revision questions Flashcards
(41 cards)
The hindbrain is also known as the:
Selected Answer:
rhombencephalon
Answers:
A.
diencephalon
B.
mesencephalon
C.
rhombencephalon
D.
telencephalon
c
The phenomenon whereby damage to the left side of the brain results in impaired function on the right side of the body is caused by neurons:
Answers:
A.
branching
B.
decussating
C.
segregating
D.
synapsing
b
Sorry, that’s wrong! Decussation is the term used to describe crossing over in biological systems. It comes from the Latin word “decussis” meaning “the figure ten”. The figure ten, in Roman numerals, is of course an X.
The word chiasm is sometimes used to describe a place where a decussation occurs.
The mobility of an ion in water is proportional to the size of its:
Answers:
A.
charge
B.
ionic radius
C.
hydration shell
D.
nucleus
Well done! The size of the hydration shell determines the “drag” on the ion as it moves through water. The hydration shell size increases with the charge density of the ion: it will decrease with ionic radius and increase with the magnitude of the charge.
The time a molecule takes to move a given distance via diffusion is:
Selected Answer:
Answers:
A.
greatest when the molecule can only move in one dimension
B.
greatest when the molecule can move in two dimensions
C.
greatest when the molecule can move in three dimensions
D.
the same no matter how many dimensions the molecule can move in
A
A simple test for multiple sclerosis is:
Selected Answer:
Answers:
A.
edrophonium test
B.
MRI scanning
C.
peripheral nerve biopsy
D.
visual evoked potential test
D
Sorry, that’s wrong! MRI can also diagnose MS, but is obviously much more complex. VEP measures the time it takes for stimulus to evoke an electrical signal in the brain – it is a measure of nerve conduction velocity. When myelin is lost from neurones, nerve conduction velocity decreases.
A component of the diencephalon is the:
Selected Answer:
Answers:
A.
cortex
B.
medulla
C.
pons
D.
thalamus
D
Well done! The diencephalon is the posterior part of the forebrain. It is contains the thalamus and the hypothalamus. The cortex is part of the telencephalon. The pons and medulla are parts of the rhombencephalon.
Selected Answer:
Answers:
A.
AMPA receptor
B.
GABAA receptor
C.
muscarinic acetylcholine receptor
D.
NMDA receptor
B
Channelrhodopsin is derived from what type of organism?
Answers:
A.
Drosophila flies
B.
green algae
C.
halobacteria
D.
Xenopus frogs
B
Well done. Channelrhodopsins are non-specific cation channels derived from green algae. They have a seven transmembrane domain structure and contain a retinal chromophore. Although superficially similar to G protein coupled receptors, channelrhodopsins have a built in, light-activated channel.
The “dark current” in rod cells is carried by which ion?
Selected Answer:
Answers:
A.
Ca2+
B.
Cl-
C.
K+
D.
Na+
D
Well done! In the dark, levels of cGMP are high in rod cells leading to the opening of cGMP gated sodium channels. When rhodopsin is stimulated by light, it causes the activation of cGMP phosphodiesterase and the level of cGMP falls. The cGMP gated sodium channels close and the dark current is switched off.
Martha has a genetic defect that alters her ability to constrict her pupil to light and disturbs her circadian rhythm. This mutation is likely to specifically affect a subtype of which retinal cell?
Answers:
A.
cone cell
B.
ganglion cell
C.
horizontal cell
D.
rod cell
B
Photosensitive retinal ganglion cells project their axons to the suprachiasmatic nucleus and are involved in the regulation of circadian rhythms.
Which of the following is not a type of mechanoreceptor in the skin:
Selected Answer:
A.
Foliate papillae
B.
Ruffini’s ending
C.
Merkel’s disc
D.
Meissner’s corpuscle
A
Correct, well done! Foliate papillae are folds within the tongue in which taste buds are embedded. Ruffini’s endings, Merkel’s discs and Meissner’s corpuscles are all sensory mechanoreceptors in the skin.
Leaf movements in Mimosa pudica are triggered by a loss of turgor due the efflux of which molecules or ions?
Selected Answer:
A.
fructose
B.
sucrose
C.
Cl- + K+
D.
Cl- + Ca2+
C
The physiological function of acetylcholine binding protein is to:
Answers:
A.
bind to post synaptic acetylcholine receptors
B.
hydrolyse acetylcholine
C.
reduce the free synaptic levels of acetylcholine
D.
trigger responses from glial cells
C
Well done! Acetylcholine is removed from mammalian synapses by the action of an enzyme, acetylcholinesterase. In the snail, however, an extra mechanism is present. When acetylcholine (ACh) is released into synapses in the snail’s nervous system, it binds not only to nicotinic acetylcholine receptors (nAChRs) on the post synaptic neurone, but also on nearby glial cells. In response, the glial cells release AChBP into the synapse. AChBP acts as a molecular sponge for acetylcholine, lowering its levels in the synapse.
The dorsal roots of the spinal cord contain the:
Selected Answer:
Answers:
A.
axons of afferent neurones
B.
axons of efferent neurones
C.
axons of motor neurones
D.
axons of afferent and efferent neurones
A
Sorry that’s wrong! The term afferent indicates that that the neurone is bringing information into the CNS (efferent means that it is carrying information out of the CNS). The dorsal roots contain the axons of afferent sensory neurones. The ventral roots, of efferent motor neurones.
A disease that involves loss of myelin from neurones is:
Selected Answer:
Answers:
A.
Alzheimer’s disease
B.
Guillain-Barré syndrome
C.
Parkinson’s disease
D.
Schizophrenia
B
In Guillain-Barré syndrome the Schwann cells insulating alpha motor neurones is attacked. Alzheimer’s disease is a CNS disorder characterised by the formation of neurofibrillary tangles. Parkinson’s disease involves destruction of the nigro-striatal pathway in the brain. Schizophrenia is a neurodevelopmental disorder that is characterised by over-activity of dopaminergic neurones in the limbic system.
Marine fish-hunting snails produce the following class of toxins:
Answers:
A.
Agatoxins
B.
Conotoxins
C.
Dendrotoxins
D.
Digoxins
B
There are various types of conotoxin, which come from marine fish hunting snails. Some block nicotinic acetylcholine receptors, some block calcium channels.
Digoxin is derived from the foxglove. It binds to the K+ site of the ATPase and blocks the function of the protein. Digoxin is used to treat heart failure and some types of cardiac dysrhythmia.
Agatoxin is a calcium channel blocker from funnel web spiders. Dendrotoxins are derived from mamba snakes. Some of them block potassium channels, others block muscarinic acetylcholine receptors.
The duration of a typical cardiac action potential is approximately:
Selected Answer:
Answers:
A.
2 µs
B.
200 µs
C.
2 ms
D.
200 ms
D
A protein that forms a framework for the generation of intracellular vesicles is:
Answers:
A.
clathrin
B.
synaptotagmin
C.
t-SNARE
D.
v-SNARE
A
The definition of the term “quantal content” is the:
Answers:
A.
amount of neurotransmitter in each vesicle
B.
identity of the neurotransmitter released
C.
number of vesicles released in response to a stimulus
D.
size of the end plate potential evoked by one vesicle
C A quantum (plural = quanta) is the amount of neurotransmitter contained within a single vesicle. Quantal size is the response evoked by release of a single quantum of neurotransmitter. Quantal content is the number of vesicles released in response to an action potential. Quantal content can be determined by dividing the Quantal size by the size of a miniature endplate potential (which is evoked by the spontaneous release of a single vesicle of neurotransmitter).
Conductance is defined as follows:
Selected Answer:
Answers:
A.
Current/resistance
B.
Current/Volts
C.
Volts/current
D.
Volts/resistance
B
Ohm’s Law states: Volts (V)=I.R; R=V/I.
Therefore: conductance =1/R = I/V
The person shown in the photograph above has a disorder of the neuromuscular junction. They are being treated using an acetylcholinesterase inhibitor. They are most likely suffering from:
Answers:
A.
botulism
B.
multiple sclerosis
C.
myasthenia gravis
D.
tetanus
C
Sorry, that’s wrong. Myasthenia gravis is an autoimmune disease in which the nicotinic receptors of the NMJ are attacked. It tends to affect small muscles such as those in the face first (hence the droopy eyelids), with limb and trunk muscles becoming involved as the disease progresses. Myasthenia gravis can be treated using a reversible acetylcholinesterase inhibitor. When AChE is inhibited, the concentration of ACh in the synapse increases, meaning that the remaining ACh receptors are more likely to be activated and trigger an action potential
Calcium-induced calcium release from the sarcoplasmic reticulum occurs in:
Answers:
A.
skeletal and cardiac muscle
B.
smooth muscle and cardiac muscle
C.
smooth muscle and skeletal muscle
D.
cardiac muscle, smooth muscle and skeletal muscle
B
Well done! The answer is smooth and cardiac muscle. In skeletal muscle SR calcium release occurs because of a physical linkage between L-type calcium channels and the ryanodine receptor. In cardiac and smooth muscle there is no physical linkage but rather, calcium entering through the L type channels activates the ryanodine receptor (which is a calcium channel on the SR).
Which of the following features is present in nicotinic receptor subunits but absent in ELIC?
Answers:
A.
cys-loop
B.
ligand binding site
C.
selectivity filter
D.
transmembrane domains
A
Well done! ELIC is a ligand-gated ion channel. By definition this means it has a ligand binding site and must have transmembrane domains in order to act as a channel. It is cation selective so has a selectivity filter. It lacks the cys-loop. This difference prompted the renaming of the superfamily of receptors containing the nicotinic receptors from the “cys-loop” receptors to the “pLGIC”: pentameric ligand gated ion channels.
An increase in pressure inside the skull can sometimes cause “coning”. Coning will result in damage to which part of the brain?
Answers:
A.
brain stem
B.
cerebrum
C.
cortex
D.
hippocampus
A
Well done! An increase in pressure inside the skull can push the brain backwards and down through the foramen magnum, the large opening at the base of the skull. When this happens, serious disability or death frequently results due to damage to the brain stem.
