Chap 47 & 48 - Nervous system

Question 1

Typical resting membrane potential

Answer 1

-80 to -60 mV

Question 2

Ions that maintain resting membrane potential

Answer 2

K+ diffuses outside through a few open ion channels.
Na+ restricted to outside of cell.

Cl- and a few charged proteins involved as well

Question 3

Graded potential

Answer 3

Shift of membrane potential proportional to the size of the stimulus - dissipates quickly, usually.

Question 4

Action potential trigger

Answer 4

If cell depolarises (a graded potential) enough to reach a threshold, Na+ channels open and action potential is triggered.

Question 5

Refractory period

Answer 5

Period of time after a stimulus where it is unresponsive to another event of the stimulus.
- Na+ channels are inactive and cannot be triggered again.

Question 6

Stages of the action potential

Answer 6

• Depolarisation to the threshold (trigger)
• Rising phase (Na+ channels open)
• Falling phase (Na+ channels inactive, K+ open)
• Undershoot (More open K+ channels than at rest)

Question 7

Myelin sheath cells

Answer 7

• Schwann cells (PNS)
• Oligodendrocytes (CNS)

Question 8

Nodes of Ranvier

Answer 8

Exposed spots between Schwann cells - Na+ channels are only located here where axon is in contact with interstitial fluid.

Question 9

Saltatory conduction

Answer 9

Action potentials “jump” between nodes of Ranvier along axon.

Question 10

Ionotropic receptors

Answer 10

Neurotransmitter receptors that are gated ion channels.

Question 11

Metabotropic receptors

Answer 11

Neurotransmitter receptors that are G-protein coupled receptors.

Question 12

Trigger for neurotransmitter release at axon terminals

Answer 12

Ca2+, taken in by channels that open in response to action potential.

Question 13

EPSP vs IPSP

Answer 13

Excitatory & Inhibitory post-synaptic potential.

The response of the post-synaptic neuron to neurotransmitters; excitatory = depolarisation; inhibitory = hyperpolarisation.

Question 14

Neurotransmitter classes

Answer 14

• Amino acids (glutamate, GABA)
• Biogenic amines (adrenaline, serotonin, dopamine)
• Neuropeptides (endorphins)
• Gases (nitric oxide)
  Acetylcholine is special and by itself?

Question 15

Astrocytes

Answer 15

Starry glial cells
Regulate nutrient/waste transport, supply extra glycogen, can form new neurons if needed.

Question 16

Ependymal cells

Answer 16

Line the ventricles; circulate cerebrospinal fluid.

Question 17

Pons location

Answer 17

Right on top of medulla oblongata.

Question 18

Corpus callosum

Answer 18

Big cord connecting the two hemispheres of the cerebrum.

Question 19

Sympathetic system signaling path from CNS to effector

Answer 19

• A neuron from CNS to ganglion near spinal cord
• Acetylcholine
• Second neuron to effector
• Noradrenaline

Question 20

Parasympathetic system signaling path from CNS to effector

Answer 20

• A neuron from CNS to ganglion near internal organ
• Acetylcholine
• Second neuron to effector
• Acetylcholine again

Question 21

Motor system signaling path from CNS to effector

Answer 21

• Only one neuron - no in-between ganglia
• Acetylcholine used at skeletal muscles.

Question 22

fMRI

Answer 22

Functional magnetic resonance imaging.

Question 23

Thalamus

Answer 23

In diencephalon.
Filters sensory information passed to cerebrum.