APS136 3 Flashcards
An adaptation is..
a trait that increases the fitness of an organism in its environment (increases chance of survival)
- trait is selected for
- genetically determined, therefore heritable
Camels can go without water for … … and without food for … …
2 weeks,
2 months
Acclimation is…
a physiological compensatory response to environmental change (experimental) - a short-term response to the environment
- not heritable
- may be immediate or build up over time
- experimental
- e.g. yoga in unnaturally hot room or moving fish into new water
Acclimatisation is..
a physiological compensatory response to environmental change (natural) - a short-term response to the environment
- not heritable
- may be immediate or build up over time
- natural
- e.g. acclimatising to naturally hot outside conditions (rather than unnatural lecture theatre conditions)
Plasticity is…
the ability of living organisms to change their ‘state’ in response to any stimuli
- occurs at any level of complexity: molecular, cellular, systemic and behavioural
- limited
- e.g. rockhopper penguins
At high altitudes there is low … … and low … …
barometric pressure
atmospheric oxygen
The concentration of oxygen at 4000m is about … lower than at sea level
40%
Each haemoglobin molecule has … oxygen binding sites
4
Normal oxygen saturation is between…
96-100%
- oxygen saturation is the % of haemoglobin binding sites that carry oxygen
At low partial pressures of oxygen, e.g. in the body tissues, Hb has … …, so oxygen is …
low affinity,
released
At high partial pressures of oxygen, e.g. in the lungs, Hb has … …, so oxygen … ….
high affinity,
binds readily
At high altitudes (with low oxygen saturation), you can suffer from … and the oxygen transport system must respond to…
hypoxia,
maintain sufficient tissue oxygen concentration
The Andeans in Bolivia have been living at high altitudes of 4000m for…
13,000 years
A population of Tibetans have been living at altitudes of 4000m for…
25,000 years
High-altitude erythrocytosis is…
increased red blood cell production at high altitudes
Andeans had … Hb concentrations than their closest living ancestors at low altitudes, showing that they were…
higher,
physiologically stressed
There is … … … in Hb between Tibetans living at high altitude and their closest ancestors living at low altitudes
no significant difference
- must be compensating in a different way
The … had higher oxygen saturation than the …, suggesting they were…
Andeans, Tibetans,
less stressed by hypoxia at the same altitude
The altitude study show…
elevation in haemoglobin is not a universal response to high altitude hypoxia
- the Tibetans respond instead by having a higher respiration rate and higher nitric oxide which increases vasodilation
What is the downside to higher erythrocytosis?
Higher Hb leads to more viscous blood, which can put strain on the heart
- a trade-off as it is better for dealing with hypoxia but puts heart at risk
The altitude at response was much lower (1600m compared to ~4000m) for the …
Andeans
- Tibetans required much stronger stimulus
Homeostasis is…
any self-regulating process by which biological systems maintain stability whilst adjusting to variable environmental conditions
- dynamic equilibrium
Internal environment is … not …
stable, static
- continuous change occurs but relatively uniform conditions prevail
Why maintain a steady state?
External environments vary - some external conditions would be lethal to individual cells
- internal processes require certain conditions
- enzymes are often heat-activated
- chemical reaction rates are often temperature dependent
- proteins may denature at very high temperatures
- maintaining concentration gradients
Stimulus –>
receptor –> control centre –> effector
The receptor…
monitors the internal environment
The control centre…
sends a message to the effector (via the nervous or endocrine system) when a parameter exits its normal range
The effector…
re-establishes the internal environment to the set point
Feedback…
returns the output to the input part of the system
In birth, the hormone … stimulates contractions, the contractions themselves stimulate … production, and this is an example of … …
oxytocin, oxytocin, positive feedback
Homeostatic mechanisms are … so are … if not necessary, e.g….
costly, lost,
naked mole rat has lost fur as no need to regulate temperature in stable underground environments
At night, hummingbirds can enter a state of…
torpor - conserve energy as temperature falls to 18-20C (normal 38-40C)
- so can pygmy possums
Pygmy possum body temperature in torpor seemed to…
map onto the ambient temperature as it was changed
Black bears hibernate for …, and their heart rate is … and more …
5-7 months, slower, irregular
Why use performance enhancing drugs (doping)?
- build muscle mass and strength
- increase O2 delivery to exercising tissue
- Mask pain/injury
- decrease weight
- hide use of other drugs
Erythropoietin (EPO) is naturally produced in the body in response to… and causes the bone marrow to..
a reduction in blood oxygen concentration,
release lots of red blood cells with Hb to bring up oxygen saturation
Natural stimuli for erythropoiesis include…
- low atmospheric O2
- exercise
- haemorrhaging
Doping using erythropoietin can increase O2 supply by … but side-effects include…
7-10%,
- Blood thickens
- Heart has to work harder
- increased risk of heart attack/stroke
Meldonium is used to treat
coronary heart disease as it increases blood flow and therefore flow of oxygen
- banned in 2016
- curling dude and maria sharapova
How much do lil rotifers weigh?
0.01 micrograms
How much do phatass blue whales weigh?
100,000 kg
Larger animals experience greater…
gravitational forces
Larger animals have a smaller…
surface area to volume ratio
Larger animals tend to:
- move more slowly
- Have slower digestion rates
- Have slower respiration rates
- Lose heat to the environment less quickly
- Lose water to the environment less quickly
Allometry is..
the study of differential growth
- how body parts or physiological processes scale with body size
Static allometry is when…
body proportions differ between individuals of the same age and sex within a species
Isometric scaling is when…
body proportions stay the same with development (e.g. frogs)
Ontogenetic allometry is when…
body proportions change with development (e.g. humans)
Evolutionary allometry is between…
individuals of different species
When describing allometric relationships, y =
ax^b
y = size of body part x = measure of whole body size a = an initial growth index. Size of y when x=1 b = scaling exponent. Proportional change in y per unit x
If b = 0, size of variable body part is…
unrelated to whole body size - remains exactly the same (not talking about proportion here buddy)
If b = 1, the variable body part scales…
at the same rate as the whole body size (isometric scaling)
if b < 1, the variable body part increases…
slowly relative to body size (negative allometry)
If b > 1, the variable body part increases…
at a faster rate than the whole body size (positive allometry)
Using a log-log scale…
linearises the relationship
For allometric graphs, the units on both axes must…
be the same
Skeletons become…
more robust and larger relative to overall body size as body size increases
Isometric doubling of length will increases surface area … and volume (thus …) …
fourfold, mass, eightfold
- organism has 8x mass to support but area to support weight increases 4x
- organism has 8x metabolically active tissue to support, but respiratory surface areas only increase 4x
Similarly sized endotherms will always have higher … than their ectotherm counterparts
BMRs
(base metabolic rate)
- and unicellular lower than ectotherms
Marine mammals have higher BMRs than … …, which have higher BMRs than …
terrestrial mammals,
marsupials
Metabolic Rate (MR) =
Body weight (W)^0.75
Mass specific MR =
MR/W
therefore
Mass specific MR = W^0.75/W^1 = W^0.75-1 = W^-0.25
Due to the higher SA:V ration, relative to the white rhino the meadow vole has…
- higher heart rate
- higher respiration rate
- higher food intake per gram body weight
If body temperature is too low…
- metabolism slows down
- oxygen supply is inadequate
- cells can freeze (membranes rupture, breakdown of tissue)
If body temperature is too high…
- proteins denature
- oxygen supply in inadequate
- Membrane structure is altered
Heat moves from…
hot areas to cold areas
What is the mammal optimum temperature range?
Lizards?
Insects - some species of butterfly?
36-38C
32-40C
28-39C
Radiation is the transfer of heat, without …, by … …
contact, electromagnetic waves
- accounts for 60% of heat transfer
Conduction is the transfer of heat with…
contact
- accounts for 3% of heat loss
Convection is the movement of….
air/fluid across the body surface
- accounts for 15% of heat loss
Evaporation accounts for…
22% of heat loss
The last form of heat loss is…
respiration
Larger animals lose heat…
less quickly due to the smaller SA:V ratio
Lower temperature gradient means…
slower heat transfer
Insulation reduces…
heat loss to the environment
Ectothermy is also known as…
poikilotherms
Ectotherms derive their heat from the … and are temperature …
environment, conformers
Endotherms have a … temperature, regulated by deriving heat from …
metabolism
What are the benefits of being an ectotherm?
- Metabolic rate 5x slower (require less food, H2O & resources)
- Can devote large proportion of energy budget to reproduction
- Good colonisers of poor/arid environments
What are the costs of being an ectotherm?
- No nocturnal environmental niches (unless in tropical and summer temperate climates)
- Cannot sustain high activity bursts as risk O2 debt (reptiles tend to be ambush predators) - fatigue rapidly
- Susceptible to sustained predation by endotherms
What are the benefits to endothermy (homeothermy)?
- Can sustain high activity bursts
- Nocturnal activity in all habitats possible
- Able to exploit colder environments
- Forage widely and migrate over long distances
What are the costs of endothermy?
- Require large body sizes with low SA:V ratios
- metabolic rate is 5x faster than ectotherms
- need more food and water
- cannot devote large proportion of energy budget to reproduction
- Poor colonisers of poor/arid environments
What is the thermoneutral zone?
The range of temperatures in which an animal does not expend energy to maintain Tb
Tb is..
body temperature
Above the thermoneutral zone is called the … … … and below is called the … … …
upper critical limit,
lower critical limit
Which part of the brain is responsible for thermoregulation?
Hypothalamus
Vasoconstriction:
- diameter of superficial blood vessels decreases
- blood flow to skin decreases
- skin cools
- less heat lost to E through radiation, conduction and convection
- heat is trapped in the body core
Shivering:
Rapid skeletal muscle contractions
- consumes ATP
- generates heat (increases heat production by 500%)
- When primary fuel (glycogen) runs out, body uses proteins and lipids as fuel
Which hormones can increase cellular metabolism and therefore heat?
- Adrenaline (released from adrenal medulla, increases heart rate)
- Thyroxine (released from thyroid, increases basal metabolic rate)
Insulating Brown adipose tissue is rich in … which break down fuel into heat only, rich in … …, specialised for rapid … … and found in … mammals, … mammals and the … of human adults.
mitochondria, blood supply, heat production, newborn, hibernating, necks & shoulder blades
White adipose tissue has…
no intracellular organelles and little blood supply
Stork legs, whale tongues, and dolphin fins have…
countercurrent heat exchange
Blubber is…
a thick layer of vascularised adipose tissue under the skin of sea mammals - low thermal conductivity of skin, with low metabolic activity
Fur/hair/feathers reduce convection by…
trapping a layer of insulating warm air close to the skin surface
- effect lost if air replaced by water or oil (oil spills)
Vasodilation:
- diameter of blood vessels increases
- blood flow to skin increases
- skin heats up
- more heat lost to E through radiation, conduction and convection
Perspiration:
- Glands in skin secrete sweat onto surface to increase heat loss by evaporation - evaporative cooling (water has a greater capacity for absorbing heat than air and absorbs heat when it evaporates, releasing heat)
- sweat also increases convection rate
Panting:
- evaporation of moisture from the mouth and tongue
- exchange hot air in the lungs with cooler external air
Birds don’t have sweat glands but have a method called…
a gular flutter - rapidly flap membrane in the throat to increase evaporation
Urohidrosis:
defecation on legs for evaporative cooling
Blood plasma is … water
Breast milk is … water
Mucus is … water
Sweat is … water
92%
88%
95%
99%
Why do we need to regulate body fluids?
The concentration of body fluids is usually different to that of the external environment
Solutes can be moved…
actively (against a concentration gradient) or passively (along a concentration gradient)
What factors affect diffusion rate?
- Temperature (higher temperature, higher rate as faster moving particles)
- Size of particles (smaller particles, faster rate)
- Electrical charge (can facilitate or prevent passage)
- Concentration gradient (greater gradient, faster rate)
Osmolarity is…
a measure of the osmotic pressure exerted by a solution across a perfect semi-permeable membrane (only water can cross) compared to pure water
Osmolarity =
(number of particles per molecule of solute) X (moles/litres)
measured in osmoles/litre (Osm/L)
Molecular weight of glucose is…
180
The cell is … to the extracellular fluid
hyperosmotic
Tonicity is…
the effect of a solution on a cell volume
It depends on:
- solutes
- membrane permeability
Depends on concentration of non-penetrating solutes only
Give examples of osmoconformers?
Elasmobranches (sharks and rays) and lots of marine invertebrates
Frogs have limited…
osmoregulation
What generates nitrogenous waste?
The breakdown of proteins and nucleic acids
- in the digestive system
- for energy or conversion into fats/carbohydrates
- Amino group (NH2) is removed
When NH2 joins a hydrogen ion it forms … which is highly … and raises the … of body fluids, inhibiting key …
ammonia, toxic, pH, enzymes
Which animals excrete ammonia?
Bony fishes, aquatic amphibians, aquatic invertebrates
What are the advantages and disadvantages of excreting ammonia?
- Doesn’t require energy
- small molecule –> rapid diffusion
BUT - very toxic
- affects osmolarity as highly water-soluble
SO - animals that excrete ammonia need access to lots of water
Which animals excrete urea?
Mammals, most amphibians, cartilaginous fish
Urea is produced in the … by combining ammonia with …
liver, CO2
Urea is … less toxic than ammonia and requires less … to excrete, but requires … to make
1000x, water, energy (1 and a half ATP)
Uric acid is produced by…
birds, insects, reptiles and some amphibians
Uric acid is completely … and even less … than urea.
Insoluble (excreted as a semi-solid - great for conserving water),
toxic
But uric acid requires … as much energy to make as urea
3x
Uric acid is useful if development takes place inside an …
egg
- even urea would build up toxic concentrations
Tadpoles excrete .. but adult frogs excrete …
ammonia, urea
Terrestrial turtles excrete … but aquatic turtles excrete …
uric acid, ammonia
The west african lungfish excretes … in water but when water dries up it excretes … on land
ammonia, urea
Protozoa have organelles called … … which expel water with nitrogenous waste out into the environment
contractile vacuole
Annelids, molluscs and platyhelminthes expel waste using …
nephridia
- and excrete through nephridiopores
Insects collect waste with … …
malpighian tubules (attached to gut)
How do seabirds excrete salt?
Nasal salt glands + excrete out of nostrils
Insects are susceptible to water loss as…. so they excrete … to conserve water.
they have a relatively high SA:V ratio, uric acid
Malpighian tubules are…
- blind-ended tubes
- have walls exactly one cell thick
- found between midgut and hindgut
- float in haemolymph
Coccids have … malpighian tubules whereas desert locusts have …
2, 250
Salts and nitrogenous waster are … … into gut lumen through malpighian tubules, and water follows by …. Re absorption occurs from the …, and salts and valuable organic molecules are pumped back into the …, with water following by …
actively transported, osmosis, rectum, haemolymph, osmosis
Kidneys receive … … blood, high in … … from the … ….
High pressure, waste products, renal artery
The … … leaves the kidney with filtered blood
renal vein
Waste products are passed into the … on the way to being excreted.
ureter
The kidney receives … of the cardiac output from our bodies
20-25%
What are the four stages the kidneys use to remove nitrogenous waste from the blood?
- Filtration (blood fluids collected)
- Reabsorption (selective transport of needed substances back to tissue fluid/blood)
- Secretion (of un-needed (toxic/excess) larger substances into filtrate)
- Excretion of filtrate
The membranes in the kidney are … …
selectively permeable
The renal cortex is important in the process of …, whereas the renal medulla is important in the process of…
Ultrafiltration,
regulating water and salt in the blood
The functional units of kidneys are called…
nephrons
- single long tubule surrounded by network of capillaries
Blood pressure in the … forces fluid into the lumen of the … …
glomerulus, bowman’s capsule
- non-selective process, occurs by diffusion
The ascending limb of the loop of henle is … to water
impermeable
ADH (antidiuretic hormone) is also known as…
vasopressin
- increases water permeability of the distal tubule and collecting duct
In the thermoneutral zone…
no metabolic energy is required to be spent on temperature regulation
What are the two strategies used to minimise damage at extreme temperatures?
- Tolerance - capacity to endure environmental conditions without adverse reaction
- Avoidance - prevent damage from occuring
Heat shock proteins (HsPs) are present…
in all major compartments of all cells (animals, prokaryotes, plants)
- limit consequences of damage from heat stress
- they are molecular chaperones
The functions of heat shock proteins are…
- to promote the proper folding or refolding of protein
- to prevent potentially damaging interactions with proteins
- to aid in the disassembly of formations of protein aggregates
Expression of HsPs is a … response
stress
Stress conditions … proteins, these … proteins are … and HsPs proteins are produced/upregulated/induced, and these … denatured proteins.
Denature, denatured, detected, refold
HsPs have … and … H bonds
better, more
+ better shape harder to denature
Heat shock proteins also perform a secondary function in the … …
immune system
- usually found intracellularly, so if found extracellularly suggests that cell membranes have been damaged
- helps to present antigens from diseased cells to T cells, which destroy diseased cells
- (serve as warning signal to the body)
Drosophila larvae were genetically engineered to have more copies of HsPs genes. Compared to wild type flies they showed…
greater mortality and slower development
How are sub-zero temperatures damaging?
Ice formation causes external fluid to freeze, and therefore solute concentration of the external fluid to increase so water leaves by osmosis and cells shrink. The cell membrane structure degrades and ice crystals are pointy so cause cell damage
Freeze avoidance:
avoid freezing by keeping the bodily fluids liquid
Freeze tolerance:
can tolerate the formation of internal ice
How do insects avoid freezing?
- Selection of a dry hibernation site in which no ice nucleation from an external source can occur
- Physical barrier such as wax-coated cuticle that provides protection against external ice across the cuticle
- Depress the temperature at which bodily fluids will freeze, by:
- supercooling (removing or inactivating ice-nucleating agents in the gut or intracellular compartments (water can cool to -42C without freezing))
- cryoprotectant synthesis (increase solute concentration, therefore decreasing freezing point - most common is glycerol, which attracts water molecules)
How do insects tolerate freezing?
- Limit supercooling, initiate freezing of body fluids at relatively high temperature
- Produce ice structuring proteins (antifreeze proteins), which bind to small ice crystals to inhibit growth/recrystallisation of ice
- Produce ice nucleating proteins which allow insects to control the formation of ice crystals within their bodies, avoiding a sudden, total freeze - allows the insect to moderate the rate of ice growth, adjust more slowly to the mechanical and osmotic pressures imposed by ice formation
Arctic woolly bear moths can withstand … during annual period of diapause. They accumulate … (glycerol and betaine) in late Arctic summer. They form a … to eliminate nucleators.
- 70C, cryoprotectants, hibernaculum
- they are freeze-tolerant
Goldenrod gall moth larvae supercooling points drop from -14C to … during autumn. The water content is decreased and the … content is increased.
38C, glycerol
- they are freeze-avoidant
The wood frog uses both strategies. It can supercool to … and can survive weeks at -8C in a frozen state with … of total body water as ice - tolerates freezing of … water
- 3C, 48%, extracellular
- no anticipatory accumulation of cryoprotectants during autumn - triggered by initiation of ice formation in the body
Red bark larvae can survive temperatures of … due to high concentrations of glycerol deliberately dehydrating tissues to concentrate ice-structuring proteins, so the body water forms a glassy substance rather than freezing
-150C
The snow flea can synthesise an … (ice-structuring) protein that can be made synthetically for use in extending the storage life of donor organs for human transplantation
antifreeze
- rich in glycine
r =
(∆P x A)/D
∆P = difference in partial pressure A = surface area D = distance
r = rate of diffusion
Insect tracheae penetrate to..
individual cells - don’t need blood to carry oxygen to cells
Insect ventilation is …. Larger insects may exhibit … … … which compress and expand the trachea, pumping air through.
tidal, rhythmic body movements
Insects can close spiracles when…
Insects have … around spiracles to trap water
the environment is dry - to minimise water loss,
hairs
Many insects have … … which store air and are useful when the environment is dry or energy demands are high
air sacs
Respiratory surfaces must always be…
moist
Per cycle birds have 2 …
inhalations
- can have 8-9 air sacs
- unidirectional so no mixing of air
Birds have a type of blood flow called…
crosscurrent flow
Bird lungs are…
relatively small for their body size
The fact that lungs are inside the body minimises…
water loss
In humans, not all air is exhaled due to tidal ventilation. This means that the percentage of air that is oxygen is…
lower in the lungs than in the outside air
Marine mammals can store oxygen in their … as well as their lungs
muscles
- they are more efficient at extracting oxygen
- they can also temporarily cut off circulation to some parts of the body
CO2 levels rise –> chemoreceptors –>
medulla –> increased breathing rate
- negative feedback
Currently … of bird species are experiencing maximum ambient temperatures above their … … …. This is predicted to rise to … by 2080
15%, upper thermal tolerance, 36%
Currently … of mammal species are experiencing maximum ambient temperatures above their upper thermal tolerance. This is predicted to rise to … by 2080
16%, 47%
… come in different colour morphs: common, black and white. Different phenotypes have slightly different body temperatures and are more/less common at different …
Springboks, temperatures
- we expect number of black morphs to decrease
Phenotype plasticity is…
the ability of a single genotype to produce different phenotypes when exposed to different environments
Fish are ectotherms, so as environmental temperatures rise, … … increases and therefore … requirements increase. This is a problem as … concentrations in the sea are falling due to a … …
metabolic activity, oxygen, oxygen, warming climate
We will probably see a decrease in fish … … in the future due to increasing temperatures and decreasing oxygen availability
body size
- may have follow on effects on other species
In an experiment cape white eye birds were housed at current ambient temperature and 4C higher, and physiological measurements (metabolic rate and water loss) were taken. What was found?
No difference
In another experiment, perch physiology was studied in waters warmed by a nuclear plant. What was found
Perch from the control area had lower oxygen consumption and cardiac output than those in the warm waters near the nuclear plant.
Insects in the tropics live closer to their … … … than those found nearer the poles
thermal tolerance limits
