FINAL EXAM- Olfaction Flashcards
Is intra- or inter-specific conflict worse? why?
- between group conflicts are worse as escalation occurs faster
- group competition often about territory and resources on those territories
what was the first sensory modality?
olfaction
what other sensory modality is sometimes connected to olfaction?
taste
Flehman response
- licking to bring molecules on tongue directly to the VNO (secondary olfactory system)
- raise head to allow air into mouth and cause molecules to spin, getting them closer to the VNO
what causes the quick processing of molecules during olfaction?
molecules are only one layer away from your brain which allows quick processing compared to other modalities such as vision
what proximity is olfaction designed for?
close proximity–> which causes constraints, and is under environmental constraints (ex. wind direction/ strength)
describe the speed at which volatile molecules travel?
-do not move quickly
=quite stationary
-if no wind, then will stay near source
Name 3 means in which olfactory molecules can be dispersed?
- current flow or fluids (air or water)
- diffusion –> gas expansion
- close to source is highest intensity
- gases expand - direct contact
- gustation often involved- but not actually for taste
implicit processing for olfaction is _____?
=smelling (unconscious)
explicit processing for olfaction is _____?
=sniffing (conscious)
-motor system involved, actively processing info around you
In what 4 dimensions does olfaction differ in?
- Directionality
- high to low concentrations, currents will influence - Speed
- diffusion is slow, trade off for permeance - temporal pattern
- almost none, or lost quickly - Spectrum
- no physical continuous dimensions
what is the production of chemical signals highly dependent on?
- The type of transmission (diffusion, current-borne, contact)
- The medium (air vs. water)
- often species specific
- dependent on density, composition, scent
- liposoluble (more persistent) or hydro-soluble
Contact odours
- usually pheromones
- dependent on what trying to contact
- hydrophobic
- lipids, large hydrocarbons
Waterborne odours
- size restriction of molecules do not count
- large organic compounds
- need to be water soluble (determined by polarity)
Airborne odours
- Volatile: evaporation needed but don’t want too quickly
- Stimulus: molecular size, weight and shape are important
- Environment:
1. wind and convection turbulences
2. Atmospheric conditions (can cause movement)
3. micro-meteorology
4. pedology: soli composition can influence how molecules decoded
describe a scent plume
- if you could see molecules, you would see a scent plume
- related to climatic/ environmental conditions
what are the main interferences with scent plumes?
- wind
- temperature
- humidity
- barometric pressure
what tool can be used to visualize wind?
=smoke bombs
**cant visualize movement of scent molecules just the wind, though scent molecules follow similar rules
what is key to understanding scent plumes?
=stability of the atmosphere
compare surface temp with temp aloft, the greater the difference= the more unstable/ greater the turbulence
what conditions are bad for sniffing?
- cold and dry conditions (i.e. winter)
- high positive ion concentrations
describe ‘tracking’
when an animal has acquired a scent/ trail, and is right on it
head drop= acquired scent
describe ‘trailing’
- before having acquired a source of an odour, looking for it
- related to ‘air scenting’
Plume Pattern: Looping
-high degree of convectional turbulence (diff in temp of ground and higher/ certain altitude)
- daytime
- cool air at high altitude, warm air at surface
-directionality hard to figure out (plume goes up and down, up and down)
Plume Pattern: Coning
- Normal/ stable thermal conditions
- cloudy days
- no dramatic cooling or warming
- great air scenting conditions
Plume Pattern: Fanning
- scent plume compressed vertically and fans out horizontally (higher than ground)
- calm clear night
Plume Pattern: fumigating
- stable air aloft, unstable air on ground (cooler scent plum diffuses down through warmer air)
- sunrise/ dawn
Plume pattern: lofting
- dusk/ sundown
- ground cooling but air still warm
diffusion vs. current flow–> which is dominant
current flow is dominant
What 3 factors influence the gradient of odour transmission?
- velocity (speed)
- viscosity of medium (state of semifluid)
- spatial scale (the ‘space’)
- some animals may have mental representation of space/ plum (at least innate)
Describe Reynolds number (Re)= gradient
=inertial forces/ viscous forces= how likely to stick somewhere
- mean flow velocity, length (distance), kinematic fluid viscosity
- goal is to quantify the transition between laminar and turbulent patterns of flow
explain the results of Reynolds number
small Re= mostly diffusion
moderate Re= laminar flow
high Re= turbulent flow
what is the diffusion coefficient
=D= degrees of freedom of a molecule in the medium
Factors defining D (3)
- size of molecule
- interaction of molecule with medium
- interaction of molecules with each other
what should be known in order to describe a ‘stimulus field’ ?
- the amount of chemical released
2. the threshold of detection for recipient/ reciever
Once a stimulus field is described, what can be determined?
- spreading
- fading
- density
Diffusion example: single, discrete puff
Q= number of molecules released k= receiver detection threshold
Active space:
- Sphere- above ground
- hemisphere= ground level
-relationship between these determines fade-out time
Diffusion example: single, continuous emission
Q= molecules/ sec –> smooth concentration gradient
not efficient way to communicate
Diffusion example: continuous emissions from a moving source
concept of a trail/ or tracking applies here
=sequence of puffs
Ex. snails, slugs, ants, snakes, etc.
Q= number of molecules released k= receiver detection threshold D= degrees of freedom of a molecule in medium L= length of a trail
current flow will increase what two things?
- speed of transmission
2. distance of transmission
Name 2 factors in current flow
- minimal: convection (vertical displacement)
2. maximum: advection (horizontal displacement)
Describe laminar flow
-displacement of molecule unidirectional, without turbulence, with constant velocity
- more likely with:
- slow velocity
- less dense media
- short distances - spread prediction easy, predictable, therefore navigation easier to track plum
- not common in normal environmental conditions (b/c wind, temp differences)
describe turbulent flow
- opposite of laminar: vortices, eddies, waves, etc.
- more likely with:
- high velocity (reduce range of transmission)
- dense media
- long distances
-
flows are created by ___ and ___?
- temperature differential
- Coriolis forces (from rotation of planet)
* cause convention effects
Name the 3 main factors that determine laminar vs. turbulent flow
- velocity (speed) of the flow
- density of medium (water vs. air)
- distance of defined flow space (things fade with distance)
what are hyperbaric conditions?
=high pressure conditions
scent dissipates quickly, but hugs the ground (pressure on ground)
in humans, threshold scores are higher in hyperbaric conditions
what are hypobaric conditions?
=low pressure
molecules NOT compressed to ground, can move freely–> initial scent will travel farther and higher
how does temperature influence taste and smell?
high temp warms things, which increases taste and smell- evaporation occurs faster
what are two interacting factors in terms of temperature?
evaporation and boiling point
how does temp influence evaporation?
- low evaporation at low temp; slow fading
- high evaporation at high temp; quick fading
how does molecular weight impact evaporation?
low evaporation at high molecular weight
at what boiling point are you more likely to smell?
low boiling point
how does rain impact evaporation?
rain keeps odour in ground (not all evaporated) –> if warm day
how does temperature impact turbulence?
high temp= thermal convection= high turbulence
impact of air humidity on spread of odours?
high humidity in air will decrease spread of odours= bad for trailing
humid air is heavier
unless lipid based, will diminish quickly
impact of ground humidity on spread of odours?
high humidity in ground will trap odours at ground level= good for tracking
definition of odorants/ odours/ scent/ smells
generic and/or neutral stimuli
may be organic, but not necessarily with biological significance
definition of ‘semiochemical’
=chemical volatile used in communication, also potentially signification or representation (can communicate a lot of info)
biological significance
definition of ‘pheromones’
for intra-specific communication
‘social odours’
definition of ‘allelochemicals’
inter-specific communication (between species)
kairomones
=subtype of allelochemicals where RECIEVER benefits
allomones
=subtype of allelochemicals where SENDER benefits
synomones
=subtype of allelochemicals
=mutualistic in nature (sender and receiver benefit)–> bidirectional
‘primer effect’ of pheromones
=changes via endocrine and neuroendocrine system (eg. McClintock effect)
prime endocrine system–> any changes will be detectable
‘signaller effect’ of pheromones
-communicate info about the individual themselves (sex, age, status)
‘releaser effect’ of pheromones
chemical acts as a sign stimulus to trigger a specific behavior (stimulus specific)
generate response from receiver
‘modulator effect’ of pheromones
influence (short term) mood and emotions, etc.
Rodent pheromonal effects are _____-dependent, and induced by ______
- testosterone-dependent
2. induced by normal adult males
Lee-Boot effect
- females housed together will experience a slowing and eventual cessation (suppression) of estrus
- response to environmental constraints; population control before it is an issue)
Witten effect
synchronization of estrous cycles of a group of females in presence of a novel male
Vandenbergh effect
early onset of puberty of females housed with adult males
Bruce effect
termination of pregnancy caused by presence/ smell of a new/strange male (not the father)
T/F - producing a pheromone is a behavior?
technically TRUE (implicit and explicit)
pheromone release is based on what 2 things?
- system used
2. hormones
what are the main channels for pheromone release?
- secretory glands (endocrine and exocrine)
- excreted waste material (urine, feces, sweat, etc.)
- plant-based chemicals
endocrine glands vs. exocrine glands
Endocrine: ductless glands secreting hormones in the blood vessels
exocrine glands: glands with ducts (ex. salivary, sweat, mammary, etc.)–> communicate info quickly, ducts used to get molecules outside body (released in volatile form)
intracrine system
regulation of intracellular events
autocrine system
hormones act on the cell that released them
paracrine system
hormones act on cells adjacent to them
neurocrine system
release of NT in synapse (pre to postsynaptic cell)
neuroendocrine system
release of neurohormones form the neurosecretory cells
what system is most likely involved in communication of pheromones?
exocrine system
advantage of endocrine cells
-blood system/ vascular system
ADVANTAGE: get from one gland to whole body quickly
involve HPA and HPG axis
exocrine glands…
- controlled by___?
- released in ___?
- controlled by endogenous hormones
2. released in the lumen of the glands
3 types of exocrine glands?
- Merorine
- Apocrine
- Holocrine
Exocrine gland: Merocrine
- process
- appearance
- efficiency
- function
- types
- Exocytosis: vesicles open-up and molecules go to bloodstream
- watery to slimy (if high content of protein=mucous)
- fast release–> less solid present
- mate attraction and alarm substances
- eccrine sweat glands (palms. soles, armpit, forehead)
digestive glands
nasal mucosa glands
Exocrine gland: Holocrine
- process
- appearance
- efficiency
- types
- death + breakdown of entire cell in inner lining of glands
- thick, more solid, oily–> sebum
- slow release, evaporate less quickly, sticky
- Sebaceous glands (humans; all over body except palms and soles)
Exocrine gland: Apocrine
- process
- appearance
- efficiency
- types
- combo of other two processes (part of cell ‘pinch off’)
- milky (not clear, a little solid within)
- intermediate efficiency
- -Apocrine sweat glands (humans; armpits, pubis, naval, nipples)
- Mammary glands- communication between young and mother
species specific gland examples:
- hamster
- ground squirrel
- salamander
- birds
- hamster= lateral glands
- squirrel= dorsal and cheek (mark den entrance)
- salamander= chin gland (scent mark ground)
- birds= uropygial (oily secretion rubbed on feathers for waterproofing)
Ungulates: 5 discrete glands
- caudal: tail
- tarsal: back of leg to mark resting sites
- interdigital: behind digits to track
- preputial: odour in urine
- preorbital: corner of eye, territory marking (branches)
do humans release pheromones?
human body highly suggestive of ability to release pheromones, but not a lot of literature/ evidence suggesting we do- there is data that we implicitly process pheromones
ex. synchronization of menstrual cycles
why do fish have a protective mucous layer?
the mucous is rich in protein
- good for contact (proximity)
- feeds the young
what specific gland do snakes have? and its function?
=Cloacal glands
-produce thick and smelly mucous to scare predators and used to communicate
what is special about female garter snakes?
- have own identifiable chemicals
- holocrine-like mechanism from the skin
- gives info to males about reproductive state and size of female
excreted products include ….
- urine
- feces
- breath
- saliva
- sweat
- from gills
excreted products provide information on: (6)
- gender –> males have more androgens, females estrogens
- dominance status –> correlation between androgen levels and rank
- fertility
- receptivity
- general health –> implicit interaction between endocrine and immune systems
- kin relatedness
sexual steroids
=Androgens, estrogens progestogens
stress steroids
=cortisol, corticosterone
sources of steroids
=testes, ovaries, adrenal glands (cortex), placenta
steroid hormones originally vs. after use
Originally: hydrophobic, liposoluble
After use: hydrophilic, hydrosoluble derivatives
by product of steroid hormones are cues or signals?
=CUE
are steroid hormones species specific?
steroid hormones often not species specific
HPA axis vs. HPG axis?
HPA= stress
HPG= sex
how does the HPA axis influence the HPG axis?
LT overactivity of HPA axis can cause suppression of the HPG axis and impact immune system
*low ranking animals may have suppression of HPG axis
what system may be involved in fear?
SAM system
SAM system
- involved in fear and panic
- quick signalling/ response to stressful events
- focused on adrenaline and noradrenaline
HPA axis vs. SAM system
HPA axis= slow response to stressful event
SAM system= much quicker to stressful event
*animals may be able to smell fear
steroid hormones….
- synthesized from _____?
- sources?
- behavioral involvement
- cholesterol
- adrenal cortex, placenta, gonads (NS to lesser extent)
- sex and stress
protein hormones ….
- what are they?
- sources?
- behavioral involvement
- small protein=peptide hormone, large protein= polypeptide hormone
- pituitary gland hormones, neurohormones, large group of hormones
- reproductive and social behavior
monoamine hormones ….
- also known as?
- sources?
- behavioral involvement
- modified amino acid
- -catecholamines (adrenal medulla and CNS)
- Indoleamines (melatonin): CNS and pineal gland
- Thyroid hormones (derived from tyrosine): thyroid glands
- stress and arousal, biorhythm, sleep
What binding protein family is involved in transporting pheromones to a liquid secretion?
Lipocalin family
Ex. saliva in boars and hedgehogs
Ex. Aphrodisin in female hamsters (motivate male to mount female)
active scent marking can involve …. (2)
- anal glands for feces- very active in mammals
2. preuptial glands for urine (pheromones scent urine)
how and why do beavers scent mark mud mounds?
scent mark mud mounds with castoreum (mixture of urine and feces) for territorial defense
detectable from far away
what three chemical components do male rats have for active scent marking?
have two that attract opposite sex and one that attracts the same sex
“group scent” as they are social animals
scent marking example with salamanders and lizards
- fecal pellets to mark territories
- some species are careful not to mark too close to home to prevent predators from knowing where they are (ex. foxes)
3 main sources of odorants in house mouse?
- major histocompatibility complex (MHC) –> from preuptial gland secretion
- urinary protein odours
- preuptial gland secretion
* all have volatile and nonvolatile component
What is the function of the major histocompatibility complex (MHC)
- recognition system for most vertebrates; kin recognition and selection of non-related mates
- fingerprint, gives info about genetic relatedness, info about health of immune system
- use kidney-urine channel (binding to urinary metabolites)
what are major urinary proteins (MUP)?
= are lipocalins (male mouse urine has 3-4x more protein than females= smellier)
FUNCTIONS:
- for individual recognition
- indicate endocrine and immune stress
- provide gender information
*r-selected: quantity over quality
Preputial gland…
- uses what as channel?
- main chemical compound and its effects?
- urethra to scent urine as it passes
- farnescene
- high level in dominant males
- triggers aggression in other dominate males
- supress aggression in subordinate males
- attractive to females
bacteria derived volatiles can come from bacteria that is ____ or ___?
- within glands bacteria (vaginal fatty acid) or
2. external bacteria (areas with hair)
amount of bacteria in glands is representative of what?
-level of health
- males are less likely to seek out a female treated with antibiotics
- humans tend to have normal bacteria levels, when sick we smell different due to overload of bacteria
- marker is the scent of parasites that signal you are not healthy
two dimensions of the spread of scents?
- complexity of release mechanism (how?)
2. placement of chemical (where?)
what is dissemination often associated with?
specific postures and behaviours or correlates of postures and behaviours
describe preening in birds
=birds spread the smell as much as they can all over their body
-if odour right on body it means you can rub it on other objects
examples of behaviors associated with direct release of scent in a fluid medium
usually release comes with specific motor behavior
- insects and fish- calling posture (use wing to spread)
- spraying urine in mammals (territorial defense or get attention of opposite sex)
- self generated current/ wafting (bats, fish, insects)
what is the best way to advertise self?
to scent your own body, thus enhancing own chemical profile
2 ways of depositing scent on senders own body
- Bare skin via skin glans (skin glands produce and then spread around)
- Hair dispersal (specialized hairs are osmetrichia)
- hair can help diffusion of scent molecules
describe ‘self-anointing’
= acquisition of odour of other species
Ex. rolling in decomposed material in canids
Active vs. passive methods of the deposition of scents onto solid substrates
Passive= no specific behavior necessary (problem: info useful to both conspecifics and predators)
Active= specialized behavior associated with marking (literal scent marking behavior with urine and feces)
Ex. wild cats–> go back to same spot (latrine) to eliminate
canids–> scent mark everywhere within territory
has to do with how social species is- use to communicate (alpha scent marks more than sub)
how is vasopressin associated with urine retention?
more social species have higher levels of vasopressin then oxytocin to help regulate scent marking behavior
- males scent mark more= higher vasopressin levels
- females have higher oxytocin levels
what is overmarking?
- area used for urination competition; communal urination site
- alpha pees and then others challenge by overmarking/ peeing over it
what is a keeper substance?
=increased permeance
-lipids and waxy esters (thicker, oilier, less volatile)
Ex. sebum slows release
two main components of the olfactory system
- primary/ main= olfactory bulb
- accessory/ secondary= VNO or Jakobsen’s organ
* both processed by limbic system
what happens if bypass thalamic processing of scent?
get emotion before cognition
what is ‘smound’
=perceptual object by merging sound with smell
–> about how quickly both reach limbic system (more likely to be associated)
why are olfaction and taste differences unclear in fish?
have taste and olfactory receptors on barbs
–> very specific cell receptors
name the 3 pathways fish have to process scents?
- crypt cell receptors (pheromones)
- microvillus receptors (food odours)
- ciliary receptors (alarm substances)
microsmatic vs. macrosmatic
microsmatic= sense of smell not great (i.e. humans)
macrosmatic= sense of smell is dominant
do humans have a VNO? what do we have?
- not a lot of evidence suggesting we have VNO–> if do it is vestigial
- have turbinates= grooves in nasal cavity that swirls scent inside when inhale
is VNO exclusive for pheromones? is it necessary to process them?
- No not exclusive
- not necessary either (can be destroyed and still process pheromones –> VNO may be able to process nonbiologically relevant odours, can identify prey in some species
how is the olfactory system associated with emotions?
- direct access to limbic system (can bypass thalamus)
2. cortical access via thalamus (higher order processing)
what is the main olfactory motor behavior in mammals?
sniffing
what system do air breathers rely on to process scent?
respiratory system
olfaction is insignificant in cetaceans and birds with the exception of ____
- turkey vultures (can detect leaks in pipelines)
- tube nosed seabirds (use in flight often at night)
- nocturnal birds
- kiwi (gets food from ground)
- oilbirds (search for ripe fruit)
black footed albatross–> can detect bacon fat in ocean 30km away
VNO is present is ______, and absent/ vestigial in _____?
PRESENT:
-tetrapod’s=amphibians, reptiles, terrestrial mammals
ABSENT:
-fish (not completely), crocodiles, turtles, birds, primates, aquatic mammals, some bats
are pheromones always species specific?
not necessarily
when is mating behavior disrupted in hamsters in relation to processing of pheromones ?
when both VNO and olfactory epithelium are damaged–> both send projections to amygdala, so if lesioned will also disrupt behavior
brain regions involved in pheromones in mammals (3)
- preoptic area (POA): processes pheromones
- hypothalamus: detect fear, detect threats from visual system, direct info from olfaction, critical in taste
- amygdala: connected to primary olfactory bulb
- olfactory epithelium
* all involved in mammalian sexual behavior*
what does removing VNO do?
-in some animals nothing, in others can disrupt sexual behavior and/or act as model of depression
what is the VNO specialized for?
- for large non-volatile chemicals
- for small soluble chemicals via water or mucus
examples of behaviors specific to VNO pheromone processing?
- Amphibians: nose-tapping or trickling of water
- reptiles: tongue flicking
- mammals: nose rubbing, vascular pumping action (look like in trance, intense and rare)
olfactory bulbs are rich in what kind of receptors?
=dopamine receptors
olfactory responses are dopaminergic in nature
what is critical in order to determine the source of odours?
know directionality–> intensity of gradient also key
what is kinesis?
random walk based on movement when in smooth gradient, speed and turning rate are modulated
what is taxis?
non-random, guiding behavior when in smooth gradient- based on info as you go
tropotaxis vs. klinotaxis
both subtype of taxis (non-random behavior)
Tropotaxis= simultaneous sampling or stereo-olfaction
ex. nostrils in mammals, forked tongue in snakes
Klinotaxis= sequential sampling (temporal gradient used to infer position of source)
- horizontal: back and forth movement of head
- vertical: up and down movement of head
in turbulent flow, what two processes must be engaged in order to determine orientation of scent?
- detection of direction of source
2. detection of direction of flow
Anemotaxis vs. rheotaxis
Anemotaxis= orientation in relation to wind
rheotaxis= orientation in relation to current
function of mechanosensors
often used to identify directionality of wind or water currents (not useful with swimming or flying animals)
describe ‘casting’?
=zig-zagging across the flow (complex pattern to find anything when a lot of air displacement or no wind at all)
