Chapter 1

Question 1

Glia

Answer 1

Responsible for regulating the activity of neurons and the communication between them. In detail, they protect and buffer the central nervous system against chemical changes, provides a immune surveillance, alter the properties of neuronal signalling and nourishes the neurons.

Question 2

Electric potential

Answer 2

Voltage difference

Question 3

Membrane potential

Answer 3

Voltage difference between the inside and outside of the cell.

Question 4

Action potential

Answer 4

Single membrane potential reaching threshold level to start a chain reaction of more membrane potentials

Question 5

Dendrities

Answer 5

They receive stimuli

Question 6

Axon terminals/ Terminal boutons

Answer 6

Specialised swellings in the end of axon branches that transmits the signal to a gland, glia muscle or another neuron

Question 7

Receptors

Answer 7

Protein structures found in the membrane of the tissues that binds to specific chemical transmitters to activate internal mechanism of the cells.
Receptors are also cells that react to physical or chemical stimuli.

Question 8

Synapses

Answer 8

A small region of close proximity terminal branch of an axon and another cell.

Question 9

Plasticity

Answer 9

The ability of the brain to constantly delete or make new connections. This is the basis of developmental maturation, learning, memory recovery from injury, every functional adaptation.

Question 10

Synaptic cleft

Answer 10

A gap of 20 nanometers between axonal bouton and dendroit

Question 11

Synaptic vesicles

Answer 11

A small sac that caries neuro transmittors

Question 12

Glutomite

Answer 12

Glutamatergic - CNS excitation

Question 13

Aspertate

Answer 13

Glutomatergic - Brain and spinal chord excitation

Question 14

Gamma amino butyric acid

Answer 14

GABAergic - CNS inhibition

Question 15

Glycine

Answer 15

Glycinergic - Rapid inhibition in spinal chord

Question 16

Acetylcholine

Answer 16

Cholinergic - muscle activation, attention

Question 17

Dopomine

Answer 17

Dopaminergic - reward, movement

Question 18

Nor-adrenaline/ nor-epinephrine

Answer 18

Nor-adrenergic - arousal, smooth muscle control

Question 19

serotonin

Answer 19

Seratonergic - relaxation, mood, sensory processing

Question 20

Substance P

Answer 20

Peptidergic - Pain signalling, other functions

Question 21

Neuropeptide Y

Answer 21

Peptidergic - Appetite control

Question 22

Opiods

Answer 22

Peptidergic - Pain modulation, satiety

Question 23

Adenosine tri-phosphate (ATP)

Answer 23

Purinergic - Many functons

Question 24

What is the length range of axons?

Answer 24

They can be very short or be half the body length of the animal.

Question 25

What is the size of the cell bodies?

Answer 25

The cell bodies size varies from 10 micrometers to 50 micrometers. Hair is 100 micrometers in width.

Question 26

What is the basis of most connections within the nervous system?

Answer 26

The firing of action potentials and transmitting through neurotransmitter.

Question 27

How is an action potential formed?

Answer 27

When the receptors in the dendrites are stimulated, they open ion channels to let the flow of + and - ions across the membrane. The addition of all charge differences inside the membrane has to be higher than a certain level(threshold level) for an action potential to be initiated. If the action potential is initiated, there will be rapid change in membrane potential across the cell, which travels towards the axon terminals.

Question 28

How are neurotransmitters released?

Answer 28

As the action potential reaches the terminal branches, they activate the release of calcium ions. These calcium ions in turn activate cellular machinery which release small bags of neurotransmitters. These bags or sacs are called vesicles. The vesicles reaches the membrane where the sac breaks and the neurotransmitter is diffused in to the synapse.

Question 29

How does the neurotransmitter work?

Answer 29

The neurotransmitter diffuses across the 20 nanometer synaptic cleft and binds with protein structures called receptors. The receptors are found on glands, muscles, glia and other neurons. This can cause a wide variety of effect on the the postsynaptic cell.

Question 30

What are ionotropic receptors?

Answer 30

Ionotropic receptors are receptors that open ion channels to cause change in the charges of the membrane to either initiate or inhibit an action potential.

Question 31

What are metabotropic receptors?

Answer 31

Metabotropic receptors are receptors that activate cellular machinery to alter the ion channels, to activate gene expression or cause changes in the structure of the neuron.

Question 32

What are excitatory and inhibitory neurotransmitters?

Answer 32

They are the ones that bind to ionotropic receptors to open ion channels for the initiation or inhibition of action potentials. Excitatory(glutamate and aspartate) transmitters open sodium ion channels causing depolarisation of the cell(positive charge). This promotes the firing of an action potential. Inhibitory(GABA and glycine) transmitters on the other hand, open chloride channels which polarise the cell, inhibiting the firing of an action potential.

Question 32

What are the different ways neuronal firing is affected?

Answer 32

Action potential-neurotransmitters
Gap junction
Hormones
Composition of extra cellular fluid
Feedback from dendrites
Activity of nearby glia
Distance of the synapse from the axon hillock

Question 32

How many neurons are there in the brain?

Answer 32

86 billion neurons in human brain. 6 billion in the rhesus monkey and 200 million in the rat brain.

Question 32

What are gap junctions?

Answer 32

Gap junctions are small opening in the cell membranes that allows neurons to connect to each other. This allows membrane potentials and ions to move across neurons without a physical barrier. In the cortex, inhibitory neurons are often gap-junction coupled.

Question 33

What are the functions of astrocytes?

Answer 33

Cellular environment
Tending synapses
Metabolic regulation
Signalling and communication
Governing capillary flow
Providing neurons with preprocessed food

Question 34

What is gene expression?

Answer 34

Gene expression is the process by which gene blueprints are used to make certain non DNA products, mostly proteins. This can be detected by a number of tests like in situ hybridization.

Question 35

Is there a clear distinction between-
A) neurons and glia
B) ionotropic and metabotropic receptors

Answer 35

A) No, neurons and glia have some functions that are really similar, blurring the line of distinction.
B) No, ionotropic and metabotropic receptor functions also overlap. Some ionotropic receptors can open calcium channels that can cellular machinery to be activated. Some metabotropic receptors opens ion channels by activating secondary messengers.

Question 36

How many glial cells are there?

Answer 36

Originally, it was thought to be 10 times more than neurons, but now it is estimated to be around the same number of neurons.

Question 37

What are ependymal cells?

Answer 37

Ependymal cells are cells that line the ventricles in the brain. They form specialised structures with blood vessels called choroid plexus. This cluster secretes CSF. Some of these ependymal cells have the ability to divide and form new cells and constantly replace old cells in the olfactory bulb and the dentate gyrus of the hippocampus.