Nerve Cells I

Question 1

Define nerve cells

Answer 1

Excitable cells stimulated to produce small electrical currents

Question 2

Define neurons

Answer 2

Transmit electrical signals over short/long distances

Question 3

Describe knowledge of neurons from squid experiments

Answer 3

Axon extends head to tail (to move tail)

Axon 1mm in diameter (seen by human eye)

Question 4

What are neurons surrounded by?

Answer 4

Plasma membrane

Question 5

Describe plasma membranes

Answer 5

Impermeable to ions, permeable to water (semi-permeable)

Question 6

Describe active transport

Answer 6

Na/K pump
3Na out // 2K in
Develop conc grad across membrane

Question 7

Describe ion channels

Answer 7

Transmembrane proteins (span across) - Allow ions to pass across cell membranes

Question 8

Describe the importance of ion channels

Answer 8

Gating - Channel opening (activation)/ Closing (inactivation)
Permeation - Which ions can pass, Amount of current flow through

Question 9

Which 4 main processes activate ion channels?

Answer 9

Chemicals, Electrical, Mechanical, Thermal

Question 10

Describe chemicals in term of ion channels

Answer 10

Ligand gated ion channels eg acetylcholine

- Ligand binds to ion channel activated by changing channel conformation

Question 11

Describe electricals in terms of ion channels

Answer 11

Voltage gated ion channels eg Na/Ca/K

- Activated by voltage changes by electrical stimuli in plasma membrane close to ion channel

Question 12

Describe mechanical in terms ion channels

Answer 12

Mechanoreceptors - Distortion of plasma mem causes activation of ion channel

Question 13

Describe thermal in terms of ion channels

Answer 13

Thermoreceptors - Detect changes in temperature

Question 14

What are the different types of voltage gated ion channels?

Answer 14

Na+, K+, Ca+

Question 15

Describe link between human genome and VG channel proteins

Answer 15

Human genome provided complete list of genes coding for VG channel proteins

Question 16

Name a type of non-gated ion channel

Answer 16

Leaky channels

Question 17

Describe leaky channels and its importance

Answer 17

Permanently open (leaks), important for setting resting membrane potential

Question 18

Describe ion channel gating

Answer 18

Ion movement through channel - Fast, passive, driven by electrochemical grad of ion

Question 19

Describe ion channel permeation

Answer 19

Very large and charged ions unable to diffuse through channel

Question 20

Describe channel permeability in terms of selectivity filter

Answer 20

Inside channels are specific combo of AA - Act as gatekeeper, only allow one type of ion to pass