Module 1 - Nerves Notes PDF

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Module one nerves in biological / physiological psychology...

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Psychological/Biological Psychology Module 1: Cells of the Nervous System

Cell body/Soma Plasma Membrane – separates the inside of the cell from the outside. Nucleus – contains the chromosomes, the “brain” of the cell that generates the impulses Mitochondria – it does the metabolic activities and provides energy Ribosomes – helps facilitate the chemical reaction; synthesizes the new protein molecules Endoplasmic Recticulum – works as the transport system; transport the newly synthesized proteins to a new location

Neurons – Receive information and transmit it to other cells Founder: Charles Sherrington & Santiago Cajal (known for the detailed drawings of the nervous system) Dendrites – Lined with synaptic receptors; receive signals/impulses from other cells  The greater the surface, the more impulses it can receive Axon – transports the impulse to another neuron; varies in length  The longest is the spinal cord (contains the axon that connects to our legs, etc.)  Blue part – Myelin Sheath is an insulating system that covers the axon itself (mapabilis) Axon Terminal – releases chemicals that crosses the junction between neuron and other cells  Schwann Cell – darker blue part in the Myelin Sheath that produces myelin sheath; type of glia cell from peripheral nervous system; enveloped by Axon

Motor Neuron – helps you do activities; spinal cord; efferent axon (carries information away from the structure) Sensory Neuron – instincts; afferent (carries information into the structure) Sensory Neuron Motor Neuron Affarent Efferent Located in the dorsal root ganglion of the Located in the ventral root ganglion of the spinal nerve Unipolar Comprises of a short axon 10 million sensory nerves in the body

spinal cord Multipolar Comprises of a long axon Half million of motor neurons are found in

the body Found in eyes, skin, ears, tongue and Found in muscles and glands nose Glia (Neuroglia) -

Outnumbers neurons in the cerebral cortex

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For brain (no other parts of our body has glia cells)

Parts of Glia:  Astrocytes  Microglia  Oligodendrocytes  Radial Glia Astrocytes -

Star-shaped

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Wrapped around the synapses

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Synchronizes closely related neurons

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Important for breathing

Tripartite Synapse -

Tip of an axon; contributing to how we learn and how we remember

Microglia -

Removes viruses and fungi from the brain

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Works as a shield; removing dead/damaged neurons

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Contribute to learning by removing weakest synapses

Oligodendrocytes -

Build the myelin sheaths that surround and insulate certain vertebrate axons

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Speed ups the insulating neurons for the axons

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Brain needs more insulation/myelin sheaths to process messages

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Produces chemicals, not part of the myelination

Radial glia -

Guide the migration of neurons and their axons and dendrites during the embryonic development

The Blood-Brain Barrier (p. 23) -

The mechanism that excludes most chemicals from the vertebrate brain

Active transported chemicals: 1. Glucose (main fuel of the brain) – the only chemical that can enter the brain in large quantity 2. Amino acids (building blocks of protein) 3. Purines 4. Choline 5. A few vitamins 6. Iron Membrane of a Neuron

Things to remember: 1. Cations = + 2. Anions = -

3. Electrical gradient – or polarization; positive and negative just like in batteries Resting potential -

Difference in voltage

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Focuses on electrical gradient

Factors where RP depends: 1. Electrical Gradient 2. Concentration Gradient – gano katapang Resting potential prepares the neurons to respond rapidly and makes it stable until its stimulated

INSIDE CELL = slightly negative OUTSIDE CELL = slightly positive

 Potassium channel are many in number compared to sodium channel  Membrane has selective permeability (some chemicals pass through the membrane more freely than others: oxygen, carbon dioxide, etc.)  At resting potential, potassium channels are almost closed (little flow) and sodium channels are closed  Sodium-potassium pump – it does active transport; only transport three sodium ions outside (+) and two inside potassium ions (-)  We can identify resting potential through microelectrode (vault meter: -70 milli vaults)  What causes polarization? -

Selective permeability

Action Potential (1) At rest, the membrane voltage is -70 mV (2) The

membrane

begins

to

depolarize when an eternal stimulus is applied (3) The

membrane

voltage

begins a rapid rise toward +30 mV (4) The membrane voltage starts to return to a negative value (5) Repolarization continues past the voltage,

resting

membrane

resulting

in

hyperpolarization (6) The

membrane

voltage

returns to the resting value shortly after hyperpolarization Action Potential = Message Hyperpolarize = increased negative charge (no action) Depolarize = increased positive (may action) If message is sent, small depolarization and goes back at rest More stimuli, more depolarization  At action potential, sodium (Na) is still concentrated outside than inside  If peak is reached, sodium gate will close (potassium channels remain open)

SUMMARY 1. Resting State a. Charge: -70 mV b. Potassium: inside (-) c. Sodium: outside (+) 2. Depolarization a. Sodium channels activates and rush inside the cell (making the inside more positive) 3. Repolarization a. Sodium channels are inactivation b. Potassium channels open and they rush outside the cell, causing the action potential spike to stop (negative) 4. Hyperpolarization a. Potassium channels stay open b. Membrane polarity: inside becomes more negative until the membrane polarity passes -70 mV (allows excess potassium to efflux)...