Transcript Slide 1
Chapter 21
Brain Structure and Function
Attention Deficit Disorder
Copyright © 2010 Pearson Education, Inc.
21.1 The Nervous System
The nervous system
Neurons carry electrical and chemical
messages to and from the brain
Neurons receive, process, and respond to
stimuli.
Three general categories of neurons
1. Sensory neurons
2. Interneurons
3. Motor neurons
Copyright © 2010 Pearson Education, Inc.
21.1 The Nervous System
Interneurons
(within brain or
spinal cord)
Motor
neurons
(from brain)
Sensory
neurons
(to brain)
See and
smell
cookies
Smile and
salivate
Copyright © 2010 Pearson Education, Inc.
Figure 21.2
21.1 The Nervous System
Sensory detectors can be either:
1. Sensory neurons
2. Specialized cells that communicate with
neurons
General Senses
•Temperature
•Pain
•Pressure
•Touch
•Proprioception
Copyright © 2010 Pearson Education, Inc.
Table 21.1
21.1 The Nervous System
Special Senses
•Smell
•Taste
•Vision
•Hearing
•Equilibrium
Copyright © 2010 Pearson Education, Inc.
Table 21.1
21.1 The Nervous System
Special Senses
•Smell
•Taste
•Vision
•Hearing
•Equilibrium
Copyright © 2010 Pearson Education, Inc.
Table 21.1
21.1 The Nervous System
The nervous system is divided
into two parts:
1. Central nervous system
brain and spinal cord
2. Peripheral nervous system
nerves extending from
vertebrae out to body
Interneuron
relays signal
Sensory neuron
senses heat
Motor neuron
withdraws hand
from heat
Hot stimulus
Reflex arc
sensory neuron that synapses
to an interneuron and then
motor neuron
action without higher
processing (e.g., knee jerk
reflex)
Copyright © 2010 Pearson Education, Inc.
Figure 21.4
21.1 The Nervous System
Focus on Evolution
Muscle & Nervous
tissue is unique to
the animal kingdom
Enables animals to
sense environment &
move in search of
food
All animal nervous
systems have similar
properties.
Copyright © 2010 Pearson Education, Inc.
Brain
Spinal
cord
Sense
organs
Nerves
Figure 21.1
21.1 The Nervous System - Focus on
Evolution
Primitive Animal Nervous System
Nerve Nets
• Found in hydras, sea
anemones & jellyfish
•Limited travel
through environment
•No brain
Copyright © 2010 Pearson Education, Inc.
Figure E21.2
21.1 The Nervous System - Focus on
Evolution
Nerve Cords
•Found in insects
•Processing of
information
centralized in CNS
•Simple brain plus
many enlarged
‘ganglia’
Copyright © 2010 Pearson Education, Inc.
Figure E21.2
21.1 The Nervous System - Focus on
Evolution
Vertebrate Nervous
Systems
• Greater degree of
centralization
•Single large brain
•Regions of brain
become specialized for
specific tasks
Copyright © 2010 Pearson Education, Inc.
Figure E21.3
21.2 The Brain
Human Brain
The brain rests in the skull in cerebrospinal
fluid, which bathes and cushions it.
Two major cell types in the brain
1. Neurons transmit nervous impulses
Brain has 100-200 billion neurons
2. Glial cells support neurons by providing protection
& nutrients
Almost 10 times as many glial cells as neurons
Copyright © 2010 Pearson Education, Inc.
Figure 21.6
21.2 The Brain
The brain is divided into 5 regions
1. Cerebrum
2. Cerebellum
3. Thalamus
4. Hypothalamus
5. Brain stem
Copyright © 2010 Pearson Education, Inc.
21.2 The Brain - Cerebrum
Lobes of the Cerebrum
1. Frontal lobe
2. Temporal lobe
3. Parietal lobe
4. Occipital lobe
Copyright © 2010 Pearson Education, Inc.
Other Important Structures
•Right & Left Hemispheres
•Central fissure
•Corpus callosum
•Caudate nuclei
Figure 21.7
21.2 The Brain - Cerebrum
Brain Hemispheres
•Many nerves cross over, so left brain
controls right side of body, and visa versa
•Left Hemispheres
•Controls speech, reading, & solving math
•Right Hemispheres
•Interprets spatial
relationships, music &
art
Copyright © 2010 Pearson Education, Inc.
Figure 21.7
21.2 The Brain - Thalamus and Hypothalamus
Thalamus and hypothalamus
lie deep in the brain between the
hemispheres and act as control center.
Thalamus relays information from spinal
cord to brain.
Thalamus suppresses some information and
enhances other.
Hypothalamus is the control center for
sex drive, pleasure, pain, hunger, and
other basic drives.
Copyright © 2010 Pearson Education, Inc.
21.2 The Brain - Cerebellum
Cerebellum
Control of balance
Coordination of muscular movement
Damage to the cerebellum results in jerky,
awkward movements
Copyright © 2010 Pearson Education, Inc.
21.2 The Brain - Brainstem
Brainstem
Controls involuntary activity.
The brainstem is composed of the midbrain,
pons, and medulla oblongata
Copyright © 2010 Pearson Education, Inc.
Figure 21.8
21.2 The Brain
ADD and Brain Structure and Function
Some researchers suggest there are
differences between brains of people with
ADD and people without.
Corpus callosum smaller in individuals with
ADD
Decreased folding on cerebrum in ADD
individuals
Differences could be a result of genetics, or
development and life experiences
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons
Neurons
Neurons are highly
specialized cells
Parts of Neuron
Dendrites
Cell Body
Axon
Terminal Boutons
Copyright © 2010 Pearson Education, Inc.
Figure 21.9
21.3 Neurons - Neuron Structure
Myelin speeds up nervous impulses
Many neurons have their axons covered by a
myelin sheath made by Schwann cells
the unmyelinated patches are the nodes of
Ranvier.
Copyright © 2010 Pearson Education, Inc.
Figure 21.10
21.3 Neurons - Neuron Function
Neuron Function
Cell accumulates K+ ions inside and Na+ ions
outside
(a) Resting nerve cell
Outside cell
Inside cell
All channels are closed.
The inside of the cell has
a more negative charge
than the outside of
the cell.
Nodes of
Ranvier
K+ channel
Na+ channel
Nerve cell
Copyright © 2010 Pearson Education, Inc.
Figure 21.11a
21.3 Neurons - Neuron Function
Nervous Impulse = Action Potential
Stimulation of a neuron causes ion gates to open, and
Na+ rushes in, changing polarity (depolarization)
Action potential (nervous Impulse) – a brief change in
polarity of the surface membrane, which moves down
the length of an axon
Copyright © 2010 Pearson Education, Inc.
Figure 21.11b
21.3 Neurons - Neuron Function
PLAY
Animation—Communication Within Neurons: The Axon
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons - Neuron Function
How Neurons Work
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons - Neuron Function
Synapse = junction between neurons
Terminal boutons, space, & dendrites or
cell body
Synaptic transmission = Transmission of
impulses between neurons
neurons use neurotransmitters to
communicate chemically across the
synapse
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons - Neuron Function
Synaptic Transmission
1.
2.
3.
4.
5.
Action potential reaches terminal bouton of presynaptic cell
Calcium gates open, allowing Ca2+ to rush in
Ca2+ causes synaptic vesicles to release neurotransmitters
Neurotransmitter binds to receptors on postsynaptic cell
Opening or ion channels triggers action potential in
postsynpatic cell
Copyright © 2010 Pearson Education, Inc.
Figure 21.12
21.3 Neurons - Neuron Function
Two ways to stop synaptic transmission
1. Neurotransmitter is digested by enzymes
2. Reuptake of neurotransmitters by presynatpic cell
Copyright © 2010 Pearson Education, Inc.
Figure 21.12
21.3 Neurons - Neuron Function
PLAY
Animation—Communication Within Neurons: The Synapse
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons
Alzheimer’s, Depression, Parkinson’s, and ADD
Many mental diseases are linked to problems
with neurotransmitters.
Alzheimer’s and Parkinson’s diseases seem
to be related to impaired neurotransmitter
production.
Depression appears to be related to an
imbalance in several neurotransmitters, but its
unclear if this is a cause or a result of
depression.
ADD may be result of lower levels of
neurotransmitter dopamine.
Copyright © 2010 Pearson Education, Inc.
21.3 Neurons - ADD Perscription Drug Action
Ritalin
•Blocks reuptake receptors
on presynaptic cells
•Increases dopamine in
synapse
Adderall & Dexedrine
•Both are amphetamines
•Increase levels of dopamine
in synapse
Copyright © 2010 Pearson Education, Inc.
Figure 21.13