Biology Journal 2/28/2014
What could be some
muscles in your body
that are involuntary (they
work without you
consciously thinking
about it)?
What could be some
muscles in your body
that are voluntary (they
only work when you
consciously thinking
about it)?
Biology Journal 3/3/2014
What is the purpose of neuron cells?
How are they structured to carry out
this function?
Biology Journal 3/4/2014
What does the myelin sheath do?
What do you think could happen if it
wasn’t on any of your neurons?
Biology Journal 3/5/2014
What does it mean for an axon to be “polarized?”
What does it mean for an axon to be “depolarized?”
What does it mean for an axon to be “repolarized?”
Polarized: (-) inside axon, (+) outside axon. This is the
starting, or “resting” potential.
Depolarized: (+) inside axon, (-) outside axon. This
occurs when the Na+1 diffuses into the axon.
Repolarized: (-) inside axon, (+) outside axon. This
happens when the K+1 diffuses out of the axon.
Label this neuron cell
Axon terminals
Dendrites
Node of Ranvier
Cell body (soma)
Myelin sheath
Nucleus
Schwann cell
Axon
What do we call the neurons that are
stimulated by sound, light, touch, smell, and
taste?
Sensory Neurons
What do we call the neurons that stimulate
muscles and cause them to contract?
Motor Neurons
What do we call the nerves that send
signals to other nerves?
Relay Neurons
Assessment Statements
6.5.1
State that the nervous system consists of the central nervous system (CNS) and peripheral
nerves, and is composed of cells called neurons that can carry rapid electrical impulses.
6.5.2
Draw and label a diagram of the structure of a motor neuron.
 Dendrites and cell body with nucleus
 Axon and myelin sheath
 nodes of Ranvier
 motor end plates
6.5.3
State that nerve impulses are conducted from receptors to the CNS by sensory neurons, within
the CNS by relay neurons, and from the CNS to effectors by motor neurons.
6.5.4
Define resting potential and action potential (depolarization and repolarization).
6.5.5
Explain how a nerve impulse passes along a non-myelinated neuron. Include the movement of
Na+ and K+ ions to create a resting potential and an action potential.
6.5.6
Explain the principles of synaptic transmission.
 the release, diffusion and binding of the neurotransmitter
 initiation of an action potential in the post-synaptic membrane
 subsequent removal of the neurotransmitter
6.5.1
State that the nervous system consists of the central nervous system (CNS) and peripheral
nerves, and is composed of cells called neurons that can carry rapid electrical impulses.
Nerves, Hormones, and
Homeostasis
What could be some living things that
have a nervous system? What could
be some organisms that don’t?
Neurons
Specialized cells that transmit electrical signals
through them, and chemical signals to other cells.
Neurons can take many shapes, but
they all have common parts.
6.5.3 Draw and label a diagram of the structure of a motor neuron.
• The myelin sheath is a layer of fat cells
around the axon. It speeds up the
electrical signal by insulating it.
It works kind of like an insulated
electrical wire.
What could happen if an electrical wire
wasn’t insulated?
What could happen if an axon wasn’t
insulated by a myelin sheath?
The destruction of the myelin
sheath is the cause of many nervous
system disorders, the most wellknow of which is multiple sclerosis
(MS)
The synapse is the connection from one
neuron to the next.
At the synaptic gap, chemicals called
neurotransmitters transmit the signal from one
neuron to the next.
A motor neuron stimulates a muscle (causes it
to contract).
A relay neuron stimulates another neuron,
passing along signal.
A sensory neuron is
stimulated by
changes in the
environment (your
senses).
What are your 5 senses?
Each is made out of a number of more specific,
specialized sensory neurons…
Sight
Touch
Hearing
Taste
Smell
(cones) and light (rods)
temperature, pressure, pain
specific frequencies of sound
salty, sour, bitter, sweet, umami (protein)
olfactory receptors can detect 1000’s of
different molecules
The nervous system consists of the central nervous
system (brain and spinal cord) and peripheral nervous
system (nerves).
What is an ion?
An ion is an atom with a charge (+ or -)
They can be more than one atom, too; this is called
a polyatomic ion, such as NH4+1, or SO4-2
An action potential deals with 2 ions:
sodium and potassium.
Na+1
K+1
What is a protein channel, or
transport protein?
Protein channels are proteins in the cell
membrane of cells that allow specific
molecules to pass through the membrane.
What’s the difference between active and
passive transport??
Active transport moves molecules from a low concentration to a
high concentration and requires energy.
Passive transport moves molecules from a high concentration
to a low concentration and happens automatically.
An action potential is an electrical signal sent
down the axon of a neuron.
Action Potentials travel in one direction
1. Dendrites receive a
signal
2. action potential is
started at axon.
3. action potential
reaches terminal, and is
transferred to the next
neuron (or to a muscle)
Youtube Videos
Action Potentials: A very good narration of the action
potential, with very good graphics.
https://www.youtube.com/watch?v=7EyhsOewnH4
Action Potentials: Another narration with graphics; not quite
as good as the first one, just different.
https://www.youtube.com/watch?v=ifD1YG07fB8
Nerve Impulse Animation: A 1 minute video showing the
parts of a neuron in excellent detail. No narration.
http://www.youtube.com/watch?v=dSkxlpNs3tU
Action Potential and Epilepsy: Narrated by guy with Spanish
accent. Has really nice images of globular membrane
proteins in action. Ends with tie-in to epilepsy.
http://www.youtube.com/watch?v=MtJyHp_AZL8
Series of events in an action potential
When an action potential reaches the axon terminus,
the signal passes to excite the next neuron (or to a
muscle).
What kind of neurons are shown here?
The myelin sheath speeds up the action
potential by having the voltage change quickly
“skip” from gap to gap (nodes of Ranvier).
1
2
3
4
What do muscles do
when someone is
electrocuted? Why do
you think that is?
http://bcs.whfreeman.com/thelifewire/content/chp44/4402s.swf
From McGraw Hill: http://goo.gl/tI2MD
http://www.blackwellpublishing.com/matthews/actionp.html
http://www.blackwellpublishing.com/matthews/channel.html
http://outreach.mcb.harvard.edu/animations/synaptic.swf
The Endocrine System
A stimulus is received and processed.
Hormones are secreted directly into the blood.
They are carried to the target tissues (the place of intended action).
The action of the hormone changes the condition of the tissue.
This change in monitored through feedback.
Most hormonal change results in negative feedback.
Key endocrine glands:
1.
2.
3.
4.
5.
6.
7.
8.
Pineal gland
Pituitary gland
Thyroid gland
Thymus
Adrenal gland
Pancreas
Ovary (female)
Testes (male)
Endocrine glands from: http://en.wikipedia.org/wiki/Endocrine_gland
The Endocrine System
A stimulus is received and processed.
Hormones are secreted directly into the blood.
They are carried to the target tissues (the place of intended action).
The action of the hormone changes the condition of the tissue.
This change in monitored through feedback.
Most hormonal change results in negative feedback.
Key endocrine glands:
1.
2.
3.
4.
5.
6.
7.
8.
Endocrine glands from: http://en.wikipedia.org/wiki/Endocrine_gland