Transcript Overview of the Day

Overview of the Day
Neuroscience, Part 1
Neural Systems
Hormonal Systems
The Nervous System
Provides the biological substrate for
psychological activity (the body's fast
communication system consisting of all
the nerve cells in the central and
peripheral nervous systems)
Major Parts
 Central Nervous System (brain and spinal cord) the system that
enables our humanity--thinking, feeling acting
 spinal cord (info. highway connecting PNS to brain)
 brain (receives info., interprets it, and decides what to do)
 Peripheral Nervous System (carries info. to and from the CNS)
 somatic/skeletal nervous system (controls voluntary movement of
skeletal muscles
 autonomic nervous system (controls glands and muscles of internal
organs [e.g., heart]). The sympathetic and parasympathetic systems
work together to keep us in a steady internal state
sympathetic: readies body in response to threat
 parasympathetic: calms body; conserves energy

Nerves
cables, made up of millions of bundles of neurons,
that are part of the PNS, and which connect the CNS
with muscles, glands, and sense organs
Example: Bee Sting
Stinger in your finger -->
PNS-->
Spinal cord-->
Brain-->
Spinal cord-->
PNS-->vocal muscles (ouch!!) & arm and
hand (swat bee)
Building Blocks
 Neurons--the basic unit of the nervous system
 approximately 10 - 100 billion of them in human body
 speed of neural transmissions range from 2 to 200 mph
 Parts of neurons
dendrites (receive information)
axon (passes info. along to other neurons or muscles or glands)
terminal branches of axon (forms junctions with other cells)
myelin sheath (insulates axons and helps speed their impulses)
 Neural Networks
neurons in brain cluster into work groups called neural
networks; learning occurs as feedback strengthens connections
that produce certain results
How Neurons Work
 Action potential
 neuron fires an impulse (action potential) when it is stimulated by
pressure, heat, light, or chemical messages from other neurons
 Threshold
 if the excitatory impulses a neuron receives are greater than inhibitory
impulses exceeds a minimum intensity, called a threshold, then
neuron transmits an electrical impulse (action potential) down its axon
to other neurons
 threshold is all or nothing.
then how can we detect differences in intensity (soft vs.
loud music)?
more neurons fire when intensity is greater

Neurotransmitters
chemical messengers that allow neurons to communicate with
one another
between neurons is a small space (1 millionth of an inch thick)
called synaptic cleft
 when action potential reaches knob-like terminals at axon's end, it
triggers release of neurotransmitter
 they cross synaptic cleft and bind to receptor cites on dendrites of next
neuron: receptor cites are specific to each type of neurotransmitter
Common
Neurotransmitters
 Acetylcholine
-
neurotransmitter that is at every junction
between a motor neuron and muscle
 curare a poison that causes paralysis: blocks Ach receptor sites, leaving
neurotransmitter unable to affect muscles
 Endorphins - released in response to pain or vigorous exercise
responsible for “runner’s high”
 Serotonin
-
affects mood
antidepressant drugs alter production or transmission of
serotonin
Endocrine System
Secretes hormones, chemical messengers,
that travel through the bloodstream and
affect other tissues and brain
Non-specific and slower than CNS and
PNS
 difference between nervous system and endocrine
system: cell phone in football game vs. PA
announcement
Summary
Nervous system (CNS, PNS)
Neurons (parts, how they work)
Neurotransmitters
Endocrine system