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role of the oligodendrocytes, astrocytes and microglia
- oligodendrocytes - myelinate neurons
- astrocytes - form synaptic connections: every synapse has 2 neurons and an astrocyte
- microglia - an immune/surveillance cell of the nervous system
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what does the diencephalon comrise
the hypothalamus, thalamus and the pineal gland
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role of thalamus
sensory integration
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anatomical relevance of the central sulcus
- runs from the longitudinal fissure to the transverse fissue
- in between the precentral gyrus (primary motor cortex) and the postcentral gyrus (primary sensory cortex)
- seperates the parietal and frontal lobes
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what connects the 2 hemispheres of the brain
the corpus callosum
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role of the parietooccipital sulcus
seperates the parietal and occipital lobes
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what are the divots/folds of the cerebellum called
folia
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what is found within the transverse fissue
the insula
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3 layers of the meninges
the dura mater (thicker outer layer), arachnoid membrane and the pia mater
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what are the folds of the dura mater that sit within the longitudinal fissure, the 2 hemispheres of the cerebellum and between the cerebrum and cerebellum
- longitudinal fissure - falx cerebri
- 2 hemispheres of cerebellum - falx cerebelli
- cerebrum and cerebellum - tentorium cerebelli
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clinical relevance of the subdural space
a bleed of the dura mater will cause this space to swell, placing pressure on the brain
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role of the arachnoid villi
protrude through the dura mater to the large blood vessel spanning the longitudinal fissure called the superior sagittal sinus, allowing CSF to be reabsorbed to the vasculature
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where is CSF made
in the choroid plexus of the ventricles
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what is hydrocephalus
condition in infants where there are born without arachnoid villi and therefore can't reabsorb CSF, causing a pressure build up within the brain
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role of the pons
- translates to brain
- connects the rest of the brain stem with the cerebellum and the cerebrum, allowing them all to communicate
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what are the pockets of grey matter deep within the cerebrum called
the basal ganglia
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oligodendrocytes vs schwann cells
both wrap axons in myelin, oligodendrocytes are of the CNS while schwann cells are of the PNS
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what regions is the spinal chord divided into
cervical, thoracic, lumbar and sacral
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what regions of the spinal chord are enlarged
cervical and lumbar
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around which vertebra does the spinal chord end
lumbar 2
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what is the end of the spinal chord called
the conus medullaris
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what attached the spinal chord to the coccyx (base of the spine)
the filum terminale (note that it is not a nerve, but an extension of the pia mater)
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what are the columns of white matter in the spinal chord reffered to
funiculus
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label 
a - endoneurium, surrounding nerve fibre (neuron)
b - perineurium, wrapping a fascicle (a bundle of endoneurium wrapped nerve fibres)
c - epineurium
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where are the cell bodies of motor and sensory neurons located
- motor neurons - within the CNS (spinal chord)
- sensory neurons - in the periphery (dorsal root ganglia)
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how many spinal nerves do we have, and how many to each section, and how many vertebra
- 31 - 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, 1 coccygeal
- 30 vertebra (only 7 cervical)
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what are the 4 rami
dorsal (towards back, for somatic neurons) , ventral (towards front, for somatic), white (where the preganglionic sympathetic neuron enters) and grey (where the postganglionic sympathetic neuron leaves, to enter target tissue)
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dermatome vs myotome
a dermatome is the an area of skin that is mainly supplied by the one spinal nerve while a myotome is a region of muscles supplied by a spinal nerve
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what is the phrenic nerve
projects to the diaphragm (essential for breathing), made up of nerves C3,4 and 5
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what do the brachial and lumbosacral plexus control
- brachial - upper limbs
- lumbosacral plexus - lower limbs
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what are the 12 cranial nerves
olfactor, optic, occulomotor, trochlear, tigeminal, abducens, facial, vestibulo-cochlear, glossopharyngeal, vagus, accessory, hypoglossal
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role of olfactory nerve (I)
primary sensory nerve needed for smell
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role of optic nerve (II)
primary sensory nerve needed for vision (innovates the retina)
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occulomotor (III)
nerve that moves the eye
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trochlear (IV)
also moves the eye
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trigeminal (V)
innovates sensations of the face
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abducens (VI)
also moves the eye
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facial (VII)
movement of facial muscles
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vestibulo-cochlear (VIII)
vestibulo means balance and cochlear means hearing
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glossopharyngeal (IX)
- glosso - tongue pharyngeal - pharynx
- sensations such as taste and pain of the pharynx
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role of vagus (X)
major parasympathetic nerve, innovates the heart, lungs, GI tract
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role of accessory (XI)
innovates muscles of the neck such as the trapezius
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role of hypoglossal nerve
nerve that allows you to move your tongue
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where do the cranial nerves arise from
- C1 and 2 - cerebrum
- 3 - 12 - brain stem
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where does the cell body of preganglionic neurons of the autonomic NS lie
the lateral horn
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difference between the ganglionic connects of the parasympathetic vs sympathetic NS
- parasympathetic has a long preganglionic neuron and a short post ganglionic neuron, forming a ganglia within the target tissue
- sympathetic has a short preganglionic and a long postganglionic
- - pre enters through white ramus, synpases with post in the ganglia and then exits through the grey ramus
- - forms a ganglionic chain next to the spinal chord
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origins of the 2 types of autonomic nerves
- sympathetic - thoracolumbar
- parasympathetic - craniosacral
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what is the threshold potential
-50 mV
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around what membrane potential do VNas become inactive
around 30mV
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what are the 2 refractory periods
- absolute refractory - when sodium channels are inactive state so an action potential cannot occur
- relative refractory - when the membrane is hyper-polarised due to the high amount of K+ (as K+ channels take longer to close) and therefore an action potential is unlikely to occur
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where do graded potentials summate
the trigger zone (often axon hillock)
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difference between ligand affinity and efficacy
affinity is the likelihood of the ligand to bind to the receptor and efficacy is the likelihood of the ligand to activate the receptor
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what is Ka is a measure of
measure of affinity - it is the dissociation constant (k-1)/(k+1)
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what does it mean if a ligand has a low Ka
It has high affinity
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what does is mean if the concentration of ligand is equal to the Ka
receptor occupancy is 0.5
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what is Emax
- the plateau at the top of a concentration-effect curve, a measure of efficacy
- the maximal response that a drug can actually produce
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what is potency
- how far along the X axis the concentration-effect curve sits
- EC50 is a measure of potency that is the drug concentration required to elicit 50% of the maximal effect
- the lower the EC50 the more potent the drug
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what is tachyphylaxis
the fast desensitisation to a drug (on a scale of minutes or less)
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mechanisms of tachyphylaxis
receptor internalisation, change in receptor expression levels, exhaustion of mediators, physiological adaption
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what is the effect of adding a reversible antagonist on the concentration-effect curve
shifts the curve to the right (reduces apparent potency)
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what is Kb
the dissociation constant of competitive antagonisms, the measure of the affinity of the agonist
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what is IC50
like EC50, but for a competitive antagonist. it is the concentration of antagonist required to reduce a response to a fixed concentration of agonist by 50%. Low the lower the IC50, the stronger the agonist.
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what is the effect of an insurmountable (irreversible) competitive antagonist on the concentration-effect curve of a drug
reduces apparent E max, and reduces apparent potency (increases EC50)
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how does a chemical antagonist work
binds to destroy the ligand itself, or prevent it from binding it's receptor
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how does a functional antagonist work
opposes the biological effects of the agonist by acting at a different receptor (one that inhibits the effects of the agonist target receptor)
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