Neurophysiology Flashcards
(99 cards)
1
Q
What is the nervous system
A
A collection or network circuit of neurons and glial cells. It is highly conserved, seen in all classes of life
2
Q
What is the most simple nervous system
A
Forms a net
3
Q
Nervous system of planaria
A
Has a little brain (concentration of neurons) and has two nerve cords down either side of its body which forms communication from tip to tail, and left to right
4
Q
What is the nervous system of a leech
A
Central nerve, one coming either side
5
Q
What is the nervous system of an insect
A
Brain, and in each segment, there is a cluster of nerves on each segment (ganglions)
6
Q
What is the nervous system of a vertebrate
A
Brain, central spinal cord, each vertebrae has dorsal and ventral nerve roots which allow information to get from sensory, into spinal cord, and to the brain (and the other way around)
7
Q
Grey matter
A
Neurons
8
Q
White matter
A
Axons, covered in myelin
9
Q
What is myelin
A
White lipid fat that coats axons to allow for fast transmission of the signals.
10
Q
Function of the nervous system
A
- Information processing - each vertebra has information coming in through the dorsal and out through the ventral motor nerve route
- Senses the environment (light, vision, sound, temperature, vibration, smell, taste)
- Allow organisms to respond to the environment
- Coordinates bodily functions
- Voluntary movement
- Reflexes
- Memory, learning, emotion
11
Q
CNS
A
Brain and spinal cord
12
Q
PNS
A
Everything but brain and spinal cord
13
Q
How does the nervous system work
A
Sensory information comes in (afferent neurons) it gets processed in the central nervous system, and then the information goes out (efferent neurons) to have a reaction.
14
Q
Sympathetic nervous system
A
Fight or flight
15
Q
Parasympathetic nervous system
A
Rest and digest
16
Q
Enteric division
A
Digestive tract, moves food through the gut
17
Q
Function of forebrain
A
sense of smell, regulates sleep, complex learning
18
Q
What does the forebrain contain
A
olfactory bulb and cerebrum
19
Q
Function of midbrain
A
routes information (sorts information to parts of the cortex where it needs to go)
20
Q
Function of hindbrain
A
Motor control (movement) and involuntary activity (heartbeat, breathing)
21
Q
Why do we have a highly folded cerebellum
A
Allows a higher surface area, more neurons can fit in that space, more grey matter and higher ability for processing (allows us to speak and communicate and have a higher level of intelligence)
22
Q
Brainstem function
A
important for controlling involuntary parts of life (respiration rate, heart rate)
23
Q
3 regions of the Frontal lobe
A
Motor cortex, prefrontal cortex, Brocas area
24
Q
Motor cortex function
A
Initiate voluntary movement
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Prefrontal cortex function
decision making, planning
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Brocas area function
Speech formation
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Somatosensory cortex function
area where all sensory information from periphery goes to be processed
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Parietal lobe
Contains somatosensory cortex
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Temporal lobe contains (2 things)
Auditory cortex, Wernickes area
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Auditory cortex function
Hearing
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Wernickes area function
Language comprehension
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What does the occipital lobe contain
Visual cortex
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Function of visual cortex
Process visual stimuli and pattern recognition
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Cerebellum location
Above brain stem
35
Cerebellum function
Help movement, modulate the information going to and from the motor cortex, know where parts of the body exist in time and space
36
Neurons
Excitable cells specific to the nervous system
37
Glia
Group of other cells that support neurons, most abundant in the brain
38
Why and how are your bodies immune system and brain separated
Blood-brain barrier - stop immune system from entering the brain to prevent infection in the brain
39
Pericytes
Involved in blood-brain barrier to stop certain cells going through blood vessels easily
40
Why can the brain not get infected
Heat, swelling, pain comes with infection, skull is in a fixed position and therefore brain cannot swell
41
Astrocytes (glial cell) function
- Communicate with cells around the blood vessels
- Modulate the blood-brain barrier
- Metabolic support of neurons
- Do not generate action potentials
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Microglia function
- Star shaped
- Survey environment
- Like resident immune cells in brain
- Scavenge, consume dead and dying cells
Allow for normal brain function
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Oligodendrocytes function
- Lay down myelin on the axons of the neuron
- Have fatty lipid sheets that they wrap around the axons
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Schwan cells
cells outside the CNS that lay down myelin
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Why is coating cells in myelin important
fast conduction of action potentials over long distances, allows the action potential to jump
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Function of the axon
transmits the action potential
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Function of dendrites
receive information from other areas and direct it towards the cell body
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Axon hillock
where the axon potential is generated
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Synapse
A widened area in close proximity to the next neuron (but not touching) - the synapse is the area that makes the next neuron more excited/inhibited
50
How does neuron size correlate with signal conduction
Bigger the neuron, the more myelin it contains, the faster it conducts signals
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Sensory (afferent neurons)
Send signal to the CNS (pain, touch, light, blood pressure). Neurons tend to be small and unmyelinated = slow
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Interneuron
Transmit signal within the CNS. communicates between sensory and motor information. Tend to be small, short axons
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Motor (efferent) neuron
Send signal from the CNS to muscles and glands (large and fast)
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Unipolar
One axon
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Bipolar
2 axons
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Pseudounipolar
axons off to the side
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Multipolar
all the dendrites, big axon, and synapses
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Cone snails using all the types of specialist cells
- Sensory neurons sense environment
- When it senses a fish swimming past it gets integrated by interneurons
- Motor neurons send motor output and send probiscis out to paralyse prey
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Key role of a neuron
Transmit signals by receiving info, processing it, and generating a response
60
How are signals transmitted within a neuron
Electrically via ion movement
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How are signals transmitted between neurons
Chemically, using neurotransmitters
62
Why is a resting neuron excitable
due to its resting membrane potential (negative - charge of inside of neuron vs outside of neuron (ions)
63
How do Voltage gated ion channels work
- When a certain threshold (voltage) is reached, they will open/close
- Ion channels and ion pumps in the cell membrane allow ions to cross the cell membrane
- These channels/pumps are specific for a particular ion(s)
64
What is the RMP
The difference in voltage (charge) across a membrane at rest
65
Normal conc of Na and K
Normally, sodium is present in high conc outside cell, and potassium is present in high conc inside the cell.
66
Sodium potassium pump ratios
3 sodium for 2 potassium
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Purpose of sodium potassium pump
Change membrane potential via pumping of more sodium than potassium
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Voltage of gradient of RMP
-65 million volts
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What is Nernst potential
Is the membrane potential at which there is no net (overall) flow of that particular ion from one side of the membrane to the other.
70
What is Hyperpolarisation
Making the inside of the cell more negative
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Effect of hyperpolarisation
(harder to create action potential, more stimulus required for neuron signalling - may be useful in chronic pain
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What is depolarisation
Making the cell more positive
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Why are action potentials "all or nothing"
If the stimulus is strong enough, a point of ‘no return’ is reached, where voltage-gated Na+ channels open
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How much energy does a neuron take to fire
-55 million volts
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Are action potential one or multi directional
Axon hillock moves down the axon in only one way
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Neuron at a resting state
Lots of sodium outside, lots of potassium inside
At rest, both voltage-gated channels are closed
This means Na stays outside, K stays inside
Only sodium-potassium pump maintains RMP.
77
How does depolarisation work
Stimulus comes in, and opens some sodium channels. This allows Na to flow into the cell. The cell becomes slightly more positive due to influx of positive ions. Reaches a threshold (action potential becomes all or nothing
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What happens in the rising phase
All sodium channels open. Sodium comes into the cell making inside very positive
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What happens in the falling phase
All sodium channels open Sodium comes into the cell making inside very positive
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What happens during the Absolute refractory period
No other stimulus can elicit action potential. Allows transport of action potential to go only in one direction
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What is the meaning of undershoot
Membrane potential returns to normal
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What is a Graded potential
a hyperpolarization or depolarization that shifts the membrane potential a little but does not cause an action potential and is decremental
83
Where does myelin come from
Schwann cells (PNS) and oligodendrocytes (CNS)
84
What are nodes of ranvier
Where voltage-gated Na channels are present.
85
What is saltatory conduction and why is it good
Myelin allows the action potential to leap along the axon to move faster (jump) and with this, neuron signals can travel faster and over long distances.
86
Multiple sclerosis
Myelin sheaths around neurons are lost. Axons don't have myelin, therefore, struggle to get action potentials from a to b. The resulting poor signal transmission leads to fatigue, paralysis and cognitive impairment
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Why are MS rates higher in Dunedin than Auckland
Seems to be higher the further from the equator you are (sunlight and vit D is a factor)
88
What are the 3 min clinical forms of MS
Relapsing-remitting, Secondary progressive, Primary progressive
89
Relapsing Remitting MS
(85-90% - autoimmune disease where T and B cells infiltrate blood brain barrier, get into CNS, and attack myelin coating). Characterised by immune attacks, resolution, than repeated attacks.
90
Symptoms of MS
Poor balance, fatigue, spasticity
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What is/causes Parkinsons
Decreased dopamine results in disordered movement
92
Symptoms of parkinsons
Tremors, poor balance, and muscle coordination, cognitive impairment
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How to treat parkinsons
Disease can be treated, but not cured. Taking L-dopa (dopamine pre-cursor) can restore dopamine levels,
94
What are senses
Transformation of external energy into an action potential. Your sensory organs are designed to receive/convert energy, but its your brain that perceives these signals as images or sounds
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4 steps in sensory pathways
Sensory reception, Sensory transduction, Transmission,
Perception
96
Sensory reception
The detection of a stimulus by sensory cells
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Sensory cells
either themselves a neuron, or are cells that interactions with a neuron via neurotransmitters.
98
Sensory transduction
Changing membrane potential
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