Homeostasis BIO.A.4.2.1. homeostasis Maintaining a stable internal environment.
Homeostasis
description
Transcript of Homeostasis
HomeostasisHomeostasis
Chapter 7Chapter 7Zoology 1450Zoology 1450
TopicsTopics
OsmoregulationOsmoregulation Endocrine regulationEndocrine regulation Thermal regulationThermal regulation Immune Response (briefly)Immune Response (briefly)
Part 1: Osmoregulatory Part 1: Osmoregulatory Systems in FishesSystems in Fishes
Maintaining homeostasis with Maintaining homeostasis with respect to solute concentrations respect to solute concentrations
and water contentand water content
IntroductionIntroduction Maintaining steady-state equilibrium in the Maintaining steady-state equilibrium in the
internal environment of aquatic and marine internal environment of aquatic and marine organisms is challenging.organisms is challenging.
Much is done involuntarily (hormones, enzymes, Much is done involuntarily (hormones, enzymes, osmoregulation, etc.) so little physical action is osmoregulation, etc.) so little physical action is required, however…required, however…
““Pick-up-and-move” still an option!Pick-up-and-move” still an option! (Poor environment.)(Poor environment.)
DefinitionsDefinitions
HomeostasisHomeostasis = maintaining steady state = maintaining steady state equilibrium in the internal environment of an equilibrium in the internal environment of an organismsorganisms
Solute homeostasisSolute homeostasis = maintaining equilibrium = maintaining equilibrium with respect to solute (ionic and neutral solutes) with respect to solute (ionic and neutral solutes) concentrations (i.e. salts)concentrations (i.e. salts)
Water homeostasisWater homeostasis = maintaining equilibrium = maintaining equilibrium with respect to the amount of water retained in with respect to the amount of water retained in the body fluids and tissuesthe body fluids and tissues
Definitions, continuedDefinitions, continued
Osmotic concentrationOsmotic concentration - Total - Total concentration of all solutes in an aqueous concentration of all solutes in an aqueous solution.solution.
UnitsUnitsosmolalsosmolals = 1 mole of solute/liter of water = 1 mole of solute/liter of water milliosmolalsmilliosmolals = 1/1000th of one osmolal = 1/1000th of one osmolal
Osmoregulation in different environmentsOsmoregulation in different environments
Challenge to homeostasis depends onChallenge to homeostasis depends on
Solute concentration of body fluids and Solute concentration of body fluids and tissues…tissues…
……concentration of environmental solutes concentration of environmental solutes marine: ~34 ppt salinity = 1000 mosm/lmarine: ~34 ppt salinity = 1000 mosm/l freshwater: < 3 ppt salinity = 1 - 10 mosm/lfreshwater: < 3 ppt salinity = 1 - 10 mosm/l
Osmoregulation in different environmentsOsmoregulation in different environments
Each species has a range of environmental Each species has a range of environmental osmotic conditions in which it osmotic conditions in which it cancan function: function: stenohalinestenohaline - tolerate a - tolerate a narrow rangenarrow range of of
salinities in external environment salinities in external environment euryhalineeuryhaline - tolerate a - tolerate a wide rangewide range of salinities of salinities
in external environmentin external environment short term changes: estuarine - 10 - 32 ppt, short term changes: estuarine - 10 - 32 ppt,
intertidal - 25 - 40intertidal - 25 - 40 long term changes: diadromous fishes long term changes: diadromous fishes
(salmon)(salmon)
Four osmoregulatory strategies in fishesFour osmoregulatory strategies in fishes
1. Isosmotic (nearly isoionic, osmoconformers)1. Isosmotic (nearly isoionic, osmoconformers)2. Isosmotic with regulation of specific ions2. Isosmotic with regulation of specific ions3. Hyperosmotic (fresh H3. Hyperosmotic (fresh H220 fish)0 fish)
4. Hyposmotic (salt H4. Hyposmotic (salt H22O fish)O fish)
Osmoregulation StrategiesOsmoregulation Strategies
OsmoconformingOsmoconforming (no strategy) Hagfish internal salt (no strategy) Hagfish internal salt concentration = seawater. However, since they live IN the concentration = seawater. However, since they live IN the ocean....no regulation required!ocean....no regulation required!
Osmoregulation StrategiesOsmoregulation Strategies
Elasmobranchs (sharks, skates, rays, chimeras)Elasmobranchs (sharks, skates, rays, chimeras)
Maintain internal salt concentration ~ 1/3 seawater, Maintain internal salt concentration ~ 1/3 seawater, make up the rest of internal salts by retaining high make up the rest of internal salts by retaining high concentrations of concentrations of ureaurea & & trimethylamine oxidetrimethylamine oxide (TMAO). (TMAO).
Bottom line…total internal osmotic concentration Bottom line…total internal osmotic concentration equal to seawater! equal to seawater!
How is urea retained? How is urea retained? Gill membrane has low permeabilityGill membrane has low permeability to urea so it is to urea so it is
retained within the fish. Because internal inorganic retained within the fish. Because internal inorganic and organic salt concentrations mimic that of their and organic salt concentrations mimic that of their environment, passive water influx or efflux is environment, passive water influx or efflux is minimized.minimized.
ionic conc. approx 1/3 of seawaterionic conc. approx 1/3 of seawater drink copiously to drink copiously to gaingain water water Chloride cellsChloride cells eliminate Na eliminate Na++ and Cl and Cl-- kidneys eliminate Mgkidneys eliminate Mg++++ and SO and SO44
==
advantages and disadvantages?advantages and disadvantages?
Osmotic regulation by marine teleosts...Osmotic regulation by marine teleosts...
Saltwater teleosts:Saltwater teleosts:
drinkdrink
active tran.active tran.
passive diff.passive diff.
NaNa++, Cl, Cl--
MgMg++++, SO, SO44==
HH22OO
NaNa++, Cl, Cl--
NaNa++, Cl, Cl--
chloride cellschloride cells
MgMg++++, SO, SO44==
kidneyskidneys
Chloride Cell Chloride Cell fig 6.2fig 6.2: :
pavementpavementcellcell PCPCPCPC
activeactivepassivepassive
chloride cellchloride cell
accessory accessory cellcell
sea watersea water
internalinternalmitochondriamitochondria
tubular systemtubular system
NaNa++
KK++ NaNa+ + KK+ + ATPaseATPase
NaNa++, , ClCl--
NaNa++
ClCl--
ClCl--
ClCl--ClCl--
gutgut
carriercarrier
NaNa++
NaNa++
NaNa++
pumppump
++
Ionic conc. Approx 1/3 of seawaterIonic conc. Approx 1/3 of seawater Don’t drinkDon’t drink Chloride cellsChloride cells fewer, work in reverse fewer, work in reverse Kidneys eliminate excess water; ion lossKidneys eliminate excess water; ion loss Ammonia & bicarbonate ion exchange mechanismsAmmonia & bicarbonate ion exchange mechanisms
advantages and disadvantages?advantages and disadvantages?
Osmotic regulation by FW teleostsOsmotic regulation by FW teleosts
Freshwater teleosts:Freshwater teleosts: activeactivepassivepassive
HH22OO
NaNa++, Cl, Cl--
NaNa++, Cl, Cl--
don’tdon’tdrinkdrink
waterwaterkidneyskidneys
Ion exchangeIon exchangepumps; beta chloride cellspumps; beta chloride cells
Ion Exchange MechanismsIon Exchange Mechanisms
gill membranegill membrane
freshwaterfreshwater interiorinterior
activeactive
pumppump
activeactive
pumppump
NaNa++
ClCl--
NHNH44++ or H or H++
HCOHCO33--
ATPATP
ATPATP
Freezing Resistance:Freezing Resistance: What fishes might face freezing?What fishes might face freezing?
hagfishes?hagfishes?isotonicisotonic
marine elasmobranchs?marine elasmobranchs?isotonicisotonic
freshwater teleosts?freshwater teleosts?hypertonichypertonic
marine teleosts?marine teleosts?hypotonichypotonic
Solution for Antarctic fishSolution for Antarctic fish Macromolecular compoundsMacromolecular compounds
peptides (protein)peptides (protein) glycopeptidesglycopeptides (carbohydrate/protein)(carbohydrate/protein){rich in alaninerich in alanine
molecules adsorb (attach) to ice crystal surfacemolecules adsorb (attach) to ice crystal surface
interfere with ice crystal growth (disrupt matrix)interfere with ice crystal growth (disrupt matrix)
Why is this important???Why is this important??? ice ruptures cells; hinders osmoregulationice ruptures cells; hinders osmoregulation
What about rapid ion flux?What about rapid ion flux?
EuryhalineEuryhaline Short-term fluctuations in osmotic state of Short-term fluctuations in osmotic state of
environment, e.g. in intertidal zone or in environment, e.g. in intertidal zone or in estuaries where salinity can range from 10 to estuaries where salinity can range from 10 to 34 ppt with the daily tidal cycle:34 ppt with the daily tidal cycle: these fish have both kinds of chloride cellsthese fish have both kinds of chloride cells
when salinity is low, operate more like FW fisheswhen salinity is low, operate more like FW fishes when salinity is high, operate like marine fisheswhen salinity is high, operate like marine fishes kidneys function only under low salinity conditionskidneys function only under low salinity conditions
EuryhalineEuryhaline
DiadromousDiadromous fishes (spend part of life in salt fishes (spend part of life in salt water, part in freshwater – water, part in freshwater – catadromouscatadromous (migrate seaward) or (migrate seaward) or anadromousanadromous (migrate (migrate up river)up river)
hormone-mediated changes associated hormone-mediated changes associated with metamorphosis - convert from FW with metamorphosis - convert from FW adaptations to SW or vice versa, depending adaptations to SW or vice versa, depending on direction of migrationon direction of migration
What about stress??What about stress??
Stressors (handling, sustained exercise such as Stressors (handling, sustained exercise such as escape from predator pursuit) cause release of escape from predator pursuit) cause release of adrenaline (epinephrine) - for mediating escape, etc.adrenaline (epinephrine) - for mediating escape, etc.
Adrenaline causes diffusivity of gill epithelium to Adrenaline causes diffusivity of gill epithelium to increase, i.e. “leaky cell membranes” water & ions)increase, i.e. “leaky cell membranes” water & ions)
This accentuates the normal osmoregulatory This accentuates the normal osmoregulatory challenge for FW or marine fisheschallenge for FW or marine fishes
How to reduce stress in stressed fishes?How to reduce stress in stressed fishes?
Minimize the osmotic challenge by placing Minimize the osmotic challenge by placing fish in conditions that are fish in conditions that are isosmoticisosmotic add salt to freshwater, e.g. in transporting fish add salt to freshwater, e.g. in transporting fish
or when exposing them to some other short-or when exposing them to some other short-term challengeterm challenge
dilute saltwater for same situation with marine dilute saltwater for same situation with marine speciesspecies
Thermoregulation in FishesThermoregulation in Fishes
Temperature effects on fishTemperature effects on fish
Temperature exhibits the greatest influence on Temperature exhibits the greatest influence on fish’s lives!fish’s lives!
Affects metabolismAffects metabolism Affects digestionAffects digestion Signals reproductive maturation and behaviorSignals reproductive maturation and behavior
Fish are conformers (well, sort of...)Fish are conformers (well, sort of...)
Body temperature is that of the environment Body temperature is that of the environment ((poikilothermic ectothermypoikilothermic ectothermy))
Each species has particular range of Each species has particular range of temperatures that they can temperatures that they can toleratetolerate and that and that are are optimaloptimal
Big difference!Big difference!
Behavioral Thermoregulation in FishesBehavioral Thermoregulation in Fishes
Although fish are Although fish are ectothermsectotherms, they can , they can alter their body temperature by moving to alter their body temperature by moving to habitats with optimal temperaturehabitats with optimal temperature
Hot FishesHot Fishes Some fish can maintain body temperature greater than Some fish can maintain body temperature greater than
ambient - tunas, billfishes, relatives (nearly ambient - tunas, billfishes, relatives (nearly endothermicendothermic))
Tuna use Tuna use retiaretia (similar to rete mirable) in muscles to (similar to rete mirable) in muscles to conserve heat & exchange Oconserve heat & exchange O22..
Also, red muscle isAlso, red muscle is medial medial rather than distal rather than distal
Billfishes have warm brains - heat organ from muscles Billfishes have warm brains - heat organ from muscles around eyearound eye
Practical applicationPractical application
You’re management decisions and actions You’re management decisions and actions must account for fish responses to must account for fish responses to temperature gradients and limitationstemperature gradients and limitations
Endocrine Systems of FishesEndocrine Systems of Fishes
Pituitary Gland - Master GlandPituitary Gland - Master Gland
Linked with hypothalamus of brainLinked with hypothalamus of brain Produces hormones that affect other Produces hormones that affect other
endocrine tissues - indirect influenceendocrine tissues - indirect influence Produces hormones that affect non-Produces hormones that affect non-
endocrine tissues directlyendocrine tissues directly
Pituitary GlandPituitary Gland
Indirect influenceIndirect influence ACTH - adrenocorticotrophic ACTH - adrenocorticotrophic
hormonehormone stimulates interrenal tissue production stimulates interrenal tissue production
of cortisol, stress responseof cortisol, stress response TH - thyrotrophic hormoneTH - thyrotrophic hormone
stimulate thyroid production of thyroxin stimulate thyroid production of thyroxin (growth, metamorphosis-i.e. flounder)(growth, metamorphosis-i.e. flounder)
GTH- gonadotrophic hormoneGTH- gonadotrophic hormone stimulates gonads to produce stimulates gonads to produce
androgens/estrogensandrogens/estrogens
Pituitary GlandPituitary Gland
Effects non-endocrine tissues directlyEffects non-endocrine tissues directly pigmentation - melanophore stimulating hormone (MSH)pigmentation - melanophore stimulating hormone (MSH)
affects long-term control of coloraffects long-term control of color osmoregulation - prolactin, vasotocinosmoregulation - prolactin, vasotocin
controls fresh/saltwater systemscontrols fresh/saltwater systems growth – somatotrophic hormonegrowth – somatotrophic hormone
stimulates > length, cell multiplicationstimulates > length, cell multiplication
Thyroid GlandThyroid Gland
isolated follicles distributed in connective tissue isolated follicles distributed in connective tissue along ventral aortaalong ventral aorta
controls metabolic ratecontrols metabolic rate affects metamorphosis, maturationaffects metamorphosis, maturation facilitates switch between fresh & salt waterfacilitates switch between fresh & salt water
GonadsGonads
gamete and sex hormone productiongamete and sex hormone production controls gametes maturationcontrols gametes maturation cause formation of cause formation of secondary sex secondary sex
characteristicscharacteristics: color, shape, behavior: color, shape, behavior in fish, several sex hormones also serve as in fish, several sex hormones also serve as
pheromonespheromones - e.g. goldfish males respond - e.g. goldfish males respond to hormones released with ovulationto hormones released with ovulation
Other endocrine tissues in fishesOther endocrine tissues in fishes chromaffin tissueschromaffin tissues-located near kidneys & heart-located near kidneys & heart
produce adrenaline/noradrenaline – “fight or flight”produce adrenaline/noradrenaline – “fight or flight” increases blood flow through gills, ventilation rateincreases blood flow through gills, ventilation rate
interrenal (inside kidney) tissuesinterrenal (inside kidney) tissues produce cortisol, cortisone - stress response produce cortisol, cortisone - stress response
hormones (reduce inflamation)hormones (reduce inflamation)
Other endocrine tissues in fishesOther endocrine tissues in fishes pancreatic isletspancreatic islets
produce insulin - controls glucose, glycogen produce insulin - controls glucose, glycogen metabolism (glucagon production)metabolism (glucagon production)
corpuscles of Stanniuscorpuscles of Stannius produce stanniocalcin - controls Caproduce stanniocalcin - controls Ca2+2+ uptake at gills uptake at gills
Immune SystemImmune System
IntroductionIntroduction
Obviously, the immune system is important in Obviously, the immune system is important in homeostatic processes.homeostatic processes.
Immune systems of fish have two components: Immune systems of fish have two components: non-specific non-specific and and specificspecific..
As we will see, both are involved in protecting fish As we will see, both are involved in protecting fish from visible as well as invisible disease causing from visible as well as invisible disease causing agents.agents.
Non-specific immunityNon-specific immunity
Skin & ScalesSkin & Scales—specific solid layers of protection —specific solid layers of protection from pathological and chemical stressors.from pathological and chemical stressors.
Mucus secretionMucus secretion—traps microorganisms; —traps microorganisms; preventing entry into body cavity or circulationpreventing entry into body cavity or circulation
MacrophagesMacrophages (phagcytes) and cytotoxic cells—part (phagcytes) and cytotoxic cells—part of the inflamatory response which destroy of the inflamatory response which destroy pathogens within the body before they can do harm.pathogens within the body before they can do harm.
Specific Immune ResponseSpecific Immune Response
More of an active response More of an active response where an “invader” is detected where an “invader” is detected and destroyed.and destroyed.
Primary organs: kidney, Primary organs: kidney, thymus, spleen, intestine.thymus, spleen, intestine.
AntigensAntigens—invading —invading compounds which provoke an compounds which provoke an immune response.immune response.
Source: Cancer Research Institute (2002) www.cancerresearch.org/immhow.htmlSource: Cancer Research Institute (2002) www.cancerresearch.org/immhow.html
Specific immune response: What if something does get in??Specific immune response: What if something does get in??
White blood cells called White blood cells called B lymphocyte cells (B lymphocyte cells (B cellsB cells) and T ) and T lymphocyte cells (lymphocyte cells (T cellsT cells)—bind to foreign cells and begin )—bind to foreign cells and begin replication and attachement to antigens (sort of markers for replication and attachement to antigens (sort of markers for things to come...). things to come...).
Occasionally, invader actually goes trough a macrophage Occasionally, invader actually goes trough a macrophage firstfirst...then B cell responds......then B cell responds...
Once B cells replicate, Once B cells replicate, antibodiesantibodies are produced which bind are produced which bind specifically to pathogens and tag them for destruction specifically to pathogens and tag them for destruction (eating) by (eating) by macrophages!macrophages!
“Looks like meat’s back on the menu
boys!!!”
Questions???Questions???