Nervous System Flashcards
(38 cards)
Explain how the nervous system is divided.
CNS and PNS
PNS goes to Afferent and Efferent
Efferent goes to Somatic and Autonomic
Autonomic goes to Sympathetic and Parasympathetic
What are the different types of cells in nervous system?
Glial cells and neurons
What are glial cels?
Functions: support, development, function (myelination)
They outnumber neurons
What are the different types of glial cells?
Schwann cells (PNS)
Oligodendrocytes (CNS) - similar to above, different location. Create myelin sheath.
Astrocytes (CNS - growth factors + signalling
What are the different types of neurons?
Sensory, motor, and interneurons
What are some characteristics of neurons?
Post-mitotic = dont divide
Membrane proteins respond to voltage
Synapses (electrical and chemical)
Intricate connection patterns
How is the neuron structured?
Dendrites are projections off the cell body = inputs Cell body (soma) = cell metabolism Axon hillock = AP inititation Axon = AP propagation Synaptic terminal
How is the nervous system compared to other vertebrates?
Generally similar, few specializations
Which animals and vertebrates did we talk about for nervous system specializations?
Amphioxus (not a vert.) (subphylum cephalochordata) Lamprey (Agnatha) Sharks Bony Fish Amphibians Reptiles Birds Primates (Mammalia) Blue Whale (Mammalia)
How is the Amphioxus’ nervous system?
Simple
Hollow dorsal nerve cord that stays hollow
No distinct brain; 10,000 neurons only
Unique NMJ - muscles send projections to nerve cord, not vice versa
Peripheral nerves - no myelin
Simple photoreceptors, chemoreceptors, mechanoreceptors - no functional eyes or olfactory epithelia
What are the characteristics of the Lamprey nervous system?
Simple brain - cephalization Diffuse ANS No myelin Electrical and chemical synapses Smallest brain/body mass ratio
What are the characteristics of the shark nervous system?
Brain/body mass ratio > bony fish
ANS more distinct
Myelin present!
Separate rase, smell receptors
What are the characteristics of the bony fish nervous system?
Diverse brains
Lateral line –> pressure sensors (prominent in schooling fish)
Mauthner nerve cells - fast start reflex triggered and connects to opposite body wall muscles
What are the characteristics of the amphibian nervous system?
NS similar to fishes
Cerebrum not well developed
Spinal nerves modified for limbs - increased muscles in limbs
Cerebellum less complex than fish
What are the characteristics of the reptile nervous system?
Small brain/body mass ratio
Cerebrum more developed - takes on role of other parts of the brain (before mostly smell)
Thalamus = important relay center
What are the characteristics of the bird nervous system?
Brain/body mass ratio = high
Cerebrum enlarged - more thinking + learning
Some sensory nerves are decreased (touch, smell) - because eyesight important and smell sucks
Cerebellum is large and highly folded
What are the characteristics of the primate NS?
Brain/body mass ratio = highest
Front, occipital lobes are increased
High speed conduction (myelin)
Occipital = vision; Frontal = learning + memory
What are the characteristics of the blue whale nervous system?
Largest brain (9-10kg) Highly folded cerebrum Inferior colliculi enlargement (important for coordination of sound)
Why does the brains have folds in it? Where do we see it more?
Usually bigger mammals have more folded brains
Folding is important because otherwise the brain wouldn’t fit
What does the brain/body mass ratio mean?
It gives us an idea of intelligence
What vertebrates have the top 3 brain/body mass ratios?
Humans, porpoises, chimps
Which dinosaur was the smartest? How do we know?
Troodon
We think this because it had the largest brain case, and use this to estimate brain/body mass ratio
Which dinosaurs were dumb?
Sauropods, really small heads compared to their bodies
So small they shouldn’t even be able to coordinate movement
Which animals were outliers on the brain/body mass ratio chart?
Dogfish and sting rays - but they aren’t smart
It is because there are only certain parts of the brain that correlate with intelligence. Eg. large medulla does not equal smart
