Neurophysiology Flashcards
Define the ENS
Largest component of the autonomic nervous system
How many neuron cell bodies does the ENS hold?
300,000,000
Describe the functions of the ENS
Motility, water and electrolyte balance, acid secretion, responses to inflam
What is the defining feature of Herschprungs disease?
No ENS
What are the layers of the small intestine?
Mucosa, Mucosal plexus, Submucosal plexus, Circular muscle, Myenteric plexus, Longitudinal muscle
How many species of bacteria are within the ENS?
1,000 species
What modulates the mix of bacteria within the microbiome?
Probiotics, stress, diet, medications
Describe some methods of functional recording?
Ca imaging, Intracellular recording, Organ bath
What is Immunohistochemistry?
Method used to identify the chemistry of neurons
How does one analyse the microbiota? 2 ways
Through looking at RNA genes within fecal samples as well as genome wide sequencing
What is Metabolomics and what technique is used for it?
The study of identifying and quantifying the chemical array in samples
Mass spectroscopy is the technique
What are the 3 possible causes of diarrhea?
Infectious disease, Intrinsic dysfunction and health care induced
Describe Infectious disease as a cause with some examples
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
Describe Intrinsic dysfunction as well as some examples
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
Describe health care induced diarrhoea with some examples
Cancer chemo.- provides large GIT problems
Antibiotic induced- Clostridium difficile- destroys colon mucosa and dysentery, low concentrations it is used for botox
What type of neuron is needed for Cholera Toxin to work and where?
Enteric neurons that when with CT induce activity in myenteric plexus sensory neurons
What type of calretinin neurons does CT induce expression of?
Small calretinin but not large
What layers of the ENS are affected and which are not with Cholera Toxin
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
What is another substance that increases excitability of myenteric sensory neurons?
Toxin A from Clostridium difficile
What are the differences between recurrent and non-recurrent Cdiff?
Recurrent- Sometimes never get through it have increased levels of GABA
Non-recurrent- Dangerous, treatable with Vancomyosin (antibiotic)
What does GABA do in myenteric neurons?
EXCITE
What happens with an increase in antibiotic use?
Increases in Clostridium sp which alter behaviour similar to that of autism
What mutations with Autism are relevant to the ENS?
Neuroligins and Neurexins
Describe the Neuroligin mutation and what occurs from it
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
What is a virus and what are its 2 classes?
Intracellular parasite that has to enter the cell to replicate
2 classes are RNA (replicate within cell cytoplasm) and DNA (replicate within cell nucleus)
Name the further 3 sub classes
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
Describe the 3 type of Optically activated channels
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
What is inhibited in the brain for Depressed patients?
Ventral Striatum
Describe the inputs of the Nucleus Accumbens
Ventral tegmental area (Dopaminergic signalling, reward and motivation)
Hippocampus (spatial and emotion related input)
Pre frontal cortex (executive control)
Amygdala (emotion and fear)
