Lecture 1 - Intro to the nervous system Flashcards
Given that neuroscience is interdisciplinary, what others subjects must neuroscientists know?
- Biology
- Chemistry
- Physics (Neurons are electrically charged)
- Mathematics
How many neurons are in the human brain?
100 billion neurons
What is the size of a neuron?
10^-6 m (1 millionth of a meter)
What percent of the brain is used?
100%
What is the brain’s power in watts?
20 W (the whole body is 100 W)
What is the most common neurotransmitter?
Glutamate
What is the voltage of a neuron at rest?
-65 mV
What are the ions involved in neuro-electric activity?
Sodium (Na+), Potassium (K+), Chloride (Cl-), Calcium (Ca++)
How is the neuron like other cells?
- Enclosure (lipid bilayer membrane)
- Organelles (nucleus, mitochondria, etc.)
How is the neuron unlike other cells?
- Rapid excitation (action potential)
- Unique morphology (axons, dendrites)
What is the role of a dendrite?
It receives signals from other neurons (input)
What is the role of an axon?
It sends signals to other neurons (output)
What is one thing that all neurons must absolutely have?
An axon
What are three different morphologies that a neuron can have?
- Cortical pyramidal cell (longer cell body)
- Cortical stellate cell
- Cerebella Purkinje cell (dendrites form a square shape)
What is CNS and what consists it?
The Central Nervous System, and it is all parts of the nervous system within bone: thalamus, spinal cord, brain stem (midbrain, medulla, pons), cortex
What is PNS and what consists it?
The Peripheral Nervous System, and it is all parts of the nervous system not within bone: peripheral nerves
What are the four parts of the spinal cord and it what order from the brain?
- Cervical
- Thoracic
- Lumbar
- Sacral
What is the rule for the numbering of dermatomes?
The higher the number the more caudal, the lower the number the more rostral
Are there more Glial Cells or Neurons in the NS?
There are 3x more Glial Cells than Neurons in the nervous system
What are the three types of Glial Cells and what are there roles?
- Astrocyte: Maintain ionic movement
- Oligodendrocyte: Myelinate neurons
- Microglia: Scavenge cellular debris
What is the Nissl Stain and who invented it?
Franz Nissl invented the Nissl stain, and it consists of using dyes like thionine or cresyl violet to dye the endoplasmic reticulum, and be able to see the cell bodies and layers (some are neuropil).
However, the image he got was not detailed.
Who is Korbinian Brodmann and what did he do?
He used the Nissl stain to find different areas in the cerebral cortex. He found 52 cortical areas now known as Brodmann’s areas. He also noticed that the older the cortex, the fewer the layers (the neocortex is 6 layers).
AREAS 3, 2, 1: Primary somatosensory cortex
AREA 4: Primary motor cortex
AREA 17: Primary visual cortex
AREAS 41, 42: Primary auditory cortex
How do you prepare for a Nissl Stain?
- Tissue Fixation (Cross linking + Coagulation)
- Tissue Sectioning
Since the lipid bilayer membrane is impermeable to ions what are the two ways that ions can get through?
Ion transports (ion movement against concentration gradient)
Ion channels (ion movement with the concentration gradient)
What is CSF and what does it consist of?
CSF stands for Cerebral Spinal Fluid and it has Na+, Cl-, K+, etc.
What is the sodium potassium pump?
Pump that uses ATP to pump three Na+ out and two K+ in
Why is the resting potential negative?
At rest, the neuron is primarily permeable to potassium (potassium leak channels), making the inside of the cell negative (close to the K+ equilibrium potential)
What is the electrochemical equilibrium and how is it reached?
The equilibrium potential would be the result of the neuron being permeable to only ion (the potential at which the net flow of an ion is 0).
2 events cause this:
1. Diffusion (ions move with concentration gradient)
2. Electrostatic force (opposites attract) explained by Coulombs Law:
What is the Nernst Equation?
Ex = (58/z)log( [Xout]/[Xin] )
How do you navigate the nervous system?
- Rostral
- Dorsal
- Caudal
- Ventral
There are also 4 lines/axis that help navigate the nervous system:
1. Horizontal
2. Parasagittal
3. Midsagittal
2. and 3. are both Sagittal sections
4. Coronal
What are four neuroscience rules?
- Symmetry
- Localization of function
- Frontal lobe: Cognition and Language
- Parietal lobe: Movement + Touch
- Occipital lobe: Vision
- Temporal lobe: Language + Hearing - Contralaterality
- Left side of the brain needed to move right hand
- Right side of the brain needed to move left hand - Topography
- Motor Homunculus (precentral gyrus of the frontal lobe)
- Somatosensory Homunculus (postcentral gyrus of parietal lobe)
Midline
Line separating left and right
Ipsilateral
Same side
Contralateral
Opposite sides
Decussate
Cross the midline
Proximal
Close to point of reference
Distal
Far from point of reference
Efferent
Projecting away from point of reference
Afferent
Projecting towards point of reference
Medial
Close to midline
Lateral
Far from midline
Why does it make sense for z to be at the denominator in the Nernst equation?
K+ and X++ have the same tendency to move down the concentration gradient, but since X++ has two positive charges it is more attracted to negatives charges, and so the cell would need to be half as negative to attract X++ than it would need to be to attract K+, explaining why z is in the denominator.
Why does it make sense for the equilibrium potential of Na+ to be positive, and the equilibrium potential of K+ to be negative?
K+ is more concentrated inside the cell, so the inside would need to be negative to attract potassium back in, whereas Na+ is highly concentrated on the outside of the cell, so the cell would need to be positive to resist the inward flow of sodium.
Who invented the Golgi Stain and how does it differ from the Nissl Stain?
Camilo Golgi invented the Golgi stain where a smaller % of neuron is stained, allowing a more detailed image/structure of the neuron to be seen.
What is the Log Rule?
a^x = N –> logaN=x
How many km is 1 cm?
10^-5 km
