Nervous System Structure + Function Recap

Question 1

What is sensory function?

Answer 1

Senses internal and external changes.

Question 2

What is integrative function?

Answer 2

Analyses and stores information.

Makes decisions on appropriate voluntary and involuntary responses.

Question 3

What is motor function?

Answer 3

Initiates muscular activity / glandular secretions.

Question 4

What are some functions of the Central Nervous System (CNS)?

Answer 4

Integrates sensory information.

Generates thoughts and emotions. (in complex models).

Stores memory.

Makes decisions.

Initiates motor activity.

Question 5

What are some functions of the Peripheral Nervous Systems (PNS)?

Answer 5

Arises from the brain and spinal cord.

Carries nerve impulses to and from CNS.

Connects the CNS to sensory receptors, muscles and glands.

Question 6

What are the cell types in the nervous system? (+their function)

Answer 6

Neurons = electrically excitable cells specialised for signalling. Do NOT divide.

Neuroglia = diverse support and development of functions. DO divide.

Question 7

What is the structure of Neurons? (+their function)

Answer 7

Cell body (soma) = has normal cell organelles, site of protein synthesis + degradation.

Dendrites = short, bristle-like, highly branched processes, receive nerve input.

Axon = long, thin process, propagates nerve impulse to another neuron, muscle or gland. Terminates at axon terminals / synapses.

Question 8

Name some elements of neuronal structure?

Answer 8

Question 9

What is an action potential?

Answer 9

When information is transmitted along the axon in the form of electrochemical signals / nerve impulses.

Question 10

Which ions are involved in action potentials?

Answer 10

Sodium (Na+) and Potassium (K+)

Question 11

What is the resting potential?

Answer 11

= -70mV

Question 12

What happens to the resting potential after receiving incoming signals?

Answer 12

Cell membrane is depolarised.

Membrane potential rises from resting potential.

Question 13

What is / happens at the threshold potential?

Answer 13

When the membrane potential is depolarised beyond a certain critical level.

= -55 mV

Action potential (nerve impulse) is triggered in the axon.

Question 14

What is hyperpolarisation?

Answer 14

When the membrane potential is decreased.

Makes action potential less likely.

Question 15

What are some properties of Action Potentials?

Answer 15

All or none = full action potential or none

Saltatory Conduction = impulses jump between nodes of Ranvier in myelinated axons (speed = 150 m/sec)

Intensity of signal = conveyed by frequency of nerve impulses.

Refractory period = short period where another action potential cannot be stimulates = unidirectional movement

Question 16

What are the 2 types of synapses?

Answer 16

Electrical (gap junctions).

Chemical.

Question 17

Where are neurotransmitters stored?

Answer 17

In membrane bound synaptic vesicles.

Question 18

What is the amount of neurotransmiteer in one vesicle called?

Answer 18

Quantum.

Question 19

What types of effects can a neurotransmitter cause?

Answer 19

Excitatory.

Inhibitory.

Question 20

What are the mechanisms to terminates transmitter’s activity

Answer 20

Catabolism (degradation).

Re-uptake of transmitter into axon terminal or glial cells.

Question 21

What does the arrival of an action potential cause?

Answer 21

Causes influx of Ca2+, fusion of vesicles with pre-synaptic membrane, release of transmitter into synaptic cleft, binds to receptor on post-synaptic membrane.

Question 22

How is behaviour defined? (+some example)

Answer 22

Any orderly movement with recognisable and repeatable patterns.

e.g. courtship, predation, migration, locomotion, flying, feeding

Question 23

What are some examples of homeostasis?

Answer 23

Respirartory rate, heart rate, maintenance of balance.

Question 24

How to tackle neurobiological research questions?

Answer 24

Molecular / Cellular level.

Genetic level. (Neurogenetics)

Neural network / circuit level.

Question 25

What are ways to study the human brain?

Answer 25

Neuroanatomy.

Clinical studies.

Functional neuroimaging.

Question 26

Why use model organisms?

Answer 26

Strong conservation of genes and function over long evolutionary distances.

(master-regulatory genes).

Question 27

What are the 2 ways to manipulate gene expression?

Answer 27

Forward Genetics = to identify genes responsible for particular phenotype

e.g. random mutagenesis

Reverse Genetics = alter specific genes to determine role in phenotype / biological function

e.g. site-directed mutagenesis, gene silencing, transgenes

Question 28

Similarities / Differences between invertebrates and vertebrates?

Answer 28

Have same basic plan = CNS + PNS, all have a brain.

Vertebrates = more neurons devoted to information processing.
Invertebrates = have fewer but larger and more complicated neurons.

Mammalian neuronal axons = myelin sheath.
Invertebrates = no myelin, but giant axons.

Vertebrate CNS = encased by bony skull + spinal column.
Invertebrate CNS = often built around digestive tract.

Question 29

Why use Drosophla melanogaster?

Answer 29

Easy to grow.

Short life cycle.

Display all characteristics of multicellular organisms

e.g. complex organ structure, complex social, sexual and learning behaviours.

Question 30

What does the fly nervous system look like?

Answer 30

Question 31

The promoter that control GAL4 driver lines can be:

Answer 31

Minimal = GAL4 expressed in pattern of any enhancers nearby. = enhancer trap GAL4 lines.

Characterised = specific endogenous gene. GAL4 expressed in same pattern as endogenous gene.

Question 32

What are UAS-reporter transgenes used for?

Answer 32

To identify characterise the pattern of expression of a particular GAL4 driver line.

e.g. UAS-GFP, UAS-LacZ

Question 33

Where can genes of interest (GOI) be cloned?

Answer 33

Downstream of a UAS promoter.

Question 34

Types of target genes?

Answer 34

Wild type genes = to over express normal copies of GOI

Truncated = to express a dominant negative version of a GOI

RNAi = to reduce mRNA levels of GOI

Cell death gene = to ablate cells in which it is expressed

Tetanus toxin = to alter synaptic transmission

Question 35

What is an example of an invertebrate model? Why is it used?

Answer 35

Caenorhabditis elegans (nematode).

Cells divide in stereotypical manner, lineage of every cell can be traced to the egg.

Worms are easy to grow.

Display all characteristics of multicellular organism.

e.g. complex organ structure, social, sexual and learning behaviours.

Simple organism with a nervous system - only 302 neurons.

Easy to disrupt specific genes (mutagenesis / transgenes).

Can knockout genes vua RNAi = feed worms dsDNA containing sequence of GOI.

Question 36

What is an example of a vertebrate model? What are some pros vs cons?

Answer 36

Mus musculus (mouse).

Pros
= more closely related to humans (genome, physiology, anatomy)
= genome sequence and expression databases
= many genetic tools for forward/reverse genetics
= complex behavioural analysis assays / in vivo imaging available

Cons
= nervous system more complex
= longer life cycle
= more expensive
= more ethical considerations