HOMEOSTASIS PT2 Flashcards
define homeostasis
the process involved in maintaining a constant internal environment, within tolerance limits despite changes in internal and external environment
list internal conditions that need to be controlled
CO2
O2
Salts
water
wastes
ph
temp
glucose
list what the the steady state control system
SR MERF
stimulus
receptors
modulator
effector
response
feedback
define stimulus and provide an example
is the change in internal environment this could be increase temperature of blood
define receptors and provide an example
receptors detect the change, for temperature the thermoreceptors detect the change in temp
define modulators with an example
this is the control center process which recieves info from recptors and compares to the normal/ optimum levels and sends meassage to effectors. for an increase in temperature this may be the hypothalamus
define effectors with an example
the muscle or gland that carries out the response such as a blood vessle or skeletal muscles
define responses with an example
counteracts the stimulus such as blood vessles vasodialating due to hot conditions in efforts to cool the body temp
define feedback and give an example
original stimulus is now changed. this could be a negative or positive feedback loop.
why does CO2 need to be maintained within limits?
when disolved in water forms carbonic acid lowering pH and effecting enzyme activity
why does oxygen and nitrogenous wasteslevels need to be maintained within limits
oxygen- to supply energy (ATP) for cellular functioning
nitrogenous waste- toxic in high concentrations inhibit the reaction that form them also raises pH
why does temperature, salts and water levels need to be maintained
temperature- affects enzyme activity
salts - Na from NaCl is important in regulating fluid levels as well as nerve transmition and muscle contraction
water- mainntains concentration of cell contents at correct level for cellular reactions and the solvent for metabolic reactions
what are ectotherms
ectotherms gain heat from external environments like warm rocks, sun and water
- body temp fluctuates
- includes invertebrates, reptiles ampibians
outline the characteristics of an endotherm
gains body heatfrom metabolic activity(internally)
- high metabolism
- relatively consistant temperature
- birds mammals, some insects(bumble bees)
list the advantages and disadvantages of being ectothermic
advantages-
little energy required
can feed less
stay in shelter for longer
disadvantages
- inactive at nigh or cold
- more likely to get eaten
- restricted geographical area
list the advantages and disadvantages of being endothermic
advantages-
active 24hrs a day
body temp consistant
any geographical location
able to avoid preadtors
makes them good predators
disadvantages
requires large amounts of energy
need insulation and cooling mechanisms
how do organisms loose body heat
some lost through urine, faecese, lungs
most lost through skin
through conduction, convection radiation and evaporation
list some physiological adaptations for terrestrial animals in hot environments and describe how they regulate temperature
sweating or panting
- water has a 50% cooling effect of air as the water evaporates it takes the heat with it.
coat thinning/fur flattening
- thick coat is shed in warm weather
- thick fur trapps air close to skin preventing heat loss so therefore once removed it promotes heat loss
vasodialation
- smooth muscles in the wall of an artery flowing to the skin relaxes and the artery increases in diameter to increase blood flow.
decreased metabolic rate
- as heat is a product of metabolism
list some structural adaptation and describe how they help in regulating the body’s temp.
large SA:VOL raito
having large extremities aid heat loss.these feature s are like elephants ears thin flat and big.
insulating fur
- shades skin prevents skin from absorbing suns radiation
list some behavioural adaptations and describe hoe they help in regulating the body’s temp
wallowing in water
- as long as temp of water is lower than the animals it will loose heat in the water
burrowing and laying in shade
- prevents heating by radiation
increase SA
- spreading out, flapping ears to create air flow
standing on 2 legs like a lizard
- to limit the amount of heat being conducted
list some physiological adaptations of terrestrial animals in cold and how they reduce heat loss
vasoconstiction
- blood vessles constrict to skin restricting bloodflow
- reduces temp of skin so heat isnt transferred via radiatino as heat remains underneath fat layer
increase MR
- hormones like adrenaline are released and heat is a by product of this
decreased MR = torpor (inactivity)
- hibernation- long term decrease in mr and body temp (days)
- diunation- short term decrease in MR and body temp (hrs)
shivering
- involentary repeates muscle contraction requires energy from metabolism creating heat as a by product
piloerection
- hairs stand up involentarily trapping air close to skin providing insulation via convection
list some structural adaptations and describe how they prevent heat loss
small SA:VOL ratio
- fatter rounder shape
- smalll extremeties
insulating fat
- blubber is a good insulator of heat as it a poor conductors thus preventing conduction to core.
- allowing skin to be cooler which decreases the heat gradient between it and the water
insulating fur
- thick fur trapas layer of air close to body
- air is a good insulator and poor conductor
for example the polar bear
counter current heat exchange
list some behavioral adaptation and describe how they prevent heat loss
huddling/clusters
- ectotherms such as bumble bees huddle together and shiver
- effectively reducing SA of individuals exposed to cool air
- penguins share time on outside of huddle
staying in burrows
- creates a warmer microclimate
- reducing temp gradient
basking in the sun
- absorbs heat energy from the sun throughradiation
migration
- moving to an area with a warmer climate
- removing the need for physiological and structural adaptations
describe characteristcs of the artic hare that enable it to prevent heat loss
- fat
- thick fur
-smaller SA:VOL ratio
-small extremeties - black ear tips which absorb heat and prevent damage to the ears
- burrows to avoid cold
- active by day
does a small animal have a large or small SA:vol ratio
the smaller it is the greater the SA: vol
will an organism with high SA:vol lose a greater proportion of heat (or faster) than an organism with a smaller SA:vol?
yes
why dont marine mammals have fur?
water compresses fur pushing the air out and is also not very hydro dynamic
how does blubber prevent heat loss
- poor conductor of heat
- fat has little blood flow as it has a low o2 requirement
- allows skin to be cooler reducing the heat gradient between it and the water
- reducing heat loss by conduction
decribe blood flow without countercurrent heat exchange
- artery and vein not touching
- arterial blood flowing to foot looses some heat to surrounding tissues
- large differences between foot temp and ambient temp means high rate of heat loss
- venous blood returning to core loses some heat due to surrounding tissue
- venous blood temp well below core temp therofre energy must be used to reheat blood to 37
blood flow with countercurrent heat exchange
- artery and vein touching
- arterial blood loses heat to venous blood
- cooler artial blood means the difference between foot temp and ambient temp is less which mean lower rat of heat loss
- foot temp kept slightly above ambient temp
- venous blood returning to core is warmed by the blood
- venous blood almost back to core temp therfore little energy required to heat blood 37
how is nitrogenous waste produced
- produced as a result of the breakdown of amino acid- deaminiation
- resulting in the production of ammonia which may be converted into uric acid or urea depending on the animal
describe the characteristics of ammonia is and what animals carry ammonia
- extremely toxic (high pH)
- very soluable in H2O
- energy inexpensive to produce (small molecules)
- needds to be excreted into very dilute urine
- excreted directly into surroundings
only aquatic invertebrates and vertebrates such as fish (through gills) and larval amphibians which have a large water supply
- as they produce soft shelled eggs in water so the ammonia produced by the embryo can diffuse into the environment
describe the characteristics of urea and what animals produce urea
- mildly toxic (100 000x less than NH3)
- moderately soluable (excreted dissolved in H2O
- energy expensive to produce (complex molecule)- organisms with a high MR
- mammals and amphibians animals with access to water
- allows internal development as foetal urea can be passed across the placenta
describe the characteristics of uric acid and which animals have it
- virtually non toxic
very low solubility - energy expensive (2x urea) - complex molecule
- excreted without loss of H2O allowing birds and repiltes to live in very dry areas
- low toxicity ans insolubility means it can be stored in hard shells, dry eggs during development
- allows birds to fly because they dont hve to carry heavy water with their nitrogenous wastes
how do you get water into your body? and how do you lose it? (terrestrial organisms)
- food
- drink
- metabolism
how to lose water
- lungs, kidney, skin and faeces
what is the importance of water in terrestrial organisms
excretion- removeal of waste products of metabolism (nitrogenous waste)
- temp regulation
- gas exchange- as it occurrs through moisture on membranes
- components of blood
- some nutrients needs to be absorbed
how does urine prevent water loss
- composed mostly of water, urea, ions, uric acid.
- substances reabsorbed in kidney (loop of henle) such as H2O, glucose, AA and most of the salts and urea
- long loop of H = more water absorbed
list some environmental, physiological and structural factors affecting water gain/loss
ENVIRONMENT
- availabilty of water
- temp
PHYSIOLOGY
- kidney (loop of H)
- large intestine
- diuretics increase urine production
antidiuretics decrease urine production
STRUCTURE
- SA:vol skin
- scales
- gills
describe the stimulus response model for high water balance
s- high H20 in blood
r- osmorecptors in hypouthalamus
m- hypothalamus
e- prosterior lobe of petuuritary stops ADH ( to increase urine production)
r- collecting ducts less permiable
f- decrease in h20 of blood
describe the stimulus response model for low water balance
s- low h20 in blood
r- osmoreceptors in hypothalamus
m- hypothalamus
e- posterior lobe of petuitary secretes ADH
r- collecting ducts more permibale to increse H20 absorption
f- h2o in blood
list adaptations for reptiles to decrease water loss
- scaley skin impervious to to water- descrease evap
- N excreted as uric acid paste- decrease in water loss
- nocturnal= cooler less evap
adaptations for mammals such as kangerroos
- metabolic water
- concentrated urine
- feed at dawn/ dusks = less heat produced
- long/large intestine= dry feaces
list the adaptions of ambipians
near water or humid environments
- some live underground in dry weather to create internal environment= increase in humidity
- some have waxy top layer to decrease evap
describe the difference betwenn isotonic, hypertonic and hypotonic
isotonic- same concentration
difference in ion concentration
A hypertonic solution has a higher concentration of solute than another solution, meaning water will flow into it.
A hypotonic solution has a lower concentration of solute than another solution, meaning water will flow out of it
WHAT ARE OSMOCONFORMERS
osmoconformers- maintain ion and water levels to be isotonic with surroundings
bodily fluid varies with that of the water (isotonic)
- intertidial species can tolerate large variations mile starfish and jellyfish
what are osmoregulator
osmoregulators- maintain ion and water levels are an optimum level which is either hypertonic or hypotonic to their surroundings
- TISSUES ARE HYPERTONIC
- REGULATE SALT AND WATER LEVELS TO MAINTAIN OPTIMUM LEVELS REGARDLESS OT THE CONC OF SURROUNDINGS
example: freshwater fish
describe the water regulation characteristics of marine bony fish
- hypotonic
- lose water(osmosis)
- gain salt (diffusion
- excrete excess salt through secretory glands in gills(active trans)
- sml vol high conc urine
(most N is excreted gills as NH3) - drink large amounts of salt water
decribe water regulation characteristics of cartilaginous fish (sharks/rays)
- kidney reabsorbs urea- maintaininf high urea levels
- lrg vol low conc
- excrete salt through gland in rectum
decribe the water regulation characteristics of marine birds
- ingest large amounts of salt
- excess water secreteed through nasal gland
- uses countercurrant blood flow to remove large amounts of salt
describe water regulation of freshwater animals and their adaptions
- low levels of dissolved ions
- alll freshwater fish are osmoregulators eg the ion conc in freshwater is lower that that of any living organsim
- amobea- contractile valcuoles which collect and expell excess water
- mammals- reabsorptions of salt in the kidney
- invertebrates- nephridial organs
how do freshwater fish in particular regulate thei water and salt concentration
- large amounts of dilute urine
- high filtration rate in kidneys
- large number of glomeruli
- reabsorprion of ions in kidney y active transport
- active uptak eof ions thrigh gils
- scales/mucus layer prevents water from entering body
draw a diagram of the movement of water an ions in freshwater fish and saltwater fish
describe the water up take in plants
- water moves into root hairs by osmosis
- from a low solute conc high solute conc
- across cell membrane
- passive process
- water moves along conc gradient due to there being a higher solute conc in plant than soil
- solutes move into root cells by active transport
why do plants need water
for phtotsynthesis
whats transpiration and how does it help a plants function
evaporation of water from the cells of the leaves, through the stomata
- helps cooling’
-tranport of minerals
- dissolving gases for exchange
- guardcells control water and gas exchange
what do guard cells do
when turgiid this wall stretches more than thicker one causing them to open
- they close to reduce exchnge of H2O , CO2
WHAT ARE SOME FACTORS EFFECTING TRANSPIRATION
- temp
- humidity
- wind
- light
- SA
- soil water
what are xerophytes and list some adaptations of these plants
plants adapted to dry habitat
- waxy cuticles
- stomata, on lower level of leaf, less openings to loose water
- low SA, less stomata less evap
- deep root system like jarrah tree
- only opening stomata at night; take up and store CO2 overnight + its cooler
- leaves hang vertically= less direct light
what are haplophytes and describe the water uptake in salty environment
plants in salty habitats
- conc of salts is higher in soil than root
- water moves root to soil
- plants will die from lack of water
- build up of a salt ( in cells) can interfere with ; enzyme production + hormones, metabolism/ cell function
describe how halophytes manage salts in their roots
returning sat to roots (vacuole)
- salt conc in cell> soil
- water moves from soil to roots
waxy cuticle on roots prevent salt entering
prevent salt entering roots by:
- filtration mechanism at roots(casparian strip)
describe how halophytes manage salts in leaves
- salt glands
- salt bladders
- accumulate salt in leaves and bark then drop
- store water in leaves (dilute salt)
- active transport to remove salt( into vacuoles: removesfrm cytoplasm, stops interfering with cell function
describe some adaptations halophytes have to reduce water loss
- reducing the number and size of leaves
-few stomata - sunken stomata
- silverhairs
- waxy cuticles
