Communication in the brain

Question 1

how many neurones in the brain

Answer 1

86 billion

Question 2

whats the functions of glial cells in the CNS

Answer 2

Half of the volume of the CNS

Support roles

Glue, nutrients, waste, transmission of signals, maintenance of synapses

Oligodendrocytes (produced myelin), astrocytes (supports Blood Brain Barrier ), microglia (help repair process)

Question 3

function of cell body

Answer 3

Contains all the organelles which maintain the life of the cell

Includes nucleus, which hold genetic information

Relays signal down to the axon

Question 4

function of dendrites

Answer 4

Specialized projection that receive signals from neighboring neuron

Thin, bushy-like structures that receive signals from outside the neuron

Relays the information into the cell body

Question 5

function of axon

Answer 5

a think long structure that transmits signals from the cell body to the terminal buttons

The axon is wrapped in myelin, a fatty sheath that allows it to transmit information more rapidly

Question 6

function of axon terminal

Answer 6

Once information hits the axon terminal, it is transmitted outside by the cell neurotransmitters, which reside in the terminal button

Question 7

function of myelin sheath

Answer 7

Insulation- 80% lipids and 20% protein

Created by oligodendrocytes in the CNS (glial cell)

Question 8

label the neuron

Answer 8

answer found on notes

Question 9

what does gray and white matter consist of

Answer 9

Gray matter consists primarily of neuronal cell bodies (soma)

White matter areas of the brain mainly consist of myelinated axons

Question 10

what is the loacation of grey matter in the cerebellum

Answer 10

In the cerebellum, gray matter is primarily found surrounding white matter in the brains external areas. This coating the neurons surrounding the cerebrum is known as the ‘cortex’

Question 11

what is nuclei

Answer 11

Regions of the gray matter that are located in deeper regions of the brain

Question 12

whats the structure of white matter in the cerebellum

Answer 12

White matter is organized into tracts of axons. In the cerebrum and cerebellum, white matter is predominantly found in deeper areas- with gray matter coating the white matter

Question 13

whats is the grey and white matter like in the spinal cord

Answer 13

In the spinal cord, things are largely reversed- the white matter is distributed around the central gray matter “butterfly”

Question 14

what is action potential

Answer 14

An action potential is a brief electrical impulse that travels along a neurons axon, signaling that the neuron is active

Concentration gradients are key behind how action potentials work

Question 15

what is a concentration gradient

Answer 15

A concentration gradient is the difference in ion concentration between the inside of the neuron and the outside of the neuron (called extracellular fluid)

Question 16

what is the concentration gradient of neurones

Answer 16

Neurons have a negative concentration gradient most of the time, meaning there are more positively charged ions outside than inside the cell.

Question 17

what is the regular state of negative concentration gradient called

Answer 17

resting membrane potentail

Question 18

during resting membrane potential what is the state of the ions

Answer 18

More sodium ions (Na+) outside that inside the neuron

More potassium ions (K+) inside than outside the neuron

Question 19

what is the resting membrane potential of a neurone ?

Answer 19

-70mV (millivolts)

Question 20

what causes the resting potential of a neurone to be negative

Answer 20

• small excess of negative ions inside the cell

Question 21

the neuronal membrane is very permeable to waht? and why is this

Answer 21

permeable to k+ ions
why- there are k+ leak channels
they are open when the membrane is resting
as k+ escapes the cell theres less positive charge relative to the outside

Question 22

how is resting potential maintained?

Answer 22

1- Neurons are electrically excitable – all cells in body exhibit basic electrical properties

2- Concentrations of ions (Na+, K+) differ between inside and outside the cell

3-Sodium (NA+) higher outside cell and Potassium (K+) inside the cell

4- Concentration differences cause ions to continuously move down the concentration gradient through ion channels which are highly permeable to K+

5-At some point the movement will stop with a inside of cell negative compared to outside-giving cell a resting potential of about -70mV

6- Ion channels can open/shut depending on conditions

Question 23

what is action potential

Answer 23

A short term change in the electrical potential that travels along a cell. It releases the neurotransmitter into the synaptic cleft.

Question 25

the five steps of the formation of action potential

Answer 25

1- A stimulus from a sensory cell or another neuron causes the target cell to depolarize toward the threshold potential 2- If the threshold of excitation is reached, all na+ channels open and the membrane depolarizes 3- At the peak action potential k+ channels open and k+ begins to leave the cell. At the same time, na+ channels close. 4- The membrane becomes hyperpolarized as k+ ions continue to leave the cell. The hyperpolarized membrane is in the refractory period and cannot fire 5- The k+ channels close and the na+/k+ transported restores the resting potential

Question 26

what is a synapse

Answer 26

structural arrangement, comprising the cell providing the information and the cell receiving it.

Question 27

what is an axon terminal

Answer 27

this is where the electrical message is changed to a chemical signal using neurotransmitters to communicate with the next group of nerve cells, muscle cells, or organs

Question 28

briefly explain how synaptic transmission works

Answer 28

Each type of neurotransmitter lands on and binds to a specific receptor on the target cell (like a key that can only fit and work in its partner lock) After binding the neurotransmitter then triggers a change or action in the target cell, like an electrical signal in another nerve cell

Question 29

what is signal termination

Answer 29

synaptic cleft must be cleared After neurotransmitters deliver their message, the molecules must be cleared from the synaptic cleft (the space between the nerve cell and the next target cell) they do thus in one of three ways

Question 30

what are the three pways in which the synaptic cleft is cleared

Answer 30

re uptake, diffusion, degradation

Question 31

explain how the three processes of siganl termination work

Answer 31

Are reabsorbed and reused by the nerve cell that released it (a process called reuptake) Fade away (a process called diffusion) Are broken down by enzymes within the synapse so it can't be recognized or bind to the receptor cell (a process called degradation)

Question 32

spatial summation?

Answer 32

adds together all inputs receives at the same time (remember neurons are connected to 100s/1000s of other neurons)

Question 33

temporal summation

Answer 33

add together inputs in the dame place but slightly different times If a presynaptic neuron fired quickly twice in a row, the second one may arrive before the first one has dissipated, bumping the membrane potential above threshold for an action potential

Question 34

whats a neurotransmitter

Answer 34

Chemical messengers that transmit signals from a neuron to a target cell across the synapse

Question 35

where do neurotransmitters target

Answer 35

Target may be a Nerone but could also be another type of cell such as a muscle or gland cell

Question 36

where are neurontransmitters found

Answer 36

Packed into the synaptic vesicles of presynaptic cells

Question 37

how are nuerotransmitters released

Answer 37

Released by electrical impulse into the synaptic cleft Diffuse to the postsynaptic membrane Reacts and activate receptors on postsynaptic neuron Potentially leading to further electrical impulse

Question 38

what are the two types of receptors

Answer 38

Ligan gated ion channels and G protein couples receptors

Question 39

how do ligan gated ion channels work

Answer 39

Rapid ion flow directly across the outer cell membrane Composed of 3-5 protein subunits that form a pore Neurotransmitter binding to the receptor opens the pore and directly indices ion fluxes

Question 40

how do G protein couples receptors work?

Answer 40

Does not work as simply as ligand-gated ion channels Set into motion chemical signaling events within the cell When the NT associates with the extracellular recognition site, an intermediate molecule withing the postsynaptic cell, called G-protein, is activated and either directly or through a series of enzyme reactions, open or closes ion channels located at other places on the cell membrane. Because the action of metabotropic receptors is not as direct, their action Is slower

Question 41

two types of neurotransmitters and what they do

Answer 41

Inhibitory These types have inhibitory effects on the neuron; they decrease the likelihood that the neuron will fire an action potential Excitatory Have excitatory effects on the Nerone. This means they increase the likelihood that the neuron will fire an action potential

Question 42

role of Epinephrine

Answer 42

prddcued in stressful situation increases heart rate and blood flow, leading to physical boost and heightened awareness is a nuerotransmitter in the sense that within the brain it helps neurones communicate with one another, however because its mainly produced in the adrenal glands and has functions periphally (outside the brain) it can also be considered a hormone

Question 43

role of norepinephrine

Answer 43

affects attention and responding actions in the brain. contracts blood vessels, increasing blood flow also produced by adrenal glands plays a role in the sleep-wake cycle important for memory storage and emotions

Question 44

role od dopamine

Answer 44

pleasure and addiction movement and motivation. people repeat behaviours that lead to dopamine release binds to dopaminergic receptors throughout the brain

Question 45

role of serotonin

Answer 45

contributes to well-being and happiness. helps sleep cycle and digestive system regulation. affected by excercise and light eposure is a indolamine serotonin is also know as 5-hydroxytryptamine (5ht) these nuerones are found as discrete clusters of cells along the midline of the brain stem pathways projecting from the pons and midbrain to the cortex and the limbic sytem and other areas of the CNS

Question 46

role of GABA

Answer 46

calms firing nerves in the CNS. high levels improve focus. low levels cause anxeity. also contributes to motor control and vision

Question 47

role of acetylcholine

Answer 47

involved in though, learning and memory, activates muscle action in the body. also assocaiated with attention ans awakening

Question 48

role of glutamate

Answer 48

most common neurotransmitter, involved in learning and memory. regulates development and creation of nerve conacts

Question 49

role of endorphins

Answer 49

released during exercise, excitment and sex . producing well- being and euphoria, reducing pain

Question 50

what is ester acetylcholine

Answer 50

An ester of choline and acetic acid that serves as a transmitter substance of nerve impulses within the central and peripheral nervous systems

Question 51

role of acetylcholine

Answer 51

Acetylcholine is the chief neurotransmitter of the parasympathetic nervous system, the part of the autonomic nervous system (a branch of the peripheral nervous system) that contracts smooth muscles, dilates blood vessels, increases bodily secretions, and slows heart rate. * Acetylcholine is a neurotransmitter that plays a role in memory, learning, attention, arousal and involuntary muscle movement. Medical conditions associated with low acetylcholine levels include Alzheimer's disease.

Question 52

relationship between ACETYLCHOLINE and alzheimers

Answer 52

In the brain of a person with Alzheimer’s disease, there are lower levels of a chemical called acetylcholine. Acetylcholine helps to send messages between certain nerve cells. In Alzheimer’s disease some of the nerve cells that use acetylcholine are also lost. Because of these changes in the brain, symptoms of Alzheimer’s disease get worse over time. * Donepezil, rivastigmine and galantamine all prevent an enzyme called acetylcholinesterase from breaking down acetylcholine. This means there is a higher concentration of acetylcholine in the brain, which leads to better communication between nerve cells. This may ease some symptoms of Alzheimer’s disease for a while.

Question 53

what is a amino acid neurontrasmitter

Answer 53

The amino acid neurotransmitters are common neurotransmitters in the central nervous system. Glycine, glutamate, and GABA are classed under amino acid neurotransmitter

Question 54

what are the three neurotransmitters classed under amino acids and what do they do

Answer 54

Glutamate- Most abundant excitatory NT in the brain. It actually binds to a range of different receptors. Implications for learning and memory. Dysfunction proposed to play a role in schizophrenia * GABA-Most abundant inhibitory NT. Produced from Glutamate through an enzyme and binds to a range of receptors. * Glycine-It acts on the spinal cord (similar to GABA in the brain). It is also a co-agonist (both glycine and glutamate are needed for some receptors to be activated)

Question 55

whats agonist

Answer 55

* Agonists are substances that bind to synaptic receptors and increase the effect of the neurotransmitte

Question 56

what are antagonists

Answer 56

Antagonists also bind to synaptic receptors but they decrease the effect of the neurotransmitter.

Question 57

what is a Catecholamine

Answer 57

help the body respond to stress or fright and prepare the body for fight or flight

Question 58

three treatments for depression

Answer 58

tricyclics, MOAIs, SSRIs

Question 59

what do tricyclics do?

Answer 59

they block the reuptake of serotonin and norepinerphrine in the presynaptic terminals, which leads to i ncreased cocncentration of these neurotransmitters in the synaptic cleft. the increases conc likely contributes to a anti-depressive effect

Question 60

what do MAOIs do?

Answer 60

an enzyme called monoamine oxidase is involved in removing the nurostransmitters norephinerinem serotonin and dopamine from the brain. MAOIs prevent this from happening which makes more of these brain chemicals available to effect changes in both cells and circuits that have been impacted ny depression

Question 61

what do SSRIs do?

Answer 61

block the reabsorbtion (reuptake) of serotonin the the neurones

Question 62

DA = NE= ACh= 5HT=

Answer 62

DA = dopamine NE= norepinephine ACh= acetylcholine 5HT= serotonin

Question 63

drug = L-dopa mechanism= use= agonist/antagonist=

Answer 63

drug = l-dopa mechanism= increases synthesis of DA use= parkinsons disease agonist/antagonist= agonist for DA

Question 64

drug = Adderall mechanism= use= agonist/antagonist=

Answer 64

drug = adderall mechanism= increases release of DA, NE use= ADHD agonist/antagonist= agonist for DA NE

Question 65

drug = ritalin mechanism= use= agonist/antagonist=

Answer 65

drug =ritalin mechanism= blocks removal of DA,NE AND lesser (5HT) from synapse use= adhd agonist/antagonist= agonist for DA, NE mostly

Question 66

drug = aricept mechanism= use= agonist/antagonist=

Answer 66

drug = aricpet mechanism= blocks removal of ACh from syanpse use= alzheimers agonist/antagonist=agonist forACh

Question 67

drug =prozac mechanism= use= agonist/antagonist=

Answer 67

drug =prozac mechanism=blocks removal of 5HT from synapse use= depression , ocd agonist/antagonist=agonist for 5ht

Question 68

drug = seroquel mechanism= use= agonist/antagonist=

Answer 68

drug = seroquel mechanism= blocks DA and 5HT receptors use= schizo, bipolar agonist/antagonist= antagonsit for DA and 5HT

Question 69

drug = Revia mechanism= use= agonist/antagonist=

Answer 69

drug = revia mechanism= blocks opiod post- synaptic receptors use= alcoholism, opiod addiction. agonist/antagonist= antagonist (for opiods )

Question 70

what are the effects of MDMA 'edstasy'

Answer 70

-more serotonin ends up in the synaptic space. this occurs for two reasons 1- ecstasy can prevent the transported from carrying serotonin back into the terminal 2- ecstasy can cause the transporters to work in trnasporter- reverse-mode --- they actauly bring serotonin from the terminal into the synaptic space, so more serotonin is present in the synaptic space and more serotonin receptors become activated