Neuroanatomy and neurophysiology 2

Question 1

what is lateralisation

Answer 1

the two halves of the brain are functionally different and that each hemisphere has functional specialisations,

e.g. the left is dominant for language, and the right excels at visual motor tasks

Question 2

what is contralateral control

Answer 2

left brain controls right side

right brain controls left side

Question 3

parts of a neuron

Answer 3

dendrites - receive message

soma - cell body, controls metabolism and maintenance of cell, correlates message

axon - carries message through neuron from soma to axon terminals (trough action potential)

terminal buttons - secrete neurotransmitters whihc effect communicating cells

myelin - insulates some axons to promote efficient transmission of action potential - insulator

lipid bilayer - two layers of fatty molecules making up the cell membrane

Question 4

the resting membrane potential

what is it

Answer 4

there are different chemical compositions inside and outside the cell at rest

result of relative concentrations of k+, cl-, -ve charged protein ions and Na+

RMP is approximately equal to -70mV

Question 5

the action potential

what is it

Answer 5

triggered by an exchange of ions across the neuron membrane

the neuron releases an action potential when the membrane depolarisation reaches the threshold (-55mV)

Question 6

the myelin sheath

Answer 6

electric insulator
- prevents current flow across membrane

current can flow across membrane at breaks in the myelin ( called nodes of ranvier)

• Na+ channels concentrated around NoR
• AP can only generated in these gaps

AP “jumping” from break to break increases its speed

non-myelinated axons are much slower - AP is generated repeatedly along axon

Question 7

synaptic transmission

Answer 7

when AP reaches terminal buttons it releases neurotransmitters into the synapse and are received by the dendrites of the next neuron

Question 8

what are the five neurotransmitters and their functions?

Answer 8

Acetylcholine (ACh)

• activates motor neurons controlling skeletal muscle
• regulation of attention, arousal, memory

Dopamine (DA)

• control of voluntary movement
• important in reward, motivation, pleasure emotions

Serotonin (5-HT)
- emotional state, impulsiveness, dreaming

GABA
- widely distributed inhibitory neurotransmitter

Endorphins

• resembles opiate drugs in structure and effect
• pain relief and some pleasure emotions

Question 9

how can synaptic transmissions be terminated?

Answer 9

3 ways of removing neurotransmitters from the synapse

reuptake
- the whole transmitter molecule is taken back into presynaptic axon terminal

diffusion
- neurotransmitter drifts out of synaptic cleft where it cant effect a receptor

deactivation
- an anzyme changes the structure of the neurotransmitter so its unrecognisable by the receptor