Knowledge Clips (Kennis clips) summary Brain and Cognition1 Radboud uNI UuN

Revision time KC1

Staining technique of individual neuron type

 Each neurontype a different colour.
 The colour is only visible if you shine light on it; they do not themselves produce light



 Golgi Nerve net theory> interconnected pipe network with substance flowing in it
 Cajal’s neuron theory> Neurons are not interconnected; separate entities (cells) that
communicate with each other, not by directly connecting with each other but via chemical
substances.

Dendrite (Antenna) Cell body (Yes or no) terminal buttons/axons (neurotransmission)



Behaviour cannot be assigned to a single neuron type; neurons work together in networks

 Neural network: groups of neurons that work together to produce a function
 Dependent on how they are interconnected what function they produce

Let op: onduidelijk of neurons wel of niet interconnected zijn; in de kennisclips wordt gezegd van wel
maar ook van niet. het punt hier is dat je moet weten dat neuronen niet direct met elkaar linken
door elkaar aan te raken; ze communiceren via synapsen (connections met synaptic cleft)



Neurons are with us for life:
 Connectivity verandert wel door Experience, maar er vindt geen replacing of neurons plaats.


Morphological (structural) details:
 Dendritic spines zitten OP de dendrieten Point of contact with other
neurons
 Endfoot /terminal button> which functionally connects (but does not
touch) a dendritic spine of another cell.
 Axon Hillock net onder de cellbody. The axon begins at the axon hillock
and may branch out in one or more axon collaterals (branches). The
teleodendria zijn axon sprieten en lopen uit in terminal buttons
(synoym: teleodendria en endfoots)
 Decision is made in axon hillock (cell body dan?)
 Integrates all the information from the dendrites

Three types of neurons:
 Sensory neurons bring information to the central nervous system (brain and spinal cord)


closest to the outward world

Visual and auditory neurons

Somatosensory neuron (dendrite is IN our skin via nerve endings
cell body and axon in our spinal cord)
 Motor neurons send signals from the brain and spinal cord to muscles

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,  Zit in cortex and in spinal cord
 Control the muscles by innervating to muscles
 Motor neurons drive our muscles
 Interneurons Responsible for all computation between motor and sensory neurons
 Most numerous
 Associate sensory and motor activity in the central nervous system
 Stellate cell (thalamus)/ Pyramidal cell (cortex)/ Purkinje cell
(cerebellum)

EXCITATION and INHIBITION
 Neurons either excite or inhibit other neurons
 Receiving neurons (POST) sum the excitatory and inhibitory input. This means these
postsynaptic neurons receive inout from multiple neurons (which are either excitatory or
inhibitory)




Five types of Glial Cells;
 Ependymal cells : Produceren CSF
 Astrocytes (starshaped) dragen bij aan hersen bloed barriere;
 Produceren scars na injury
 Neuronal nutrition
 Microglial cells: remove dead tissue (brain immune system). Are derived from blood. Provide
growth factors (chemicals that help by self repair of tissue) and aid in repair.
 Oligodendroglial cells: forms myelin around CNS nerves and spinal cords> cannot help repair
neurons. Isolate neurons
 Schwann’s cells (PNS) : these cells wrap around peripheral nerves to form myelin (faster
communication)> can help repair neurons

ASTROCYTES
Contribute to the blood brain barrier and help form scars after injury + provide nutrients and
structural support.
 Tiny blood vessel: the smaller the blood vessel,
the more difficult it is to tighten. Looser
connections the smaller the cells become.
 Astrocytes help tightening junctions to prevent
that large molecules enter the brain (protection
against chemicals but it also makes it difficult for
antibiotics (large) to cross the blood brain barrier). Astrocytes (cellen)
zitten dus op de bloedvaten.
 Can also increase the amount of blood that run through these
bloodvessels by dilating the blood vessels > higher input of oxygen and
nutrients.
 SCAR FORMATION

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,MICROGLIA
Function as an offshoot of the immune system
Identify and attack foreign and dead tissue (phagocytosis)
Plaatje C: een toxin in de nucleus. All the neurons have died. The microglial cells are cleaning up.
Plaatje B: tiny is microglia, large is neuron

NEURONAL REPAIR
Schwann cell’s in the peripheral nervous system repair such as after a cut of the axons.
 The part that is connected to the neuron’s cell body LIVES
 Part after the cut DIES (away from cell body)
 Cell body: Harry, the boy who lived.
 Axon after the cut: Voldemort, het mormeltje who died.

The peripheral axon dies> swann’s cell shrinks and divides forming glial cells> remaining axon sends
out sprout > Sprout finds the schwann’s cells path along the original trajectory and becomes a new
axon> the schwann cells then wrap around the new neuron

THERE IS NO REGROWTH AND REPAIR IN THE CENTRAL NERVOUS SYSTEM
 (oliodendroglial do not possess this ability)
 Strokes, traumatic brain injury

Note: Inside the ventricles zit Cerebral Spinal Fluid (produced in ependymal cells)

KC2 Internal structure of a cell

Cell membrane: scheidt de hele cell van intracellular fluid van extracellular fluid
 (niet alleen de cell’s body; ook de dendrites and endbuttons)
 Semipermeable> special transporter cells (made in the cell) embedded in the cell membrane
 Transports chemicalls in and out of the cell

Intracellular fluid:
Fluid in which the cell’s internal structures are suspended. Mostly water with some chemicals
dissolved in it
 these substances play a role in the communication with other neurons

Nuclear membrane surrounds the nucleus (celkern)
 in de celkern zitten onze chromosomen (23 pairs) and genes (gen is stukje op DNA)
 nucleus is dus de genetic blueprint for all the proteins that can be produced in the cells> are
sent to endoplasmic reticulum (folded layers of membrane where proteins are assembled):
the workfloor (assembling of proteins)
 Transcription nucleus
 Translation Endoplasmic Reticulum




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, The ER workfloor receives instructions from the nucleus sends information to the golgi’s bodies:
the mailroom= packages proteins and gives it a sending address. Packaged for transport via tulebules
and microfilaments (shaping of cells)
 Lysomes: VESICLES containing enzymes that break down waste

SAMENVATTING:
 cell membrane: barrier and gatekeeper phospholipid bilayer (attracts water maar laat
laat het niet door. Chemical composition is
hydrophilic van buiten (trekt water aan) en is
hydrophobic van binnen.
binnen= vet. Fatty acid tails no binding to water.
Buiten= Attraction to water AND its dissolved
chemicals
 Nucleus: blueprints of genetic code
 ER: Assembly of proteins. Near nucleus, niet in de nucleus. Wel in cell body
 Golgi’s bodies: mailroom wrapping of packaging and giving a destination address. In cells
body, niet in nucleus

In de nucleus begint het proces van protein synthesis. DNA is not a protein, it encodes the
information that is necessary to synthesize proteins.




Remember that:
Elke chromosome bestaat uit twee strands of DNA. Een gen is een DNA segment en zit op een
bepaalde locatie op de chromosome strand.
Genes are segments of DNA (blueprints encode synthesis of particular proteins)
Chromosome is a book of blueprints.
 Elke chromosome thousands of genes
 Gen: sequence of nucleotide bases that encodes for a protein (eerst voor amino acids)
 Genes are the blueprint for particular proteins (it contains instructions for particular protein)
 Nucleotide is een onderdeel van DNA of RNA dat uit een base bestaat (Adenine, guanine,
thymine of cytosine bij DNA) bij RNA is Thymine Uracil..

A =T & C=G.
Sequence of nucleotides is dus bijvoorbeeld AGCTTCA.
NUCLEUS Executive office  ER Factory floor Golgi’s Bodies mailroom




Protein synthesis:
1. DNA uncoils to expose a gene, A sequence of nucleotide bases that encodes a protein
2. One strand of the gene serves as a template for transcribing a molecule of mRNA (in nucleus)



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