Physiology, Ethics and Prions

Question 1

what are the 3 types of papillae on the tongue which contain taste buds?

Answer 1

1. circumvallate- at rear of tongue- most abundant
2. fungiform- at tip of tongue
3. folate- posterolateral side of tongue

Question 2

where are taste receptors found?

Answer 2

in the taste hairs of taste cells

Question 3

which type of receptors sense salt and acid tastes?

Answer 3

ion channel coupled receptors

Question 4

what type of receptors sense sweet, bitter and umami tastes?

Answer 4

G protein coupled receptors

Question 5

what is the process of taste transduction?

Answer 5

saliva dissolves tastings so that they can bind to receptors
binding causes depolarisation of taste cells which opens Ca channels causing neurotransmitter release which excite primary sensory neurones of cranial nerves

Question 6

where do the nerves from the tongue synapse and travel?

Answer 6

the nucleus of the solitary tract in the medulla, these then decussate and project up to the thalamic nucleus (VPM nucleus), from here neurones project to the primary gustatory centre

Question 7

where is the primary gustatory centre?

Answer 7

the insular cortex

Question 8

where is the primary olfactory cortex found?

Answer 8

the temporal lobe

Question 9

what sort of receptors are olfactory receptors?

Answer 9

G protein coupled receptors

Question 10

what are the steps of learning retention?

Answer 10

1. encoding- sensory input
2. transfer- consolidation (short term to long term memory)
3. recall

Question 11

what is long term potentiation?

Answer 11

a process by which synaptic connections become stronger with frequent activation. it is thought to be the basis of learning and memory. it is a form of synaptic plasticity

Question 12

what changes occur at molecular levels to change from short term to long term memory?

Answer 12

short term memory relies on existing networks and post- translational modification. long term memory relies on long term potentiation accompanied by structural and functional changes of neural networks that require de novo gene expression

Question 13

what is the memory consolidation theory?

Answer 13

during consolidation newly encoded memory traces are reactivated in the fast learning store and that then drives the strengthening of representations in the slow learning store (Long- term store)

Question 14

where is the fast learning store?

Answer 14

hippocampus

Question 15

where is the slow learning store?

Answer 15

neocortex

Question 16

when does memory consolidation mainly occur?

Answer 16

during sleep

Question 17

what is the role of the amygdala in sensory recognition systems and memory?

Answer 17

the amygdala is important for convergence of sensory information it responds to visual, auditory, somatosensory, visceral sensory, gustatory and olfactory stimuli.
connections to the pre-frontal cortex allow it to integrate the emotional significance of stimuli.
projections to the hypothalamus, brainstem and spinal cord allow it to play a role in the expression of emotional behaviour by influencing activity

Question 18

what are the major functions of the amygdala?

Answer 18

1. emotional learning and memory
2. fear and fear conditioning
3. reward behaviour

Question 19

what physical effects of ageing on the brain?

Answer 19

volume decrease

decrease in the number of dendritic synapses and loss of synaptic plasticity

Question 20

what neurochemical changes occur with ageing?

Answer 20

dopamine levels decline/ dopaminergic pathways decline
monoamine oxidase levels increase- may increase free radicals
calcium dysregulation

Question 21

what cognitive changes are associated with ageing?

Answer 21

decline in semantic memory
slower reaction times
lower attentional levels
slower processing speeds

Question 22

what is semantic memory?

Answer 22

ability to recall facts

Question 23

what is amnesia?

Answer 23

pure loss of memory without other cognitive disorders

Question 24

what are the types of amnesia?

Answer 24

retrograde amnesia- loss of memory for events before a specific time/ retrieving previously established memories
anterograde amnesia- inability to establish new memories

Question 25

what sort of amnesia can damage to the medial temporal lobe cause?

Answer 25

MTL- hippocampal formation, parahippocampal gyrus

can cause severe anterograde amnesia

Question 26

what is korsakoffs syndrome?

Answer 26

amnesia caused by thiamin deficiency secondary to to malnutrition in chronic alcoholism
results in anterograde and retrograde amnesia, confusion, apathy

Question 27

what are prions?

Answer 27

misfolded proteins with the ability to transmit their misfiolded shape onto normal proteins
these abnormal proteins can accumulate and cause disease

Question 28

what is Creutzfeldt-jakob disease (CDJ)?

Answer 28

a progressive fatal neurodegenerative disease
can be:
variant (consumption of food contaminated with BSE)
sporadic- spontaneous conversion of normal protein into prion
iatrogenic- accidental exposure to infected tissue
familial- inherited

Question 29

what are the clinical features of CJD?

Answer 29

rapidly progressive dementia
monoclonal jerks 
cerebellar dysfunction 
behavioural abnormalities
death- usually 1 year after onset of symptoms