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revision questions Flashcards

1
Q

The hindbrain is also known as the:
Selected Answer:

rhombencephalon
Answers:
A.

diencephalon

B.

mesencephalon

C.

rhombencephalon

D.

telencephalon

A

c

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2
Q

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

A

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.

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3
Q

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

A

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.

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4
Q

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

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5
Q

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

A

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.

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6
Q

A component of the diencephalon is the:
Selected Answer:

Answers:
A.

cortex

B.

medulla

C.

pons

D.

thalamus

A

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.

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7
Q

Selected Answer:

Answers:
A.

AMPA receptor

B.

GABAA receptor

C.

muscarinic acetylcholine receptor

D.

NMDA receptor

A

B

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8
Q

Channelrhodopsin is derived from what type of organism?

Answers:
A.

Drosophila flies

B.

green algae

C.

halobacteria

D.

Xenopus frogs

A

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.

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9
Q

The “dark current” in rod cells is carried by which ion?
Selected Answer:

Answers:
A.

Ca2+

B.

Cl-

C.

K+

D.

Na+

A

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.

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10
Q

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

A

B
Photosensitive retinal ganglion cells project their axons to the suprachiasmatic nucleus and are involved in the regulation of circadian rhythms.

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11
Q

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

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.

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12
Q

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+

A

C

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13
Q

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

A

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.

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14
Q

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

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.

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15
Q

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

A

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.

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16
Q

Marine fish-hunting snails produce the following class of toxins:

Answers:
A.

Agatoxins

B.

Conotoxins

C.

Dendrotoxins

D.

Digoxins

A

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.

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17
Q

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

A

D

18
Q

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

A

19
Q

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

A 
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).
20
Q

Conductance is defined as follows:
Selected Answer:

Answers:
A.

Current/resistance

B.

Current/Volts

C.

Volts/current

D.

Volts/resistance

A

B
Ohm’s Law states: Volts (V)=I.R; R=V/I.

Therefore: conductance =1/R = I/V

21
Q

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

A

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

22
Q

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

A

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).

23
Q

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

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.

24
Q

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

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.

25
Q

A type of drug used to treat multiple sclerosis is:

Answers:
A.

acetylcholine

B.

corticosteroids

C.

myostatin

D.

TNF-alpha

A

B
Sorry that is wrong. Glucocorticosteroids such as methylprednisolone have immune suppressant and anti-inflammatory effects and so are useful in an autoimmune disorder like MS. They are mostly used to shorten recovery time during relapse phases.

26
Q

In mammalian neurones, the density of Na+ channels in the internodes is approximately:

A.

10 /µm2

B.

100 /µm2

C.

1000 /µm2

D.

10000 /µm2

A

B

27
Q

In a classic series of experiments (shown in the figure above) the German scientist Otto Loewi examined chemical transmission in isolated frog hearts. In one heart, he stimulated a nerve that regulates the heart beat (X). He them pumped buffer (Y) from the bath surrounding this heart into an organ bath with a second heart in it.

When the heart in the first organ bath is stimulated, the heart in the second bath will:

Answers:
A.

begin to beat

B.

slow down

C.

speed up

D.

stop beating

A

B
Sorry, that’s wrong. Nerve X is the vagus (cranial nerve X). It gets its name from its “wandering” nature (akin to vague) and is part of the parasympathetic nervous system. The right branch of the vagus innervates the sino-atrial (SA) node (the “control centre”) of the heart and when stimulated, releases acetylcholine, which act on muscarinic acetylcholine receptors on the SA node. Activation of muscarinic receptors slows the heart rate.
In Loewi’s experiment, acetylcholine that has overspilled into the bathing medium is able to act on the SA node of the second heart, so its rate of beating also slows.

28
Q

A technique that can be combined with the patch clamp to relate the expression level of a protein in a single cell to the function of that cell, is:

Answers:
A.

fluorescence imaging

B.

immunocytochemistry

C.

RT PCR

D.

SDS PAGE electrophoresis

A

C
Sorry that’s wrong! After the patch clamp experiment is finished, the cell can be sucked into the patch electrode. The mRNAs present in the cell are then turned into DNA using reverse transcriptase. The next stage is quantitative PCR using primers for the protein of interest.

29
Q

Sensory cells in both the auditory and vestibular systems are called:

Answers:
A.

Hair cells

B.

Ganglion cells

C.

Pacinian corpuscle

D.

Saccule cells

A

A
Both the organs for audition and the vestibular system are in the inner ear and both are composed of hair cells. Retinal ganglion cells are in the retina of the eye, while Pacinian corpuscles detect vibration as part of the somatic sensory system. Saccule cells are not a distinct cell type. The saccule is part of the vestibular apparatus and therefore contains sensory hair cells.

30
Q

In order for actin to interact with myosin:

Answers:
A.

tropomyosin must bind calcium

B.

tropomyosin must bind to myosin

C.

troponin must bind calcium

D.

troponin must bind to myosin

A

C
In skeletal and cardiac muscle, the binding of calcium by troponin is critical in the regulation of muscle contraction. There are three subunits in troponin: C, I and T. In relaxed muscle, tropomyosin prevents access of myosin to actin. Upon binding of calcium to troponin C, the conformation of troponin changes and it pulls tropomyosin (which is attached to troponin T) away from actin. This allows access of myosin and thus muscle contraction to occur.

31
Q

A typical symptom of myasthenia gravis is:

Answers:
A.

convulsions

B.

drooping eyelids

C.

rigid paralysis

D.

slowed nerve conduction

A

B
Drooping eyelids are a common first symptom of myasthenia gravis. Myasthenia gravis tends to affect small muscles such as those in the face first, with limb and trunk muscles becoming involved as the disease progresses.

32
Q

An example of a cytokine is:

Answers:
A.

bradykinin

B.

β-interferon

C.

kinesin

D.

substance P

A

B
Interferons are cytokinins produced in response to pathogens. They can activate and modulate the immune system.

Substance P is a neuropeptide neurotransmitter involved in pain signalling. Bradykinin is an autocoid (a local hormone) that causes blood vessels to dilate. Kinesin is an ATP-powered motor protein.

33
Q

The Drosophila mutant dunce shows deficits in olfactory associative conditioning because it has a mutation in a gene coding for:

Answers:
A.

acetylcholinesterase

B.

adenylate cyclase

C.

cAMP phosphodiesterase

D.

netrin

A

C
Just as in Aplysia, cAMP has been shown to be important in learning in Drosophila fruit flies. The dunce mutant is in an enzyme coding for a phosphodiesterase that breaks down cAMP. Another mutant, rutabaga, has a defect in the enzyme that synthesises cAMP – adenylate cyclase. Flies with either dunce or rutabaga have learning deficits, but in flies with both mutants, the effect is cancelled out.

34
Q

At synapses in the CA1 region of the hippocampus, entry of calcium via ligand-gated ion channels requires activation of:

Answers:
A.

AMPA receptors

B.

NMDA receptors

C.

AMPA and NMDA receptors

D.

AMPA and NMDA receptors and Mg2+ channels

A

C
AMPA receptors are sodium selective glutamate-gated ion channels and NMDA receptors are sodium/calcium selective glutamate-gated ion channels. However, NMDA receptors are blocked by Mg2+ ions at the resting membrane potential. In order to relieve this block, AMPA receptors must first be activated and depolarise the membrane. This removes the Mg2+ ions from the NMDA receptors and allows calcium to enter the cell.

35
Q

The occipital lobe of the brain:
Selected Answer:

Answers:
A.

contains the the primary visual cortex.

B.

contains the primary sensory cortex.

C.

contains the primary auditory cortex.

D.

is involved in the coordination of movement.

A

A
The occipital lobe contains the primary visual cortex. The primary sensory cortex is in the parietal lobe while the primary auditory cortex is within the temporal lobe. The cerebellum is involved in the coordination of movement.

36
Q

In a typical neuron, an inhibitory postsynaptic potential (IPSP) will result from:

Answers:
A.

chloride efflux or potassium influx

B.

chloride efflux or potassium efflux

C.

chloride influx or potassium efflux

D.

chloride influx or potassium inlux

A

C
Given the typical distribution of ions across a neuronal cell membrane, either chloride influx or potassium efflux will result in hyperpolarisation: the neurone will be less likely to fire an action potential.

37
Q

A light-activated chloride pump, used in optogenetics to inhibit neurons, is:

Answers:
A.

channelrhodopsin

B.

halorhodopsin

C.

metarhodopsin

D.

scotopsin

A

B
Halorhodopsin is an archaebacterial protein with a 7 transmembrane domain structure and a retinal chromophore. Unlike channelrhodopsin it does not have a built in ion channel, but rather acts as a light-driven chloride ion pump.

38
Q

The Gloeobacter violaceus ion channel (GLIC) is:

Answers:
A.

amine gated

B.

chloride selective

C.

proton gated

D.

tetrameric

A

C

The GLIC ion channel is a proton-gated pentameric cation channel.

39
Q

The Pawn mutant of Paramecium cannot generate voltage gated calcium currents. The consequence of this mutation is that Pawn:

Answers:
A.

cannot reverse direction of locomotion

B.

is immobile

C.

reverses in response to weaker stimuli than wild type

D.

swims backwards for longer than wild type

A

A
Paramecium can generate a Ca2+ based action potential that reverses the ciliary beat, allowing it to avoid obstacles and predators. Pawn lacks this ability.

40
Q

When light activates rhodopsin:

Answers:
A.

phosphodiesterase is activated; sodium channels close

B.

phosphodiesterase is activated; sodium channels open

C.

phosphodiesterase is inhibited; sodium channels close

D.

phosphodiesterase is inhibited; sodium channels open

A

A
When rhodopsin is activated by light it, in turn, activates the G protein transducin. Transducin stimulates cGMP phosphodiesterase, causing cellular levels of cGMP to fall. This switches off cGMP gated sodium channels.

41
Q

In skeletal muscle the calcium required for contraction enters the cytoplasm via the:

Answers:
A.

Ca2+ ATPase

B.

dihydropyridine receptor

C.

L-type calcium channel

D.

ryanodine receptor

A

D
The ryanodine receptor is the correct answer. The terminal cisternae (also known as lateral sacs) are the portion of the sarcoplasmic reticulum adjacent to the t-tubules. The terminal cisternae contain ryanodine receptors (also known as the SR release channel). These are calcium channels whose opening is triggered via a physical linkage to voltage gated L type calcium channels (also known as dihydropyridine receptors) in the T tubules. Opening of the ryanodine receptors releases the Ca2+ that is accumulated in the SR by the Ca2+ ATPase.

Excitable cells (6 decks)

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