L2 - NS Evolution Flashcards
Describe the NS of a singled celled organism
Receptive and response
Very basic properties
What is an example of a single celled organism whos NS can be studied?
What can it respond to>
Euglena
Can respond to photons of light which are transduced by a pigment localised to the eyespot
What can be said about the NS of the Euglena
Very basic
Little oppurtunity for more complex behaviour
What occurs with multicellularity
Specialisation
What type of behaviours can be seen in multicellular organisms
Anticipatory and responsive behaviours
Describe the flow of water through a sponge
In through the wall of the body - out throught the osculum
What iregulates flow of water in the sponge
Myocytes
Define what is meant by a myocyte in a sponge
Specialised muscle cells which are able to repsond to strech
Describe the proposed evolution of the myocyte in the sponge
Initially was found spanning the wall of the outer epithelium acting as an independent effector
Later found beneath the wall of the eipithelium recieveing communication from a sensorimotor neurone found in the epithelia which was responding to stimuli
Define what is meant by ‘motor neurones’
Recieve input from true sensory cells
Output to effectors and other motor neurones
What have recent studies in hydra found
Presence of neurosecretory cells
what is another word for neurosecretory
Neuropeptidergic
What types of chemicals are secreted by neuropeptidergic cells
Hormones
E.g. insulin, glucagon, somatostatin (controls growth hormone)
What is the important implication of the neurosecretory cells in the Hydra
These can regulate myocytes so it can be said there is a two way flow of information
What is also found in Hydra
Interneurones
Describe where interneurones are found
Lie between sensory and motor neurones/myocytes
What are the two types of interneurones what does this allow for
Can be excitatory or inhibitory
This allows for more complex behaviours to be seen
What two properties are seen in flat worms
CLustering and organisation
What is gangliation
The coming together of many neurones to form a cluster
Ganlia (PNS) nuclei (CNS)
What is cephalisation
Emergence of differences between the head and neck
What is bilateral symmetry
The symmetry around the anterior - posterior axis
What is fasiculation
Large bundles of axons instead of just a singular neurones
What is are commissures
The decussation across the midline to synapse with effects of the contralateral side of the body
Where in Amelids is there a large clustering of ganglia
Around the pharynx
What does this clustering around the pharynx give
Suprapharyngeal ganglia (primitive brain)
Why is the C.elegans such a useful model organism
The entire NS has been mapped out
How many neurones C.elegans
302
How many glia C.elegans
56
What are the three nerve cords found within the C.elegans
Ventral, dorsal and lateral
In the C.elegans what do most neuronal cells originate from
AB cells
What is the first division on the P0 cell in C.elegans
P1 and AB
What is produced in the division of the AB cells in C.elegans
ABa and ABp
What is produced in the division of P1 in C.elegans
EMS and P2
What is produced in the divsion of P2 in C.elegans
C and P3
What is produced by the division of P3 in C.elegans
D and P4
What do the P4 cells form
Germ line
What do the EMS cells divide into C.elegans
MS E
What do the MS E C and D cells in the C.elegans go on to form
Body, muscle, gut and the gonads
What do the AB cells form
Hypodermis and neuronal cells
What do the neuronal cells in C.elegans share a lineage with
The hypodermis (skin)
What is the major nerve cord in drosophila
What can be seen from it
Major ventral nerve cord
Can see lots of gangliation and cephalisation
DROSOPHILA LIFECYCYLE - Day 0
Egg
DROSOPHILA LIFECYCYLE - Day 1
Hatching of the larva
This then has 3 larval stages
DROSOPHILA LIFECYCYLE - Day 5
Pupation forms the pupa
DROSOPHILA LIFECYCYLE - Day 9 -
Metamorphis and the adult is produced
In a diagram of the early drosphila embryo what happens to the neurogenic region after the involution of the mesoderm
Delaminates and buds off forming neuroblasts
What do the neuroblasts then go on to form
The ventral nerve cord
What is the neurogenic region found next to
The ectoderm
What does the division of a neroblast produced
Another neuroblast
Ganglion mother cell
What do ganglion mother cells produce
Neurons and glia
Neuroblasts are known as
The dividing projenitors of the nervous system
What is common feature of vertebrates
Common body plan
What strucuture does the vertebrate NS develop from
Neural plate
Describe the neural plate
Single layered neuroepithelium
What side of the vertebrate does the neural plate develop
On the dorsal side
What is one of the most ancinent parts, evolutionarily of the CNS - what is its function
The hypothalamus is an autonomous integrating centre
What is the hypothalmus proximal to
The pharynx
What organism was used as an early pregnancy test
Explain how this would
Xenopus frog (vertebrate) When the female was exposed to high levels of progesterone (such as the concentrations found in a pregnant womens urine) it caused ovulation
What is next to the skin in the xenopus
Neurogenic region Whe
Which was does the neurogenic region migrate
Downwards
At what time point does the first neural differentiation take place in humans?
What does this mark?
2 weeks
Marks the point at which scientific experimentation is no longer allowed
What surface is the NS found on in vertebrates
Dorsal
What surface is the NS found on in invertebrates
Ventral surface
