Physiology 3.8 + 3.10 Flashcards Preview

NMSK-B III > Physiology 3.8 + 3.10 > Flashcards

Flashcards in Physiology 3.8 + 3.10 Deck (35):
1

How many neurons are activated in a seizure?

many

2

What is epilepsy?

recurrent unprovoked seizures; 1% of population

3

What is a seizure?

episode of abnormally synchronized and high-frequency firing of neurons in the brain; 10-15% of population

4

What are the most common causes of seizures in infancy and childhood?

-febrile seizure
-congenital disorders
-perinatal injury

5

What are the most common causes of seizures in patients over 60?

cerebrovascular disease

6

How are simple and complex seizures differentiated?

consciousness

7

How are partial and generalized seizures differentiated?

localized versus whole brain

8

How are Petit Mal and Grand Mal seizures differentiated?

generalized; less dramatic versus whole body shaking

9

myoclonic

-sudden, rapid, muscular jerk
-fastest of all mvmt disorders (after tremor)
-can be focal unilateral or bilateral

10

clonic

rhythmic jerking

11

tonic

sustained contraction

12

tonic-clonic

alternating pattern of sustained contraction and rhythmic jerking

13

atonic

no tone

14

automatisms

repetitive behaviors
-lip smacking
-swallowing
-stroking wringing
-patting

15

status epilepticus

seizure of along duration; grater than 5 minutes

16

What is a seizure aura?

-brief, simple partial seizure without outward behavioral menifestaiton
-feeling of extreme fear or anxiety

17

What is the most prevalent seizure seen in children?

absence seizure (genetic)
-seizure with a staring spell

compared to other staring spell seizures:
-no aura
-short duration
-no automatisms
-no lathargy

18

interictal

period of time in between seizures; fire multiple action potentials as long as membrane potential is above the threshold

19

What is the main idea of how seizures occur?

imbalance between excitatory and inhibitory synapses

20

Flow of which ions causes ESPS?

into cell:
Na+
Ca2+

21

Flow of which ions causes ISPS?

into cell:
Cl- [GABAa/Glycine]

out of cell:
K+ [GABAb]
Na+

22

How can neurons become hyperexcitable in a partial seizure?

-toxins (glutamate analog)
-calcium waves in glia (absorb and release glutamate)

23

Repetitive discharge of neurons during a seizure lead to what?

-increased K+ outside the cell
-accumulate Ca2+ in presynaptic neuron; leads to further synaptic release
-Ca2+ entry through NMDA glutamate channels of postsynaptic neuron

24

What is the paroxysmal depolarization shift?

-20-40 mV positive shift in membrane potential
-shift triggers a train of action potentials at the peak of the shift

25

What allows for the activation of the paroxysmal depolarizing shift within a seizure?

glutamate-AMPA channels
glutamate-NMDA channels
Calcium influx

26

What is the afterhyperpolarization?

-PDS; limits the duration of the depolarizing shift
-mediated by Ca2+ and K+ channels, GABAa (Cl-) and GABAb (K+)

27

What are the three things which must be considered when understanding the loss of control of neural circuits in a seizure?

1) loss of local inhibition**
2) increased excitability of neurons
3) spread of excitation

28

Why are inhibitory neuron effects strongest in the cerebral cortex?

"inhibitory surround" restricts the center excitability and its spread

29

How does penicillin affect the local spread of excitability?

-antagonizing GABA
-weak GABAa natagonist and can be convulsant
-"generalized penicillin epilepsy"

30

Which brain structure could facilitate the spread of neuronal activity across long distances, such as in the Jacksonian march of a seizure?

thalamus

31

Which cells become entrained in a generalized seizure?

cortical and thalamic cells

32

What is the difference between a generalized seizure and an absence seizure?

absence:
-inhibition is preserved
-depolarizing and hyperpolarizing phases become stronger

33

What are thalamocortical oscillations?

T-type Ca2+ channels in thalamic relay cells are activated by hyperpolarization
**K+ conductances affect the relay cells in the thalamus**

34

What is status epilepticus?

repeated generalized seizures without a return to full consciousness; 5-10 minute standard

35

How is the brain damaged from seizure?

excitotoxicity