Download Neurons Firing of a neuron

Biological psychology
a branch of psychology concerned
with the links between biology and
behavior.
“Everything psychological is
simultaneously biological.”
Phrenology
Franz Gall
Neurons
• Neuron
– Sensory neurons
• carry incoming information from the sensory
receptors to the brain and spinal cord
– Motor neurons
• carry outgoing information from the brain
and spinal cord to the muscles and glands
– Interneurons
• neurons within the brain and spinal cord that
communicate internally and intervene
between the sensory inputs and motor
outputs
https://www.youtube.com/watch?v=8o
rIQL3S1l4
Neural Communication
Neurons
Neurons
detects
Neurons
Neurons
Neurons
Neurons
Neurons
Neurons
• Firing of a neuron
– Transmit message when stimulated by senses or
chemical signal from neighboring neuron
–Action potential
• a neural impulse; a brief electrical charge that
travels down an axon
• involves exchange of ions
– Resting potential (polarized)
• positive outside/negative inside
– Selectively permeable
• positive ions can’t mix with negative when
neuron’s “gate” is closed
Neurons
• Firing of a neuron
–when neuron fires; first part of axon gate
opens
Depolarize
positive ions flood through axon – next
channel/section of axon opens (dominoes)
Refractory period
resting/pause…neuron pumps +ions out &
can fire again
“hop” from one myelin section to next
Firing of Neurons
–
signals are mostly excitatory versus inhibitory
– Threshold
• IfWhen
enough
NT are
received,
cella
excitatory
signals minus
inhibitory
signals the
exceed
membrane
positive
minimum
intensitybecomes
(threshold) permeable
the combined &
signals
trigger
action potential.
ions rush intoancell
–All or none response
• more neurons can be fired or neurons can fire more
often, but the impulse/action potential’s strength &
speed are all or none – either fire or not
Action Potential
Action Potential
Action Potential
Action Potential
Action Potential
How can you tell the
difference between a gentle
caress on your face vs a
slap?
Neurons
Speed of a neuron impulse
– Range from 2 to 200 MPH
– Measured in milliseconds
• (thousandths of a
second)
A strong stimulus can
increase the number of
times a neuron fires, NOT
how fast it fires or the
intensity of the impulse
A weak stimulus causes
neurons to firing less
frequently NOT SLOWER
How Neurons Communicate
• Synapse
• Synaptic gap (synaptic cleft)
• Neurotransmitters
– chemical messengers that cross the synaptic gaps
between neurons. When released by the sending
neuron, neurotransmitters travel across the synapse
and bind to receptor sites on the receiving neuron,
thereby influencing whether that neuron will generate
a neural impulse
• Reuptake
https://www.youtube.com/watch?v=4OS2C4NemJI
How Neurons Communicate
Reuptake
How Neurotransmitters Influence Us
– If the NT is acting on the brainstem, it
affects basic functions like breathing &
heartbeat
– if it acts on midbrain, affects memory &
emotion
– if it acts on the cortex, higher functions,
like memory integration, problem solving
& perception
How Neurotransmitters
Influence
Us
Alzheimer’s
muscle & memory
• Acetylcholine (AcH)
•
•
•
•
•
•
pleasure, too much = schizophrenia
movement,
emotion
too little = Parkinson’s
Dopamine
(happy),
Serotonin mood
too little = depression
hunger, sleep
Norepinephrinealertness, arousal
GABA inhibitory NT
NT
Glutamate excitatory
too much = overstimulate brain
Endorphins
How Drugs and Other Chemicals Alter NT
Agonists
– molecule that is similar enough
to a NT to bind to its receptor
site and MIMIC its effect.
– black widow spider venom floods system
violent muscle spasms
with Ach =
Antagonists
– also bind to receptor site but
they BLOCK a NT function
– Botulin is a bacteria that is an agonist for
Ach =
paralysis
Objective 4:
What are the functions of the nervous system’s main divisions?
The Nervous System
The Nervous System
The Nervous System
The Nervous System
The Nervous System
The Nervous System
homeostasis
Be careful filling in your chart…your sympathetic &
parasympathetic sides are switched
CNS: A Simple Reflex
A Simple Reflex
Reflex:
Single sensory neuron & single motor
neuron; communicate through an
interneuron
Spinal cord links
peripheral nervous
system to brain
Objective 5:
How does the endocrine system transmit its messages?
• Endocrine system
– Chemical communication system; secretes hormones
into the bloodstream (“slow” but can outlast NT)
–Hormones
• manufactured by endocrine system; in blood
–Adrenal glands
• Epinephrine & norepinephrine
• Fight or flight response (arouse body in times of
stress)
–Pituitary gland (master gland)
• In brain; controlled by hypothalamus
• Influence the release of other hormones
Point to remember…
brain
pituitary
other glands
hormones
brain
connection between nervous system &
endocrine system