L8 Animal Sensory Systems

Animal Sensory systems

Chemoreception

• A chemical ligand triggers receptor, causing signal transduction

• How an organism detects and responds to chemical stimuli

Mechanoreception

Stretch waves includes hearing (hair cells bend to pressure of incoming sound waves)

The process of detecting mechanical stimuli such as pressure, touch, and sound through specialized receptors

Photoreception

A photon strikes a receptor, which induces an ion cannel to open

how an organism detects and responds to light

Polymodal sensilla

complex organs that contain both mechano- and chemoreceptors for feeling and tasting their environment

insect antennae

Can insects detect water and ammonia

yes

what do insects detect?

What is olfaction

sense of smell which allows an organism to smell odors

Label

Retronasal

breathing through the mouth

The odorants curve up into your nasal sinus

• Thus, when your nose is clogged you cant smell as good

Olfactory epithelium

odorants enter the nasal cavity and adhere to mucosa in the olfactory epithelium

Olfactory bulb

Bipolar sensory neurons penetrate the braincase to the olfactory bulb

Olfactory pathway

Why are olfactory receptor neurons (ORN) called bipolar?

Bc morphologically their cell body is the middle of the cell, but they still transmit APs (action potentials) one way to the olfactory bulb

orthonasal olfaction

breathing through the nostrils

Watery mucosa

Enhances smelling by trapping odorants which allows them to bind to an odor receptor more easily

Olfaction in fish

Water passes through their nares (allows for always fresh sampling)

This leads to olfactory epithelium in the olfactory rosette

Sharks have a lamellae which is similar to a rosette

positive chemotaxis

Going toward stimulus

negative chemotaxis

Going away from stimulus

Pheromones — how works / purposes

AKA chemoattractant

Signal only sent within the same species

Helpful for finding a mate, immediate relative, ones offspring, territories, other animals rank or sec

Chemosensory sensilla

small hairlike sensory organs that detect chemical stimuli

Activation of salty TRCs

sodium directly enters Na+ channel from the salt which opens voltage gated Ca+ channels, leading to depolarization and NTM (antagonistic signaling molecules) release

Activation of Sour TRCs

protons from acidity blocks potassium channel, which prevents K+ efflux, depolarizing the cell

This opens the VG-Ca+ channels, leading to NTM release

Protons inhibit potassium channels

Activation of sweet TRCs

Sweet substance binds to GPCR, which activates adanylate cycase to cAMP which inhibits K+ channel which depolarizes the neuron and causes NTM release

Different GCPR activated → Ca+ influx

Activation of bitter or umami TRCs

different GPCRs are activated

Why do some ppl have different flavor preferances or aversions?

bc we have different populations of GPCR heterodimers in our taste receptor cells

Some ppl are more sensitive/insensitive to certain tastants depending on the density and type of taste receptors

Thermoreception

Detection of heat

Pit vipers use this to find prey in the night

TRPs (transient receptor potential) open in response to heat

Differential heat detection in left or right side of organisms head will tell them the direction of their prey

TRPs

transient receptor potentials

A1 channels

line the membrane of pit organs

What are pit organs + 2 animals that have them

pit viper (located in their face and look like nostrils) and bats (located left, right, and above their nostrils)

these are indentations on the face which detect heat — it may be like seeing bc this information is sent to the optic tectum in the brain

Pit viper uses them to sense where a prey is and vampire bats use them to sense where a spot with a lot of blood is on an animal

Nociception

Sense of harm/pain

Proprioception

Sense of awareness of the position of one’s body parts in space

Chondrichthyes

Cartilaginous fish

Who usually has electroreception

Chondrichthyes — cartilaginous fish

What are the electro sensors called in sharks? other info?

Ampullae of Lorenzini (AoL)

they detect weak electromagnetic fields + maybe touch and temp

They go deep into the dermis and open to the water through a large pore

A conductive gel fills the canal from the external surface pore to the ampullae —- in this is keratin sulfate (the highest conductivity known for biological material)

Are the AoL (Ampullae of Lorenzini) in sharks considered an active or passive form of electrolocation?

Passive

The 3 steps of active electrolocation

1. discharge from caudal electric organ

2. Detection in dermal sensors

   1. Interpretation in the brain

How is electrolocation in elephantnose fishes is benificial in this species? Where is the signal dispersed from their body? Is this passive or active?

Their electric wave they create around them is distorted when their is something in it like a rock/worm, and thus they can detect it in the dark

dermal electroreceptors

active

EOD

Electric organ discharge

Electrical communication for JAR

JAR = Jamming avoidance response

When species in close vicinity that both use electrolocation will dim their frequency or go up a few Hertz in order to not interfere with their signals

evidence for independent evolution of electric organs in fish? How do they differ between taxa?

active electrolocation and communication evolved independently in two taxonomic orders

Africa and in South America

New world (south america) knifefishes and electric eels emit waves

Old world fishes (africa) elephantfish emit pulses (lower trace)

Differences in EODs are explained by mutations in the VG-Na+ channels

Gustation

Tasting