Neuroanatomy Flashcards
What are the two areas of the nervous system and what is included in each of these categories?
PNS
- Cranial nerves (come off brain stem)
- Spinal nerves (come off spinal cord)
- Ganglia (dorsal root ganglia and autonomic ganglia)
CNS
- Brain and spinal cord
What are ganglia?
They are cell bodies of neurones that exist outside of the nervous system
Whats the purpose of the CNS?
Its the control centre for information processing, responding to sensory information, some are voluntary and some are involuntary
Whats included in the CNS and PNS when organising the nervous system in higher order organisms ?
PNS
- Nerve
- ganglia (aggregations of neurones)
- sensory receptors
CNS
- Brain
- spinal cord
Label this neuron…
Why are there several dendrites in neurons?
They are multi-polar so there are several denrites
What is around the axon in a neuron?
myelin which is white in colour and provides insulation to help speed up conduction in the neuron
Tell me 3 functions of a neuron?
Recieve stimuli
Transmit nerve impulses or action potentials
Activate muscles
What the role of a dendrite?
They collect electrical signals and carry input to cell body. They do this with chemical signals as well
Whats the role of the cell body/ Soma (these mean the same thing)?
It integrates signals and generates action potentials
Whats the role of an axon?
Transmits signals over long distances from the cell body to the axon terminals in order to communicate to the next neuron or organ its transmitting information to
Neurons in all species are the functional units of the nervous system, they are organised into a functional network which is capable of what?
- resonse to stimuli
- information processing
- communication
Differences in the nervous system amongst species are due to what?
Not the neurones but how they are organised
What are the ways in which neurons can be organised in different species give an example of a species which possess this type of organisation?
Nerve nets (simple organisms have nerve nets): hydras, jellyfish etc.
Cephalisation: starfish (echinoderms)
CNS: humans, cats, dolphins
PNS: humans, cats, dolphins
Name a multicellular organism without a nervous system?
sea sponges
Invertebrate nervous systems are specialised for what?
- stimulus/ response
- receptor/ effector
- reflexes, conditioned responses e.g. escape from predators
What are nerve nets?
What organisms is it found in?
The simplest form of the nervous system found in some invertebrates such as hydras and jellyfish
Individual nerve cells exist in a net-like formation scattered in layers of body wall.
Why do neurones in a nerve net exist in a ‘loose network’?
In order to allow for contraction and expansion of the body cavity
What do nerve nets lack?
distinct central or peripheral regions, and anything that resembles a brain
Nerve nets have no associative activity they only have what?
Reflexes (with action potentials)
Can nerve signals travel in both directions?
In an electrical synapse the signals can travel in both directions
In a chemical synapse the signals can only travel in one direction
What type of information can neurons carry?
What does the neuron do with the information that it recieves?
Information from sensory organs that detect touch, light or other changes in the environment
These neurons in turn contact neurons that control movement of the organism e.g. swimming
Species like star fish (echinoderms) display some centralisation of the nervous system explain the organisation of the nervous system in star fish and what this allows in terms of movement ?
They have a ring of neurons located in the centre with somple bundles of neurons (radial nerves) extending from the right to the tip of each arm
Radial nerve nets form nerve nets permitting coordinated movement of each arm and the tube feet located on the surface of the arm
When species show cephalisation, how is this known from their structure?
Cephalisation is an evolutionary trend over mant generations where the mouth, sense organs and nerve ganglia become concentrated at the front end of the animal producing a head region
The animals tend to show bilateral symmetry (right and left half and a head end)
In animals with bilateral symmetry what runs down the length of the body?
In animals like flatworms which show bilateral symmetry, there are 2 nerve cords which run down the length of the body
What does cephalisation allow?
The system to be more complex and have more control over the muscles for movement
There is diversity of the nervous system across organisms, tell me all the parts as they build up to make an organism complex like us?
What does a vertebrate nervous system contain?
- sophisticated sensory mechanisms
- clear differentiation of CNS and PNS as well as sensory and motor nerves
- elaboration of brain structure
What are the 3 main parts of the brain and what does each include?
Forebrain (cerebrum, optic structures, olfactory lobe)
Midbrain
Hindbrain (brainstem- pons, meddulla, cerebellum)
What does the hindbrain allow coordination of?
motor reflexes in vertebrates; regulation of autonomic processes
Tell me some similarites or differences you can see in the following image?
- cerebrum gets larger as you move to more complex organisms
- Earlier vertebrates have a smooth cerebrum
- forebrain is up front
- midbrain is the first part of the brain stem
- hindbrain is the lower part of the brain stem
What are sulci?
Infoldings of the cerebral hemisphere that form ‘valleys’ between the gyri
(singlular= sulcus)
What are gyri?
Ridges of the infolded cerebral cortex
(singular= gyrus)
Do all mammals have a gyri and sulci?
No
What does the presence of the sulci and gyri allow?
The presence of both allows for more specialised systems in the cortex and for more neurons which all contributes to a more complex organism as there is a larger surface area present when not smooth surface
What are the subdivisions of the CNS?
What are the subdivisions of the PNS?
What is another term for the forebrain?
Prosencephalon
What is the Proscencephalon divided into and what are each part representing?
Telencephalon (cerebrum)- the outer portion
Diencephalon (thalamus and hypothalamus)- can’t see from the outside of the brain
What is another name for the midbrain?
Mesencephalon- the top of the brain stem