Intro to neurones

Question 1

What is the function of dendrites?

Answer 1

increase the surface area for synapses, they receive inputs from other neurones and convey graded electrical signals passively (without APs) to the soma

Question 2

What is the function of the soma?

Answer 2

metabolic hub of the neurone, provides axons with nergy and proteins. contains nucleus and other features

Question 3

What is Nissl substance?

Answer 3

RER of the soma

Question 4

What is the axon initial segment?

Answer 4

most excitable part of the neuron where APs are initiated

Question 5

What is anterograde direction through a nerve?

Answer 5

from the soma to the presynaptic terminal

Question 6

Which viruses exploit retrograde transport?

Answer 6

herpes; polio; rabies

Question 7

Give an example of a unipolar neurone?

Answer 7

peripheral autonomic neurone (parasympathethic postganglionic)

Question 8

What is a psudounipolar neurone?

Answer 8

one neurite that bifurcates

Question 9

Give an example of a pseudounipolar neurone?

Answer 9

dorsal root ganglion

Question 10

Give an example of a bipolar neurone?

Answer 10

retinal bipolar neurone

Question 11

Give an example of a mulitpolar neurone?

Answer 11

lower motor neurone

Question 12

What are the four functional regions of neurones?

Answer 12

input; integrative; conductile and output

Question 13

What is the overshoot of an AP?

Answer 13

brief period when polarity of the membrane is reversed so that the inside is positively charged

Question 14

Why is there an undershoot?

Answer 14

membrane potential becomes more negatively charged than the resting potential for a short period as the potassium channels dont close as soon as resting potential is reached

Question 15

What factors increase the distance that a signal will spread?

Answer 15

increased membrane resistance and decreased axial resistance of axoplasm

Question 16

How can the axial resistance of the axoplasm be decreased?

Answer 16

by increasing the diameter

Question 17

How does an AP conduct along an axon?

Answer 17

postivie charge spreads passivley to negatively charged parts since opposite charges attract

Question 18

Why does an AP not go back the way?

Answer 18

channels are refractory

Question 19

What is saltatory conduction?

Answer 19

AP jumps from one node of Ranvier to the next

Question 20

What is a node of Ranvier?

Answer 20

the space between Schwann cells

Question 21

What are the 3 types of synapse?

Answer 21

axodendritic; axosomatic and axoaxonic

Question 22

What is the most common type of synapse?

Answer 22

axodendritic

Question 23

What is the most common excitatory transmitter in the CNS

Answer 23

glutamate

Question 24

What response does glutamate generate?

Answer 24

excitatory postsynaptic potential

Question 25

What is the difference ebtween an AP and an epsp?

Answer 25

an epsp is local and graded

Question 26

What are the main inhibitory transmitters in the CNS?

Answer 26

GABA and glycine

Question 27

What type of response do GABA and glycine generate?

Answer 27

inhibitory postsynaptic potential

Question 28

What holds the pre and post-synpatic membranes together?

Answer 28

a matrix of fibrous extracellular protein

Question 29

What is the area that pre-synaptic vesicles cluster around?

Answer 29

active zone

Question 30

What is the area that contains the neurotransmitter receptors postsynaptically?

Answer 30

postsynaptic density

Question 31

What ion does the ipsp use?

Answer 31

chloride

Question 32

What is spatial sumation?

Answer 32

many inputs converge upon a neurone to determine its output

Question 33

What is temporal summation?

Answer 33

a single input may modulate output by variation in AP frequency of that input

Question 34

What type of vesicle are amino acids and amines released from?

Answer 34

synaptic vesicles

Question 35

What type of vesicle are peptides released from?

Answer 35

secretory vesicles

Question 36

What makes GABA and amines more difficult than amino acids to use?

Answer 36

amino acids are found in all cells whereas GABA and amines require specific enzymes in neurones

Question 37

How are transmitters released at synapses?

Answer 37

calcium induced release of transmitter (exocytosis)

Question 38

How are enzymes transported from the cell body to the presynaptic terminal?

Answer 38

axoplasmic transport via microtubules

Question 39

What is the labeled line principle?

Answer 39

primary sensory afferent fibres confer modality by their site of termination in the CNS

Question 40

How does mechanical stimuli cause an AP?

Answer 40

stretch of the membrane caused by the dermation causes ions channels to open and create a graded passive depolarisation which creates an AP at the first node of Ranvier

Question 41

How is the frequency of APs generated by receptor potential determined?

Answer 41

proportional to the amplitude of the receptor potential or the degree of deformation

Question 42

Where is the greatest sensitivity to change of stimulus strength?

Answer 42

low stimulus strength