Module 2 BIOM1050

what is the threshold that must be breached for an action potential to be passed on?

-50mV

what is the equilibrium potential of neuron?

-70mV

how fast does the cell go back to resting membrane potential after depolarisation?

1-2 milliseconds

4 ways neurotransmitters can be removed from synaptic cleft?

1. recycled back into presynaptic neuron, 2. diffusion, 3. broken down by enzymes, 4. taken up by astrocytes

how fast is the speed of conduction in giant squid axon?

100m/s

how fast is the speed of conduction in a myelinated axon?

120m/s

concentration of Cl outside membrane?

120mM

2 reasons why is membrane potential negative?

3 NA+ pump out only 2 K+ pump in, membrane at rest had many open K+ channels which flow out of cell along conc gradient

how many Na+ and K+ does the sodium potassium ATPase pump in and out of the cell? and what does this do to the membrane potential?

3 Na out, 2 K in - more positive being pump out making membrane more negative

what happens during hyperpolarisation?

3 x Na+ move out and 2 x K+ move in via Na/K ATPase pump

what is the time scale for a action potential - and the cell to go back to resting potential?

5 milliseconds

what are the two types of Glia cells

Astrocytes and Schwann Cells

what is responsible for coordination, motor function and cognitive and perceptual functions?

Cerebellum

supporting cells in the nerve - hold nerve cell together - vital for structural integrity and normal functioning

Gila

what neurotransmitter is fundamental in storing of memories and hence for learning?

Glutamate

what happens during the repolarisation period?

K+ channels open to make the membrane potential more negative, and NA+ in inactivated state

another name for ion channel linked receptors?

Ligand gated channels

how to work out a dilution question eg. You have 250 ml of a 4 M NaCl stock solution. What volumes of stock and distilled water must you add together to create 2 ml of a 500 mM working solution?

M1V1=M2V2 M = molarity, V=volume L

what happens during the undershoot to restore resting membrane potential?

Na/K+ ATPase pump works to restore original concentrations

what does a protein look like once its been phosphorylated?

OH group added

the refractory period where nerve can't be restimulated because Na+ channels need to finish their cycle and reached closed until they can be reopened

absolute refractory period

what is the neurotransmitter released using exocytosis from motor neurone to stimulate a muscle contraction

acetylcholine

what has the ability to change the membrane potential of the cell?

action potential which opens the voted gated ion channels

what is the structure of an amino acid chain

amine group, amino acid sequence, carboxyl group

what type of signalling is it when the chemical released by the cell, works on the cell itself

autocrine

factors effecting action potential conduction speed?

axon diameter, temperature, myelination

for an action potential to travel down second neuron, what part of neuron must breach threshold?

axon hillock

this is where the action potential is produced on a neuron

axon hillock

why can an action potential only travel in one direction down the axon?

because NA channel are inactivated and must be closed to be reopened again and this requires a refractory period.

what makes up the central nervous system

brain and spinal chord

where is the medulla oblongata located and what is it responsible for?

brain stem - registering increase in acidity, causes increase in repertory rate

what kind of receptors to hydrophilic signalling molecules use?

cell-surface receptors

responsible for long term memory

cerebral cortex

protects CNS, clear fluid, supplies nutrients and removes waste

cerebrospinal fluid

the biggest section of brain - towards the back of head - contains basal nuclei responsible for dopamine neurons important for neurons

cerebrum

synapse that uses the release of a neurotransmitter from presynaptic neuron, majority of synapses

chemical synapse

how do K+ channels respond to depolarisation? How fast?

closed open - slow

how do NA+ channels respond to depolarisation? how fast?

closed, open, inactivated - rapid

how many cranial and spinal nerves are there in mammals

cranial = 12 pairs, spinal = 31 pairs

what is the second messager in G-protine coupled receptors?

cyclic amp

when inside of membrane becomes more positive? (above -70mV)

depolarisation

synaptic transmission where neurotransmitter open ion channel on postsynaptic membrane - ligand gated ion channels

direct - ion channel

difference in speed between direct and indirect synaptic transmission?

direct = fastest

two types of chemical synaptic transmission

direct and indirect

synapse that uses gap junctions, with direction electric currents between cells

electrical synapse

what does the limbic system control?

emotions

emotional centre of brain, contains pineal gland responsible for sleep

epithalamus

what kind of postsynaptic potentials are there if depolarisation occurs at postsynaptic membrane

excitatory

what is the function of schwann cells?

form myelin sheaths

channel with 7 transmembrane spanning regions, mediate physiological events, activates a second messenger or many second messengers

g-protein

non adrenaline and adrenaline are an example of what kind of receptor?

g-protein

segmentally arranged clusters of neurons - peripheral nervous system

ganglia

area in the brain that contains dendrites, unmyelinated axons, cell bodies

grey matter

responsible for short term memory

hippocampus

example of long-distance signalling

hormonal, neuroendocrine

when inside of membrane becomes more negative? (below -70mV)

hyperpolarisation

responsible for homeostatic regulation (hormones), biological clock, temperature regulation, generation of hunger and thirst

hypothalamus

concentration of K in and outside membrane?

in - 140mM, out - 5mM

concentration of Na in and outside membrane?

in - 15mM, out - 150mM

what effect does activation of voltage gated Na+ channels have?

increases intracellular Na+

synaptic transmission where neurotransmitter binds to receptor on postsynaptic membrane and activates signal transduction involving second messenger

indirect - g-protein

what is inhibitory and what is excitatory? GABA, Glycine, Glutamate, Aspartate

inhibit - GABA< Glycine, Excite - Glutamate, Aspartate

what kind of postsynaptic potentials are there if hyperpolarisation occurs at postsynaptic membrane

inhibitory

autonomic nervous system, in/or voluntary and peripheral or central?

involuntary - peripheral

what is the order of acting time for receptors (fastest to slowest)? and what time frame do they work in?

ion - milliseconds, g protein - seconds, tyrosine kinase - minutes to hours, steroids - days - months

channel opened by ligand, which are very fast acting e.g. sending of an action potential - neurotransmitters

ion channel

which receptor family does NMDA and GABA belong to?

ion channel

what type of a receptor does glutamate bind to?

ion channel in post synaptic neurons, and g protein

which receptors are involved in neurotransmission?

ion channel, g protein

what are the 4 receptor types?

ion channel, g protein- coupled, tyrosine kinase, steroid

which are the membrane receptors?

ion channel, g-protion, tyrosine kinase

what is responsible for mining appropriate concentrations of ions across cell membranes?

ion channels

what effect does local anaesthetic have on action potentials?

it blocks the Na+ channels from going from inactivated to closed - which prevents further action potentials.

what is the purpose of refractory periods?

limits firing frequency, insures action potential only travels in one direction

parasympathetic fibre length

long fibre, short ganglia

During mRNA translation what direction is the polypeptide chain made?

n terminal to C terminal

example of direct synaptic transmission

normal nerve conduction

what causes the release of neurotransmitters from the presynaptic neuron via exocytosis

opening of voltage gated Ca+ channels in response to depolarisation, causes increase in Ca conc inside cell

what does an inhibitory post synaptic membrane cause?

opens voltage gated Cl- channels which means Cl- flows into cell, making it more negative.

cell responsible for maintaining established bone matrix

osteocyte

what type of signalling is it when secreting cell action on nearby target cells by discharging molecules of local regulator into extracellular fluid

paracrine

Example of local signalling

paracrine, synaptic

rest and digest - calming, glucose to glycogen

parasympathetic

what is the method written in? and what should it always include if a muscle or nerve is being used?

past tense - frog wringers solution to maintain conduction

postsynaptic potential vs action potential

postsynaptic = excitatory or inhibitory, local, at dendrite action - depolarisation, all or nothing, axon hillock,

3 stages of cell to cell communication?

reception, transduction, responce

the refractory period where some Na+ channels are still closed, and action potential can only be generated if really big stimulus applied as membrane is more negative than usual

relative refractory period

the name of the conduction which is produced by a myelin sheath when the action potential jumps from one node to the next - much faster conduction

saltatory conduction

3 stages of information processing

sensory input, integration, motor output

3 types of neurons

sensory, inter, motor

sympathetic nerve fibre length

short fibre, long ganglia

how is a stimulus processed

skin, sensory neuron, interneuron (CNS), motor neuron, muscle

what are the dopamine neurons responsible for? and what does a lack of these neurons result in?

smooth movement - lack = parkensons disease

when enough neurone synapsing at the same time to produce enough ESPS's for action potential

spacial summation

what is the function of myelin sheaths

speed up action potential - fatty substance can't conduct electricity so action potential jumps from node to node

receptor which is responsible for activating genes - example is testosterone or oestrogen - long distance and takes long time

steroid

what are the intracellular membrane receptors?

steroid

fight or flight - increased HR, Glycogen to glucose, adrenaline secretion, digestion inhibited

sympathetic

division of autonomic nervous system

sympathetic, parasympathetic, enteric

several ESPS's from the same synapse just after each other

temporal summation

receives input from sensory neurons and output via motor neurons

thalamus

what is the function of Astrocytes

they act as barrier around brain nerves to prevent blood getting in (blood-brain barrier)

receptors responsible for metabolism, cell growth and reproduction, example is insulin which activates glucose transporters - which joins to receptors together - starts phosphorylation cascade

tyrosine kinase

what kind of receptors to hydrophobic signalling molecules use?

uses carrier protein to travel in blood, then cross membrane to reach intracellular receptor

How do hormones, ligand or agonists simulate a cellular response?

using receptors

what happens during depolarisation?

voltage gated NA+ channel open, Na+ flows in

what is not needed to maintain resting membrane potential?

voltage gated sodium channels

somatic nervous system, in/or voluntary and peripheral or central?

voluntary, peripheral

what is a negative control

when you expect to have no result

what is a positive control

when you expect to have the greatest result

are in the brain that contains myelinated axons

white matter