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Nedwidek SLS44QM Intro to Neurology
Stuyvesant High School
February 2013
Aim: What do senses have to do with stimuli?
DN: (1) Name each of the 5~6 senses and an example of when each causes protection/why you
need it. (2) What is a neuron? (3) What is a potential? Relate stimulus to electricity.
Eyes do this: _________________; ex:
Ears (outer/inner) do this: __________________; ex:
Fingers do this: ________________; ex:
Tongues do this: _________________; ex:
Noses do this: __________________; ex:
–All of these contribute to the fight or flight/stress response to danger, but they also activate
pleasure centers (nutrition for individual survival; reproduction for species survival).
Demonstrate response to stimulus.
Draw a neuron: pg ref aud 668
A neuron is the fundamental cell type that mediates input and output of stimulus information. A
stimulus is an electric potential or difference in ion concentration across a membrane due to a
change in environment. (like a charged battery).
A potential is a change in charge (chemical or physical) that transmits information. Neurons
communicate by using chemical signals that generate electricity.
Electricity is the movement of charge, specifically e- (negative).
Neurotransmitters control the movement of ions across a membrane. This allows nerves to move
impulses. The SATII expects some detail about this. I will try to address as much as I can in
class without compromising the detail of your knowledge on the physiology.
The axon potentiates or pushes forward an electric message. (Gives)
The dendrite receives an electric message. (Gets)
The synapse (gap) regulates or controls message transmission, and ends in a synaptic terminal.
The myelin sheath, made by Schwann cells, is an insulator.
The nodes of Ranvier space each Schwann cell from one another long the axon.
Disorders of the Myelin Sheath
Defects in neuronal myelination are lethal. The two below are due to different causes and create
complementary outcomes.
Tay Sachs’ disease is a genetic defect in demyelination enzyme. It overinsulates the neuron—
reduces message transmission—causes death by age 5.
ALS (Amyotrophic Lateral Sclerosis)—otherwise known as Lou Gehrig’s disease—attacks the
myelin sheath. With no myelin, nerves overfire, resulting in loss of sensory control.
Aim: How do nerves transmit information?
DN: Name the functions of the dendrite, axon, myelin sheath and synapse. What is a
neurotransmitter?
Impulses are regulated ion gradients—these create action potentials.
What is an ion channel?
What is a gradient?
Nerves can end at muscle tissue to deliver a stimulus to contract muscle. This enables
locomotion or movement.
Neurons communicate via neurotransmitters (NTs)~chemical signals.
2 types of potentials: excitatory and inhibitory. They are classified based on stimuli.
Excitatory neurotransmitters more likely make an action potential.
Inhibitory neurotransmitters less likely make action potential.
Potentials are classified based on the NTs associated with them.
Mood altering drugs target acetylcholine, dopamine, serotonin (I), norepinephrine (I),
epinephrine/adrenaline (E), and endorphins (happy)
Habituation leads to problems with withdrawal. Behaviors are controlled by centrally regulated
neurons that employ voluntary and involuntary responses. Mental illnesses like schizophrenia
lead to unpredictable and erratic behaviors. Neurotransmitters communicate information to
receptors.
Reflexes (example, knee-jerk) are involuntary. They are due to normal pain responses.
“Simple” organisms like hydra and flies use neural ganglia or nerve bundles as the center of their
nervous system.
Humans and other animals have a brain with complex facets of central control ranging from
sensory motor (universal, coordination) to complex reasoning (also universal among animals)…
Next: reflex arc steps, fight or flight, responses to stimuli steps, neuron types, vertebrate nervous
system flow chart (aud 676)