Homeostasis Flashcards
what is the definition of homeostasis?
the condition of a relatively stable internal environment, maintained with narrow limits
what internal conditions need to be controlled?
carbon dioxide, oxygen
waste
temperature
water salts
PH
glucose
what is a negative feedback loop?
an increase in one thing leads to an decrease in another eg glucose
how does the human body decrease heat loss in cold?
Vasoconstriction, reducing sweating conscious behaviours, reduction of surface area
how does the human body decrease heat production in heat ?
decrease movement, metabolic rate
how does the human body increase heat production in cold?
shivering increased movement and metabolic rate
how does the human body increase heat loss in heat?
vasodilation sweat, conscious behaviour, increased surface area
why does the body’s limits need to be maintained ?
enzyme activity
cellular functioning
nerve transmission
muscle contraction
what are the methods that heat is gain or loss?
radiation=waves of energy
conduction =contact from one molecule to another
convection=the movement of air
evaporation = water molecules get evaporated
what is and ectotherm ?
an organism that gains heat from the external environment and there body temperature fluctuates and may regulate temperature through behaviour
what are advantages of ectotherms ?
little energy requirement
can feed less often
stay in shelters longer
what are disadvantages of ectotherms ?
inactive in cold and the night
more likely to be prey
restricted by geographical range
what is an endotherm?
an organisms that gains body heat from metabolism and have a consistant temperature
what are advantages of endotherms ?
body temperature is consistent
often predators
what are disadvantages of endotherms ?
large energy requirements
need insulation or cooling mechanisms
what are physiological adaptations to heat?
sweating or panting
coat thinning
vasodilation
decreased metabolic rate
what are structural adaptations to heat?
insulating fur=shades skin
large surface are to volume ratio
what are behavioural adaptations to heat?
wallowing in water
staying out of direct sunlight
decreasing physical activity
increasing surface area
what are physiological adaptations to cold?
Vasoconstriction
increased metabolic rate
Torpor : hibernation long term inactivity, diurnation short term inactivity
shivering
piloerection
what are structural adaptations to cold?
small surface area to volume ratio
insulating fat
insulating fur
counter current heat exchange
what are behavioural adaptations to cold?
huddling/clusters
staying in burrows create a microclimate
basking in the sun
migration to avoid cold
what is the relationship between SA:VOL and shape?
- spheres are shapes that have the smallest SA:VOL
- longer and thinner shapes have the highest SA:VOL
what is the relationship between SA:VOL and size?
the smaller the size the greater the SA:VOL
what is the relationship between SA:VOL and heat loss?
heat is loss at a set rate per area
the higher the SA:VOL ratio the greater loss of heat
what is the relationship between SA:VOL and metabolism?
the smaller the organism the greater the SA:VOL therefore the greater the metabolism to maintain homeostasis
why do marine mammals not have fur?
water compresses fur pushing out the air
it is not hydrodynamic
how does blubber prevent heat loss?
-poor conductor of heat
-little blood flow
-reduces the heat gradients
-reducing heat loss by conduction
counter current heat exchange?
- artery and vein are touching or close
- arterial blood loses heat to venous blood
- cooler arterial blood means the difference between foot temperature and ambient temperature is less which means lower rate of heat loss
- foot temperature kept slightly above ambient temperature
- venous blood returning to core is warmed by the arterial blood
6.venous blood is almost back to core temperature therefore little energy is required to reheat blood
what is nitrogenous waste ?
a product (ammonia) of breaking down amino acids
what are the characteristics of ammonia?
-extremely toxic
-very soluble in water
-energy inexpensive to make
-needs to diluted to be excreted
-excreted directly into surroundings
-only invertebrates and vertebrates
-produces soft shell eggs in water so the ammonia produced buy the embryo can diffuse into the environment
what are the characteristics of urea?
-mildly toxic
-moderately soluble
-energy expensive
-mammals and amphibians
-allows internal development as foetal urea can pass across the placenta
what are the characteristics of uric acid?
-non-toxic
-very low soluble
-energy expensive
-excreted without the loss of water
-allows birds to fly without the weight pf water
-birds and reptiles
-stored in hard shelled, dry eggs during development
how do humans lose water?
-lungs
-skin
-kidneys
-faeces
what is the fluid balance?
the fluid loss=the fluid gained
what is the importance of water ?
excretion
Temperature regulation
why is water important for excretion ?
the removal of the waste products of metabolism nitrogenous waste
why is water important for temperature regulation ?
gas exchange occurs through moist membranes
what is urine composed of?
water, urea, ions, uric acid
what does the loop of henle reabsorb?
water, glucose, amino acids, salt and urea
what does a longer loop of henle result in ?
more water reabsorption
what are factors that effect water gain or loss?
Environment: availability of water, temperature
structure: SA:VOL ratio, skin ,scales, gills
physiology: kidneys(loop of henle), large intestines
write a SRMERF for low water ?
S: low water in blood
R: osmorecptors in hypothalamus
M: hypothalamus
E: posterior lobe of the pituitary gland secretes ADH
R:collecting ducts become more permeable
F:increase in water in blood
write a SRMERF for high water ?
S:high water in blood
R: osmorecptors in hypothalamus
M: hypothalamus
E: posterior lobe of the pituitary gland stops ADH
R:collecting ducts become less permeable
F:decrease in water in blood
what adaptations do camels have?
-sweating at only high temperature
-concentrated urine
-dry faeces
-metabolism of fats produce water
-oval blood cells
what adaptations do kangaroo rats have?
-water from metabolism of food
-respiratory moisture condenses in nasal passage
-long loop of henle produces concentrated urine
-dry faeces due to long large intestine
-burrows during the day
what adaptations does a kangaroo have?
-metabolic water
-elongated large intestine = dry faeces
-concentrated urine
-efficient locomotion
-feed at dusk and dawn
what adaptations do reptiles have?
-scaly skin=decreased water evaporation
-nitrogenous waste excreted as uric acid
-shade during the day=decreased evaporation
what adaptations do amphibians have?
-near water or in humid environment
-some secrete waxy covering = decreases in evaporation
-some live underground
what adaptations do invertebrates have?
-waxy cuticle
-uric acid paste=low in water
-seek shade
-absorb water from air
what is the definition of isotonic?
same concentration of dissolved ions
what is the definition of hypertonic?
high concentration of ions
what is the definition of hypotonic?
low concentration of ions
what is the definition of osmocomformers?
maintains ions and water levels to isotonic with surrounding
what is the definition of osmoregulators?
maintains ions and water levels at an optimum level which is either hypertonic or hypotonic to their surroundings
what happens to marine organisms in water?
sea water is hypertonic to most organisms resulting in osmosis of water out of the organism and diffusion of ions moving into the organisms
what do marine osmoconformers do in salt water?
there body fluid composition varies with that of the water surrounding them
what do marine osmoregulators do in salt water?
regulate their salt and water levels to maintain optimum levels regardless of the concentration of their surrounding
what do bony fish do in sea water ?
they are hypotonic compared to sea water so they lose water through osmosis and gain ions through diffusion but have salt secretory glands
what do cartilaginous fish do in sea water ?
excrete salt via salt gland in rectum
what do marine organisms do in sea water ?
-kidneys produce urine high in urea and salt
-survive on metabolic water
-food sources high in water
-highly efficient at reabsorption of water from rectum
what do marine birds do in sea water ?
-high levels of salt in food and water
-excess salt excrete via nasal glands
-use counter current blood flow to remove large amounts of salt
-glands secrete solution with high concentrated of salt then sea water
what do osmoregulator do in fresh water ?
ameoba=contractile vacuoles collect and expel excess water
mammals=reabsorption of salts in the kidneys
invertebrates=nephridial organ like kidney
what adaptations do fresh water fish have?
-large amounts of diluted urine
-active uptake of ions through gills
-scales prevent water entering the body
how is water gained and loss in xerophytes?
-gained via root hairs
-loss via evaporation
why do plants need water?
for photosynthesis
what is transpiration ?
evaporation of water from the cells of the leaves through the stomata
what are the benefits of transpiration ?
keeps leaves cool, transport of mineral, dissolving gases for exchange
what is gas exchange in guard cells
when turgid thin wall stretches more then thicker ones causing them to open lossing water=decreased gas exchange
what factors effect transpiration?
temperature
wind
surface area
Humidity
light
soil
water
what does leaf size have to do with evaporation ?
small leaf = low surface area = less stomata = less evaporation
large leaf = large surface area = more stomata = more evaporation
what characteristics of xerophytes leaves?
-leafs surface has hair
-small and narrow
-curl or roll
-drop leaves in dry season
-leaves hang vertically
-thick waxy cuticle
what characteristics of xerophytes roots?
-shallow roots
-deep roots that hit the water table
what characteristics of xerophytes?
-stomata on a lower leaf surface
-reduced number of stomata
-pits in the stomata
how do halophytes manage salt in there roots?
return salt to roots
waxy cuticle to stop salt
Casparian strip
how do halophytes manage salt in there leaves?
salt glands
salt bladder
Accumulation of salt in leaves and bark to be dropped
store water in leaves
active transport to remove salt
how do halophytes reduce water loss?
-reduce number and size of leaves
-few stomata
-sunken stomata
-silver hairs
-waxy cuticles
