The Nervous System Flashcards
How do protists and bacteria respond to stimuli?
With receptor proteins in the membrane
How do amoeba tackle bacteria?
The bacteria’s waste molecules bind to the amoeba’s chemoreceptors and the amoeba chases the bacteria so it can then capture it.
What is neural plasticity?
The ability of the brain/neuron to adjust in response to new situations or environments.
Where is short term memory accessed?
The hippocampus
How does the hippocampus aid memory?
By transferring short term memory to long term memory.
Where are long term memories stored?
The cerebral cortex
In what organisms are the simplest nervous systems found?
Cnidarians
What is a nerve net?
Interconnected nerve cells
What are nerves?
Bundles consisting of axons of multiple nerve cells.
What is the structure of a sea stars nervous system?
A nerve net found in each arm connected by radial nerves to the central nerve ring.
What is cephalization?
Clustering of sensory organs at the front of the body.
In what kinds of organisms is cephalization found?
Bilaterally symmetrical organisms
What is ganglia?
Segmentally arranged clusters of neurons.
What is the function of the peripheral nervous system?
It transmits information to and from the central nervous system and regulates movement and the internal environment.
What is the function of afferent neurons?
To transmit information to the central nervous system.
What is the function of efferent neurons?
To transmit information away from the central nervous system.
What are the two efferent components?
The motor system and the autonomic system
What is the function of the motor system?
To carry signals to skeletal muscles and is voluntary.
What is the function of the autonomic system?
To regulate smooth and cardiac muscle and is involuntary.
What are the divisions of the autonomic nervous system?
Sympathetic, parasympathetic and enteric
What is the function of the enteric division?
To control activity of the digestive tract, pancreas and gallbladder.
Where is the cell body of the parasympathetic preganglionic neuron found?
In the central nervous system.
Where is the postganglionic neuron of the parasympathetic system found?
Near the target organ.
What does the postganglionic neuron of the parasympathetic system release?
Acetylcholine.
What is the difference between the preganglionic neurons of the parasympathetic and sympathetic nervous systems?
The sympathetic preganglionic neuron is shorter.
What does the postganglionic neurons of the sympathetic neuron release?
Catecholamines.
When does the vertebrate brain develop?
During embryonic development.
What fills the spinal cord canal and brain ventricles?
Cerebrospinal fluid
What is the function of cerebrospinal fluid?
To cushion the brain and spinal cord, provide nutrients and removes waste.
What is grey matter made up of?
Neuron cell bodies, dendrites and unmyelinated axons.
What is white matter made up of?
Bundles of unmyelinated axons.
What is a ladder system?
Paired longitudinal nerve cords.
How was the ventral nerve cord formed?
The two cords of the ladder system fused together.
What is the peripheral nervous system made up of?
Nerves and ganglia
What kind of nerve cords do invertebrates have?
Ventral nerve cord.
What kind of nerve cords do vertebrates have?
Dorsal nerve cords.
What does the nerve cord give rise to?
The central canal and brain ventricles.
What is the function of glia?
To nourish support and regulate neurons.
What is the function of astrocytes?
To induce capillary lining cells in the central nervous system to form tight junctions.
What does the function of astrocytes result in?
The blood - brain barrier
What are the two subgroups of glia?
Macroglia and microglia
What are examples of macroglia?
Oligodendrocytes and Schwann cells - involved in myelination
What are the phases of brain development?
- Neural plate induction
- Neural proliferation
- Migration and aggregation
- Axon growth and synapse formation
- Cell death and synapse rearrangement
When does induction of the neural plate occur?
2-3 weeks after conception.
What is the neural plate?
A patch of tissue on the dorsal surface of the embryo that becomes the nervous system.
What induces neural plate development?
Chemicals such as growth factors.
What are growth factors?
Chemicals produced in the developing and mature brain that stimulate neuron development and help neurons respond to injury.
What is the function of radial glia?
To act as guidewires for the migration of neurons.
What establishes the cerebral cortex?
Sequential migration and aggregation of neurons.
What is migration and aggregation?
Movement of undifferentiated neurons.
What happens after migration and aggregation?
Axons and dendrites begin to grow to mature shape and size.
What is the function of growth cones?
To respond to signals.
What do axons and dendrites form?
Synapses with other neurons or tissues.
What is synaptogenesis?
Formation of new synapses
What cells release signals that induce synaptogenesis?
Glial cells.
What is required for synaptogenesis?
Chemical signal exchange between pre and postsynaptic neurons is needed.
What percentage of neurons die after migration?
40-75%
Why causes neuron death after migration?
Failure to compete for chemicals called neurotrophins.
What are the roles of neurotrophins?
Promote neuron growth and survival, guide axons and stimulate synaptogenesis.
What are the steps of synaptic rearrangement?
- Release and uptake of neurotrophic factors
- Neurons receiving insufficient neurotrophic factor die
- Axonal processes compete for limited neurotropic factor
What is the postnatal growth consequence of synaptogenesis?
Increased dendritic branches and myelination.
What may underlie the greater plasticity of the young brain?
Overproduction of synapses.
What does early visual deprivation lead to?
Fewer synapses and dendritic spines in the visual cortex and deficits in depth and pattern vision.
What does an early enriched visual environment lead to?
Thicker cortices, greater dendritic development and more synapses per neuron.
What is the left hemisphere responsible for?
Language, math, logic and processing of serial sequences.
What is the right hemisphere responsible for?
Pattern recognition, nonverbal thinking and emotional processing
What is lateralization?
Differences in hemisphere function.
How do the two hemispheres communicate?
Through fibres of the corpus callosum.
What are the areas of the cerebrum?
The frontal lobe, the temporal lobe, the occipital lobe, the parietal lobe and the insular cortex.
What are the areas of the frontal lobe?
The prefrontal cortex, the motor cortex and Broca’s area.
What is the prefrontal cortex responsible for?
Decision making and planning.
What is the motor cortex responsible for?
Control of skeletal muscles.
What is Broca’s area responsible for?
Forming speech.
What are the areas of the temporal lobe?
The auditory cortex and Wernicke’s area.
What is the auditory complex responsible for?
Hearing
What is Wernicke’s area responsible for?
Comprehending language
What are the areas of the Occipital lobe?
The visual cortex and the visual association cortex.
What are the areas of the parietal lobe?
The sensory association cortex and the somatosensory cortex.
What is the function of the sensory association cortex?
Integration of sensory information.
What is the function of the somatosensory cortex?
The sense of touch
What does the cerebral cortex control?
Voluntary movement and cognitive function.
What is the cerebrum responsible for?
Awareness, language, cognition, memory and consciousness.
What part of the brain is responsible for emotions?
The limbic system
What parts of the brain make up the limbic system?
The amygdala, hippocampus and the thalamus.
What is the function of the amygdala?
To store emotions in memory
What is the limbic system responsible for?
Motivation, olfaction, behaviour, memory and emotions.
What are examples of nervous system disorders?
Schizophrenia, depression, drug addiction, Alzheimer’s and Parkinson’s.
What can contribute to nervous system disorders?
Genetic and environmental factors.
What makes addictive drugs addictive?
They enhance the activity of the dopamine pathway which causes cravings.
What is the physiological effect of opium and heroin?
They decrease inhibitory neuron activity.
What is the physiological effect of cocaine and amphetamines?
They block the removal of dopamine from the synaptic cleft.
What is the physiological effect of nicotine?
It stimulates dopamine releasing VTA neuron.
