Hydrocephalus can be caused by different mechanisms. Name two possibilities.
Hydrocephalus is an increase in the volume of the cerebral ventricles, which is
caused by
- oversecretion of CSF (malfunction of the choroid plexus) or
- impaired absorption of CSF (at the arachnoid villi).
- oversecretion of CSF (malfunction of the choroid plexus) or
- impaired absorption of CSF (at the arachnoid villi).
What happens if similar changes occur in older patients?
• In older patients the skull is fixed.
• Hydrocephalus therefore causes intracranial pressure which results in brain damage.
• Hydrocephalus therefore causes intracranial pressure which results in brain damage.
What are nociceptors?
A nociceptor is a sensory receptor that sends signals that cause the perception of pain in response to potentially damaging stimulus.
What is the structural and functional difference between A- and C-fibers?
•A-fibers have a large diameter and are myelinated whereas
•C-fibers have a small diameter and are not myelinated.
•C-fibers have a small diameter and are not myelinated.
Explain why two sensations (e.g. first and second) can be elicited by activation of nociceptors? How do these sensations differ?
•Pain is sensed in two phases, the first very fast one is conducted via A-fibers and the second slower one by C-fibers.
•Pain transmitted by C-fibers is unlocalized due to peptidergic transmitters (e.g. Substance P which enhances and prolong action of glutamate).
•Pain transmitted by C-fibers is unlocalized due to peptidergic transmitters (e.g. Substance P which enhances and prolong action of glutamate).
Menthol elicits a cool sensation. Give a neurobiological explanation for this observation.
Menthol triggers cold-sensitive receptors in the skin like capsaicin evokes burning pain by activating an ion channel that also responds to heat.
What is the function of the sarcomere?
•Sarcomere: Basic functional subunit of myofibrils, repeated along length of myofibril
•The sarcomere is the functional unit in a muscle fiber which contracts on activation.
•The sarcomere is the functional unit in a muscle fiber which contracts on activation.
Sliding filament hypothesis: What is the molecular basis of contraction? F-actin, myosin, troponin-tropomyosin, Ca-Ions, ATP. Which of these components represent the trigger for contraction? What happens if ATP is lacking? What’s the role of troponin-tropomyosin?
•The thick and thin filaments comprise the contractile machinery of the muscle.
•In a contracting muscle adjacent thick and thin filaments slide past each other, propelled by cyclical interactions between the myosin heads of the thick filaments and binding sites on the actin of the adjacent thin filaments.
•This mechanism is triggered by Ca2+ influx and uses ATP as energy source.
•The troponin-tropomyosin complex and F actin form the thin filament.
•In a contracting muscle adjacent thick and thin filaments slide past each other, propelled by cyclical interactions between the myosin heads of the thick filaments and binding sites on the actin of the adjacent thin filaments.
•This mechanism is triggered by Ca2+ influx and uses ATP as energy source.
•The troponin-tropomyosin complex and F actin form the thin filament.
In humans, injury of the spinal cord is often followed by a so-called “spinal shock”. What are the symptoms of a “spinal shock” and why does it occur in humans but not in mice?
•Spinal cord injury
•-> Neurons involved in reflex arcs no longer receive basal level of excitatory stimulation from brain.
•-> Become hyperpolarized and thus less responsive.
•Recovery is possible.
•A spinal shock does not occur in mice because reflex circuits are not controlled by the brain.
•-> Neurons involved in reflex arcs no longer receive basal level of excitatory stimulation from brain.
•-> Become hyperpolarized and thus less responsive.
•Recovery is possible.
•A spinal shock does not occur in mice because reflex circuits are not controlled by the brain.
How does the activation of the nervus vagus influence peripheral tissue (e.g. the heart)?
The parasympathetic system conserves energy as it slows the heart rate, increases intestinal and gland activity, and relaxes sphincter muscles in the gastrointestinal tract.
In which organs are Leptin and Ghrelin produced?
•Ghrelin is produced by P/D1 cells lining the fundus of the human stomach that stimulate appetite.
•Ghrelin levels increase before meals and decrease after meals.
•It is considered the counterpart of the hormone leptin, produced by adipose tissue (fat), which induces satiation when present at higher levels.
•Ghrelin levels increase before meals and decrease after meals.
•It is considered the counterpart of the hormone leptin, produced by adipose tissue (fat), which induces satiation when present at higher levels.
In which brain region are leptin and ghrelin receptors localized?
Receptors for ghrelin and leptin are expressed by neurons in the hypothalamus.
To which part of the nervous system and to which subsystem does the nervus vagus belong?
The nervous vagus belongs to the autonomic nervous system or more precisely to the parasympathetic nervous system.
What is the effect of leptin and ghrelin on food intake and energy expenditure?
•The ghrelin level is high before food intake and decreases after food intake.
•Thus, ghrelin is a hormone which stimulates appetite.
•On the contrary, leptin reduces appetite.
•The level of leptin in the blood stream is high if the body has much adipose tissue.
•Thus, ghrelin is a hormone which stimulates appetite.
•On the contrary, leptin reduces appetite.
•The level of leptin in the blood stream is high if the body has much adipose tissue.
Which of these is true about the cerebellum?
•Parallel fibers of ganule cells inhibit purkinje cells in all directions and thereby leading to contrast enhancement.
•Neighboring purkinje cells receive input from the same granule cells with increasing delay thereby providing a possibility for temporal segmentation of movement.
•Neurons of the subcortical nuclei are excited by axon collaterals of climbing neurons. Thus, the transmission can only occur if purkinje neurons are inhibited by inhibitory interneurons.
•Parallel fibers of ganule cells inhibit purkinje cells in all directions and thereby leading to contrast enhancement.
•Neighboring purkinje cells receive input from the same granule cells with increasing delay thereby providing a possibility for temporal segmentation of movement.
•Neurons of the subcortical nuclei are excited by axon collaterals of climbing neurons. Thus, the transmission can only occur if purkinje neurons are inhibited by inhibitory interneurons.
•Neighboring purkinje cells receive input from the same granule cells with increasing delay thereby providing a possibility for temporal segmentation of movement.
•Neurons of the subcortical nuclei are excited by axon collaterals of climbing neurons. Thus, the transmission can only occur if purkinje neurons are inhibited by inhibitory interneurons.
•Neurons of the subcortical nuclei are excited by axon collaterals of climbing neurons. Thus, the transmission can only occur if purkinje neurons are inhibited by inhibitory interneurons.
To which phylogenetically old functional system does the striatum belong?
Basal ganglia (extrapyramidal system)
The genetic disease “Chorea Huntington” is characterized by a degeneration of the striatum. Explain the symptoms of the disease.
•The striatum contains GABAergic nerve cells which are affected by “Chorea Huntington”.
•These neurons degenerate which causes uncontrolled muscle movement (tics).
•This is why “Chorea Huntington” is also called “Veitstanz”.
•These neurons degenerate which causes uncontrolled muscle movement (tics).
•This is why “Chorea Huntington” is also called “Veitstanz”.
What is the reason for the high convolution of the cerebral cortex?
The high convolution of the cortex increases the surface and therefore leads to a increased number of neurons.
What is a column or module in the cerebral cortex?
•A module is the basic functional unit of the cortex.
•All of the neurons within a module receive input from the same source and respond to a single class of receptors.
•All of the neurons within a module receive input from the same source and respond to a single class of receptors.
Which of the following structures or cells are present in a column?
•pyramidal cells
•Schaffer collateral pathway
•granule neurons
•purkinje cells
•parallel fibers
•basket cells
•pyramidal cells
•Schaffer collateral pathway
•granule neurons
•purkinje cells
•parallel fibers
•basket cells
•pyramidal cells
•granule neurons
•basket cells
•granule neurons
•basket cells
Explain your proposal (layer V - sensory) with respect to a discussion of the input and output regions of the cerebral cortex.
Layer IV and V receive input and send output to subcortical regions, respectively.
What is the function of the hippocampus with respect to memory formation?
•Although the hippocampus is involved in memory formation, it actually does not store any declarative memory.
•However, it reveives input from the cortex via the entorhinal cortex and sends a modified signal back to the cortex.
•However, it reveives input from the cortex via the entorhinal cortex and sends a modified signal back to the cortex.
Would you expect that the mice (with lesioned hippocampus) develop a retrograde amnesia? Explain.
•Retrograde amnesia is a form of amnesia where someone will be unable to recall events that occurred before the onset of amnesia.
•Since the hippocampus is not needed for memory recall a retrograde amnesia will not develop.
•Since the hippocampus is not needed for memory recall a retrograde amnesia will not develop.
Why does PKA inactivation affect LTP?
•PKA plays an essential role in LTP in both the mossy fiber pathway and the Schaffer collateral.
•It is part of second-messenger cascades leading either to more transmitter release in presynaptic cells or to recruitement of non-NMDA receptors in postsynaptic cells, respectively.
•It is part of second-messenger cascades leading either to more transmitter release in presynaptic cells or to recruitement of non-NMDA receptors in postsynaptic cells, respectively.
Which of these is correct about the amygdala?
•The amygdala is part of the limbic system which is a phylogenetically old system of the brain.
•The amygdala is one of the few brain regions that lack peptidergic neurons.
•The amygdala consists of several nuclei which show a topical organization.
•Although the amygdala is also involved in learning processes, LTP is restricted to the hippocampus.
•Valium acts on GABAergic interneurons in the amygdala and decreases anxiety by increasing hyperpolarization.
•The amygdala is part of the limbic system which is a phylogenetically old system of the brain.
•The amygdala is one of the few brain regions that lack peptidergic neurons.
•The amygdala consists of several nuclei which show a topical organization.
•Although the amygdala is also involved in learning processes, LTP is restricted to the hippocampus.
•Valium acts on GABAergic interneurons in the amygdala and decreases anxiety by increasing hyperpolarization.
•The amygdala is part of the limbic system which is a phylogenetically old system of the brain.
•The amygdala consists of several nuclei which show a topical organization.
•Valium acts on GABAergic interneurons in the amygdala and decreases anxiety by increasing hyperpolarization.
•The amygdala consists of several nuclei which show a topical organization.
•Valium acts on GABAergic interneurons in the amygdala and decreases anxiety by increasing hyperpolarization.
Where is the SCN localized?
The SCN (suprachiasmatic nucleus) is localized above the optic chiasm (part of the hypothalamus).
How is the action of the SCN modulated and compelled to the light cycle?
The SCN receives input from the retinohypothalamic tract.
How does the SCN control products of melatonin?
The SCN is connected to the pineal body which secrets melatonin into the blood flow.
What is melatonin? How does its concentration change during day and night?
•Melatonin is a hormone secreted by the pineal body.
•It is an internal signal for “darkness”.
•Thus, it increases during night and decreases by day.
•It is an internal signal for “darkness”.
•Thus, it increases during night and decreases by day.
Which brain structure innervates the pineal body?
The pineal body is innervated by the SCN and activating systems in the brain stem.
How does the pineal body get information about light?
•In higher vertebrates, the pineal body is not a light sensitive organ itself.
•Instead, it receives information about light from the SCN.
•Instead, it receives information about light from the SCN.
In higher vertebrates, CNS and PNS neurons differ in their neurogenerative capacity. In which respect?
Neurons in the CNS do not regenerate whereas neurons in the PNS may regenerate.
Neurons in the CNS do not regenerate whereas neurons in the PNS may regenerate. What is thought to be the cause for this difference?
•Neurons in the CNS are in principle able to regenerate but this ability is suppressed by central myelin (this may be why myelination occurs late in development).
•The suppression can be abolished by antibodies against NI-35 (“nogo”) which seems to be the main factor.
•In the PNS myelin is not generated by oligodendrocytes but by Schwann cells.
•The suppression can be abolished by antibodies against NI-35 (“nogo”) which seems to be the main factor.
•In the PNS myelin is not generated by oligodendrocytes but by Schwann cells.
Explain, how neurodegeneration can propagate via transsynaptic effects.
If a cell is injured, the postsynaptic cells degenerate because of missing excitation whereas the presynaptic cells degenerate because of missing neurotrophic factors.
What happens during Myasthenia gravis? What are the typical symptoms?
•During Myasthenia gravis acetylcholine receptors at motor end plates are blocked by antibodies.
•This leads to fluctuating weakness and fatiguability of muscle movement.
•The muscle weakness increases during periods of activity and improves after periods of rest.
•This leads to fluctuating weakness and fatiguability of muscle movement.
•The muscle weakness increases during periods of activity and improves after periods of rest.
Why are ACh-esterase inhibitors like neostigmine helpful?
•Muscle function is improved by cholinesterase inhibitors, such as neostigmine and pyridostigmine.
•These slow the natural enzyme cholinesterase that degrades acetylcholine in the motor end plate;
•The neurotransmitter is therefore around longer to stimulate its receptors (which there are less of in this disease).
•These slow the natural enzyme cholinesterase that degrades acetylcholine in the motor end plate;
•The neurotransmitter is therefore around longer to stimulate its receptors (which there are less of in this disease).
Give an example of another autoimmune disease.
•Multiple Sclerosis is an example for another autoimmune disease.
•Symptoms include changes in sensation, visual problems, muscle weakness, depression, difficulties with coordination and speech, severe fatigue, cognitive impairment and problems with balance caused by demyelination of axons due to a malfunction of the autoimmune system.
•Symptoms include changes in sensation, visual problems, muscle weakness, depression, difficulties with coordination and speech, severe fatigue, cognitive impairment and problems with balance caused by demyelination of axons due to a malfunction of the autoimmune system.
Kartensatzinfo:
Autor: szara
Oberthema: Biology
Thema: Neurobiology
Veröffentlicht: 06.04.2010
Tags: Functional Neuroanatomy
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