Week 1 & Week 2 lectures (The nervous system & cells and signalling) Flashcards
What are two subdivisions of the forebrain?
Telencephalon
Dilencephalon
What are the prinicple structures of the telencephalon?
Cerebal cortex
Basal Ganglia
Limbic System
What are the prinicple structures of the diencephalon?
Thalamus
Hypothalamus
What is a subdivision of the midbrain?
Mesencephalon
What are two principle structures of the mesencephalon?
What are two subdivisions of the hindbrain?
Metencephalon
Myelencephalon
What are two principle structures of the metencephalon?
Cerebellum
Pons
What is the principle structure of the meyelencephalon
Medulla Oblongata
What are the functions of the frontal lobe?
Motor control
Executive function
What are functions of the parietal lobe?
What is a function of the temporal lobe?
What is a function of the occipital lobe?
Vision
What is the function of the basal ganglia?
Movement
What is the function of the limbic system?
Motivation and emotion
What is the function of the thalamus
Relay and integration of sensory information
What is the function of the hypothalamus?
Controls autonomic nervous system and endocrine functions
What is the function of the tectum?
Visual and auditory processing
What is the functionof the tegmentum?
Sleep, arousal, movement
What is the function of the cerebellum
Motor coordination, muscle tone and balance
What is the function of the pons and medulla
Sleep and arousal
What is the function of the medulla oblongata?
Control of vital functions
What are the 12 cranial nerves?
Olfactory
Optic
Oculomotor
Trigeminal
Trochlear
Abducens
Facial
Vestibulocochlear
Glossopharyngeal
Hypoglossal
Vagus
Cranial accessory
What nervous system are the cranial nerves part of?
The peripheral nervous system
Which cranial nerves link directly to the cerebellum?
The olfactory and optic
What is 1 called?
What is 2 called?
optic nerve
What is 3 called?
oculomotor
What is 4 called?
The trochlear nerves
What is 5 called?
The trigeminal nerves
What is 6 called?
abducens
What is 7 called?
The facial nerves
What is 8 called?
The vestibulocochlear nerves
What is the 9 called?
The glossopharyngeal nerve
What is 10 called?
What is 11 called?
The cranial accessory
What is 12 called?
The hypoglossal nerves
How many cervical segments are there in the spinal chord and where are they situated?
8
How many thoracic segments are there in the spinal chord?
12
How many lumber segments are there in the spinal chord?
5
How many sacral segments are there in the spinal chord?
Where are cervial nerves?
Neck shoulders arms and hands
Where are thoracic nerves?
Trunk and arms
Where are lumber nerves?
Lower back and front below waist
Where are sacral nerves?
Bottom and back of legs and genitals
Which root does incoming sensory information travel to the spinal chord via?
The dorsal route
Which root does outgoing motor information travel to the rest of the body via?
The ventral root
What does contralateral mean?
The opposite side of the midline
What is the midline?
The line from the top of the middle of your head, down the centre of your body
What does ipsilateral mean?
On the same side as the midline
What does medial to the midline mean?
Close to the midline
What does lateral mean relative to the midline?
Further from the midline
What are the three meningeal layers called?
Dura Mater
Arachnoid
Pia Mater
What are 3 key functions of the meninges?
Protecting the brain and spinal chord from mechanical injury
Providing blood supply to the skull and cerebal hemisphers
Providing a space for the flow of cerebal spinal fluid
What are the characteristics of the dura matter?
Tough, inflexible
Divided into several sublayers
What are the characteristics of the arachnoid layer?
Delicate
impermeable
Avascular
Web like appearance
What are the characteristics of the Pia Mater?
Tender
Adheres closely to the brain
Fuses with the lining of the ventricles to form structures which produce cerebospinal fluid
What happens to the meninges in the PNS?
The dura Mater and the Arachnoid are fused with each other
What structure produces CSF?
The choroid plexus
What is the function of CSF?
What are 3 stages in the formation of the neural tube?
- Notochord forms
- Notochord signals ectoderm to fold
- Neural tube is complete
What are 3 of the layers in a neural tube?
Ectoderm
Mesoderm
Endoderm
Where is the endoderm and what does it go on to form?
On the inside
Forms many of the bodily organs
Where is the mesoderm and what does it go on to form?
In the middle of the neural tube
Goes on to form much of the skeleton and the muscles
Where is the ectoderm in the neural tube and what does it go on to form?
On the outside
Forms the nervous system and the skin
What is neurulation and when does it occur post gestation?
The development of the neural tube
Occurs 22 days post gestation
How does neuralation occur?
- The ectoderm layer at the top of the embryo starts to thicken into a structure called the neural plate
- The plate starts to fold in the middle so that a groove is created.
- The groove then closes then is completely seperated from the area above it.
What are the resulting structures of neuralation?
The epidermis, which is the layer above the neural tube
The Neural Tube which is the basis of the CNS
The neural Crest, Which is the topmost edge of the neural tube, and forms the PNS.
What disorder is caused by the failiure of the neural tube to close?
Spina Bifida
What are the 3 types of Spina Bifida?
Occulta
Meningocele
Myelomeningocele
Which is the most common and mildest type of Spina Bifida?
Occulta
What happens in meningocele spina bifida?
The meninges protude out through the spine but the spinal chord develops normally
What happens in myelommeningocele spina bifida?
The spinal chord and the meninges protude out the back
What are 3 categories of symptoms of Spina Bifida?
Movement problems
Bladder and Bowel problems
Associated Hydrocephalus
What are movement problems in Spina Bifida?
Weakness or paralysis in lower limbs
Deformed or dislocated bones
What are bladder and bowel problems in Spina Bifida?
Urinary continence
UTI
Kidney problems
Bowel incontinence
What are associated hydrocephalus in spina bifidus?
Short attention span
Difficulty solving problems
Difficulty reading
Difficulty understanding some spoken language
Difficulty planning
How does the WHO define a risk factor?
Any attribute, characteristic or exposure of an individual that increases the likelyhood of developing a disease or injury
What are 6 risk factors for spina bifida?
White ethnicity
If mother has diabetes
If mother was obese
Female
If mother has folate deficiency
If mother was on certain medications
How does the neural tube from the brain?
- The tube begins to curve slightly
- Some bulbous regions develop
The top bulbous region becomes the forebrain
The mid one becomes the midbrain
The bottom one becomes the hindbrain
When does the primary differentiation process occur?
(when the neural tube differentiates the brain and spinal chord)
3-4 weeks old embryo
At how many weeks does the secondary differentiation process occur?
5 weeks old embryo
What happens in the secondary differentiation process?
The forebrain splits into the telencephalon and diencephalon
The hindbrain splits into the metencephalon and the myelencephalon
At 5 weeks old, how many secondary brain vesciles are there and what are they?
5:
telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
What does the telencephalon go on to form?
The cerebrum
What does the diencephalon go on to form?
The thalamus, hypothalamus and epithalamus region
The eye cup
What does the mesencephalon go on to form?
The midbrain structure
What does the metencephalon go on to form?
The pons
The cerebellum
What does the myelencephalon go on to form?
The medulla oblongata
What are the 3 different types of validity?
Face validity
Construct validity
Predictive validity
What is face validity?
Does the model look like the condition?
What is construct validity?
Do we similar changes to the biology in the model?
What is predictive validity?
Can we predict changes in the human condition based on the animal model?
What are the 3 R’s in animal research regulation
Replacement
Refinement
Reduction
Where is the nucleoulus?
In the nucleus
What is the nucleolus comprised of?
Proteins and nucleic acids
What are ribosomes made of?
Ribonucleic acids and proteins
What is the function of the rough endoplasmic reticulum?
Protein snthesis
What is the function of the smooth endoplasmic reticulum?
Lipid synthesis, regulation of calcium, metabolism of carbohydrates
What are two broad classes of cells in the nervous system?
Glia cells and neurons
What are 4 types of glia?
Microglia, macroglia, Epedymal cells, satellite cells
What are two types of macroglia?
What are two types of macroglia?
Schwann cells/ Oligodendrocytes
Astrocytes
What is the difference between oligodendrocytes and schwann cells?
oligodendrocytes in the CNS
Schwann cells in the PNS
What are 4 functions of the astrocyte? (star cells)
Regulating local supply of oxygen and glucose close to neurons
Providing structural support and stability to neurons
Mopping up leaked or excessive neurotransmitters
Regulating the concentration of pottasium ions
What is formed by the oligodendrocytes?
Rows of semi rigid tissue between neurons.
What are 3 functions of the oligodendrocyte tissue?
Structural support
Provide nutrients to neurons
Provide myelin Sheaths
What are 4 functions of microglia?
Acting as macrophages- engulfing bacteria and debris from dead or dying cells
Remodelling the nervous system during development
Secreting chemicals important in glial cell and blood vessel formation
Responding to immune system activation and neurodegeneration
What are ependymal cells and what is their function?
They form a layer lining the brain ventricles and the central canal of the spinal chord
They secrete CSF and may assist in its circulation
Where are satteliete cells found and what are 2 functions?
They surround sensory neurons in the PNS
They regulate the extracellular chemical environment
They protect, nourish and maintain neurons
What disorders are satelleite cells associated with?
They are associated with neuropathological states such as chronic pain
This is because they are highly sensitive to injury and inflammation
What is E?
A protein Channel
What is D?
Cholestrol
What is I?
A glycolipid
What is C?
A peripheral protein
What is B?
A carbohydrate
What are the Na+ and K+ concentrations of the extracellular space?
Na+ : 142 mM
K+ : 4 mM
Why does the electrostatic gradient push Na+ ions into the cell?
Because there are more Na+ ions outside the cell. This means outside the cell is positive and they want to move into the negative space
What are the Na+ and K+ concentrations in the intracellular space?
Na+ = 10mM
K+ = 140 mM
In which direction does the electrostatic gradient push K+ ions
in which direction does the concentration gradient push K+ ions?
Electrostatic gradient keeps K+ ions inside of the cell
Concentration gradient pushes K+ ions outside of the cell
In which direction does the electrostatic gradient push Na+ ions
In which direction does the concentration gradient push Na+ ions
Both electrostatic gradient and concentration gradient pushes Na+ ions into the cell
Why does the electrostatic gradient keep K+ ions in the cell?
There are more K+ ions inside the cell
But the inside of the cell is negative, which the K+ ions are attracted to
Therefore the electrostatic gradient keeps K+ ions inside the cell
Is the membrane more permeable to pottasium ions or sodium ions?
Pottasium ions
what is the function of the membrane being more permeablet to pottasium ions?
It helps keep the resting potential negative
Is the sodium pottsium pump active or passive?
Active
What ratio of sodium to pottasium ions does the sodium pottasium pump in and out?
3 sodium ions out
for every 2 pottasium ions in
What is the function of the sodium pottasium pump?
It ensures the sodium and pottasium ions stay in their correct concentrations and also ensures the cell maintains a negative charge
In which order do the stages of hyperpolarisation polarisation repolarisation and depolarisation occur?
Polarisation (at rest) - depolarisation - repolarisation - hyperpolarisation
at how many Mv does repolarisation occur?
+40Mv
What Mv is the threshold for the voltage gated sodium channels?
-55Mv
What opens first, the voltage gated sodium channels or the voltage gated pottasium channels?
the sodium channels
At what Mv do the sodium channels shut?
+40 Mv (the peak)
What stage of the process are the voltage gated pottasium channels involved in?
During Depolarisation they are just begining to open slowly so there is little impact
During repolarisation is when they are fully open, and pottasium leaves the cell causing the cell to become more negative (pushed out by the new electrostatic gradient caused by the influx of na+ ions, as well as the concentration gradient)
When do the voltage gated pottasium channels close?
Near resting potential
How long does the refactory period for the voltage gated sodium channels last?
From the peak to when the potential returns to resting state
What is the relative refactory period?
- The pottasium channels close slowly, so some k+ ions are able to escape even after the refactory period leading to a more negative external environment
- This means that although the sodium channels could open again, they are further from the threshold than they normally are so a bigger stimulus would be required for them to fire
What is the maximum firing rate of most neurons?
around 1000 per second
Why does the hyperpolarisation stage occur?
Because the pottasium channels close slowly so pottasium is still leaving the cell even after it has returned to rest, making the cell more negative
What ensures that the action potential only moves in one direction?
The refactory period of the sodium channels ensures the action potential cannot spread backwards
What is amplitude?
The difference between resting potential and peak of action potential
Do you determine the size of the stimulus by the amplitude or the frequency?
By the frequency
What 3 factors influence the speed at which the actioin potential travels down the neuron and why?
Temperature- greater kinetic energy
Greater axon diameter- means less internal resistance to the movement of ions so they move quicker
Myelination - Prevents ions from leaking from the axon so the action potential spreads quicker, as it only needs to be regenerated at the nodes of ranvier
How does the nerve impulse travel across a synapse?
- The action potential arrives at the end of the presynaptic neuron
- The depolarisation causes the voltage gated calcium channels to open
- Calcium floods into the cell
- Calcium reacts with snare proteins causing the vescicles to fuse to the membrane and empty their contents
- the nuerotransmiter diffuses and some will bind to the receptors on the post synaptic neuron
- The binding causes ion channels in the post synaptic neuron to open, changing the polarisation of the cell
What is an excitatory post synaptic potential?
Na+ specific ion channels open
Na+ enters the cell
This brings positive charge in the cell and triggers depolarisation
What is the difference between direct gating and indirect gating post synaptic receptors?
Direct gating- The place where the transmitter binds is in the same structural unit as the channel itself
Indirect gating- The transmitter binds to a receptor seperate from the channels, the binding triggers a cascade of chemical events which causes a channel elsewhere to open
Direct gating is quicker
Indirect gating can mean many channels open from one receptor binding
42wWhat is an inhibitory post synaptic potential?
Ion channels selective for K+ open
Ion channels selective for Cl- open
K+ leaves the cell
Cl- enters the cell
Cell becomes more negativez- hyperpolarisation
What is temporal summation in combining post synaptic potentials?
What is spacial summation in combining post synaptic potentials?
Inputs arriving simultaneously in different places are added together
What are 4 ways that the neurotransmitter signal gets turned off?
- Enzymes - break down neurotransmitter into ingredients which can be recycled
- Reuptake- Neurotransmitter can be taken back into pre synaptic neurons
- Diffusion- neurotransmitter drifts away so cannot bind
4.
Which amino acid is glutamate produced from?
Glutamine
Which receptors can glutamate bind to?
Ionotropic (NMDA & AMPA)
Metabotropic (mGlu)
Does glutamate result in depolarisation or hyperpolarisation of the post synaptic neuron?
Depolarisation
How is glutamate removed from the synapse?
taken back up by glutamate transporters into the presynaptic neuron
transporters are found in neurons and also astrocytes
Once taken up, it is broken back down by enzymes into glutamine
What is GABA made from?
GABA is made from glutamate
What receptors can GABA bind to?
Ionotropic receptors or Metabotropic receptors
How is GABA removed?
By transporters into the pre synaptic neuron
Transporters found on neurons and astrocytes
Does GABA result in depolarisation or hyperpolarisation?
Hyperpolarisation
What is the the rate limiting step in the production of glutamate and GABA?
The availability of glutamine
What is dopamine produced from?
Tyrosine
What is the rate limiting step in the production of dopamine?
The enzyme tyrosine hydroxylase
Does dopamine bind to metabotropic receptors or ionotropic receptors?
Metabotropic receptors
What are the two classes of metabotropic receptors that dopamine binds to and are they excitary or inhibitory?
D1 (excitatory)
D2 (inhibitory)
How is dopamine removed from the synapse?
By enzymes and reuptake channels
What dopamine pathway is involved in attention and working memory?
The mesocortical pathway
From the Ventral Tegmental area to the prefrontal cortex
What dopamine pathway is involved in goal directed behaviours?
The mesolimbic pathway from the ventral tegmental area to the nucleus accumbens
What dopamine pathway is involved in voluntary movement?
The nigrostriatal pathway
from the substantia nigro pars compacta to the dorsal striatum
Where does the tubero-infundibular dopamine pathway run to and from?
What are 4 diseases that dopamine is involved in?
ADHD, parkinsons, schizophrenia, addiction
What is this image showing?
Dopamine pathways
What is noradrenaline made from?
What is the rate limiting step in the production of noradrenaline?
The enzyme tyrosine hydroxylase
What are the receptors that noradrenaline binds to?
Two classes of metabotropic receptors (a & b)
Are noradrenaline receptors excitory or inhibitory?
They can be either
Where are all noroadrenic neurons located?
In the midbrain in a structure called the locus coeruleus
How is noradrenaline removed from the synapse?
By enzymes and reuptake channels
what are 4 things that noradrenaline is involved in?
Sleep/arousal
Pain processing
ANS functioning
Attention
What is serotonin produced from?
Tryptophan
What is the rate limiting factor in the production of serotonin?
The enzyme tryptophan hydroxylase
Does serotonin bind to metabotropic or ionotropic receptors
It can bind to both but it is mostly metabotropic receptors
Is seratonin excitory or inhibitory?
It can be either
Where are serotenergic neurons located?
In the hindbrain in a strucutre called the raphe nucleus
How does serotonin get removed from the synapse?
Using enzymes and reuptake channels
What are 6 things that serotonin is involved in?
Sleep
arousal
pain processing
Risk taking
Aggression
Mood
What are 4 disorders that serotonin is implicated in?
ADHD, Schizophrenia, deppresion, OCD
What is the rate limiting step for the production of acetylcholine?
The uptake of choline
What are the two categories of receptors for acetylcholine?
Nicotinic (ionotropic)
Muscarinic (metabotropic)
How is acetylcholine removed from the synapse?
Its removed by the enzyme acetylcholinsterase
Where are ACh neurons found?
The pons and the basal forebrain
What are 4 things ACh is involved in?
Sleep learning memory and attention
What disease is ACh involved in?
Alzheimers
