Brain Anatomy Flashcards
What are the 3 primary vesicles that form the brain?
Prosencephalon, mesencephalon and rhombencephalon
What 2 secondary vesicles does the prosencephalon become?
Telencephalon and diencephalon
What 2 secondary vesicles does rhombencephalon become?
Metencephalon and mylencephalon
What secondary vesicle does mesencephalon become?
Stays as mesencephalon
What part of brain does telencephalon become?
Cerebral hemispheres
What part of the brain does the diencephalon become?
Thalamus and hypothalamus
What part of the brain does the mesencephalon become?
Midbrain
What part of the brain does the metencephalon become?
Pons and cerebellum
What part of the brain does the myelencephalon become?
Medulla oblongata
Neurons are not the most common cell in the central nervous system. True or false?
True. Supporting cells outnumber neurons
What is the soma of the neuron?
The cell body
What is the function of dendrites and axons? (And which tends to be longer?)
Dendrites bring info towards cell body and axons carry info away (axons tend to be longer)
The typical neuron has one dendrite and multiple axons. True or false?
False - one axon and multiple dendrites
What are the 4 major types of glial cells of the CNS?
- Astrocytes
- Oligodendrocytes
- Microglia
- Ependymal
What is the role of astrocytes?
Support
Maintain blood-brain barrier
Homeostasis
There is no connective tissue in the brain - true/false?
True.
What is the function of oligodendrocyte in CNS (and what is name of cell with same function in PNS)?
Produce myelin
Schwann cell in PNS
Schwann cells produce one layer of myelin around multiple axons in PNS and oligodendrocytes produce multiple layers of myelin around one axon in CNS - true/false?
False.
CNS has one layer myelin sheath around many axons
PNS has multiple layers myelin around one axon
What are Nodes of Ranvier and what are their function?
Short regions of axon that don’t have myelin sheath. It is gap between myelin sheaths along the cell.
Function is to allow nerve impulses to jump along axon which speeds it up
What is the function of microglia cells?
Immune monitoring and antigen presenting
Which glial cells in CNS are of hemopoietic origin? (Like come from similar place as macrophages)
Microglia
What is the function of ependymal cells and what shape are they?
- Line the fluid filled spaces (e.g. ventricles) - kind of epithelial cells
- ciliated cuboidal/columnar shape
What are the gyri, sulci and fissures of the brain?
- gyri are the bumpy bits
- sulci are the valleys between gyri
- fissures are deep sulci
What is the difference between cells in grey matter and white matter?
- Grey matter contains the neuron cell bodies, processes and synapses
- White matter contains the axons
Grey matter is mostly on the outside in brain and inside in spinal cord and white matter is inside in brain and outside in spinal cord - true/false?
True
In the spinal cord what are the grey matter and white matter areas known as?
- Grey matter areas called posterior and anterior horns
- White matter areas called posterior, lateral and anterior columns
What is the Sylvian line on the brain?
Lateral fissure that separates temporal lobes from superior frontal and parietal lobes of brain
What are the internal capsules of the brain?
White matter strips on both sides that bring info between cortex and brain stem
What are the medial and lateral margins of the lentiform nucleus called?
Medial -> globus pallidus
Lateral -> putamen
What is the corpus callosum?
Sits above lateral ventricles and is biggest white matter communication between brain hemispheres
What gyrus sits above the corpus callosum?
Cingulate gyrus
What is the name of an important sulcus at the posterior aspect of the brain?
Parieto-occipital sulcus
What sulcus forms the border for the primary visual cortex?
Calcarine sulcus
Where is the fornix in the brain, what is it and what system is it a part of?
- underneath corpus callosum
- Band of white matter
- forms part of limbic system
What is the name of the point where the two thalami touch?
Interthalamic adhesion
Through which foramen does CSF drain from the lateral ventricle to third ventricle?
Interventricular foramen
In relation to thalamus, where does the pineal gland sit?
Posterior to thalamus
What is the name of the channel that leads the third ventricle to the fourth ventricle?
Cerebral aqueduct
What two lobes does the central sulcus separate?
Parietal and frontal lobes
What two points form the imaginary posterior border line of the parietal lobe, what forms the anterior and what borders it inferiorly?
Posterior: parieto-occipital sulcus to preoccipital notch above cerebellum
Anterior: central sulcus
Inferior: lateral sulcus
What is the insular lobe involved in?
pain perception
In which layer of the brain is there trabecular connective tissue?
In the subarachnoid space (spider webs - arachnoid)
What is the choroid plexus?
Tissue that secretes CSF in the ventricles
What are the three apertures in the fourth ventricle and what is their function?
- Median aperture and two lateral apertures
- they connect 4th ventricle to subarachnoid space
What passes through the third ventricle?
Interthalamic adhesion
What are the two blood supply systems to brain & where does each supply most?
- internal carotid system (anterior mostly)
- vertebra-basilar system (posterior mostly)
Where do the two brain blood supply systems connect?
Circle of Willis
What 2 arteries connect up the Circle of Willis?
- Anterior communicating artery between anterior cerebral arteries
- Posterior communicating arteries connecting the middle cerebral arteries and the posterior cerebral arteries
What artery do both the posterior cerebral arteries and the vertebral arteries branch from?
Basilar artery
What arteries do the middle cerebral arteries branch from?
Internal carotid arteries
Which arteries mainly supply the lateral, medial and posterior parts of brain, respectively?
- middle cerebral artery mostly supplies lateral
- anterior cerebral artery mostly supplies medial and upper cortex (top of brain)
- posterior cerebral artery supplies back and bottom edge around outside
Where does most of the brain’s blood drain into?
Drains from dural venous sinuses into internal jugular vein through jugular foramen
-small bit down front of face
Where are the dural venous sinuses located in terms of layers of the brain?
In between two layers of the dura mater
Where are voltage ion channels concentrated on neurons?
Nodes of Ranvier
What is saltatory conduction?
Jumping of conduction from one Node of Ranvier to the next
What are the names of the demyelinating disorders? (CNS and PNS types?)
- CNS -> multiple sclerosis
- PNS -> Guillan Barre syndrome
In action potentials, sodium exit from cell depolarises cell and potassium entry into cell repolarises it. True/false?
False.
Sodium entry into cell depolarises, potassium exit repolarises
What are the 9 basic steps of chemical neurotransmission?
- uptake of precursor
- synthesis of transmitter
- storage of transmitter
- depolarisation by AP
- Ca2+ influx through voltage-activated Ca2+ channels
- Ca2+-induced release of transmitter (exocytosis)
- receptor activation
- enzyme-mediated inactivation of transmitter
OR - reuptake of transmitter
If transmitter is taken back up after the neurotransmission process, which two cells can take it back in?
-Pre-synaptic neurone
or
-glial cell
What holds the pre- and post-synaptic membranes together in the synaptic cleft?
matrix of extracellular protein
What are the two active zones on pre- and post-synaptic membranes respectively?
- presynaptically active zones is where vesicles of neurotransmitter cluster
- post-synaptically active zones is receptors
What are the three types of synapse in order of uncommon to very common? (in terms of connections)
- axoaxonic
- axosomatic
- axodendritic
What is the most frequent transmitter in the excitatory synapses of the CNS?
glutamate
What are the 2 most frequent transmitters in the inhibitory synapses of the CNS?
- gamma aminobutyric acid (GABA)
- glycine
What is the inhibitory postsynaptic potential?
the hyperpolarising effect GABA or glycine have at post-synaptic ionotropic receptors (more negative)
What is the excitatory postsynaptic potential?
the depolarising effect glutamate has at post-synaptic ionotropic glutamate receptors (more positive)
What is summation in neurophysiology?
process that determines whether or not an AP will be generated by combined effects of both excitatory and inhibitory signals
What is the difference between spatial summation and temporal summation? Do they happen separately or together?
-Spatial summation is when cell receives multiple simultaneous excitatory and inhibitory signals.
Temporal summation is the number of repeated inputs.
-happen together, complement each other
What’s the difference between an ionotropic receptors and metabotropic receptors? Which is indirect and which is direct gating?
- Ionotropic receptors are where receptor is incorporated into channel - direct gating
- Metabotropic receptors are where receptor and channel are separate - indirect gating
Ionotropic receptors are slower than metabotropic receptors. True/false?
False. They’re faster
What type of receptor is nicotinic acetylcholine receptor? (ionotropic or metabotropic)
ionotropic
What type of receptor is muscarinic acetylcholine receptor? (ionotropic or metabotropic)
metabotropic
A single cell can have both types of receptors e.g. nicotinic and muscarinic ACh receptors which leads to both fast EPSP and slow EPSP. True/false?
True
What are the three types of ionotropic receptors glutamate can activate?
- NMDA receptors
- AMPA receptors (non-NMDA)
- Kainic acid receptors (non-NMDA)
Which glutamate receptor mediates faster excitatory synaptic transmission in the CNS?
non-NMDA faster that NMDA
Whats the difference between the follow types of white matter tracts: association fibres, commissural fibres and projection fibres?
- association fibres connect cortical sites in same hemisphere
- commissural fibres connect one hemisphere to other
- projection fibres connect to deeper structures e.g. thalamus, corpus striatum and spinal cord etc
Glutamate, GABA, glycine, acetylcholine and 5-HT can all activate ionotropic ligand-gated ion cahnnels. (LGICs) that mediate fast neurotransmission. Which one of these can’t activate metabotropic G-protein coupled receptors that mediate slow neurotransission?
Glycine
Non-NMDA receptors permeable to
Na+ and K+
NMDA receptors permeable to
Na+, Ca2+, K+
Certain anaesthetics e.g. ketamine are selective blockers of which channels?
NMDA channels
