2.1 Neuron Properties

Question 1

Endocrine vs. Nervous System

Answer 1

NERVOUS: -fast -short duration -neurons directly contact target cells to deliver neurotransmitter ‘message’ ENDOCRINE: -slow -long duration -blood delivers the hormone ‘message’

Question 2

Dendrites

Answer 2

receive synaptic INPUTS from neuronal axons

Question 3

Cell Body

Answer 3

Has the same organelles as any other cell

Question 4

Trigger Zone

Answer 4

(in between the cell body and axon) Action Potentials are started here, the axon runs with them

Question 5

Axon

Answer 5

fire rapid impulses (Action Potentials) to synaptic terminals

Question 6

Presynaptic and Postsynaptic Terminals

Answer 6

Presynaptic release OUTPUT signal to Postsynaptic (next neuron or target tissue); release neurotransmitters at synapses

Question 7

Answer 7

Multipolar:

Brain

Spine

Motor

Question 8

Answer 8

Bipolar:

Retina

Ear

Nose

Question 9

Answer 9

Unipolar:

Sensory Receptor Neurons

Question 10

Why do membrane potentials exist?

Answer 10

becasue of electrochemical gradients: concentration gradients of charged (+/-) ions seperated by a cell membrane

Question 11

When do Cellular Membrane Potentials exist?

Answer 11

1) Ions can be pumped (actively transported) through ion carriers embedded in the cell’s plasma membrane
2) Ions are maintained at a different concentrations on either side of the cell membrane: concentration gradient
3) The ion (the potential) can change (flux) by flowing through ion channels.

Question 12

Ion Pumps

Answer 12

• Use primary and secondary active transport mechanisms to create ion concentration gradients
• Major ions that are pumped in neurons: Na+, K+, Cl-, Ca2+
• Requires constant source of energy or gradients ‘erode’ very quickly

Question 13

Types of Ion Channels

Answer 13

• Passive/Leakage (nongated) Channels
• Ligand Gated Channels
• Voltage Gated Channels
• Mechanically Gated Channels

Question 14

Passive/Leakage (nongated) Channels

Answer 14

open randomly, important in maintaing the baseline neuronal membrane potential; ion flow is sensative to concentration gradient

Question 15

Ligand Gated Ion Channels

Answer 15

open in response to binding of a ligand (neurotransmitter, hormones, ions)

Question 16

Voltage Gated Ion Channels

Answer 16

Respond to changes in transmembrane potential (when the potential deviates from the ‘normal’ resting membrane potential)

Question 17

Mechanically Gated Ion Channels

Answer 17

Respond to mechanical vibration, pressue.

-Activated by physical stretching of plasma membrane