Transcript Nervous Systems

Lecture 14 – Ch. 49: Nervous Systems
I.
Neuron Review
II. Relationship
between Stimuli
 Input
III. Nervous System
Organization
IV. Brains
V. Preparation for
next lecture
The Nervous System
Includes all nerve cells (neurons) and support cells
Neurons
Specialized “excitable” cells: receive input, integrate, send output
1 Synaptic terminals:
Bring signals from
other neurons.
2 Dendrites:
Receive signals
from other neurons.
3 Cell body:
Integrates signals;
Coordinates.
synaptic
terminal
4 Action potential
starts here.
5 Axon: Conducts
the action potential.
dendrite
synapse
6 Synaptic terminals:
Transmit signals to
other neurons.
7 Dendrites
(of other neurons).
5
What parts of neurons are OUTSIDE the CNS?
A. All sensory, motor, and
interneurons neurons
B. Sensory neuron dendrites &
cell bodies AND motor
neuron axons
C. Interneurons only
D. Motor neuron dendrites and
interneuron axons
Neurons
Synapse: Region
connecting two neurons
or neuron and muscle
synaptic
terminal
synaptic
vesicle
Neurotransmitter
signals next
neuron.
Signal reaches
end of axon.
Synaptic vesicles
release neurotransmitter.
Neurotransmitter
may excite or
inhibit the next
neuron
gap
neurotransmitter
Receptor binds
neurotransmitter.
dendrite of
postsynaptic
neuron
Stimuli  Input
Information Coding in the Nervous System:
1) Determine stimulus type (e.g. light / sound / touch)
• All neurons use same basic signal
• Wiring pattern in brain distinguishes stimuli
2) Signal intensity of stimulus
• All signals similar in size (all-or-none response)
• Intensity coded by:
1) Frequency of action potentials
2) # of neurons responding
Stimuli  Input
Information Coding in the Nervous System:
1 fires slowly
1 fires rapidly
2 silent
2 fires slowly
1
fires moderately
2 silent
Stimuli  Input
Information Coding in the Nervous System:
3) Integrate/coordinate signals
4) Determine Output
Neural Pathways Direct Behavior:
• Reflex: Involuntary movement in response to stimulus
• Simplest behavior:
1) Receptor: Detects stimulus
2) Sensory neuron: Sends stimulus message
3) Association neuron: Integrates stimuli
4) Motor neuron: Activates effector
5) Effectors: Performs function (muscle / gland)
1 A painful
stimulus activates
a pain receptor.
2 Signal transmitted
by a pain sensory neuron.
stimulus
receptor
dorsal
root
sensation
relayed
to the brain
REFLEX
ARC
5 Effector muscle
causes withdrawal effector
response.
ventral
root
4 Motor neuron
stimulates the
effector muscle.
3 Signal transmitted
to a motor neuron by an
interneuron within the
spinal cord.
Stimuli  Input
Increased Complexity in Nervous System = Increased centralization
Nerve Net: Nervous tissue woven throughout body (no head)
Cephalization: Nervous tissue centralized in “head” region
ring of ganglia
brain
nerve cords
diffuse network
of neurons
(a) Hydra
Nerve Net
(b) Flatworm
cerebral
ganglia
(brain)
(c) Octopus
Cephalization
Nervous System Organization
Brain and spinal cord
1) Bone (Skull; Spinal Cord = vertebrae)
2) Meninges (Triple-layer of connective tissue)
• Contains cerebrospinal fluid
(cushioning / nourishment)
3) Blood-brain Barrier
• Selective barrier in blood vessels
Spinal Cord:
Nervous System Organization
Myelin = Insulation around axons
• Increases AP conduction rate
Nervous System Organization
Spinal Cord:
What part of the spinal cord contains
motorneuron cell bodies?
A.
B.
C.
D.
White matter
Dorsal root ganglia
Gray matter
Ventral roots
CNS
Nervous System Organization
Brain and Spinal Cord
Motor Pathways
PNS
Sensory Pathways
Sensory neurons
registering external
stimuli
Sensory neurons
registering external
stimuli
Somatic nervous
system
(voluntary)
Sympathetic nervous
system
"fight or flight"
Autonomic nervous
system
(involuntary)
Parasympathetic nervous
system
"rest and repose"
Nervous System Organization
If you are surprised by a “predator”, what
happens in your nervous system?
A.
B.
C.
D.
Sympathetic nervous system increases heart rate
Somatic nervous system increases heart rate
Autonomic nervous system increases saliva
Parasympathetic NS increases saliva secretion
Thought Question:
How far can you safely drive behind the
car in front if you are travelling at 60 mph?
Think about: Your reaction time
(what has to happen for you to stop if the car in front of you stops?)
How far you go per second
(at what speed are you traveling?)
The Brain:
(a)
Vertebrate Brains
(c)
optic lobe
thalamus
cerebrum
cerebellum
cerebrum
midbrain
cerebellum
medulla
forebrain midbrain hindbrain
EMBRYONIC VERTEBRATE BRAIN
cerebrum midbrain
cerebellum
(b)
GOOSE BRAIN
(d)
cerebrum
SHARK BRAIN
midbrain
(inside)
cerebellum
HUMAN BRAIN
Brains: What are the major differences?
The Brain:
Human Brain
meninges
skull
1) Hindbrain:
Automatic
Behaviors
A) Medulla: Controls
breathing, heart rate,
blood pressure
B) Pons: Controls
wake/sleep transitions;
sleep stages
C) Cerebellum:
Coordinates movement
hindbrain
cerebellum
pons
medulla
spinal cord
Human Brain
The Brain:
pituitary
gland
pineal
gland
midbrain
- Reticular
Formation
2) Midbrain: Relay /
“Screening” Center
A) Reticular Formation:
Controls arousal of brain
• Filters sensory input from body
B) Visual / Auditory Reflex Centers
The Brain:
Human Brain
cerebral
cortex
3) Forebrain (Cerebrum):
“Seat of Consciousness”
A) Cerebral Cortex
• Two hemispheres (Connection =
Corpus Callosum)
• Left hemisphere controls right side
of body (and vise versa)
corpus
callosum
The Brain:
Human Brain
Parietal
Lobe
Frontal
Lobe
Occipital
Lobe
Temporal
Lobe
3) Forebrain (Cerebrum)
A) Cerebral Cortex
Four regions:
1) Frontal: Primary motor area; complex reasoning
2) Parietal: Primary sensory area
3) Temporal: Primary auditory and olfactory areas
4) Occipital: Primary visual area
Human Brain
primary
sensory area
Frontal
Lobe
primary
motor area
premotor
area
higher
intellectual
functions
leg
trunk
arm
hand
Parietal
Lobe
sensory
association
area
face
speech
motor area
tongue
primary
auditory
auditory association
area
area: language
comprehension
memory
Temporal
Lobe
visual
association
area
primary
visual
area
Occipital
Lobe
Human Brain
Motor and
Sensory
areas
Which is a correct match between
brain region and function:
A.
B.
C.
D.
Parietal lobe : visual processing
Reticular formation : filters sensory input
Cerebellum : controls sleep stages
Cerebrum : dictates breathing rate
Human Brain
Cortical Regions Involved
in Different Tasks:
Hearing Words
Seeing Words
Reading Words
Generating Verbs
0
max
The Brain:
Human Brain
hypothalamus
thalamus
3) Forebrain (Cerebrum)
B) Limbic System
• Produce emotions; form memories
C) Thalamus
• Relays information from body to limbic system / cerebral cortex
The Brain:
Human Brain
limbic region
of cortex
B) Limbic System
• Hypothalamus:
Homeostatic control center
• Amygdala: Produces
sensations of pleasure,
fear, or sexual arousal
• Hippocampus:
Formation of long-term memory
C) Thalamus
• Relays to limbic system /
cerebral cortex
cerebral cortex
corpus
callosum
thalamus
hypothalamus
hippocampus
amygdala
Damage to the hippocampus could result in:
A.
B.
C.
D.
Failure to understand speech
Reduced fear response
Lack of homeostatic control
Loss of long-term memory formation
Things To Do After Lecture 14…
Reading and Preparation:
1.
Re-read today’s lecture, highlight all vocabulary you do not
understand, and look up terms.
2.
Ch. 49 Self-Quiz: #1, 2, 4, 5, 6, 7 (correct answers in back of book)
3.
Read chapter 49, focus on material covered in lecture (terms,
concepts, and figures!)
4.
Skim next lecture.
“HOMEWORK” (NOT COLLECTED – but things to think about for studying):
1.
Explain the difference between the somatic and autonomic nervous
systems.
2.
Diagram a basic neuron – for sensory, motor, and interneurons explain
the location of each region with respect to peripheral or central nervous
system.
3.
Compare and contrast the embryonic vertebrate brain with that of adults.
4.
List the regions of the brain (with functions) from the “outside” of the
brain, inward.