Nervous system: Synapses

Question 1

synapse

Answer 1

anatomically specialised junction between two neurones
can converge or diverge
0.2ms

Question 2

excitatory synapse

Answer 2

generate excitatory post synaptic potential: membrane potential of post-synaptic neuron is brought closer to threshold (i.e., depolarised). graded potential generated

Question 3

inhibitory synapse

Answer 3

generate an inhibitory postsynaptic potential: membrane potential of post-synaptic is either driven further from threshold (i.e., hyperpolarised) or stabilised at resting potential
made more negative

Question 4

electrical synapse

Answer 4

electrical activity of the presynaptic neurone affects that of the postsynaptic neuron
pre and post synaptic cells connected by gap junctions

Question 5

chemical synapse

Answer 5

neurotransmitters transmit the signal

Question 6

active zones

Answer 6

release regions in which vesicles are docked on the presynaptic membrane

Question 7

types of receptors in post synaptic neurone

Answer 7

ionotropic (ion channels)
metabotropic (G protein/second messenger signalling)

Question 8

removal of neurotransmitter

Answer 8

diffusion of transmitter from cleft
degradation of neurotransmitter by enzymes
reuptake into presynaptic cells for re use

Question 9

why are multiple excitatory postsynaptic potentials needed

Answer 9

one=0.5mV
need a change of 15mV
not enough to reach threshold

Question 10

temporal summation

Answer 10

repeated stimulation of one neurone

Question 11

spatial summation

Answer 11

multiple neurones activated simultaneously to produce graded potentials
inhibitory synapses can also do this

Question 12

muscle spindle

Answer 12

stretch receptors consist of peripheral endings of afferent nerve fibers wrapped around modified muscle fibers enclosed within a connective tissue capsule

Question 13

intrafusal fibres

Answer 13

specialised muscle fibres to detect changes in stretch

Question 14

extrafusal fibres

Answer 14

generate force, bulk of muscle

Question 15

what does tension depend on

Answer 15

muscle length
load
fatigue

Question 16

golgi tendon organs

Answer 16

endings of afferent nerve fibers that wrap around collagen
bundles in the tendons near their junction with the muscle
action potentials triggered when muscle stretches/contracts

Question 17

electroencephalogram (EEG)

Answer 17

recording of brain electrical activity
patterns largely due to graded potentials

Question 18

alpha rhythm

Answer 18

associated with decreased levels of attention

Question 19

beta rhythm

Answer 19

attentive to external stimulus

Question 20

5 major divisions of sensory receptors

Answer 20

Mechanoreceptors – pressure / stretch
Thermoreceptors– cold / warmth
Photoreceptors – different ranges of light
Chemoreceptors – binding of chemicals to the receptor (smell, taste, pH, O2)
Nociceptors– painful stimuli, such as heat, tissue damage

Question 21

sensory receptors

Answer 21

specialised cells that generate graded potentials called
receptor potentials in response to a stimulus
ends of afferent neurons
and can convert stimuli into graded potentials
Stimuli opens ion channels directly or indirectly

Question 22

ion flux

Answer 22

results in a change in membrane potential which results in a local graded
potential (receptor potential)
A larger stimulus results in a
larger graded potential which
results in more frequent action
potentials

Question 23

receptive field

Answer 23

The area of the body that when stimulated, leads to activity in a particular afferent neuron

Question 24

coding

Answer 24

the conversion of a stimulus into a signal
that conveys the relevant information

Question 25

modality

Answer 25

type of stimulus

Question 26

adequate stimulus

Answer 26

A given receptor is particularly sensitive to one stimulus modality

Question 27

acuity

Answer 27

The precision for locating the
stimulus depends on convergence where greater convergence causes less acuity
A neuron responds vigorously
when stimulus is in the
middle of the receptive field-more receptors activated, more ATs

Question 28

lateral inhibition