Mollusks - How the nervous system works Flashcards
how many species of Mollusca are there?
more than 100,000
Mollusca is the ____ largest animal group after arthropods
2nd
How are Mollusca diverse?
they are diverse in their
- morphology
- modes of nutrition
- reproduction
- response to environment
how are Mollusca symmetrical?
bilaterally
Mollusca are ___plastic
triploblastic
what are the four major groups of Mollusca
- polyplacophora
- gastropoda
- bivalvia
- cephalopoda
what does the mantle cavity of Mollusca contain?
gills
For land living organisms the mantle cavity is …
an extended space for surface oxygen exchange
The front end of the intestine is known as the
radula
the Polyplacophora is known as the
“bearer of many plates”
how many overlapping plates does the Polyplacophora have?
eight!
Polyplacophora are…
omnivorous
where are the gills located in Polyplacophora
in the mantle grooves?
Polyplacophora are able to withstand ___ ____
low oxygen
Bivalvia means …
“two valves”
Bivalvia have a reduction of
head
the mantle cavity of Bivalvia is modified by
siphons
how do Bivalvia get oxygen?
by using their gills
what else do the gills of Bivalvia do?
filter food
are Bivalvia sessile or mobile?
sessile
what kind of feeders are Bivalvia
filter feeders
Siphons are extensions of
posterior mantle
In Siphons water flows in the __ ___ and then across the ___ that act as ___ for food
mantle cavity ; gills ; filters
there are two exits/entries in Siphons
one water is sucked in and the other water is squished out
what is the most diverse group of mollusks?
Gastropoda
how many species of Gastropoda are there?
85,000
what kind of eaters are Gastropoda?
herbivores, predators, scavengers
what kind of fertlization do Gastropoda do?
both internal and external
Gastropoda are either _______ or hermaphroditic but can produce only sperm or eggs at any given time
dioecious
Dioecious means
separate sexes
Gastropoda means
stomach foot
how do Gastropoda move?
torsion of the body
where is the anus of a Gastropoda
over the head!
a species of Gastropoda are
land snails
where are the eyes located on Gastropoda?
on the tentacles
what is the radula modified into in cone snails?
into toxic harpoons
cone sails are also known as
cigarette snails because if you’re stung by one, the only time left tat you have is for one cigarette
nidubranchs means
naked gill
aposematic says
don’t touch me! I’m toxic!
How do Gastropoda reproduce?
love darts
- mutual exchange of sperm
Cephalopoda have an enlarged _____ and a reduced ____
head ; shell
what do Cephalopoda use their mantle and siphon for?
jet propulstion
Cephalopoda use this to shoot ink out of the mantle cavity and use this fore to push predators away
Siphon
Cephalopoda have visual communication with
colour and texture
what do Cephalopodas use as their defense?
ink sac
what kind of circulatory system do Cephalopoda have?
closed.
some Cephalopoda use their tentacles to transfer
sperm
how do Cephalopoda reproduce?
separate sexes with elaborate courtship
what kind of fertlization do Cephalopoda do?
internal
how do male Cephalopoda transfer sperm?
via a specialized arm called the hectocotylus
what happens to female Cephalopoda after they lay/hatch their effs
they die
what does the reproduction cycle of Cephalopoda NOT have?
Trochophore larva
how many arms do Nautilus?
80-90 arms
how do Nautilus regulate its buoyancy?
with gases in chambered shell
Nautilus are the only extant ____ chephalopod
shelled
when did Ammonite go extinct?
at the end of the creatceous period
Mollusks are ___ for parasites
vectors
the giant squid can reach up to
15 m long
giant squid are large enough to support intracellular recording by the first
microelectrode
what is the function of the nervous system?
to produce behaviour
what tasks does the nervous system perform?
detection and analysis of sensory signals
what tasks does the nervous system perform?
decision making
what tasks does the nervous system perform?
generation of coordinated motor output
what tasks does the nervous system perform?
disregard non-important information
the nervous system also generates…
mental activity
Dendrites
receive information from other neurons via synapses
cell body (soma)
contains nucleus and most cell organelles
what integrates info collected by dendrities and initates action potentials?
axon hillock
what is known as the “telephone line of nerve cell” that synapses at terminal to target cell
axon
what are glia cells?
electrical insulation of nerve cells
what do Neurons generate and transmit?
electrical signals
what do glial cells provide?
nutrients that maintain extracellular environemt
glial cells are part of the
blood-brain barrier
glial cells fight…
infections of the nervous system
how do neurons work?
ELECTROCHEMICALLY
what does ELECTRO mean?
difference in charge across the cell membrane
what does CHEMICAL mean?
concentration gradients of ions across cell membrane
what prevents the free movement of ions?
lipid bilayer
what controls the ion flux across the membrane?
ion channels and ion transporter proteins
what determines the membrane potential?
the interaction of two forces
what does diffusion favour?
it favours the net movement of ions down their concentration gradient
this force favours net movement of ions according to potential difference
electromagnetic force
when the two forces are balanced for a GIVEN ION this is called
equilibrium potential
Depolarization
Na+ channels open
when does depolarization become regenerative?
if the tresh-hold level of depolarization reaches around -50 mV
when Na+ channels close while voltage-gated K+ channels open this is called
repolarization
How are concentration gradients of ions maintained in the long run?
by ACTIVE processes
what does Na+/K+ pump require?
ATP
Brief “spikes” of membrane potentail from resting potential towards equilibrium potential of Na+ are called
action potentials
Graded potentials
strength and temporal pattern of input determines mebrane potential; potential decays with distance along nerve fiber; only works over short distances
how is information encoded in electrical activity or nerve cells and populations of nerve cells?
nerual code
