Neurophysiology

Question 1

Define the ENS

Answer 1

Largest component of the autonomic nervous system

Question 2

How many neuron cell bodies does the ENS hold?

Answer 2

300,000,000

Question 3

Describe the functions of the ENS

Answer 3

Motility, water and electrolyte balance, acid secretion, responses to inflam

Question 4

What is the defining feature of Herschprungs disease?

Answer 4

No ENS

Question 5

What are the layers of the small intestine?

Answer 5

Mucosa, Mucosal plexus, Submucosal plexus, Circular muscle, Myenteric plexus, Longitudinal muscle

Question 6

How many species of bacteria are within the ENS?

Answer 6

1,000 species

Question 7

What modulates the mix of bacteria within the microbiome?

Answer 7

Probiotics, stress, diet, medications

Question 8

Describe some methods of functional recording?

Answer 8

Ca imaging, Intracellular recording, Organ bath

Question 9

What is Immunohistochemistry?

Answer 9

Method used to identify the chemistry of neurons

Question 10

How does one analyse the microbiota? 2 ways

Answer 10

Through looking at RNA genes within fecal samples as well as genome wide sequencing

Question 11

What is Metabolomics and what technique is used for it?

Answer 11

The study of identifying and quantifying the chemical array in samples
Mass spectroscopy is the technique

Question 12

What are the 3 possible causes of diarrhea?

Answer 12

Infectious disease, Intrinsic dysfunction and health care induced

Question 13

Describe Infectious disease as a cause with some examples

Answer 13

Cholera and Typhoid
Cholera- Cholera Toxin- Hexamer, provides no inflam response
E.coli-produces many enterotoxins
Clostridium difficile- Toxin A and Toxin b, mucosal damage and inflammation

Question 14

Describe Intrinsic dysfunction as well as some examples

Answer 14

Inflammatory bowel disease- mucosal lining of the gut does not work with microbiome
Functional bowel disease-3 types (Diarrhoea predominant, alternating diarrhoe and constipation, constipation dominant)
Food sensitivity

Question 15

Describe health care induced diarrhoea with some examples

Answer 15

Cancer chemo.- provides large GIT problems

Antibiotic induced- Clostridium difficile- destroys colon mucosa and dysentery, low concentrations it is used for botox

Question 16

What type of neuron is needed for Cholera Toxin to work and where?

Answer 16

Enteric neurons that when with CT induce activity in myenteric plexus sensory neurons

Question 17

What type of calretinin neurons does CT induce expression of?

Answer 17

Small calretinin but not large

Question 18

What layers of the ENS are affected and which are not with Cholera Toxin

Answer 18

Sensory neurons within myenteric plexus are while sensory neurons within the submucosal plexus are not
BUT submucosal secretomotor neurons are made HYPEREXCITABLE by CT leading to over secretion

Question 19

What is another substance that increases excitability of myenteric sensory neurons?

Answer 19

Toxin A from Clostridium difficile

Question 20

What are the differences between recurrent and non-recurrent Cdiff?

Answer 20

Recurrent- Sometimes never get through it have increased levels of GABA
Non-recurrent- Dangerous, treatable with Vancomyosin (antibiotic)

Question 21

What does GABA do in myenteric neurons?

Answer 21

EXCITE

Question 22

What happens with an increase in antibiotic use?

Answer 22

Increases in Clostridium sp which alter behaviour similar to that of autism

Question 23

What mutations with Autism are relevant to the ENS?

Answer 23

Neuroligins and Neurexins

Question 24

Describe the Neuroligin mutation and what occurs from it

Answer 24

Occurs with Neuroligin 3 with 2 mutations- Gene deletion and point mutation substituting a cysteine for a arginine at position 451

This mutation alters-
Enteric neuron numbers
Altered motility
Overall microbiota, thus enteric neural development

Question 25

What is a virus and what are its 2 classes?

Answer 25

Intracellular parasite that has to enter the cell to replicate
2 classes are RNA (replicate within cell cytoplasm) and DNA (replicate within cell nucleus)

Question 26

Name the further 3 sub classes

Answer 26

Lentivirus-Designed to get DNA/RNA within cell
Adenovirus-Stays in cytoplasm
Adeno-associated virus-Needs activation from an adeno-virus before the virus can infect

Question 27

Describe the 3 type of Optically activated channels

Answer 27

Channelrhodopsin- Blue light activated, Na+ enter the cell to polarize
Halorhodopsin- Orange light, Cl- enters the cell to hyperpolarize
Archaerhodopsin- Green light, H+ exit cell to hyperpolarize

Question 28

What is inhibited in the brain for Depressed patients?

Answer 28

Ventral Striatum

Question 29

Describe the inputs of the Nucleus Accumbens

Answer 29

Ventral tegmental area (Dopaminergic signalling, reward and motivation)
Hippocampus (spatial and emotion related input)
Pre frontal cortex (executive control)
Amygdala (emotion and fear)