Chapter 4 Midterm 1 Flashcards
Why do we use 60 Hz in lights?
Is the deadliest frequency, made so that people would be cautious around it
Who was the first to propose a mechanistic theory of behaviour?
Descartes
Two types of experiments were first done to deduce the relationship between electricity and animal tissue, what were they?
Electrical stimulation- current left a stimulator and entered tissue, stimulated it and thenflowed back to stimulator through reference electrode.
- stimulating electrode delivered current ranging from 2 to 10 milliamps, can produce a response without damaging tissue.
Electrical recording- Brain makes current and this is measured by an EEG- diff in voltage between recording electrode and reference electrode was recorded.
How are seizures treated?
They are diagnosed by putting you to sleep and inducing a seizure and then measuring electrical currents using eeg.
What are the most common seizures?
Febral seizures, these seizures are induced by infections which turns into a fever, if kids pant they change alkalinity of blood this combined with heat causes seizures
What did Galvani do?
Applied an electrical current to a dissected nerve and induced a twitch in the muscle
What did Fritsch and Hitzig do?
Found that electrical stimulation of the neocortex causes movement (arms and legs)
What did Bartholow do?
First report of human brain stimulation
What did Caton do?
First to attempt to measure electrical currents of the brain and electrodes on the skull
What did Berger do?
Developed the electroencephalogram (EEG), was a graph of electrical activity from the brain and represents the average graded potential of many neurons.
What did von HelmHoltz discover?
That the flow of information in the nervous system is too slow to a flow of electricity.
Nerve conduction is 30-40 meters/second
Electricity is 3x10^8 meters/second- a million times faster
Do the ions travel along the axon?
No a wave of charge travels along the axon.
How does the wave travel through the axon?
Sodium rushes in and potassium rushes out, as the ions go up and down the wave from the ions travel across the axon
What is an oscilloscope?
is a computer than can display the change in voltage over time.
What animal has the largest axon? Why?
in north atlantic squid, this helps the squid live in very cold waters as axon can stimulate muscles to propell themsleves through water, otherwise squid couldn’t live there as ions wouldn’t be able to move in that cold of water.
What is a concentration gradient?
Is a term that describes the relative differences in concentration of a substance between two spatial locations.
Why can’t chloride ions disperse evenly in a semipermeable membrane?
Because they have attraction to sodium ions, so they aggregate towards the membrane surface.
What is the membranes resting potential?
-70 mV
What did Hodgkin and Huxley do?
Measured electric potential of axon of north atlantic squid
What are the concentrations of anions and potassium inside the axon, relative to outside the axon
Have higher concentration inside
What are the concentrations of chloride and sodium inside the axon, relative to outside the axon
have higher concentration outside
What are the three types of proteins in the cell membrane that influence the resting potential?
One where potassium can enter and leave, one where sodium can enter and leave but the protein can close, and a sodium potassium pump- where three sodium are pumped out for every two potassium inside
What happens when you have a stroke?
Don’t have enough energy for the sodium potassium pump to work as no atp (no oxygen) and so electrical conduction becomes not possible
What makes a larger EEG signal?
nerve at muscular junction than neocortex.
What hyperpolarization, how does it happen?
When the resting potential decreases, this is due to an efflux of potassium making outside of the membrane more positive, or influx of cl- making it more negative in inside
What depolarization? How does it happen?
causes membrane voltage to Due to an influx of Na+ through na+ channels
Is depolarization and excitatory post synaptic potentials (drive by a synapse) the same thing?
Yes
Is hyperpolarization and inhibitory post synaptic pathways the same thing?
Yes
How did Eccles figure out inhibitory= hyperpolarization and excitaroy= depolarization
stimulated a excitatory pathway and an inhibitory pathway and saw the EEG match these
What happens to info from other neurons that reaches dendritic tree?
Gets summated, two type sof summation spatial and temporal
What is temporal summation?
If all neurons send signals at same time to dendritic tree
Where are most the inhibitory connections? excitatory connections?
inhibitory- on cell body, near initial segment
excitatory- on dendrites
What must occur for excitation in dendritic tree to occur?
Need temporal summation and spacial summation to overcome inhibition by cell body to action potential at initial segment.
What is spatial summation?
if neruons send signals close together to the dendritic tree they sum up to make a larger signal.
Where are action potentials generated?
The initial segment
What do action potentials look like?
A big depolarization which crosses the action potential threshold of -50 mV, causing an action potential to be triggered by the opening of Na and K channels, followed by a big hyperpolarization and then returns to resting state -70 mV.
How many action potentials happen over 1 second?
A lot but they slow down overtime.
Is an action potential a excitatory or inhibitory event?
excitatory
How do sodium and potassium channels cause action potential?
Sodium rushes in- causes charge to go up, potassium rushes out and brings the curve down, overshoots minus 70 and then it stabalizes.
How does sodium channel stop sodium from going in?
Two ways, protein pinches in the middle, and 2 the ball and chain go up and close it
What is TTX?
Tetrodoxin- blocks sodium channels
What is TEA?
Tetraethylammonium, blocks potassium channels
Why is the pufferfish poisonous?
Has TTX, blocks sodium channels
What is a nerve impulse?
the action potential moves down as a wave of depolarization down nerve.
Where do action potentials generate?
At every node or other node of ranvier, this iis called saltatory conduction, increases the spped of the action potential and reduces number of pumps needed- saving energy- are mileated.
Where is MS highest?
In northern latitudes.
How does a feather cause a sensation of touch?
touch causes stretch activated cells on dendrite top opne, allows in Na and later on K exits causes nerve impulse
What is the motor end plate?
parts between muscle and synaptic end
What is acetylcholine?
Is the name of the neurotransmitter at the neuro muscular junction, potassium and sodium go through pumps and cause muscle movement when it reaches the pumps.
What is nictonic?
Is a receptor site from acetylcholine pump, found in neuro muscular junction, is on pump.
Myasthenia gravis?
Immune cells attack neuro muscular junction, stops acetylchloine from travelling means you can’t control muscles
What is motor neuron disease?
Occurs when alpha motor neurons die, #1 cause of death with ppl w this disease is aspiration.
How does the brain work?
Materialistically
Anatomically and Functionally
Cellularly
Electrically
