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Whole summary for neurosciences
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This is a whole summary for neurosciences
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Lecture 1: intro + brain anatomy- History
- critical moment: discovery of the cellular organization of the nervous system operated by
Camillo Golgi and Santiago-Ramon y Cajal by sliver staining
o reticular theory by Golgi: the neurons are connected in a big net (spiderweb)
o neuronal doctrine by Cajal: small gaps between neurons that we now call synapses,
- 3400 years after: modern neuroscience
General organisation of the nervous system
- Neuroanatomy: branch of neurosciences focussed on macro aspects
of NS, being interested in locating and examining the structure that
comprise CNS and PNS → essential knowledge for neuropathology
Macro vs micro simple division of the nervous system
- macro perspective
- clear cut between CNS (brain, spinal cord) and PNS (spinal, cranial nerves)
- CN nerves are connected to rest of body
- Whole brain is connected, brain works by connecting NS with rest of body
- main cellular components of the NS
- Neurons - microglia: immune system
- astrocytes: support - oligodendrocytes: produce myelin,
Basic view of the brain
- The brain has 2 hemispheres that comprise the cerebrum.
- Right: logic - Left: emotion, action
- skull is made in a glove like way, so it is wrapped
o creates fosases: grooves: comfortable folds that allow brain to sit
- Anterior fossa: holds part of the frontal lobe.
- Medial fossa: does the same for the temporal lobes.
o looks like settle where optic chiasm, mammillary bodies and part of diencephalon sit.
- Sphenoid: connection between frontal fossa and sella turcica
- foramina: skull hosts many holes to allow the passage of
cranial nerves and vessels.
- Foramen ovale and spinosum: passage of the trigeminal nerve
- lamina cribrosa: for olfactory nerve
- foramen magnum: central big hole in occipital fossa, passage
for the spinal cord).
- central foramen: hole for spinal cord
Orientation planes in neuro anatomy
- 3 section planes:
o Coronal:
o Sagittal
o horizontal
- combine these planes you have reference points, named using a common nomenclature
,Meninges
- role is protective.
- organized in 3 layers from inside to outside:
o pia mater : tight glove, thin cell layer after which cortex begins
o Arachnoid: fit but not tight glove
o dura: oversized winter glove
▪ divided into osteal layer (towards skull) and meningeal layer (towards brain)
- spinal cord: same 3 layers of meninges,
o dura here does not have 2 separate layers but just 1.
- subarachnoid space: in between arachnoid mater and pia mater
o with empty space: let cerebrospinal fluid flow to be drained.
o drainage happens via granulations: mushrooms that drain CSF
to sinuses made by arachnoid matter and subarachnoid space
o Subarachnoid space appeared vacumed with trabeculae: pilars
- Dura matter: some parts thicker: at vulnerable places of the brain
o Between hemispheres and cerebrum/cerebellum dura is
thicker (Falx c., tentorium c.)
- some medicines can get to the brain: lipophobic
Blood supply and CSF
- the brain needs a lot of O2 (20% of the whole oxygenated blood goes directly to the brain).
- 2 arteries serves blood to the brain:
o carotid artery (more ventral)
o vertebral artery (more dorsal)
▪ When entering the cranial region the vertebral
arteries (2 branches) converge into the basilar artery.
o circle of Willis: basilar and carotid artery converge into the roundabout found in basal
(ventral) part of encephalon at the level of optic chiasm (so above the sella turcica).
▪ Function: redundancy: prevent lack of blood to the brain in case one of the 2
arteries does not function (e.g. stroke). It doubles the structures letting the
blood circulate like in the ring of a highway to avoid damages in the brain.
o From the circle 3 cerebral arteries arise: send compartmentalized blood to the brain
▪ Anterior medial part of the encephalon
▪ Medial lateral part of the encephalon
▪ posterior occipital part of the encephalon
- Venous of blood: sinuses,
- 600 km capillaries
- Capillaries form 2 barrieres: blood-brain barrier and blood-csf barrier
Ventricles and sinuses
Ventricles
- CSF filled cavities that play a role in distributing the CSF to the NS
- 4 groups of ventricles in human brain:
o 2 lateral ventricles (1 per hemisphere),
o 3rd ventricle (very skinny, connects the two lateral together)
o 4th ventricle (at the level of the cerebellum/pons, where it makes a rhomboid shape
easy to recognize if you slice the brain mid-sagittal).
, - foramen of Monro:
o In between lateral and 3rd ventricle
o allows the communication between lateral and 3rd
ventricles.
- cerebral aqueduct: connecting tube to spread CSF through the
brain and spinal cord between the 3rd and the 4th ventricle
- central canal: located after the 4th ventricle, a big tube that walks along the whole spinal
cord to provide CSF to this structure.
cerebrospinal fluid (CSF)
- used by the brain for
o nutrients and salts to feed brain cells
o protection due to the buoyancy principle (mass is reduced with
about 90%, this spares the neurons that reside in the more ventral part of the brain).
- transparent fluid: full of sodium, calcium, magnesium and glucose
- choroid plexus: pia mater invagination at the level of the ventricles which makes and sends
CSF to the ventricles.
- The last station (point 4 in the image above) is the CSF that is gathered in the subarachnoid
space and via the granulations sent to the sinuses.
Sinuses
- venous-like structures with walls made of dura mater!
- located in specific parts of the encephalon and their role is mainly to let convey CSF and
blood (from venous capillaries) to be drained outside the NS.
- about half litre of CSF per day
- Hydrocephalus: No drain will result in rising pressure,
ventricles will increase
- Via the sinuses the CSF is sent, normally through the
sigmoidal sinus to the jugular vein to leave the CNS.
- Sinuses
o Superior
o inferior sagittal
o transverse sinus
o sigmoidal sinus.
Summary
- Neurosciences: understand how the brain works
- Hands and lips most important to the brain
- Primary sensory cortex: sensory information is collected
- Connection in the brain are made from white tissue
- Cell bodies of neuro cells live in the grey tissue
- Why do people make stupid mistakes while under pressure
o Frontal cortex is inhibited: making decisions
- Small brain: cerebellum: loves towards the back of head: responsible for coordination and
movement
- TEXTbook: not using american version: pages different, international version neede
, Lecture 2 and 5
Overview
- Part 1: Resting membrane potential
- Part 2: Ion channels and transporters
- Part 3: Action potential generation, conduction
Part 1 resting membrane potential
Electrical signals in the brain
Requirements for electrical signalling between nerve cells
- fast
- travel long distances
- should not loose strength over distance
- Isolation: don’t want parallel action potentials to influence
each other
- Reliability: needs to stay at the same amplitude
Active and passive signals
- Electrophysiology: stimulating neurons with electrons and
measuring or recording
- Resting membrane potential: at -65 mV: difference
between neuron and outside
- When increasing the strength of the stimulus: the
depolarisation gets two times as big
- E potential: get totally different signal when signal is stronger
- Remain the same strength as when it was generated
Resting membrane potential
- Resting membrane potential/Electrical potential difference: electrical potential difference
measured across the membrane (inside with respect to outside)
- Based on 2 membrane properties:
o Lipid bilayer; impermeable to ions
o Specialised ion channels can conduct ions selectivity: so only one type of ion
- Equilibrium: chance of electrons moving to one side is the same as electrons moving to the
other side, net flux of 0
Based on two principles in physics:
- diffusion of particles
- electrical forces between electrical charges
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