bio of mind Flashcards
what are nerves from the brain called
efferent
what are nerves that go to the brain called
afferent
what do excitatory neurones such as glutamate do
increase the activity of target cells
What do inhibitory neurones such as GABA do
decrease the activity of target cells
Name the three types of glial cells
myelinating glial cells eg schwann cells and oligodendrocytes, supporting glial cells- provide nutrients to cells and help with repair and microglia the immune cells of the CNS
what is the somatic nervous system and name the two types of it
it is voluntary and it consists of the sympathetic and parasympathetic, sympathetic is the flight or fight and parasympathetic is the housekeeping
what does the enteric nervous system do
works autonomously to control the activity of the GI tract
what does the forebrain consist of
cerebrum, thalamus, hypothalamus
what gland is the midbrain close to
the pituary gland
what does the hindbrain consist of
pons, medulla oblongata and the cerebellum
what does the substantia niagra do
motor system, dopamine containing cells recieve visual inputs , helps bring eyes to focus
what is periaquaductal grey matter associated with
pain and fear
what is the red nucleus
motor control structure
what does the thalamus do
important relay nucleus from sensory modalities
the frontal lobe is associated with
conscious thought
what senses does the temporal lobe associate with
smell and sound
what is the resting membrane potential
-70mV
what factors contribute to the resting membrane potential
charged intracellular proteins, the Na+/K+ pump, potassium and sodium ions
what ions is the membrane freely permeable to
K+, Na + ions are only slightly permeable
what is the equilibrium potential
the electrical potential difference that balances an ionic concentration gradient
what is the ionic driving force
the difference between the real membrane potential and the equilibrium potential
what does the Nerst equation calculate
the voltage produed by a difference in concentration of a single ion across a membrane
what does a stimulus result in
results in a small patch of membrane becoming depolarised
what is hyperpolarisation
current pulses producing passive changes in the membrane potential
what happens during depolarisation
current pulses cause passive changes unless threshold is reached once reached action potential occurs
what happens in the resting state
all voltage gated channels sodium and potassium channels are closed
what happens during the depolarising phase
the na channels are open
what happens during the repolarising phase
na channels close and potassium channels open
what occurs during undershoot phase
potassium channels remain open and na channels are closed
what is the all or nothing rule
action potentials have the same size larger stimuli are encoded by a greater number of action potentials
what is refractory period
ensures one way direction of action potentials
what are the nodes of ranvier
gaps in the myelin sheath where the voltage gated channels are concentrated causes action potential to jump and is called saltatory conduction
what does an intracelular glass electrode do and what is useful for measuring
impales neuron and measures voltage inside cell compared to the outside, its useful for measuring the resting membrane potential
what is extracellular recording useful for
measuring action potentials firing
what does the voltage clamp amplifier do
compares membrane potential to the desired potential
what does current clamp recording do
measures changes in membrane potential
what does a patch clamp recording do
are single channel recording measures the current flowing through a single channel
what cane xenopus oocytes infected with
exogenous mRNA sequences and they will synthesis the foreign protein in large quantities
what are oocytes used for
when families have a gene mutation such as epilepsy
what is brain tissue fixed with that fixes proteins
Formaldehyde
what is the stain Dapi used for
it is used to detect DNA
what is the Nissl stain used to detect
used to detect neurones and glia in the brain
what is golgi used to detect
neurones in the brain
what is nauta silver stain used to detect
degenerating axons
what did electron microscopy reveal
the existence of synapses and ultrastructure of neurones
what is immunohistochemistry
is manufacturing antibodies to the candidate protein and visualising these antibodies in sections of the brain
what is axoplasmic tranport
is the movement of material down the axon
what is anterograde transport
movement of substances from the soma to axon terminal
what is retrograde transport
is the movement of substances from the axon terminal to the soma
what are gap junctions modulated by
they are modulated by PH, neurotransmitters and Ca 2+
give an overview of chemical transmission
amino acid and amine neurotransmitters are synthesised in the axon, peptide neurotransmitters are formed in the cell body, the neurotrnsmitter is taken up into vesicles by transporters, as intracellular calcium levels rise synaptic release occurs, neurotransmitter binds to the receptor molecules in the post synptic membrane, neurotransmitter is either broken down in synaptic cleft or undergoes reuptake into the terminal
what are the major neurotransmitters are
amines, amino acids and peptides
what is the criteria for a chemical to be considered a neurotransmitter
it must be synthesised in the neurone, it must be present in the presynaptic terminal
how are neurotransmitters synthesised
occurs in the cell body using the golgi and Rough ER or in the synaptic terminal using synthesising enzymes transported from the cell body
what ions trigger neurotransmitter release
calcium ions
what occurs to free vesicles
free vesicles are targeted to the active zones, vesicles dock with the active zone, the docked vesicle is then primed for exocytosis, in response to a rise in Ca ions the vesicles undergo fusion to release their contents, the fused vesicle membrane is taken up into the cell by endocytosis.
name the two snare proteins
synaptobrevin is a vesicle bound protein which binds with snap 25 on plasma membrane and synaptotagmin which is a calcium sensor
what is a metabotropic receptor
are coupled to intracellular proteins that trnasduce the signal to the cell interior
what are ionotropic receptors
they form ion channels that epolarise or hyperpolarise the post synaptic cell
what is temporal summation
is when action potentials are fired rapidly down to two postsynaptic
spacial summation
2 neurones fire action potentials simultaneously
is it the excitatory post synaptic potential or the post synaptic action potential that travels down the post synaptic axon
it is the post synaptic action potential which travels down the axon
what do electrical synapses do
facilitate communication between neural cells
neurotransmitters come in the form of small and large molecules, where are the small and large molecules synthesised
the small molecules are synthesised by enzymes and the large molecules are encoded within the genome
what is glutamate
it is the major excitatory neurotransmitter
what is Gaba
it is the major inhibitory neurotransmitter, fires chlorine ions
give three small molecule neurotransmitters
catecholamines, dopamine and noraepinephrine
what is the ionotropic receptor nAchR permeable to
it is permeable to Na+ and K+ and sometimes Ca 2+
when is the NMDA receptor only active
during high frequency stimulation
what is the structure for metabotropic receptors
made up of monomeric proteins and 7 transmembrane domains
what second messenger to metabotropic recpetors act through
G proteins
explain the sequence of events that occur when the neurotransmitter binds to a metabotropic receptor
the receptor activates a G protein, the g protein activates the effector protein, the effector protein activates second messenger pathways which lead to metabolic changes in postsynaptic cell these messengers can lead to opening/ closing of ion channels
what does the somatosensory system respond to
it responds to the external environment
what does the viscerosensory system respond to
it responds to the internal environment
what is peripheral innervation
is when the skin and muscle or viscera are innervated by a rich vast network of peripheral nerves
what are primary afferents
axons bringing information from the somatic receptors
what are motor efferents
axons taking information from cns to peripheral structures
afferents feed into the spinal cord via
spinal nerve and dorsal root
Efferents leave the spinal cord via the
ventral root and spinal nerve
you feel touch by
sensory receptors in the skin
you detect temperature via
the thermoreceptors in the skin
what receptor is associated with pain
the nociceptor
what are the three classes of somatosensory receptors
tactile sensations- mechanorecptors, thermal sensations mediated by thermoreceptors and mechanical thermal nociceptors
what is meisners copuscle
comprised of lopping axonal terminals supporting cells with low frequency vibrations
what is merkels disks
dome structure comprised of axon terminals, merkel cells small forms and shapes
what is pacinian corpuscle
sensory axon sorrounded by fluid filled capsule high frequency vibrations
what is ruffinis corpuscle
nerve terminals intertwined with collagen to do with pressure
how is a receptor potential produced
a stimulus deforms the nerve endings and alters membrane permeability producing a receptor potential which triggers and action potential
what are large diameter rapidly conducting afferents associated with
low threshold mechanoreceptors
what are small diameter slow conducting afferents assoociated with
nocicpetors and thermoreceptors
wherabouts is the grey matter on a spinal cord
is in the inside of the spinal cord
where is the white matter on a spinal cord
it is on the outside of the spinal cord
primary afferents enter the
dorsal root
where do nociceptors have their cell bodies
they have their cell bodies in the dorsal root ganglia
transduction of painful stimuli occurs in
in the free nerve endings of unmyelinated c fibres and thinly myelinated ad fibres
what happens during inflammation
pain afferents send signals to the CNS but also release signalling molecules such as substance P
what do pain afferents release
gluatamate
what to spinothalamic pathways do
they process afferent inputs from peripheral mechanothermal and polymodal nociceptors
what does the contralateral pathway do
the sensory inputs cross at the level of the spinal cord and ascend on the opposite side, information relayed to the thalamus then onto somatosensory cortex
what is the macula associated with
central vision
what is the forea
central thinner region of the retina
what is the optic disc
the orogin of blood vessels where optic nerve axons exit the eye
what do photoreceptors do
convert light energy to neural activity
cone cells are associated with
colour vision
rod cells are
achromatic(without colour) and more sensitive to light
what do bipolar cells do
create direct pathway from photoreceptor to ganglic cells
the horizontal amacrine cells have
indirect pathways
the retinal ganglion cells
axons leave the eye forming the optic nerve
what is sound
series of changes in air pressure which form a wave
how do we detect sound
the pressure wave comes down external auditory meatus and hits the hypamic membrane
what happens at the cochlea
is the point of intergration where the pressure waves are turned into nerve signals
what is the scala media
this is where the inner hair cells are situated and are sensory receptors
when do we get mechanoelectrical transduction
vibrations causes the organ of corti to move and tectoral membrane distorts the cilia and where the stereocilia are disturbed you get mechanoelectrical transduction
what is the endolymph of the scala media high in
it is high in potassium ions and as a result the opening of the channel causes the cell to depolarise, depolarisation results in the opening of voltage gated calcium channels which transmit the signal via neurotransmitter release
where is the auditory complex located
it is located on the superior temporal gyrus in the temporal lobe of the brain
olfactory epithelial lines the nasal cavity and what happens
odorants enter nasal cavity and dissolve in mucus secretion dissolved odorants bind to cilia
where are signals of smell sent
signals are sent to the pyriform cortex in the temporal lobe
what happens when odorants bind to cilia
g proteins are activated and produce cAMP and camp binds to ca 2+ and Na+ channels, chloride channels open causing depolarisation
what are the organs that contribute to taste
the tongue, pharynx, pallette and epiglottis
papilae are taste sensitive structures name the three types of papilae
circurvallate papillae which is the largest and located in posterior, the foliate papilae are elongated and posterior lateral, the fungiform papillae are the smallest and contain one or two taste buds
what do dissolved membranes interacting with receptors do
they trigger membrane depolarisation and action potential firing, an increase in intracelular calcium initiates transmitter release and the transmitters excite afferent nerve fibres
a circadium rythm must
repeat once a day, persist in the absence of external cues and be able to adjust to local time
where is the centre for homeotic circadian control
the superchiasmatic nucleus
which cells detect changes in light levels
the retinal ganglion cells have photoreceptors which detect changes in light levels
what causes sleep and coma
brain stem lesions
what are the stages of sleep
awake, stage 1,2,3,4 then rem sleep - beta theta delta
during non Rem sleep
physiological functions decrease
which cortices does cognition occur in
the frontal, temporal and parietal lobe
Association cortices receive input directly from other cortical areas which areas
Ipsilateral cortico-cortical connections
Interhemispheric cortico-cortical connections
Association cortex also receives highly processed information from primary sensory / motor areas via thalamic nuclei
Pulvinar nucleus (parietal association cortex) Medial dorsal nucleus (frontal association cortex) [Anterior and ventral anterior nuclei]
what neurones do Association cortices also receive subcortical inputs
Dopaminergic neurones in the midbrain
Noradrenergic / serotonergic neurones in the reticular formation
Cholinergic neurones in the brainstem and basal forebrain
what is attention
The state of selectively processing simultaneous sources of information
what is Attention-deficit hyperactivity disorder
Characterised by
inattention, hyperactivity, impulsiveness
Imaging suggests that prefrontal cortex and basal ganglia are smaller in sufferers
what is Contralateral neglect syndrome
Caused by
lesion to right parietal cortex
Inability to attend to objects in a portion of space
Failure to attend to stimuli presented to the side of the body (or visual space) opposite the lesion
what is Balint’s syndrome
Caused by
lesion to parietal cortex
Triad of visuospatial deficits:
Simultanagnosia (inability to perceive visual scene as a whole)
Optic ataxia (deficit in visually guided reaching)
Ocular apraxia (difficulty in voluntary scanning of visual scenes)
An emotional response consists of three components:
Behavioural E.g. muscular movements (smile, frown etc).
Autonomic E.g. Sympathetic / parasympathetic activity
Hormonal E.g. Adrenaline release
what are the Brain systems involved in emotional processing
Amygdala
Orbitofrontal cortex
Cingulate gyrus / thalamus / ventral basal ganglia
speech is produced by
Lungs (source of air)
Larynx (source of speech sounds)
Pharynx, oral cavity (incl tongue, teeth, lips) and nasal cavity (modify / filter speech).
what are the language Association cortices in left hemisphere
Broca’s area – left frontal cortex; involved in language production.
Wernicke’s area – left temporal cortex; involved in understanding spoken language.
what are Aphasias –
damage to specific brain regions which compromises language functions, without affecting sensory / motor processing.
Broca’s aphasia
(motor or expressive aphasia)
Wernicke’s aphasia
(sensory or receptive aphasia)
Conduction aphasia
difficulty repeating words (arise from lesions to pathways connecting language centres)
Dorsolateral prefrontal cortex
Initiating and shifting behaviour (initiating and changing actions, motor movements and mental plans) Inhibiting behaviour (suppression of unimportant or distracting information / behaviour) Simulating behavioural consequences (creation of mental models of the world…abstraction)
Ventromedial prefrontal cortex
Inhibition of socially inappropriate behaviour (patients with lesions to this area may laugh at inappropriate times or reveal embarrassing personal information)
Sensitivity to the consequences of action (links between stimuli or action and the rewards or punishments that follow)
the Motoneurone is teh
(Lower motor neurone)
motoneurone is associated with muscle fibers forming a functional entity called
motor unit
what is the motor pool
Somatotopic organization of motoneurons in a cross section of the ventral horn at the cervical level of the spinal cord
the muscle spindle
Detects changes in muscle length.
Contributes to proprioception i.e. detection of position and movement of body in space.
Enables regulation of muscle contraction and precisely matches force generation to motor task.
Extrafusal fibres receive their motor innervation
from alpha motor neurons.
The Golgi tendon organ is a .
mechanoreceptor
what is a psychiatric disorder of the nervous system
Schizophrenia
what are the positive symptoms
Hallucinations
Delusions
Thought disorder
what are the negative symptoms
Social withdrawal Flattening of emotional responses Anhedonia Disinterest in everyday tasks Cognitive deficits e.g. Attention, memory
what are the schizophrenia mechanism
The dopamine turnover hypothesis
Increased DA activity leads to psychosis
DA antagonists or partial agonists antipsychotic
Mesolimbic pathway ↑ – positive symptoms
Mesocortical pathway ↓ – negative symptoms
what is bipolar disorder
characterised by mood swings, mania and depression
what is depression caused by
Monoamine theory
Caused by decreased function of 5-HT and NA systems
what are depression treatments
Monoamine uptake inhibition Tricyclic antidepressants (e.g. imipramine) SSRIs (e.g. fluoxetine) SNRIs (e.g. venlaflaxine) NRIs (e.g. bupropion)
Monoamine receptor antagonists
Non-selective blockers of especially α2 and 5-HT2
E.g. trazodone
Monoamine oxidase inhibitors
Irreversible, non-competitive, non-selective for MOA-A/B (e.g. phenelzine)
Reversible, MAO-A selective (e.g. moclobemide
what is a treatment for anxiety disorders
Treatment
Benzodiazepines, barbiturates
SSRIs/SNRIs
Buspirone
Affect GABA/5HT systems
what parts of the brain are affected by alzheimers
Hippocampus: impaired short term memory
Note the widened sulci and narrowed gyri with Alzheimer’s.
what pathways in alzheimers are affected
Cholinergic pathways particularly affected
what are the alzheimer treatment
Increases ACh levels
May slow progression
May improve cognition
what are the symptoms of multiple sclerosis
Sensory changes Muscle weakness Coordination and balance Speech Swallowing Visual Fatigue, Pain Incontinence Cognitive impairment Depression Mood swings
what are the causes of MS
Autoimmune
Oligodendrocytes affected
Myelin sheath degrades
Most common in women
what happens during substancia niagra
diminished substancia niagra seen
what is Huntington’s Disease
Inherited disorder
Autosomal dominant
Polyglutamine repeat
Huntingtin
what is the pathology of huntingtons disease
Loss of neurones cerebral cortex corpus striatum
GABAergic
Cholinergic
