Neuro Flashcards
What is the difference between white and grey matter?
White matter contains myelinated axons, grey matter contains cell bodies and no myelin sheaths
What is the function of oligodendrocytes?
Myelinating axons in the brain
Define tracts
Location of a pathway
Define funiculi
Rope or cord
Define fasiculi
Bundle
Define capsule
Sheet of white matter fibres that border a nucleus of grey matter
Define Column
Longitudinally running fibres seperated by other structures
Define cortex
Laminated grey matter on the outside of the brain
Define Nuclei
Collection of nerve bodies within the CNS
Define Ganglia
Collection of nerve cell bodies outside the CNS
Define afferents
Axons taking information towards the CNS
Define efferents
Axons taking information to another site from the CNS
Define reticular
‘Netlike’, where grey and white matter mix
Define ipsilateral
On the same side
Define contralateral
On the opposite side
Define rostral
Towards the nose (Anterior)
Define caudal
Towards tail (posterior)
What are sulci?
Grooves
What are gyri?
Ridges
What are the functions of the frontal lobe?
Voluntary movement on opposite side of the body. Frontal lobe of dominant hemisphere controls speech (Broca’s area), and writing.
Intellectual functioning, thought processes, reasoning and memory
What are the functions of the parietal lobe?
Recieves and interprets sensations, including pain, touch, pressure, size and shape, and body-part awareness (proprioception)
What are the functions of the temporal lobe?
Understanding the spoken word (wernicke’s- understanding), sounds as well as memory and emotion
What are the functions of the occipital lobe?
Understanding visual images and meaning of written words
What are some of the grey matter structures?
Thalamus, hypothalamus, and basal ganglia
What is the role of the thalamus?
Relay centre direction inputs to cortical areas
What is the role of the hypothalamus?
Links endocrine system to brain and involved in homeostasis
What is the striatum made of?
Caudate and putamen
What are the basal ganglia?
Caudate nucleus, putamen and globus pallidus
What is the lentiform nucleus made of?
Globus and putamen
What is the role of the basal ganglia?
Motor control, cognition and non-motor behaviour
What is the role of the cerebellum?
Co-ordinates movement and balance
How is the cerebellum attached to the brain stem?
Via three peduncles- midbrain, pons, medulla
How is the cerebellum seperated from the dorsal brainstem?
Via the 4th ventricle which forms part of its roof
What is the cerebeullum made up of?
Folded cortex, white matter and deep inner nuclei
What do cerebellar injuries result in?
Movements that are slow and uncoordinated
What is asynergia?
The loss of coordination of motor movement
What is an intention tremor?
Movement tremors
What is hypotonia?
Weak muscles
What is nystagmus?
Abnormal eye movement
What are the functions of the brainstem?
Special senses Sensory and motor for head and neck via cranial nerves Autonomic regulation of the body Regulates consciousness Pathway between brain and spinal cord
What is the mid brain formed from?
Tectum (superior and inferior colliculi) Cerebral peduncle (tegmentum and crus cerebri)
What does the mid-brain surround?
The cerebral aqueduct
What are the two types of specialised cell found in the CNS?
Neurones (many types e.g. pyramidal, stellate, golgi, purkinje)
Neuroglia (astrocytes, olgiodendrocytes and microglia)
What is the corpus callosum?
A huge fibre bundle that connects the left and right hemispheres together
What percentage of cells in the cerebellum are neurones?
70%
What are the roles of the cerebellum?
All sensorimotor, cognitive and motivational/effective structures connect to the cerebellum via re-entrant loops
Recieves input from motor cortex, brain stem nuclei and sensory receptors
Modulates upper motor neurones
Responsible for fine coordinated voluntary movement
What can damage to the cerebellum do to movement?
Make it inaccurate, slow and uncoordinated
What are the main components of the basal ganglia?
Dorsal striatum- caudate nucleus and putamen
Ventral striatum- nucleus accumbens and olfactory tubercle
Globus pallidus- internal and external segment
Ventral pallidum
Substantia nigra
Subthalamic nucleus
What are the competing systems in the brain?
Emotions
Cognitions
Sensorimotor
Which area of the brain selects which of the competing systems should be used?
The basal ganglia
How is the basal ganglia connected to inputs of the brain?
Via recurrent loops
What are the outputs of the basal ganglia like?
Inhibitory and tonically active (slow and continuous)
What system is the hippocampus part of?
The limbic system
What are the roles of the hippocampus?
Episodic memory
Construction of mental images
Short term memory
Spatial memory and navigation
What is anterograde?
Transport from neuronal cell bodies to axon terminals
What is retrograde?
Transport from axonal terminals to neuronal cell bodies
What are class A experiments?
Diagnosis
Some behavioural, physiological or pharmacological variable is manipulated and the consequent effects on brain activity/ structure are measured
What are the issues with class A experiments?
No adequate controls to ensure that the observed changes are produced only by the specific manipulation
Are measured changes in brain specific to the claimed region
What are type B experiments?
Treatment
Some aspect of the brain structure (lesion) or activity (stimulation/inhibition) is manipulated and the consequent effect on behaviour/physiology/endocrinology is measured
What are the issues with type B experiments?
Are the effects of the brain manipulation specific to the claimed changes
Is the brain manipulation specific to the intended neural structures
What does EEG stand for?
Electroencephalogram
How does an EEG detect brain activity?
It gives an indication of regional brain activity underlying electrodes. It is sensitive to activity in the temporal regions but less sensitive to those in spatial regions. EEG is good at detecting signs of epilepsy
How does a lumbar puncture detect brain activity?
Increases in neural activity results in the increase in the release of neurotransmitters and their associated breakdown products. This can be detected in the CSF via a lumbar puncture
What are the basic components of all neurons?
Dendrites
Cell body/soma
Axon
Presynaptic terminal
How do neurons stain under H&E?
The haemotoxylin stains the nucleic acids blue and the eosin stains the proteins red
What can be used to stain myelin?
Luxor fast blue
What can be used to stain nissI?
Cresol violet
What is the early marker of Alzheimers’?
The loss of dendritic spines
What are the three functional classes of neurons?
Afferent (sensory), efferent (motor) and interneurons (within the CNS)
What neurons are the nerves of the PNS formed from?
Groups of afferent and efferent neurone axons together with connective tissue and blood vessels
In which direction do afferent neurons convey information?
From tissues and organs towards the CNS
Where are afferent neuron’s sensory receptors found?
At their peripheral ends (fartherst from the CNS)
How do the sensory receptors of afferent neurons work?
They respond to various physical or chemical changes in their environment by generating electrical signals in the neurone
What are the two branches of the afferent axon?
The peripheral process and the central process
Where does the peripheral process begin?
Where the dendritic branches converge from the receptor endings
Where does the central process run?
It enters the CNS to form junctions with other neurons
In which direction do efferent neurons convey information?
Away from the CNS to effector cells such as muscle gland or other cell types
Where are cell bodies and dendrites of efferent neurons found?
Within the CNS
Where are the axons of the efferent neurons found?
Extending out towards the periphery
What is the role of the interneurons?
To connect neurons within the CNS
Where are the interneurons found?
Within the CNS
What is a myelin sheath?
20 to 200 layers of highly modified plasma membrane wrapped around the axon by a nearby supporting cell
What are olgiodendrocytes?
Myelin forming cells in the brain and spinal cord
What are schwann cells?
Cells in the PNS that form individual myelin sheaths surrounding 1 to 1.5mm long segments at regular intervals along the axons
What are node of Ranviers?
The spaces between adjacent sections of myelin where the axons plasma membrane is exposed to extracellular fluid.
Where are myelinated axons normally found?
Somatic nerves I.E. in fast sensory/motor systems
Where are unmyelinated axons normally found?
Post-ganglionic autonomic fibres, fine sensory fibres, olfactory neurones and interneurons
What are the roles of glial cells?
Surrounding the soma, axon, and dendrites of neurones and providing them with physical and metabolic support
What are the types of glial cell?
Olgiodendrocytes Schwann Cells Astrocytes Microglia Ependymal cells
How many axons can one olgiodendrocyte myelinate?
Up to 40
How many axons can one schwann cell myelinate?
1
What are the specific roles of astrocytes?
Help regulate the composition of the extracellular fluid in the CNS by removing K+ ions and neurotransmitters around synapses
Take up glutamate then convert it to glutamine and release it, then neurones can take it up and convert it back to glutamate for reuse.
Stimulate the formation of tight junctions between the cells that make up walls of capillaries found in the CNS- this forms the blood-brain barrier which is a more selective filter for exchanged substances that is present between the blood and most other tissues
Sustain the neurones metabolically e.g. by providing glucose and removing ammonia