Neurobiology

Question 1

What are microglica cells?

Answer 1

Cells that can become macrophages, cleaning debris after infarcts (strokes)

Question 2

What are oligondendroglia?

Answer 2

Cells that form myelin sheath around axons in the brain and spinal chord

Question 3

What is the function of astroglia?

Answer 3

• Support neurons by insulating neurons/synapses from eachother
• Regulate K+ concentration
• Remove neurotransmitters and release growth factors

Question 4

What is the resting membrane potential?

Answer 4

-65 mV

Question 5

What is the resting permeability of the membrane to Na+/K+?

Answer 5

High permeability of K+ low permeability of Na+

Question 6

What causes hyperpolarisation?

Answer 6

Na+ channels are faster to close that K+ channels

Question 7

Why can action potentials not travel backwards?

Answer 7

Refractory period
Absolute - recovery of Na+ channels
Relative - period of hyperpolarisation

Question 8

What are the two types of receptors on the post synaptic membrane?

Answer 8

• Ionotropic receptors (direct gating)

- Metabotropic receptors (indirect gating)

Question 9

Describe how the following work:

a) exitatory transmitters
b) inhibitory transmitters

Answer 9

a) Cause EPSPs by activating receptors that allow Na+ influx in order to surpass the threshold
b) Cause IPSPs by activating receptors for Cl- to move away from the threshold

Question 10

How does the bleaching of rhodopsin trigger an action potential in the optic nerve?

Answer 10

1. Activates G protein
2. Activates cGMP phosphodiesterase converts 3cGMP to 5cGMP
3. This shuts the cGMP-gated Na+ channel shut, triggering hyperpolarisation (-40mV to -70mV) generating an action potential

Question 11

Name 5 receptors on the skin and what they detect

Answer 11

1. Nerve endings - temperature, pain
2. Hair follicles - touch, moving hair
3. Meissners corpuscles - light touch
4. Merkels discs - pressure
5. Pacinian corpuscles - vibration

Question 12

What are the 4 types of reflex?

Answer 12

1. Stretch (myotatic) - control movement
2. Autogenic inhibition - control of muscles force
3. Flexor - withdrawal from harmful stimuli
4. Crossed extensor - distributes load evenly

Question 13

How does a stretch reflex propagate?

Answer 13

Stimulus from muscle travels through dorsal root ganglion, motor neuron passes through ventral root and stimulates muscle

Question 14

How does a flexor reflex propagate?

Answer 14

Pain stimulus travels to spinal cord, passes through exitatory interneurones to motor neurones

Question 15

How can electrocephalography (EEG) be used to measure brain activity?

Answer 15

Electrodes placed on the head can pick up on brain activity but only if thousands of neurones are involved

Question 16

How can Positron Emission Tomography monitor brain activity?

Answer 16

Scanner detects radioactive oxygen/glucose that is injected or inhale which relates to brain activity, gamma rays used for detection.

Question 17

How does fMRI give information about brain function?

Answer 17

Monitors increase in bloodflow to certain parts of the brain, due to different magnetic properties of oxygenated and deoxygenated haemoglobin