Comparative+Animal+Physiology++Basic+Concepts++Definition+of+acclimatization:+A"physiological"change"can"occur"within"an"individual"animal"that"results"from"chronic"(continuous)"exposure"to"a"new"but"naturally"occurring"environmental"condition."It"is"a"short"term"reversible"change"Example:+Increase"in"atmosphere"causing"decrease"in"oxygen"so"ventilation"increases,"after"a"few"days,"ventilation"drops"back"down"as"other"mechanisms"facilitate"gaseous"exchange""Definition+of+acclimation:+When"an"animal"is"placed"in"an"artificially"controlled"environment"to"mimic"a"natural"condition+Example:+An"animal"is"put"in"a"hypobaric"chamber"to"increase"ventilation"rate""Definition+of+adaptation:+Changes"to"physiological"systems"which"enable"animals"to"survive"in"these"conditions."Changes"in"population"over"evolutionary"time."+Example:+Kangaroo"rat"lives"in"the"desert"with"excessive"heat"and"lack"of"freshwater,"however"it"has"adapted"nasal"counter"current"to"conserve"respiratory"water"loss,"absorb"water"from"faeces"and"excrete"highly"concentrated"urine"from"a"unique"counter"current"exchange"system"in"the"kidney"due"to"a"long"loop"of"Henle""When+is+a+process+adaptive?"Occurs"if"it"is"present"at"a"high"frequency"in"a"population"because"it"results"in"a"greater"chance"of"survival."A"change"in"a"physiological"process"in"response"to"an"environmental"change"is"said"to"be"adaptive"when it"occurs"in"several"distantly-related"animal"species"living"in"similar"environments.""Definition+of+homeostasis:"the"ability"of"animals"to"maintain"a"relatively"stable"internal"environment"even"with"changes"to"the"external"environment."Physiological"regulatory"systems"maintain"internal"conditions"within"a"relatively"narrow"range."Example:+Temperature"regulation"+Why+are+feedback+systems+important+in+homeostasis+(sensor,+effector+and+set-point+concept)?+• Sensors"are"receptors,"nerves"and"hormones"are"the"circuits"and"effectors"alter"the"internal"environment"and"return"it"to"the"normal"range"despite"the"wide"variations"in"the"external"environment++Negative+feedback+and+example:+A"change"in"the"body/environment"causes"the"body"to"react"to"counteract"change"Stress"causes"glucocorticoid"release"to"target"tissues"to"relieve"stress""""""""""+Positive+feedback+and+example:+A"change"in"the"body/environment"is"strengthened"and"increased"by"internal"physiological"changes."An"example"is"oxytocin"increase"during"birth""++++++++++Conformers+vs+regulators+and+examples:+• Conformers:"Allow"internal"environment"to"change"along"with"the"external"environment,"yet"are"able"to"compensate"for"these"changes"and"function"in"spite"of"them."They"generally"show"a"wide"range"of"internal"conditions"that"allow"survival."However,"function"may"not"be"optimal"over"the"entire"range"that"is"tolerable."Adjust"their"internal"conditions"to"reflect"the"external"environment"so"the"internal"variable"is"always"equal"to"the"external"variable."This"is"energetically"cheap"but"cells"are"subject"to"changing"temperatures.""o Example:"Sea"Star"-"internal"body"fluids"quickly"come"to"equilibrium"with"sea"water"that"surrounds"them,"so"increase"in"body"fluid"salinity"when"placed"in"high"salt"water,"but"can"re-adjust"if"placed"in"low"salt"water"and"decrease"body"fluid"salinity"• Regulators:"Internal"variable"is"kept"constant"and"therefore"differs"from"the"external"environment."They"use"physiological,"biochemical"and"behaviour"mechanisms"to"regulate"internal"environment"over"a"broad"range"of"external"environmental"changes."Maintain"the"internal"environment"within"a"narrow"range"of"conditions,"even"in"the"face"of"changing"external"conditions."Generally,"show"or"tolerate"only"a"narrow"range"of"internal"conditions"over"which"function"is"possible"and"is"optimal"in"or"near"this"narrow"range."Energetically"costly"but"cells"function"in"steady"internal"conditions."o Example:"Artic"fox"stay"active"at"low"temperatures"by"adjusting"blood"flow"through"counter"current"exchanges"and"vessels"in"the"legs"to"keep"their"paw"temperature"just"about"zero"degrees"which"is"cold"enough"to"stop"heat"loss"but"warm"enough"to"stop"frostbite"+Range+of+tolerance/resistance+and+how+this+influences+populations?+• Range"of"tolerance:"the"range"of"any"specific"environmental"variable"that"an"animal"can"survive,"animals"with"wide"ranges"for"limiting"factors"are"likely"to"be"widely"distributed."o Homeothermic"endotherms"="narrow"range"o Poikilothermic"ectotherms"="broad"range"• Range"of"resistance:"after"tolerance"levels"are"exceeded"an"animal"can"resist"changes"in"the"internal"environment"for"a"certain"period"depending"on"how"greatly"the"tolerance"levels"are"exceed"but"will"eventually"die"o Exceeding"limit"="death"• The"distribution"of"a"species"will"be"controlled"by"that"environmental"factor"for"which"the"organism"has"the"narrowest"range"of"tolerance""Hormones+and+Receptors+"Difference+between+neural,+neuroendocrine+and+endocrine+communication:+• Neural:"messenger"of"action"potential"down"the"cell,"over"nodes"of"Ranvier,"cell"communicates"with"NTs"at"junction"–"very"fast,"short"lived"action,"but"specific"• Neuroendocrine:"neural"signal"triggers"the"release"of"endocrine"molecules"• Endocrine:"hormones"transported"in"blood"–"slower"but"longer"duration"of"response"+Autocrine+vs+paracrine:+• Local"autocrine:"autocrine"secretions"affect"the"cell"they"were"secreted"from"o Eg."Cancer"cells"make"growth"factors"to"act"on"themselves"• Paracrine:"secretions"affect"neighbouring"cells;"get"released"o Eg."Cytokines"control"angiogenesis"and"the"formation"of"new"blood"vessels,"cells"next"to"the"vessels"release"molecules"to"make"new"ones"+Exocrine+secretion,+exocrine+glands+and+example:++• Exocrine"glands"release"secretions"via"ducts"onto"epithelial"surfaces+• Secretions"are"usually"aqueous"mixtures,"consisting"of"water-based"primary"fluid"and"added"components"rather"than"a"single"substance"• Examples:"sweat"glands,"salivary"glands,"prostate"glands,"pheromone"producing"cells""Pheromones+and+their+function,+example+They"are"specific"chemicals"produced"by"one"animal"to"communicate"with"another"released"into"the"environment"to"act"as"a"chemical"language"to"initiate"a"range"of"physiological"responses"(signals"presence"of"a"predator"or"looking"for"a"mate)"• Clams;"spawning"of"eggs"and"sperm"is"triggered"by"pheromones"released"at"the"same"time"as"the"gamete"•