Module 2

Question 1

What are the three stages of the nervous system?

Answer 1

1. Sensory input
2. Integration (decides on action)
3. Motor output (action)

Question 2

What’s different about sensory neurons?

Answer 2

Their cell body is halfway along their axon

Question 3

What connects two cell bodies?

Answer 3

Synaptic terminals

Question 4

What’s different about interneurons?

Answer 4

They have a very large number of dendrites

Question 5

What is glia’s role in the brain?

Answer 5

It forms the structural integrity required

Question 6

What are the two types of glia?

Answer 6

Astrocytes: Star like structure, in CNS, regulate concentrations of ions and compounds, form the blood-brain barrier (this stops large amounts of compounds from leaving blood vessels and entering the brain)
Oligodendrocytes: (CNS) and Schwann cells (PNS) = Form insulated myelin sheaths around axons (MS has inssues due to loss of these myelin sheaths)

Question 7

Explain the sodium/potassium-ATPase

Answer 7

• Pumps against the concentration gradient
• Uses ATP for energy
• Pumps 3 sodium out and 2 potassium into the cell

Question 8

What concentrations form the resting membrane potential?

Answer 8

Outside the membrane: 5mM K+, 150mM Na+, 120mM Cl-

Inside the membrane: 140mM K+, 15mM Na+, 100mM A- large anions

Question 9

Why is the resting membrane potential negative?

Answer 9

• There are many K+ channels open
• This decreases the chemical gradient and increases the electrical gradient
• This does not depend on voltage-gated ion channels

Question 10

What’s special about excitable cells?

Answer 10

They allow rapid change in membrane potential

Question 11

Definition: Hyperpolarisation

Answer 11

Inside of cell becomes more negative

Question 12

Definition: Depolarisation

Answer 12

Inside becomes more positive