Action potentials again Flashcards
Do glia engage in information processing?
How many cells in the brain are glial?
yes
3 (to 10) x as many glial cells as neurons
What inhibits chemicals from passing through the BBB?
tight junctions
Chemicals pass through astrocytes instead
Which glial cells can modulate excitability by changing driving force?
Astrocytes - change ionic environment inside cell
What is the danger of bacterial infection in the brain compared to the rest of the body?
Microglia can’t have the same massive immune response the rest of the body can, so brain infections are more dangerous
How do microglia move?
Move around in packs
Follow concentration gradient released by injured cell in cytoplasm
How do glial cells modulate information processing?
Store neurotransmitters
Have receptors for transmitters
Control ion concentrations
How do glial cells communicate with each other?
Use ATP
What modulates the birth of new axons and the growth of those axons?
Glial cells (mostly astrocytes)
What does Vm stand for?
Membrane potential (Ionic charge inside membrane compared to outside)
What cell types receive sensory input in the skin, which gets turned into action potentials?
Pacinian corpuscles
What do pacinian corpuscles look like?
Kinda like an onion with dendrite wound inside it. ‘onion layers’ rub against each other, causing ion channels to open
Glial cells are the ‘onion layers’.
What do you know you’re talking about when you see ‘receptor potential’?
A specific class of neurons that receive information from the outside environment (e.g. pacinian corpuscles, rods/cones…)
What is a distal axon?
Projects towards the periphery
What is a proximal axon?
Projects towards CNS
What happens at the initial segment of a pacinian corpuscle?
Voltage gated channels begin to allow Na+ in to cause action potentials
What basic ion - K+, Na+, Ca2+, etc - has the most driving force?
Na+. Most bang for your buck; opening sodium channels changes the charge most
What is a dermatome?
Skin slice. Region of the body innervated by sensory neurons from a single section of the spinal cord
What are the nerves of the spine called? (top to bottom)
What are the segmental slices of skin in each segment (e.g. the skin of c2) called?
Cervical (c1…c8) > thoracic (T1..T12) > lumbar (L1..L5) > sacral (S1…S5)
Dermatomes
What part of the spinal cord contains cell bodies of neurons?
The horns (ventral / dorsal)
White matter contains axons
What in the spinal cord did surgeons think was a good idea to cut to prevent intractable pain in the 1950s?
rhizome; it was a bad idea
What equation is used to calculate Vm?
(Sum of voltage in) - (Sum of voltage out)
What equation is used to calculate Vm?
(Sum of voltage in) - (Sum of voltage out)
What causes Na+/K+ pumps to increase or decrease activity?
Neural activity. How quickly the pump is working depends on the rate of activity of its neuron.
What is the point of a leak channel?
Keep the membrane stable - otherwise it might randomly have action potentials
What would happen if you cut a specific nerve?
Whatever dermatome the nerve innervates wouldn’t work
What is a dermatome?
The whole area of the skin which is innervated by a spinal cord region
What channels are open in at-rest neurons?
Leak channels. All leak channels are K+
K+ channels. Not all K+ channels are leak
Where in the neuron are EPSPs and IPSPs summating?
initial segment
Where would you see chemically-gated Na+ channels?
e.g. in the spine. Open from neurotransmitters
What ionic species causes IPSPs?
Cl- in… chemically gated if in e.g. spinal cord
Could also be K+ out
