The Nervous System and the Senses
Chapter
24
Neurons
Neuron = nerve
cells
Functions:
Receive
information (environment, other neuron)
Integrate
information, create output signal
Conduct signal to
terminal
Transmit signal
(other neuron, gland, muscle)
How Do Nerve Cells Work?
The Cell Body
Receives Signals from Dendrites
Axons Are the
Neurons Distribution Lines
Signals Are
Transmitted at Synaptic Terminals
How Do
Nerve Cells Work?
A neuron, showing
its specialized parts, their functions, and the path of a signal
How Do Nerve Cells Produce and Transmit Signals?
Action Potential- an electrical signal
Potential = voltage difference
Maintained by active
transport (20% of resting energy budget!)
How Do Nerve Cells Produce and Transmit Signals?
Nerves are not directly linked, they
communicate through synapses
Presynaptic neuron, synapse, postsynaptic
neuron
Synapse = synaptic terminal, gap,
specialized plasma membrane with receptors
How Do Nerve Cells Produce and Transmit Signals?
Excitatory and
Inhibitory Potentials Are Produced at Synapses
Excitatory =
EPSP, more positive
Inhibitory =
IPSP, more negative
Excitatory and
Inhibitory Potentials
Are Integrated in the Cell Body
If sum of inputs
is above threshold, action potential is generated
How Do Nervous Systems Process Information?
The Type of
Stimulus Is Distinguished by Wiring Patterns in the Brain
Brain knows if
light, sound, taste, etc. by where the signal came from
Synesthesia
The Intensity of
a Stimulus Is Revealed by the Frequency of Signals
frequency of firing
how many neurons fire
How Do Nervous Systems Process Information?
Information from
Many Sources Converges
in Certain Neurons
Association
neurons are the decision-making cells
Complex Responses
Require Divergence of Signals
From decision
making cells to effectors
How Do Nervous Systems Direct Behavior?
Sensory neurons:
respond to stimuli from inside or outside body
Association
neurons: integrate from many sources, including memories
Motor neurons:
activate muscles or glands (the effectors)
How Is the Human Nervous System Organized?
How Is the Human Nervous System Organized?
The Peripheral
Nervous System Links the Central Nervous System to the Body
Somatic System
Neurons Control Voluntary Movement
Autonomic System
Neurons Control Involuntary Actions
The
Central Nervous System Consists of the Spinal Cord and Brain
Hindbrain
controls breathing, sleep, movement
Midbrain: Filters
Input
Forebrain:
Emotions, thoughts, perceptions
How Is the Human Nervous System Organized?
The Spinal Cord
Is a Cable of Axons
Protected by the Backbone
Reflex Pathways
Include Neurons in the Spinal Cord
Some Complex
Actions Are Coordinated by the Spinal Cord
Forebrain
Thalamus: Relay
station, coordinates signals
Limbic System:
Emotions
Cerebral Cortex:
Thought and perception
The left and right hemispheres of the brain
arent identical
How Does the Brain Produce the Mind?
Learning and
Memory Are Areas of Active Investigation
Memory May Be
Brief or Long Lasting
As you well know!
The Temporal
Lobes Are Important for Memory
How Do Sensory Receptors Work?
The Ear Captures and Transmits Sound
Sound Is Converted into Electrical Signals
in the Cochlea
The Eye Collects and Focuses Light
How Is Light Sensed?
Light Striking
the Retina Is Captured by Photoreceptors
Cones
Color vision
Concentrated in fovea
3 varieties: red, blue, green
Rods
Sensitive to light
Not color sensitive
How Is Light Sensed?
Rods and Cones
Differ in Distribution and Light Sensitivity
How Are Chemicals Sensed?
The Ability to
Smell Arises from
Olfactory Receptors
In air = smell
Dissolved = taste
Other senses
Echolocation
Special Senses: Detecting Electrical Fields
Detecting Magnetic Fields
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