Excitable cells Flashcards
Corpus Callosum
Large tract of white matter containing axons linking the left & right sides of the cerebral cortex
Cerebral cortex forms from the
telecephalon
Rhombencephalon gives rise to the
cerebellum
medulla oblongata
pons
Dendritic spines
Involved in sensory input.
Related disorders include mental retardation and foetal alcohol syndrome.
Forebrain/prosencephalon consists of the
telecephalon and diencephalon
Rhombencephalon functions
oldest part of the brain
controls attention and sleep
Ataxia
Disorder of cerebellum
Causes a lack of coordination
Cerebellum function
motor planning
coordination of movement
Degeneration of the substantia nigra is associated with which disease?
Parkinson’s disease
Over-activity of the mesolimbic and mesocortical dopaminergic pathways is linked to
Schizophrenia
Peak in the folding of the cortex
Gyrus
Troughs in folding of nucleus
Sulci
Dendrites
Branched projections from the neurone’s cell body. Form synapses with axons of other neurones and contain receptors to respond to neurotransmitters
Type of glial cell that myelinates neurones in the CNS
Oligodendrocyte
Microfilament
Actin polymer
Thinner part of cytoskeleton
Mediates changes in cell shape
Where does sensory information enter the spinal cord?
Dorsal root
Where does motor information leave the spinal cord
Ventral root
Where is the pons and medulla contained?
Brain stem
Thalamus
Controls input to the cortex
Located at the centre of the brain
T/F Axons are present in gray and white matter
TRUE
Where is the voltage sensor of the voltage-gated sodium channel located?
4th transmembrane domain due to positive charges allowing it to move in response to changes in the membrane field.
Main functions of the ANS
- Contraction and relaxation of smooth muscle
- The rate and force of the heartbeat
- All exocrine and some endocrine secretions
What happens to the overall charge of the cell if K+ leaves?
Negative charge created - opposes further movement of K+ out of the cell. Limited K+ required to create the charge.
Capacitance
Ratio of the change in an electric charge in a system to the corresponding change in its electric potential
What cells produce myelin sheath in the PNS?
Schwann cell
Allosteric modulator
Binds the receptor at a different site to alter how receptor responds to ligand
Example of ionotropic acetylcholine receptor?
nicotinic
example of metabotropic receptors?
mAChR
Dopamine
GabaB
What type of receptor is a voltage-gated sodium channel?
GPCR
Stroke involves
reduced blood flow and oxygen to the brain
Gap junction channels are composed of…
6 connexin subunits form a connexon. 2 connexons form a gap junction.
Cytokines
Small proteins involved in all forms of disease and injury
What type of receptor is a voltage-gated sodium channel?
GPCR
Electrical synapse transmission occurs at sites known as…
Gap junction
Gap junction channels are composed of…
6 connexin subunits form a connexon. 2 connexons form a gap junction.
Categories of neurotransmitter
Amino acid
Amine
Peptide
Action potential firing is dependent on:
- Net sign of combined input
- Strength of synaptic input
- Location of synapse
- Firing frequency of presynaptic neuron
In response to a stimulus above the threshold potential, the size of a neuronal action potential…
is independent of the stimulus size
The inactivation gate of the voltage gated sodium channel is also known as the…
h gate
Voltage gated sodium channels are blocked by…
Local anaesthetics
Use of cell-attached patch clamp configuration?
To record currents through a limited number (1-2) active channels at cell surface
Use of inside-out patch clamp configuration?
Record currents through single active channel away from cell
Use of outside-out patch clamp configuration?
Records currents through single active channel away from cell
Use of whole-cell patch clamp configuration?
Record currents through active channels in whole cell.
Advantages of cell-attached patch clamp configuration?
Good for looking at single channel currents in response to regulation of channels by cell
Advantages of inside-out patch clamp configuration?
Can look at agents that modulate channel by working at its intracellular face
Advantages of outside-out patch clamp configuration?
For looking at agents that modulate channel by working at its extracellular face
Advantages of whole-cell patch clamp configuration?
Good for looking at cell currents in response to drugs added from outside, or regulation of channels by cells
Advantages of myelination
Speed
Compactness of neurones
Energy efficiency
Why are cytoplasmic levels of calcium very low?
It is sequestered into intracellular stores very quickly
What sodium channel blocker do dinoflagellates produce which causes red-time shell fish poisoning?
Saxitoxin
How many subunits do nicotinic acetylcholine receptors contain? what does this make them?
pentamers
the electrochemical gradient of ion across the cell membranes determines…
the movement of ions through channels in the cell membrane
what does fick’s law describe?
the rate of diffusion of a molecule
An example of an ion that is biochemically, but not physiologically useful in neurons is
Mg2+
What toxin do foxgloves produce?
digoxin
The production of what toxin by symbiotic bacteria is utilised by puffer fish as a defence mechanism
tetrodotoxin
Guillain-Barre syndrome
Disease where the Schwann cells insulating alpha motor neurones are attacked
Parkinson’s disease
involves destruction of the nigro-striatal pathway in the brain
Which GABA receptor is ionotropic
GABAa
ligand-gated Cl channel
Which GABA receptor is metabotropic?
GABAb
Calcium release mechanism in skeletal muscle…
DHP receptor (L type Ca channel) acts as voltage sensor, and is mechanically coupled to ryanodine receptor which allow Ca passage
Calcium release mechanism in cardiac muscle…
Calcium Induced Calcium Release
SNARE proteins
Present on the vesicle membrane and cytoplasmic membrane, it facilitates vesicle fusion upon binding together.
Clathrin
Protein involved in budding and recycling of synaptic vesicles
Botulinum toxin
Cleaves SNARE proteins, preventing ACh release resulting in fatal paralysis
Horizontal cells
Respond to light intensity, inhibitory, prevent responses to single photoreceptors being activated.
Retinal ganglion cells
Process images before brain, and has role in colour coordination.
Umami, sweet and bitter taste receptors are…
GPCRs
Sour taste receptors are
TRP channels
Mechano hair cells in ears depolarise due to an influx of…
Calcium ions
interaural time difference
Position of sound source is detected by comparing the time of the sound arrival to both ears.
Semicircular canals in ears
Detect head rotations
Otolith organs
In ears, use CaCO3 to detect force of gravity and acceleration.
Terminal cisternae
Portion of the sarcoplasmic reticulum, adjacent to t-tubules. They contain ryanoidine receptors which open allowing calcium influx.
A sensory receptor that responds to a skeletal muscle being stretched is a
Muscle spindle
Proprioceptors which respond to muscle stretching.
Muscle spindles
Retrograde amnesia
Memory loss for event prior to trauma
Anterograde amnesia
Inability to lay down new memories
Hebb’s rule
Repeated and strong activation between synapses, enhances their connection.
Evidence for activity dependent synaptic plasticity
Density of AMPA receptors in hippocampus reduced when activity deprived.
drug which increases duration of openings of GABAA receptors
Barbiturate
Drosophila mutant which shows a defect in cAMP phosphodiesterase
Dunce
Channel which can be blocked by Mg2+ ions
NMDA receptors
Sodium channel activated by glutamate
AMPA receptor
Retrograde signalling molecule released by neurons in the CA1 region of the hippocampus
Nitric oxide
Where in the axon does the AP begin
Hillcock
How do neurons encode information
Frequency modulation
Type of memory encoding for learnt skills
Procedural
Benzodiazepines
Sedatives, anti-epilepsy and anti-anxiety drugs. They work by increasing the opening frequency of the GABAA receptor chloride channel, increasing neuronal inhibition.
Startle disease
Caused by mutation in glycine receptors
Glycine receptors
inhibitory ligand-gated Cl channels heavily expressed in the spinal cord. Mutations cause hyperekplexia, an exaggerated startle reflex
area of tissue damaged in a stroke or HA.
Infarct
Key substances in excitotoxicity
Calcium
NO
Glutamate - linked to tissue damage
Interleukin 1 - inflammation
which cells handle glutamate uptake in the brain
Astrocytes
The depolarisation phase of action potentials in Paramecium is based around which ion
Ca2+
Reverses ciliary beat
Capacitance
Separation of electrical charges across an insulating material.
