Lecture 2 - Intro to Neurophysiology Flashcards
What are the two supporting cells of the PNS?
Schwann Cells and Satellite Cells
What are Schwann Cells?
Form Myelin sheaths around PNS neuron axons
What are Satellite Cells?
Support neuron cell bodies within ganglia of the PNS
What are the Four Supporting Cells of the CNS?
1.) Oligodendrocytes
2.) Microglia
3.) Astrocytes
4.) Ependymal Cells
What are Oligodendrocytes?
Form Myelin Sheaths around CNS neuron axons (like Schwann Cells in PNS)
What is Microglia?
Migrate through CNS and phagocytose debris
What are Astrocytes?
Help regulate external environment of neurons in the CNS
What are Ependymal Cells
Line the ventricles of the brain and the spinal cord
What does successive wrapping of one Schwann cell do?
Wrap around one axon (1:1 ratio)
What does one oligodendrocyte form?
Myelin on several axons (not a1:1 ratio)
What is the most abundant type of glial cell in the CNS?
Astrocytes (about 90% of the nervous tissue in the brain)
Where do astrocytes processes terminate?
At the “end feet” of capillaries, as well as at the “end feet” of neurons which can influence blood and neuron interactions/
What is the first function of astrocytes?
They take up K+ from the extracellular fluid (diffuses from neurones during nerve impulses) to maintain proper ionic environment
What is the second function of astrocytes?
They can convert the neurotransmitter glutamate into glutamine via glutamate synthase, which can be released back into neurons, which can use it to reform glutamate
What is the third function of astrocytes?
The “end feet” surrounding the blood capillaries take up glucose from the blood, metabolize it to lactate, then release it for use as an energy source by neurons, which metabolize it aerobically into CO2 and H2) for production of ATP
What is the fourth function of astrocytes?
Astrocytes are needed for the formation of synapses in the CNS
What are Astrocytes regulating?
Neurogenesis in the adult brain
What is Neurogenesis?
The process in which stem cells differentiate into glial cells or neutrons
What do Astrocytes help with the formation of?
The blood brain barrier
What can astrocytes release?
Neurotransmitters which can stimulate or inhibit the activity of neurons.
What is significant about the capillaries in the brain?
The capillaries do not have pores between adjacent endothelial cells
What do the endothelial cells have instead?
The endothelial cells are joined by tight junctions.
What can move through the blood brain barrier?
Non-polar O2 and CO2 can move through, alcohol and barbiturates (drugs) can pass through the phospholipid layer
What do other molecules have to go through to pass through?
Specific processes such as endocytosis, active transport
What receptor does nicotine bind to?
Acetyl choline receptor
What does components in tobacco smoke cause?
A decrease in MAO activity
What is MAO activity?
The enzyme used for your body break down neurotransmitters
What happens if you have elevated levels of dopamine and serotonin?
Influence mood (happier, less stressed, better memory)
What are CNS depressants?
You are slowing down brain activity, causing you to feel calm and relaxed, directly affecting brain cells
What are examples of CNS depressants?
Xanax, Alcohol, Heroin, Morphine, Cannabis
What can CNS depressants cause?
Altered speech, slow reaction time, foggy time
What neurotransmitter receptors can cause the inhibition of NO?
N-methyl-D-aspartate and substance P.
What happens if you get rabies?
It is a viral disease that affects the central nervous system and is almost always fatal once symptoms appear
Why is rabies almost always fatal?
As immune cells and antibodies cannot reach the brain due to the blood brain barrier
How can you help treat rabies?
No treatment after symptoms appear, but before a rapid treatment with ant-rabies antibodies can help attenuate the infection
What are the hardest brain conditions to treat?
Brain Cancer, Parkinsons, Alzheimers and Dementia
Why are neurological disorders so hard to treat?
So hard to get drugs past the blood brain barrier
What did scientists at Sunnybrook Hospital use to penetrate the blood brain barrier?
Focused ultrasound to deliver a chemotherapeutic agent directly into ONE patient’s malignant brain tumour
What is Somatic?
Have cell bodies in the CNS and send axons to skeletal muscles (voluntary control)
What is Autonomic?
involves TWO neurons in the efferent pathway
What is the first neuron (preganglionic) in the autonomic pathway?
The 1st cell body is in the grey matter of the CNS, it does not directly innervate the effector organ, but instead synapses with a 2nd neuron
What is the second neurone (postganglionic) in the autonomic pathway?
Has an axon that extends from the autonomic ganglion to an effector organ, where it synapses with the target tissue.
What is muscle atrophy?
As condition that causes muscles to shrink and weaken (disease, age, lack of physical activity)
What does the Autonomic nervous system help regulate?
The activity of the smooth muscle, glands and cardiac muscle
What does the Parasympathetic System involve?
Drives down
- Resting, digestion (during the night)
What does the Synthetic Nervous System involve?
- Drives up
- Fight/Flight
What does the PSNS and SNS mediate?
Opposing responses in effector organ (oppose each other)
What are the spinal nerve regions?
Cranial, Thoracic, Lumbar, Sacral,
What are organs without dual innervation?
- Adrenal Medulla
- Arrector pili muscles in the skin
- Sweat Gland in the Skin
- Most Blood Vessels
In the cases of no dual innervation, how is regulation achieved?
By increasing or decreasing in the tone (firing rate) of the sympathetic fibers
What are autonomic nerves classified based on?
Primary neurotransmitter released across synapse
What do cholinergic neurons release?
Ach (Acetylcholine)
What do Adrenergic neurons release?
NE or E (norepinephrine or epinephrine)
What is the autonomic outflow in the PSNS?
The preganglion axon releases Ach to the post ganglion axon which releases Ach to the effector cell to SLOW DOWN
What is the autonomic outflow in the SNS?
The preganglion axon releases Ach to the post ganglion axon which releases NE to the effector cel to SPEED UP
What is the ACh the neurotransmitter for?
All PRE ganglionic axons in both the parasympathetic nervous system and sympathetic nervous system (cholinergic transmission)
Ach is also released by post ganglionic axons at their synapses (cholinergic transmission)
What is the neurotransmitter released by most sympathetic post ganglion axons?
NE (adrenergic)
What is a common cause of ANS dysfunction?
Lyme disease caused by a tick bite
What happens when you get bit by an infected tick?
Substances in tick saliva disrupt the local immune response
What fails to appear when bit by a tick?
Neutrophils which are necessary to eliminate the infection
How does bacteria spread?
Via the blood stream to joints, heart, nervous system, and distant sites.
What is POTS?
Sustained increase in heart rate of greater than 4- BPM (tachycardia)
What is Synesthesia?
Letters or numbers are perceived as colours
What is Chromathesia?
Where music can be heard as colours
How many digits of numbers can the average person hold in their working memory at a given time?
7
