barbs: spines/thorns (ex roses, blackberries)
Plant Kingdom
Distinguished from brown & red algae by presence of chlorophyll
Resources req by plants1. Light psynth2. CO2 psynth3. Oxygen cell resp4. Minerals contain various elements needed by plants5. Water basic medium in which chem. Processes occur & reactant in some processes
4 major events in evolution of plants1. evolved from aquatic green algae ~500 million years ago; were terrestrial2. evolution of vascular plants (plants that have tissues specialized for transport: xylem transports water & minerals & phloem transports sugars & other o materials)3. evolution of seed plants (gymnosperms & angiosperms)4. evolution of angiosperms (evolution of flowers & fruits; some attract animals as pollinating agents)
Nonvascular plants (mosses & liverworts)Lack xylem & phloemNot close relativesMost common in warm, moist habitatsMosses
FernsSeedless vascular plantsLarge leaves often divided into leafletsSpores (single-celled reproductive structures that are carried away by wind) produced on underside of leavesMost common in warm, moist habitats
Characteristic Gymnosperms AngiospermsDiversity ~800 sp’s more than 250k sp’s
Gen Morphology woody sp’sboth woody & non-woody
sp’s
Leavesusually needle-like or
scale-likeusually flattened (“broad-
leaved” plants)Seeds naked enclosed in fruit
Pollen Transport windwind in some sp’s,
animals in many others
Monocots vs dicots
Comparison of water & land as habitats for plants
Water LandWater
availabilityclose to ea cell
below land surface; evaporates quickly above
Minerals close to ea cell on or below land surfaceGases dissolved at low conc plentiful in air
Support provides buoyancy & support much less support of plants
Lightcuts out some wavelengths &
lowers intensitymore light available
Temp little fluctuation, slow changechanges more rapid, wider
extremesReproducti
onmotile gametes swim
water seldom available for swimming gametes
Dispersalwater carries offspring to new
locationwater seldom avail to carry offspring to new locations
Adaptations of land plants to terrestrial envi’s
Problem Adaptationobtaining water & mineral nutrients when they no longer
surround entire plantroots
transport of water w/i plantxylem
supporting body in medium lacking buoyancetransport of food from sites of manufacture to sites of use phloem
preventing evaporation from surfaces exposed to air cuticleobtaining gases for psynth & respiration stomata
obtaining sunlight for psynth leavescoordinating plant growth & response to changes in envi hormonesgetting gametes together w/o reliable supply of water for
spermpollen
dispersing new individuals to suitable locations airborne spores & seeds
W4
See notes
Population: interacting group of individuals of same sp’s
Community: populations of all sp’s in an area
E.syst: interacting biotic & abiotic components of an area; dynamic
Eco.succession: predictable series of communities that replace each other in an area
Climax community: relatively stable community that arises after gen climatic conditions of area remain the same (making succession slow)
Biome: major type of e.syst; classified on dominant vegetation
See objective 4
iocmpds: small, simple; abiotic
ocmpds: structural materials found w/I living cells; provide E used by cells
Biogeochemical cycle: pattern of movement of an element from abiotic envi through living producers, consumers, & decomposers back to envi
See figure 3See figure 4See figure 5
Gen process of E flow in e.systSunlight –(converted by photoautotrops)→ chem. E (in bonds of molecules) –(cell resp)→ heat (which dissipates from e.syst)
Food chain/web: desc. Path E takes as it moves from 1 org to the nextFood chain: 1 sequence of orgs through which E can moveFood web: several paths (interconnecting food chains)
Trophic level: position in foodchain
Detritovore & decomposer: feed on dead tissue of level below; operate at all T.lev’sDetritovore: ingestionDecomposer: absorption
Gross 1o productionAmount of light E converted to chem. E by pa’s during given period
Net 1o production(g1op – E lost as heat through cell resp)Amount of E avail to 1o consumers
PsynthCO2 + H2O + sun E → C6H12O6 (sugars) + O2
Cell respC6H12O6 + O2 → CO2 + H2O + E (ATP & heat)
W5
See notes
Nutritional reqs of ht’s: o substances & io minerals
Digestion: enzyme catalyzed process of breaking down food into molecules small enough for the body to absorb
Absorption: digestive enzymes released outside body; digester nutrients absorbed into cells through plasma mem
Ingestion: food taken into a gut or gastrovascular cavity where enzymes carry out extracellular digestion
Endocytosis: plasma mem folds inward, closing particles of food in a pocket which then pinches off to form food vacuole which then fuses w/ lysosome & digestion is carried out by lysosome’s enzymes
Evolutionary trend in animals from intra- to extra- cellular digestion: ancient protists fed by endocytosis, as did 1st animals (intracellular digestion w/ aid of lysosomes) ( majority of modern animals feed by ingestion, only sponges now rely entirely on intracellular digestion)
Ecological significance of trend: animals have diversified into wide range of consumer rolls (many ways of feeding on large pieces of food) from protest-like ancestors that could only feed on microscopic particles of food
See figure 2
structure fnoral cavity physical break down by teeth; saliva chemically digests starch
stomachstores food; physical breakdown by churning; chem d by cell lining
secreting gastric juice (HCL, pepsin→chem d of protein)liver produces bile (emulsifies fat, which increases SA→easier to d
gall bladder stores bile
pancreassecretes bicarbonate ions to neutralize acidity in duodenum; enzymes
secreted break down starch & other large carbohydrates & fat
small intestinedigestion completed in SI; digested nutrients absorbed into blood;
secrete some enzymes
4 adaptations of human SI for absorption of digested nutrients: long, folded, villi, microvilli
Fns of human LI:Absorption of waterExcretes certain salts when they’re too conc’d in bloodSynth of vitamins (by bacteria)Rectum holds feces until elimination
Interference competition: interaction b/w 2 sp’s in which the use or defense of a resource by each sp reduces the amount of that resource that’s avail to the other sp; physical interactions
Exploitative competition: both sp’s suffer b/c they share limited resource; use of the resource by 1 sp leaces less to be used by other sp; no physical interactions
True predatorscarnivores that kill their prey before consuming it; usually animals
Insect parasitoidsMainly wasps & flies; lay eggs in/on/near other insectsTheir larvae consume the living tissues of the hosts, eventually killing them
Herbavores & parasitesdamage their hosts but don’t necessarily kill themh-animals that eat green plants or seeds/fruitsp-can be from any of the kingdoms; often complex life cycles w/ several hosts
detritivoresno direct effects on the pop’s that provide them w/ foodfeed on dead o material
plant & animal defenseschemicals that deter consumers or are poisonouscamouflage/cryptic colouring to blend inwarning colourationmimicry
see table 1
W6
Nervous SystemAll ans have NS → network of fibre-like cells carry electrical signals throughout body; allows response to stimuli & coordinate activities of diff body parts
neurons: individual nerve cellscell body: where organelles of a neuron, includinging nucleus, are located; long extensions of plasma mem branch off both sides of cell body…dendrites: receive signals from receptors or other neurons & carry them towards cell body; in gen highly branched & relatively shortaxons: transmit messages from cell body to other nerve cells or effectors (muscles & glands); in gen longer & branch only close to terminal end (at end of branches are swellings: axon terminals)
Sensory neurons: carry info from P receptors on surface of body or embedded in organs to brain and spinal cord of CNS
Interneurons: in CNS, connect nerve cells, form complex pathways that enable animals to perceive incoming stimuli & initiate responses; in brain responsible for coordination of responses & higher fns (thoughts & emotions)
Motor neurons: transmit info out from CNS to P effectors (glands & muscles of body)
myelin sheath: formed by Schwann cells wrapped around the nerve fibre insulation; prevents interference w/ other neurons; gaps speed up conductance of impulses along length of fibre
When impulses reach axon terminals they trigger release of neurotransmitters (common NTs: acetylcholine Ach & norepinephrine/noradrenaline). NT released into synaptic cleft (small gap b/w terminal & dendrites of another axon); NT picked up by dendrites, initiating electrical response in 2nd neuron. If nerve terminates at muscle or gland NT triggers response in that tissue. Transmitter can have either excitatory or inhibitory effect depending on type of receptor it acts upon.
Reflex arcStimuli from receptor (ex. stretch receptor in upper thigh muscle activated when muscle suddenly stretched) initiate electrical impulses that are carried
by sensory neuron to spinal cord. NTs released from axon terminal of sensory neuron excite a motor neuron which carries impulses to the muscle. Release of NT
from this P neuron causes muscle to contract, correcting the original stretching. Rapid responses such as this occur at unconscious level & help to protect body from injury & assist in balance. In many cases sensory neuron also stimulates interneurons which carry signal to the brain.
Cerebral spinal fluid circulates through centre of nerve cord & in 4 hollow spaces in brain (ventricles); carries nutrients & hormones throughout brain & spinal cord; removes wastes & provides cushioning.
MeningesL: 3 mems around brain & spinal cordF: Protection from injury
-Outermost mem is tough-Cerebrospinal fluid(CF) b/w mems acts as shock absorber
VentriclesL: 4 fluid-filled cavities in brain, continuous w/ central canal of spinal cordF: CF acts as shock absorber Nutrition- circulating CF comes from blood capillary networks over ventricles
Cerebrum (cerebral hemispheres)L: 2 very large hemispheres in anterior forebrainF: Perception & interpretation of sensory impulses Association of impulses concerned w/ emotion & intelligence Motor fn controlling muscular movement
ThalamusL: 2 swellings, 1 in each side of posterior forebrain
Peripheral NS Central NS (made up of brain; & single hollow dorsal nerve cord which integrates simple responses such as reflexes & carries info to & from brain)
Somatic NS Autonomic NS
Sympathetic NS Parasympathetic NS Entericl NS
Vertebrate NS
F: Relay station for all sensory impulses to cerebrum Some sensory impulses like pain, temp, & touch interpreted here
HypothalamusL: Below thalamus, above pituitaryF: Control of autonomic NS & so regulates heart rate, norm body temp, water balance,
movement of food through digestive tract, thirst, sleep, etc Carries messages b/w NS & endocrine syst (2 major control systs of body); lies
above pituitary & releases chems which stimulate or inhibit the pituitary
CerebellumL: Large butterfly shaped structure just below posterior portion of cerebrumF: Coordination of muscular movemens (make movements smooth not jerky) Maintenance of posture Maintenance of equilibrium (balance) by using info from inner ear
Brain StemL: Consists of midbrain, pons, & medulla oblongataF: Conduction pathway for motor & sensory impulses b/w cerebrum & spinal cord
MidbrainL: Short region posterior of thalamusF: Reflex centre for movements of eyes & head in response to sight & sound impulses
PonsL: Forms floor of anterior hindbrain; b/w medulla & midbrainF: Bridge b/w cerebellum & cerebrum & bridge b/w medulla & midbrain; all sensory fibres to cerebrum & motor fibres to spinal cord pass through it Has pneumotaxic centre which regulates respiratory centre in medulla
Medulla OblongataL: Last part of brain, just above spinal cordF: 3 vital centres located in medulla
Cardiac centre which regulates heartbeatRespiratory centre which regulates rate & depth of breathingVasomotor centre which regulates BP by controlling diameter of blood vessels
Location of entres for some reflex actions such as swallowing, sneezing, & vomiting
PNS lies outside brain & spinal cord; 2 divisions: somatic & autonomic NS; each div subdivided into sensory/afferent div carrying impulses from receptors to CNS, & motor/efferent div carrying impulses away from CNS.
Somatic: sensory neurons carry impulses to CNS from somatic receptors in head, limbs, & body wall & from specialized organs for hearing, vision, taste, & smell. Motor neurons carry impulses from CNS to skeletal muscles where they release NT acetylcholine which causes muscles to contract. Conscious control/voluntary.
2nd neuron cell body w/I ganglion1st neuron cell body w/i CNSpreganglionic fibre postganglionic fibre organ
Autonomic: 3 divs: parasympathetic, sympathetic, enteric. Autonomic sensory neurons carry impulses to CNS from autonomic sensory receptors in visceral organs. Autonomic motor neurons conduct impulses from CNS to glands, smooth muscle in visceral organs, & cardiac muscle in heart. Involuntary/not under conscious control
Symp & parasymp systems include 2 neurons & 1 ganglion. Ganglia: collections of cell bodies w/i peripheral NS.
Enteric: SNs carry impulses from gastrointestinal tract to CNS. MNs carry impulses from CNS to smooth muscle & glands of gastrointestinal tract, stimulating contractions of muscles in lining of gut as well as release of hormones & digestive secretions
Sympathetic: usually predominates during periods of stress or emergency, initiating ‘fight or flight’ response. Sympathetic nerves release
norepinephrine/noradrenaline causing increased heart rate & constriction of blood vessels (↑BP), widening respiratory pathways allow greater air flow into lungs, & stimulating release of sugars into blood for E production. At same time signals from symp syst inhibit activity of digestive & sexual organs
Parasympathetic: neurons release acetylcholine. Slows heart rate, constricts respiratory pathways, stimulates activity of digestive & sexual organs. Gen involved in relaxing body & homeostasis.
Constriction of blood vessels & activity of sweat glands controlled solely by sympNS as is mobilization of sugars & fats for E production
Medulla oblongata responsible for autonomic output regulating respiratory, cardiovascular, & digestive fn. Hypothalamus crucial for many emotional & behavioural responses. Changes in BP, heart rate, & breathing associated w/ changes in emotional state are due to action of hypothalamus on the medulla oblongata which in turn acts via autoNSb
Diff. b/w Phylums
Ph. Cnidaria-Diffuse system of nerve cells that covers body-Nerve impulses can travel in either direction along each fibre of nerve net
-Stimulation of any part of body sends messages across entire surface initiating response from entire animal
Ph. Platyhelminthes-Nervous impulses conducted in 1 direction along nerve fibres → allows info to be transferred to specific set of nerves or muscles-Nerve fibres groups together into pairs of longitudinal nerve cords that run down ventral (lower) surface-Clusters of nerve cells in anterior region act as primitive brain → receive input from sense organs & cont. movements of body; increase ability to monitor changes in envi & respond
Ph.’s Annelida & Arthropoda-Brain larger, more complicated; small clusters of nerve cells called ganglia located in each segment along longitudinal nerve cords; results in greater degree of coordination
LocomotionLocomotion: active self-propelled movement of an organism from one place to another
Locomotion in protists
Pseudopodia (eg Amoeba1. temporary projections/extensions of cytoplasm; rest of organism flows towards extension2. cytoplasm changes from a liquid to a gel-like state & back again; as a pseudopodia moves forward outer gel-like ectoplasm forms a tube through which the inner fluid endoplasm flows; at the tip the endoplasm solidifies into gel; resulting finger-like extension called pseudopodium
Flagella (eg Euglena)1. long tail-like projection from cell body; move back & forth to propel organism2. waves of undulation pass from base to tip of flagellum, propelling organism in opposite direction
Cilia (eg Paramecium)present in large #s on cell’s surgace; synchronized beating to propel organism (move in oar-like fashion)
Larger organisms too heavy to use pseudopodia or cilia alone→rely on use of specialized muscle cells containing contractile fibresMuscle cells can actively contract, causing them to shorten in lengthRelaxed fibres can be lengthened but only if pulled by some external forceTherefore the active contraction of muscle fibres, not the lengthening, which does the work of movement & locomotionw/o something firm to pull against muscles can do little other than change body shapeskeletal systems provide firm support against which muscles can act, thereby creating directional movement
Cnidaria – like hydra, sea anemone-Hydrostatic skeleton → fluid-filled gastrovascular cavity for support-Polyp-have contractile fibres in cells of both outer & inner tissue layers but they develop differently from the true muscle cells in other phyla → longitudinal & circular-nerve net (entire organism responds to a stimulus)-when pissed off, tentacles retracted or brought inside gastrovascular cavity, and body column retracted-Hydras and some sea anemones can move slowly over rocks and sea or stream beds by various means: creeping like snails, crawling like inchworms, or by somersaulting. A few can swim clumsily by waggling their bases
Annelida - earthworms-Hydrostatic skeleton → fluid-filled body cavity (coelom) b/w body wall & gut for support-Earthworms travel underground by the means of waves of muscular contractions which alternately shorten and lengthen the body. The shortened part is anchored to the surrounding soil by tiny claw-like bristles (setae) set along its segmented length. Aided by the secretion of lubricating mucus.-NS: segmented; brain directs responses to stimuli; double ganglia along nerve cord → coordinate alternate contraction of longitudinal & circular muscles-segmented: repetition of series of ~similar sections (segments) along length of body-true muscle cells: longitudinal & circular muscles
Arthropoda-Exoskeleton composed of layers of protein & chitin (material similar to cellulose) enclosing body-Vary in thickness: some regions thick & rigid, others (like joints) thin & flexible-Impermeable to water-insertion end of muscle often joined to a long tendon which is attached to exoskeleton-insect wings
A. muscles attached to base of wing (pivot)Up: inner muscles contract, outer muscles relax
B. muscles pull on thoraxUp: longitudinal muscles relax, transverse muscles contract
Necessary to have 2 muscles if there was only 1 set the wings would only move one way, rendering flight impossible
Flexor: muscles which contract to bend limbExtensors: muscles which contract to straighten limb
Origin: end of muscle attached to stationary part of exoskeletonInsertion: end of muscle attached to part of skeleton that moves
Vertebrates have rigid endoskeleton composed of bone & cartilage which is surrounded by muscles
Cartilage-Contains living cells embedded in fibrous extracellular matrix of collagen fibres (a flexible protein)-Not as rigid as bone-Used to provide cushioning (ex. in disks b/w vertebrae of backbone) & flexibility (ex. costal cartilage b/w ribs allow movement of rib cage-on ends of bone to prevent wear-b/w bones to increase stability
BoneContains living cells embedded in extracellular matrixBone matrix consists of
1. Collagen fibres2. Inorganic materials, mainly calcium phosphate, which gives rigidity & strength to bone
Axial skeleton-Forms central axis of body (skull, rib cage, vertebral column)-fn: protection & support (brain, spinal cord, organs…)
Appendicular skeleton-Consisting of appendages (limbs) & bones that attach them to spine (pectoral girdle for forelimbs, pelvic girdle for hind limbs)-fn: locomotion & interaction w/ environment
Homologous structure – structure of organisms that is derived from a common ancestor
Analogous structure: similarities in structure b/w organisms that were not in the last common ancestor of the taxa being considered but rather evolved separately
Movement in vertebrates result of skeletal muscles acting on bones. Not all skeletal muscles move bones, some stabilize joints, others move skin of the face.Skeletal muscles share 2 common characteristics:
-contractile -using E supplied by metabolism, muscle fibres can shorten)-extensible-if pulled on by outside force they can be stretched
skeletal muscle smooth muscle cardiac muclelocation attached to skeleton most internal organs heart
nervous control somatic NS autonomic NS autonomic NScell shape long, cylindrical spindle-shaped, tapered at
both endsbranched & woven together
striations (bands) yes no yes# of nuclei/cell several one one
1 ulna2 humerus3 radius4 biceps brachii tendon5 short head of biceps tendon6 scapula7 coracoid process8 acromion process9 biceps brachii10 long head of biceps tendon
Proximally, the short head of the biceps attaches to (originates from) the coracoid process of the scapula. The tendon of the long head passes along the intertubercular groove of the humerus into the joint capsule at the head of the humerus, and attaches to the scapula at the supraglenoid tubercle.
Distally, biceps attaches to (inserts into) the radial tuberosity. Because the ulnar and radial bones can rotate about each other the biceps can powerfully supinate the forearm. The biceps also connects with the fascia of the medial side of the forearm via the bicipital aponeurosis.
also see fig 2
Antagonistic MusclesAntagonistic muscles are found in pairs called antagonistic pairs. These consist of an extensor muscle,
which "opens" the joint (i.e. increasing the angle between the two bones), flexor muscle, which does the opposite to an extensor muscle.
Antagonistic pairs are needed in the body because muscles can only exert a pulling force, and can't push themselves back into their original positions. An example of this kind of muscle pairing is the biceps brachii and triceps brachii.
When the biceps are contracting, the triceps are relaxed, and stretches back to its original position. The opposite happens when the triceps contract.
Ligaments: long bands of fibrous connective tissue binding bones together
Tendons: bands of fibrous connective tissue connecting muscles to bones; when muscles contract they shorten, causing tendon to pull attached bone towards muscle
Bursae: fluid-filled sacs that ease friction b/w moving parts of joint; 13 bursae in knee joint
Arrangement of muscles
arthropod both vertebrateare inside of skeleton
antagonistic muscles attached to skeleton
are outside of skeleton
Undulation (fish)Waves of contractions move alternately down one side of body then the other; when one wave reaches tail, tail flips to that side, pushing against the water
Fins (fns in fish)Caudal/tail fin → main propelling finDorsal fin → stability while swimming
hydrostatic exoskeleton endoskeletonstructure fluid-filled compartment of an
animal, muscles change its shape
hard encasement deposited on animal’s surface
hard supporting elements (such as bones) w/i soft tissues of an animal
advantages flexibleregeneration
impermeable to waterprotection
mobilitysupport larger organisms
disadvantages no protection from water losslittle protectionheavy
limit size of organismheavymolting
no protection from water lossless protective
Common aspects of arrangement of muscles & support systems in examined animals1. sets of opposing muscles (flexors & extensors, longitudinal & circular)2. base from which muscles operate
Advantage of terrestrial environment relative to aquatic: less frictionDisadvantage of terrestrial environment relative to aquatic: no buoyancy/support
