The Nervous System Vertebrate Nervous System CNS & PNS (Somatic and Autonomic) The Spinal Cord The Brain Cells of the Nervous System Cell Division Neuron Anatomy Neuron Support System Reflex Arc Neural Transmission (Action Potential, etc.) Na+/K+ Pump Neurotransmitters Synapse Inhibition

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The Nervous System ___________ We use it to: Communicate and take in information about our surroundings through speech, hearing, touch, smell Move Think Create our perceptions of the world around us It all comes down to a bunch of 0’s (no) and 1’s (yes)

Vertebrate Nervous System __________

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The Spinal Cord Contains grey matter (nerve cell bodies and dendrites) Contains white matter (axons) _______________ Protected by the vertebra

The Brain ______________ Responsible for our voluntary movements, consciousness, behaviour, emotions, learning, reasoning, language, memory, etc. …………… The right side is responsible for sensory signals from, and controls movements of the left side of the body and vice versa for the right side of the brain.

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The three main parts ______________ Cerebrum Cerebellum Medulla (Brain Stem) ______________ Medulla (brain stem) – automatic actions (breathing, digestion, etc.)

Peripheral Nervous System ______________ Two categories 1) Somatic Nerves – Voluntary 2) Autonomic Nerves – Involuntary

Somatic Nerves – Voluntary Controls body movements by carrying information from the _________

Autonomic Nerves - Involuntary ___________ ______________ ____________ Used during stress, excitement or physical activity Increase HR, increase BP, dilate air passages and pupils Used during low-stress situations Inhibits the effects of the sympathetic nervous system and promotes …………………..

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Nervous System: Divisions This video has been removed

Cells of the Nervous System ______________ Neurons – nerve cells that conduct nerve impulses

Cell Division Glial cells divide throughout the organisms lifetime Source of most brain tumours ______________

Three types of neurons ______________ Interneuron (the middle-man): a local circuit neuron of the CNS that relays impulses between afferent and efferent neurons. Efferent neuron (motor neuron): a neuron that carries impulses from the CNS to effectors (skeletal muscles or glands)

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______________ Myelin Sheath: Fatty protection that insulates the neuron (allow the impulses to move quickly) Schwann Cells: Special type of glial cell that produces the myelin sheath Nodes of Ranvier: Gaps ………………….

Axon Axons are bundled together to form nerve fibres similar to the way small fibres are bundled together to form a fibre-optic cable

Neuron Support System Glial cells – non-conducting cells, used for structural support and metabolism for nerve cells ____________ ___________ Between the myelin sheaths are gaps called node of Ranvier which allows the ……………….

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Neural Circuits – Reflex Arc Neural circuit through the spinal cord which does not use brain co-ordination Example, touching a hot stove top The pain and thermoreceptors in your finger stimulates an afferent neuron _____________ ________________ ______________ **Since we leave the brain out of the equation, you remove your hand before you feel the pain. Why is this important?

Neural Transmission (Nerve Signaling) Nerve impulses are powered by cellular energy and the electrical impulse is just as strong at the end of the neuron as it was at the beginning. Signal does not become weaker Studies to determine ………………….

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The Signal Every fast signal sent from one part of the body to another is done through the electrical conduction down one neuron ______________

Potential Difference ______________ This is caused by the unequal distribution of “+” and “–” ions

Stage 1 - Resting Potential (Pre-stimulus) ______________

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Stage 2 - Depolarization When a signal is sent through a neuron it depolarizes (an abrupt change in the charge difference across its membrane). This is called an …………………… _______________ -50 to -55 mV is called the threshold potential, if it goes any higher, the cell will fully depolarize as Na+ channels open and Na+ rushes in, making the inside positive relative to the outside. Occurs in less than 1 ms

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Stage 4 – Repolarization (Refractory Period) Repolarization: process of restoring the original polarity of the nerve membrane __________ Sodium-Potassium pump on the cell membrane pumps Na+ back out of membrane and moves K+ ions back in

Sodium-Potassium Pump Carrier protein is embedding in the cell membrane. 3 Na+ are transported out of the nerve cell 2 K+ are transported into the nerve cell ATP is needed to run the pump

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Refractory Period Recovery period required before a neuron can produce another action potential Period of depolarization must be complete ___________ Re-establish the -70 mV potential across the membrane Approximately 1-10ms (milliseconds) Prevents the signal from going backwards

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Neurotransmitters ______________ They are made in the nerve cell body Acetylcholine is responsible for much of the stimulation of muscles, including the muscles of the gastro-intestinal system.  The drug curare causes paralysis by blocking the acetylcholine receptor sites of muscle cells.

How does the brain dictate how we feel? It can change the way we feel by triggering certain connections in the brain ___________ ___________ We feel pain when our nerve cells send the pain message to our brain using neurotransmitters If we block these messages from reaching the brain, no more pain!

Synaptic Transmission When an action potential reaches the axon terminal, it causes Ca2+ gates to open and Ca2+ to rush into the cell. ______________ This binding can either excite the next neuron by opening Na+ channels and causing a new depolarization or inhibit it and prevent a new depolarization.

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Alcohol and Inhibitory synapses Among other actions, alcohol enhances the effects of the inhibitory neurotransmitter GABA. ______________ Also, alcohol weakens the excitatory neurotransmitter glutamine, which enhances the sluggishness even farther.