Review Flashcards
Where do action potentials begin?
Initial segment
How are action potentials propagated?
An AP elicited at any point on an excitable membrane excites adjacent portions of the membrane
Common neurotransmitters
Class I: ACh
Class II: Amines - Epi, Dopamine, Serotonin, Histamine
Class III: Amino acids - GABA, glycine, glutamate, aspartate
Class IV: NO
Local anesthetics
Act on Na+ channel activation gates (block), reducing excitability
Fast vs slow conducting nerves
Fast = large diameter myelinated axon Slow = thin myelinated axon
Basic ion channels and action potentials
Ionophore component of post synaptic neuron
Cation channels allow Na+ to enter- excitatory
Anion channels allow Cl- to enter- inhibitory (stops excessive propagation of pain signals)
Skeletal muscle contraction
- AP travels along motor nerve to NMJ
- Nerve secretes ACh; opens ACh-gated channels
- Na+ diffuses in initiating AP
- AP travels along muscle membrane, T tubules
- AP depolarizes muscle, causing sarcoplasmic reticulum to release Ca++
- Ca++ initiates actin and myosin sliding
- Ca++ pumped back into sarcoplasmic reticulum, stopping contraction
What produces CSF and where does it live?
Choroid plexus
Lateral, third, and fourth ventricles
What cranial nerves are sensory?
I, II, VIII
What cranial nerves are motor?
III, IV, VI, XI, XII
What cranial nerves are both sensory and motor?
V, VII, IX, X
Signs of forebrain disease
o Seizures- only come from forebrain
o Altered mentation, behavioral change, dementia, loss of training
o Pacing, wandering, wide circles- typically towards side of lesion
o Head turn- same side as lesion
o Postural reaction deficits- opposite side of lesion
o Visual impairment, cortical blindness- opposite side of lesion
o Head pressing, star-gazing, fly-biting
o Hemiparesis on side opposite lesion
o Typically normal gait, but proprioceptive ataxia
o Hemi-inattention, hemi-neglect: if blindfold one side of them they may ignore that side if you poke them in the face
o Brain pain
Where is gait controlled?
Midbrain and brainstem
Where are cranial nerves located?
- Cerebrum: CN I
- Diencephalon: CN II
- Midbrain: III-IV
- Pons: V
- Medulla oblongata: VI-XII
What produces CSF and where does it live?
Choroid plexus
Lateral, third, and fourth ventricles