Biological Psychology - Lecture 3

Question 1

The neuron

Answer 1

• the body is composed of cells
• cells are specialised to perform specific functions (e.g. red blood cells, muscle cells)
• neurons (nerve cells) are specialised for communication

Question 2

The role of the neuron

Answer 2

• information transmission, e.g. from eye to brain, or brain to muscle
• action potential
• axon
• maintains a clear signal
  Information processing
• e.g. to interpret a pattern of visual information as being a human face
• integration of signals
• synapse/dendrites/cell body
• modify signals according to context

Question 3

The Action Potential

Answer 3

• the action potential is the ‘output’ signal of a cell, triggered by a particular combination of ‘inputs’
• begins at the axon hillock
• travels along the axon to the terminal
• triggers activity at the synapse
  Neuronal “firing”
  -first, an electrical potential is set up: the resting potential
  -this is allowed to suddenly discharge: the action potential
  -this triggers further action potentials further along the axon

Question 4

Membrane structure and function

Answer 4

• cells are enclosed by lipid (fatty) membranes
• this membrane is semi-permeable: not all particles can pass through
• different ions (electrically-charged molecules) are concentrated in the fluid inside and outside the cell

Question 5

The role of membrane proteins

Answer 5

• protein pumps actively transport ions across the membrane
• protein ion channels allow ions to cross the membrane
• Voltage-gated ion channels open at a particular membrane voltage

Question 6

The resting potential

Answer 6

• at rest, the neuron is polarised
• -70 mV (inside more negative than outside)
• this acts like a store of energy

Question 7

Setting up and maintaining the resting potential

Answer 7

• the sodium-potassium pump exchanges three sodium ions for two potassium ions
• this makes the inside of the cell relatively negative
• this uses energy

Question 8

The resting potential

Answer 8

• more negative charges inside than outside the cell (-70 mV)

Question 9

Depolarisation

Answer 9

• the membrane becomes partially depolarised (towards zero) when:
• an “excitatory” input is received from another neuron
• neighbouring membrane is depolarised (passive conduction)
• if depolarisation reaches the excitation threshold is triggered

Question 10

The action potential: rapid depolarisation

Answer 10

• voltage-gated sodium channels open when depolarisation reaches a threshold level
• sodium ions (positively charged) flood in
• the membrane potential changes from -70 mV to +40 mV

Question 11

The refractory period

Answer 11

Sodium ion channels close and briefly lock - they become “refractory”

Question 12

Function of refractory period

Answer 12

• signal can never go backwards

- keeps signals separate