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150 Cards in this Set
- Front
- Back
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What is categorised under the CNS and what is categories under the PNS? |
CNS = brain and spinal chord PNS = nerves to and from (Efferent and afferent) from CNS |
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Define afferent |
Ascending - flowing TO brain and carries sensory info |
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Define efferent |
Descending; flowing FROM brain |
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What are the 2 patterns of cellular connections in the NS? |
Divergent and convergent |
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Define divergent cellular connection |
One neuron regulates multiple targets |
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Define convergent cellular connection |
One neuron regulated by multiple inputs |
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Out of the following two responses, which is excitatory and which is inhibitory? EPSP and IPSP |
EPSP = excitatory IPSP = inhibitory |
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Describe ligand-gated ion channels |
Responses are fast and localised; have pockets in domain that directly bind to neurotransmitter which allow ions to flow through |
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Describe G-protein coupled receptors |
Responses are slow, small, longer in duration and widespread |
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How are excitatory and inhibitory responses defined? |
By ion flowing through open channel |
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Where are EPSPs and IPSPs integrated? |
The soma by summation |
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What do interneurons provide? |
Local, negative, control of activity. Transport for network functions such as enhancing signals and switching between output pathways |
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Which outweighs which: inhibitory or excitatory inputs? |
Inhibitory |
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Define luminance |
Physical stimulus property |
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Define brightness |
Subjective experience |
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Describe the inhibitory surround mechanism |
The excitatory neuron receives stimulus (light), which then tells CNS this message. 2 branches will simultaneously activate inhibitory neurons and inhibit them with GABA. This results in central excitation and inhibitory surround |
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What are all neurons firing at? |
Basal rate |
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What happens with the surrounding neurons, once there is an excitatory centre? |
They go below basal rate because they are inhibited |
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How does a strongly inhibited area occur? |
Overlapping fields |
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What do inhibitory interneurons in a neural network provide? |
Mechanism for switching between alternate pathways |
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What are some rhythmic alternating behaviours? List them |
Respiratory, locomotion, feeding, sleep/wake cycle |
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Describe the rhythmic alternating behaviours using a pacemaker as an example |
When master neuron fires, there is a release of excitatory transmitter which excites motor neurong 1 and therefore a certain behavioural outcome occurs. The inhibitor neuron is also triggered and so a release of GAB occurs onto pacemaker cell which causes it to be non-active. To active the pacemaker, the master neuron must stop firing. |
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List the 3 examples of g-protein coupled receptors |
Direct Second messenger binding Kinase-mediated phosphorylation |
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What are G-protein coupled receptors (GPCR) more like? |
Adminstrtaors |
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Describe the steps for G-protein coupled receptor signalling |
1. Binding of agonist with receptor changes interaction with docked G protein (usually GDP). 2. Alpha subunit released DP and binds to GTP therefore causing it to dissociate to its subunits 3. Beta and gamma stick together 4. The active subunits interact with downstream targets (effectors) 5. Subunits return to normal resting states when GTP is hydrolysed into GDP and phosphate Pi is released |
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Why can we get diversity in the signalling of GPCP |
Not just one type of alpha/beta/gamma so they can recombine in different ways and therefore give way to various actions |
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What is the function of Gs? |
Stimulate adenylyl cyclase |
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What is the function of Gi? |
Inhibits adenylyl cyclase |
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What is the function of Gt? |
Transducin (retina) activates phosphodiesterase |
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What is the function of Go? |
Regulates ion channels |
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What is the function of Gq? |
Couples to phospholipase |
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How do we distinguish between receptors? |
Use pharmacology to distinguish between receptors. Can do this because not all selective pharmacological agents will interact with same receptors |
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How are responses from receptors define? |
Ion channels activated/inhibited |
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What are the 3 levels of regulation by G-proteins? |
Direct Modulation Modulation Modulation by second messenger |
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What is direct modulation by g-proteins? |
Ion channel function is modulated by binding of a G-protein |
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Describe an example of direct modulation and its functional significance |
M channel of cardiac atrium is regulated by mAChR (muscarinic ACh receptor). The functional significance of this is that parasympathetic system slows the heart rate down |
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What do K channels do in direct modulation? |
Restore and maintain resting state |
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When are Kir channels open and what do they set? |
Open at negative potentials and set resting membrane potential |
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When are Kv channels open and what do they do? |
Open at positive potentials and re-polarise cells after a stimulus |
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Describe modulation by g-proteins |
Modulation by synthesis of a second messenger that binds to channel |
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What is an example of modulation by g-proteins and its functional significance |
Example is signal transduction in retina and its functional significance is the mechanism for the detection of light in the vertebrate visual system |
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What picks up light at the back of the retina? |
Photoreceptors |
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How is light perceived? What is the pathway it is processed by? |
Perceived through transducence. Pathway = processed by ganglion cells then optic nerve then thalamus then appropriate part of cortex |
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What does seeing light work on? Does it involve modulation? |
A "dark current" which basically means, a decrease in transmitter release is interpreted b the CNS as detection of light Yes |
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What is the chemical explanation of a dark current for detecting light? |
Alpha subunit interacts with enzyme which breaks down second messenger (cGMP) which is then converted to active messenger. The removal of cyclic GMP closes channels therefore depolarisation stops and so does releasing transmitter at terminal |
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How is the third type of modulation different from the second? (i.e. second messenger modulation) |
Because the first is modulated by synthesis o a second messenger that BINDS to a channel whereas the third is mediated by the activation of a kinase that phosphorylates the channel |
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What is an example of modulation by second messenger with activation of a kinase that phosphorylates the channel? |
Increase in firing rate and force of contraction of heart |
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What is the function significance of modulation by second messenger with activation of a kinase that phosphorylates the channel? |
Sympathetic NS prepares body for fight or flight response which includes increase in cardiac output |
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How does the modulation by a second messenger mediated by the activation of a kinase that phosphorylates the channel work? |
Adrenaline binds to an adrenergic GPCR which activates a Gs protein. This regulates adenylate cyclase (an enzyme) which then increases the synthesis of cAMP. cAMP activates PKA (protein kinase) that phosphorylates voltage-gated Ca channels therefore their increase in open probability increases intracellular Ca and thus promotes cardiac muscle contraction |
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Which pathway of the PNS is voluntary and which is involuntary? |
Somatic is voluntary Autonomic is involuntary |
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What do visceral sensory fibres do? |
Feedback info for reflex controls (subconscious) to regulate blood pressure, heart rate, respiration and visceral activities |
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How many neural chains does the autonomic have? |
2 |
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What are the 6 cells that the uncommitted neuronal crest cell can develop into depending on migration and determination? |
Melanocyte, glia, sensory, sympathetic-adrenal, parasympathetic, enteric |
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in the somatic system, where is the cell body located? |
Ventral horn |
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In the autonomic system, where is the first neuron located and where is the second? |
First cell body is located in the thoracic and lumbar spinal cord and second is dependent on whether it is sympathetic or parasympathetic (if sympa it is located near the spinal cord, if para it is located near the target tissue) |
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What sort of response/link are all three systems to begin with? What is the transmitter and what does it act on? |
They are excitatory. Transmitter is ACh. Receptor is nicotinic ACh which are ligand meaning their fast |
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What type of muscle cells does the somatic and autonomic system innervate? |
Somatic = skeletal Autonomic = smooth |
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What does AR stand for? What does it recognise? |
Adrenergic receptor. Noradrenaline/adrenaline |
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What does mAChR stand for? What does it recognise? |
Muscarinic acetylcholine receptor |
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What gives dual control function of an organ/tissue? |
The excitatory or inhibitory effects determine by GPCR coupling |
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State the steps for synthesis of adrenaline/noradrenaline |
Tyrosine -> DOPA -> dopamine -> noradrenaline -> adrenaline |
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What is tyrosine? |
Precursor for transmitter synthesis |
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What is the rate-limiting step of synthesising adrenaline/noradrenaline? |
DOPA synthesis |
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How is tyrosine and NA cleared? |
Co-transporters |
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Which adrenergic receptors are excitatory? |
Alpha 1 and beta 1 |
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What does the Alpha 1 receptor interact with and what does this interaction trigger? What is the main result of alpha receptor being activated? |
Interacts with g-protein in resting state (GDP) which triggers the g-protein to interact with pshopholipase C. Muscle contraction (in vascular smooth muscle and GI tract walls/sphincters) |
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What does the enzyme phospholipase C work on and what is its action? |
Lipid bilayer called phosphatidylinositol and changes it to two pieces: a phosphate head group (IP3) and a diasole tail (DAG) |
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What does the IP3 phosphate head group from the piece of phosphatidylinositol diffuse through and reacts with? |
Diffuses through cytoplasm and reacts with stores and causes calcium to be released from intercellular stores |
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What is the main result of beta one adrenergic receptor being activated? Where is it found? |
Main result is muscle contraction and increase heart sinoatrial node. Found in ventricle of heart |
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When noradrenaline binds to the beta one adrenergic receptor, what happens? |
Beta 1 is activated. Binding of GTP with alpha subunit occurs. Interaction wit adenylate cyclase occurs using ATP as a substrate and synthesises cAMP. cAMP interacts further with protein kinase A (PKA). cAMP causes a phosphate to be added to the calcium channel so they open therefore releasing calcium |
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What are the two inhibitory adrenergic response receptor? |
Alpha 2 and beta 2 |
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What is the action of alpha 2? |
Decreases insulin release (metabolic function of liver) and uses a Kir activation by G-proteins to cause hyperpolarisation (relaxation) |
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What is the action of beta 2? |
Increases calcium export from cell which results in smooth muscle relaxation, relaxes bronchiolar smooth muscle |
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When the fight or flight response is activated, what happens to heart rate, blood pressure, blood flow, blood glucose, airways and pupils?
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Heart rate, blood pressure and blood glucose increases Blood flow shifts from skin and gut to heart and muscles airways dilate pupils dilate |
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What a blood vessel is excited what does this mean for flow? |
It decreases because contraction occurs |
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What do drugs that are selective for adrenergic receptor subtypes offer? |
Therapeutic opportunities |
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What do beta 1 antagonists do in the heart? |
Block things in the heart and help manage cardiovascular disorders |
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What do beta 2 agonists do in the airways? |
Bronchodilators |
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What is another word for basal? What does basal activity mean? |
Tonic. Means that its the base rate to maintain homeostasis |
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What are feedback control mechanisms called? |
Reflex arcs |
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What do baroreceptors detect? |
Pressure |
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What is the role/goal of the parasympathetic system? |
Opposes action of sympathetic. Is organised for discrete and localised signalling with small divergence. Goal is to conserve energy and maintain organ functions at rest |
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Do you need to excrete more when the para system is activated? |
Yes |
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Where do cranial nerves originate? Where do they innervate? |
Brain stem. Innervate ganglia in heart, lung, digestive organs, eyes and glands |
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What is the main parasympathetic nerve? |
Vagus |
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What do the afferent cranial nerves carry? |
Visceral sesnroy info |
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What do efferent cranial nerves carry? |
Regulation of heart and other organs |
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What do the spinal nerves from the sacral region innervate? |
Ganglia in intestine, bladder and reproductive organs |
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What is the preganglionic neuron of the para system? What is it released onto? |
Acetylcholine. Nicotinic acetylcholine receptors (nAChR) |
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Is acetylcholine recycled? How? |
Yep. Split into parts by enzyme acetylcholinerase |
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What type of receptors are nicotinic? Do they inhibit or excited? |
Direct ligand-gated. Excite
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What type of receptors are the post ganglionic (muscarinic) receptors of the para system |
GPCR |
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Are muscarinic receptors inhibitor or excitatory? |
Both |
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Which muscarinic receptors are excitatory and which are inhibitory? |
M1 and M3 are excitatory and M2 is inhibitory |
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How do M1 and M2 act as excitatory? |
Phospholipase C causes release of intracellular clacium. Acts exactly the same as A1 |
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How does M2 act as an inhibitory response? |
Muscle relaxation caused by an increased Kir conductance or by inhibiting adenylate cyclase |
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How does the M2 inhibitory response come about? What is this opposite to? |
It inhibits adenylate cycalse (Gi) which then causes decreased cAMP production thus reducing PKA levels. Therefore calcium channel is de-phosphorylate and not as open as before so less calcium is entering which means a decrease in muscle contraction. Opposite to beta one |
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Where are M2 receptors expressed? |
SA node |
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What is an example of an anti-muscarinic drug and what are its effects? |
Atropine. It is an antagonist and helps to depress salivary and bronchial secretions. Promotes sympathetic-like effects. In moderate doses, pupils dilate, vagal effects on heart are blocked therefore heart increases. In high doses, gastric secretion and motility are decreased |
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Fill out a table comparing the differences between autonomic systems addressing the site of origin of preganglionic fibres, the length of pre and post ganglionic fibres, the degree of synaptic divergence, the transmitter used by POSTganglionic neurons, receptors expressed on target organ, general structure pattern of organisation, transmitter used by PREganglionic neuron and receptor expressed on POST ganglionic neuron
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Look in exercise book |
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What is the role of the cerebral cortex? |
Sensation, movement, self, language, personality |
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What is the role of the hippocampus? |
Memory and spatial orientation |
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What is the role of the cerebellum? |
Skilled movement, balance, co-oridation |
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What is the role of the thalamus? |
Relay station for afferent pathways |
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What is the role of the brain stem? |
More primitive role of organ functions, homeostasis, arousal and sleep |
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What is the role of the corpus callosum? |
Connects the 2 hemispheres via axon tracts |
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What does PET stand for? |
Positron emission tomography |
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What does the PET scan measure? What does it use to measure this? |
Metabolic demand. Flurodeoxyglucose |
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What does fMRI stand for? What does it measure? |
Functional magnetic resonance imaging. Brain activity through blood flow |
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Why do you have to repeat a PET scan multiple times? |
To subtract the extra stimuli |
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Where is the primary motor cortex? What is apart of this? Is there voluntary or involuntary movement? |
Frontal lobe. Cerebral cortex is part of it. Voluntary movement control |
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What does the motor area of the cerebral cortex have? |
A spatial map called the motor homuculus |
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How are the neurons of the cerebral cortex gathering? Where do they project? |
Gather in tracts through the spinal cord and project to neighbouring neurons in the cortex |
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Where is the primary sensory regions of the cortex located? |
Parietal, temporal and occipital lobe |
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What does the parietal lobe perceive?. What is the name of its map? |
Somatosensory info (touch, heat, cold, vibration, pain). Somatosensory homunculus |
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What does the temporal lobe perceive? What is the name of its map? |
Hearing, orientation. Tonotopic map |
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What does the occipital lobe perceive? What is the name of its map? |
Vision. Retinotopic map |
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What do the association areas of the cortex provide, integrate and plan? |
Provide comprehension, analysis, decision making, complex behaviours. Integrate info from multiple sensory modalities Plan voluntary movement and enable cognition, emotional behaviour and language |
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What are the 3 main functions of association areas? |
Prefrontal, parietal-occipital-temporal |
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What is the prefrontal for? |
Cognition, planning, complex associations, language production |
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What is the parietal-occipital-temporal for? |
Integrating sensory info, language comprehension |
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What is the limbic area for? |
memory, emotion, motivation |
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What are the two cortical association areas (association cortex) involved in language? |
Left frontal lobe (broca's area) and left parietal-temporal-occipital (POT) association cortex |
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What is the left frontal lobe (broca's area) involved in? |
Speech formation (production) |
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What is the left-temporal-occipital (POT) association cortex (Wernicke's area) involved in? |
Speech understanding and comprehension |
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What is the verbal output and comprehension like in broca's aphasia? Give an example |
Verbal = nonfluent Comprehension = normal. Repeating the sentence "the ladies and gentlemen are now all invited into the dining room" would be said "ladies, men, room" |
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What is the verbal output and comprehension like in wernicke's aphasia? Give an example |
verbal = fluent Comprehension = impaired When asked "where do you live?" the patient would reply "I came here before there and returned here" |
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What happens when you damage the right and left side of parietal lobe association areas? |
R - Loss of awareness of left half of body (neglect syndrome) L - inabilit to perceive objects and aphasia |
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What happens when you damage the limbic association area?
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Alter addiction |
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What does the left and right brain control? |
L - language, logic, and fine motor control R - spatial perception, artistic and musical abilities |
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What happens if the corpus callosum is severed? |
Two hemispheres function independently. The perception of self as a complete entity is not identical with consciousness but relies on connecting diverse functions in both hemispheres |
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What does the wiring of the cortex depend on? |
Use and training |
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What happens to well-used and less-used pathways in the cortex? |
Well-used take over the space Less-used are consolidated or eliminated |
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What is amblyopia? |
Loss of vision associated with a weak but functional eye as a result of preferential use of the stronger eye |
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What are cortical representations? Can these be lost? |
Regions in the cortex that are dedicated to controlling a specific type of sensory (or motor) info. Yes they can be lost in the space if not used |
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Are memories one single mechanism or multiple? |
Multiple - they are subdivided into different categories |
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What does damage to the hippocampus result it? |
Loss of ability to transfer info from short term to long term memory |
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What is memory? |
A long-lasting change in some 'plastic' element of the brain such as the synapse |
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What does LTP stand for? What is it? |
Long-term potentiation Increase synaptic strength that persists for hours to days |
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What are two possible reasons why synaptic strength arises? |
Enhanced transmitter release with each presynaptic action potential and increased EPSP amplitude for a given amount of neurotransmitter |
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What is glutamate? |
Transmiter released from pre-synaptic side of hippocampus |
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What are the 2 classes of glutamate receptors? |
Non-NMDA (aka AMPA) and NMDA |
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Describe the features of Non-NMDA/AMPA receptor types? |
Always available, respond to weak or strong stimulation, pathway for potassium and sodium |
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Describe the features of NMDA receptor types? |
Only respond to strong stimulation Allow sodium and calcium entry |
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In the resting state, are NMDA open or blocked? |
Blocked by magnesium |
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Can glutamate activate both NMDA and non-NMDA/AMPA receptors when in resting state? |
No, only AMPA |
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What results from the AMPA/non-NMDA response with glutamate? |
Magnesium unbinds from NMDA by depolarisation |
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What happens when NMDA receptors are unblocked? |
glutamate then can activate both NMDA and AMPA/Non-NMDA receptors and calcium can enter through NMDA which initiate a cascade of events leading to a long-lasting enhancement of post synaptic response |
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What is the one area of the brain involved in memory storage? |
Temporal lobe |
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What happens when LTP is induced? |
Small presynaptic stimuli generate large postsynaptic responses |
