Nerves Flashcards
Name the depression & raised folds of brain matter?
Gyrus - Raised folds
Sulcus - Depression between folds
What makes up forebrain?
Cerebrum & diencephalon
What makes up the cerebrum?
Frontal Lobe
Parietal Love
Occipital Lobe
Temporal Lobe
What makes up the diencephalon?
Thalamus
Hypothalamus
What makes up the brainstem?
Midbrain
Pons
Medulla Oblongata
What other brain structure controls automatic motor function?
Cerebrum
How many pairs of spinal nerves are there? (split them up)
31 pairs:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
What matter contains the cell bodies & axons?
In spinal corD:
- White matter contains axons
- Grey matter contains cell bodies
Where in the neurone are things syntehsised?
The cell body
When in a neuron are signals recieved?
Dendrites (post-synaptic)
What is the axon hillock?
Section just after cell body where info for APs is gathered & theyre fired from
What do axon terminals do?
Convert an axon-potential to a chemical signal for synapse.
How much of the CNS is glia?
Around 90% of CNS cells are Glia
NAme the 3 types of GLia?
Astrocytes
Microglia
Oligodendrocytes
What do astrocytes do?
Astrocytes:
- Maintain external enviroment for neurones
- Surround blood vessels & produce the blood-brain barrier
What do oligodendrocytes do?
- Dorm myelin sheafs around CNS fibres
What do microglia do?
Produce phagocytes
What is the value of the resting membrnae potential?
-70mV. Basically the inside is 70mV negative to the outside
How is the RMP produced?
- K+ pumped in/Na+ pumped out
- Leaky potassium channels let K+ out
Why doesnt half the K+ move out the cell through the leaky channels to form a chemical equilibirum?
- Because it creates an electrical gradient
- This is eventually = & opposite ot hte chemical gradient
- So the electrochemical gradient = 0
Define equilibirum potential?
The membrane potential at which electrical gradient is equal & opposite to the conc. gradient.
How does hyperkalemia cause ventricular fibrillation?
- High K+ external conc.
- Lower conc. gradient
- Lower eectrical gradient maintained at equilibirum
- Cell depolarised
- Random APs fire
- Ventricular fibirllation
Why doesnt the brain experience the effects of hyperkalemia?
Its protected by the blood brain barier
Why is the blood brain barrier protectivE?
Its capillaires are espeicially tight due to:
- Astrocytes
- Tight junctions
The astrocytes prevent ion movement into the brain ISF
What other ions have a small effect on the RMP?
Na+
Cl-
Both are small intracellular conc. & large extracellular concs.
If the potassium equilibirum potential would be -90mV. Why is the RMP closer to -70mV?
- Electrogenic nature of the Na+/Cl- pump
- Other leaky ion channels
- Large intracellular -ve molecuels
Name the 4 types of graded potentials:
- Generator (sensory receptors)
- Postsynaptic
- Endplate (NMJ)
- Pacemaker
Other names for graded potentials?
- Electrotonic potential
- Decremental
- Non-propagated
- Local potential
What are the properties of a graded ptenital?
- Decremental
- Hyper- or Depolarising
- Graded
- Can Summate
Why are graded potentials decremental?
They leak out the membrane.
Furhter from the initial site of depolarisation the weaker the current
How do graded potentials transmit stimulus intensity?
In their amplitude
Whats the process behind graded potentials being graded?
- Stronger stimulus
- More channels opened
- Bigger current
- Larger potential
Whats an EPSP?
Excitatory Post Synaptic Potential
Depolarises the membrane
Whats an IPSP?
Inhibitory Post Synaptic Ptential
Hyperpolarizes the cell
How does a fast IPSP occur?
Chlorine channels open and Cl- ions flood the cell
How does a slow IPSP occur?
Potassium channels open & K+ leaves cell
Slow because K+ channel is seperate the the receptor