2.2.a How does communication happen within the body?
Electrical Signals Nervous System
Chemical Signals Endocrine System
The nervous system is made up of neurons. Neurons communicate just like people do, but they send messages using action potentials (electricity passing through their axons). Each neuron picks up signals at its dendrites, passes the signals down the axon, into the axon terminals, and into the synapses. The synapse then drops neurotransmitter into the synaptic cleft between the first neuron’s synapse and the next neuron’s dendrites. That signals neuron #2 to pass the message on.
2.2.b What is the basic structure and function of a neuron?
Sends electrical signals through body
Dendrites (“trees”)—pick up signal
Axon—carry signal long distances (up to 3 ft)
Myelin Sheath—insulates axon
Nodes (“knots”) of Ranvier—allow nutrients in,
Axon Terminals (“ends”) —branch to meet other
Synapses—place one neuron connects to next
Synaptic Cleft—joint between neurons
Neurotransmitters (“to carry across a nerve”) —
chemicals that allow neurons to communicate
with each other
2.2.c How do the different types of neurons work together to send and receive signals? Sensory Neuron
Pick up signals through senses
(sight, smell, touch, etc)
Connect sensory neurons to motor
Receive signals from CNS,
Send info from PNS to CNS
Found in CNS
In PNS, receive info from CNS
2.2.d How are electrical impulses created in the human body? Na+/K+ pump keeps outside of
membrane + and inside – by
pumping positive ions out of the
membrane, priming the membrane
to carry charges
During an action potential, there’s
a sudden reversal of charge,
carrying a message down the axis
How do neurons convey information using both electrical and chemical signals?
ElectricalAction potentials down axis of each neuron
(WITHIN each neuron)
ChemicalNeurotransmitters conduct signal
W hat factors impact our ability to react to a stimulus?
How and why does reaction time differ in reflex and voluntary actions?
Reflex—reflex responses simply go to the spinal cord
and don’t involve the brain, so the reaction time is
VERY fast (example: blinking when something comes at
you, kicking when hit with reflex hammer)
Voluntary—Voluntary responses must travel to the
brain, take longer. The more thought that is
required (i.e. doing the OPPOSITE of what asked),
the slower the reaction time.
How do errors in communication impact homeostasis in the human body?
Bursts of electricity cause involuntary responses (seizures, odd smells, etc)
Cells that make dopamine die (no one knows why). The lack of this neurotransmitter causes problems in communication between neurons in the two brain regions that must communicate to allow smooth, controlled movements
Genetic defect on chromosome 4 (excess CAG repeats) causes synthesis of abnormal protein—the protein disrupts function of certain nerve cells, ultimately leading to their deaths (dead cells can’t communicate)
Brain cells die (cause unknown) and dead cells can’t communicate--communication breaks down, getting worse with time and eventually causing death
The immune system attacks the myelin around nerve axes in the brain, spinal cord and optic nerves, causing nerves to be unable to transmit messages due to a buildup of scar tissue (sclerosis).
The name is a (without) myo (muscle) trophic (nourishment) lateral (side) scler (hardening) osis (abnormal condition). Nerve cells waste away or die and can’t send messages to the lower motor neurons. Movement becomes less and less controlled. Eventually the lung muscles cannot...