I. Neuron Review
II. Relationship between Stimuli Input
III. Nervous System Organization
IV. Brains
V. Preparation for next lecture
Lecture 14 – Ch. 49: Nervous Systems
The Nervous System
Includes all nerve cells (neurons) and support cells
Specialized “excitable” cells: receive input, integrate, send output
Neurons
synapse
dendrite
synapticterminal
1 Synaptic terminals:Bring signals fromother neurons.
2 Dendrites:Receive signalsfrom other neurons.
3 Cell body:Integrates signals;Coordinates.
4 Action potentialstarts here.
5 Axon: Conductsthe action potential.
6 Synaptic terminals:Transmit signals toother 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
gap
dendrite ofpostsynapticneuron
neurotransmitter
synapticvesicle
synapticterminal
Neurotransmittersignals next neuron.
Signal reaches end of axon.
Synaptic vesicles release neurotransmitter.
Receptor bindsneurotransmitter.
Neurons
Synapse: Region connecting two neurons or neuron and muscle
Neurotransmitter may excite or inhibit the next neuron
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:
Stimuli Input
fires slowly
silent
1
2
fires moderately
silent
1
2
fires rapidly
fires slowly
1
2
Information Coding in the Nervous System:
3) Integrate/coordinate signals
4) Determine Output
Stimuli Input
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)
REFLEXARCstimulus
effector
receptor
dorsalroot
ventralroot
sensationrelayedto the brain
3 Signal transmittedto a motor neuron by aninterneuron within thespinal cord.
4 Motor neuronstimulates theeffector muscle.
5 Effector musclecauses withdrawalresponse.
1 A painfulstimulus activatesa pain receptor. 2 Signal transmitted
by a pain sensory neuron.
Increased Complexity in Nervous System = Increased centralization
Nerve Net: Nervous tissue woven throughout body (no head)
Nerve Net Cephalization
Cephalization: Nervous tissue centralized in “head” region
Stimuli Input
brain
(c) Octopus(a) Hydra (b) Flatworm
ring of ganglia
diffuse networkof neurons
nerve cords
cerebralganglia(brain)
Brain and spinal cord
Nervous System Organization
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:
Myelin = Insulation around axons
• Increases AP conduction rate
Nervous System Organization
Spinal Cord:
Nervous System Organization
What part of the spinal cord contains motorneuron cell bodies?
A. White matter
B. Dorsal root ganglia
C. Gray matter
D. Ventral roots
PN
SC
NS
Brain and Spinal Cord
Sympathetic nervoussystem
"fight or flight"
Parasympathetic nervoussystem
"rest and repose"
Somatic nervoussystem
(voluntary)
Sensory neuronsregistering external
stimuli
Autonomic nervoussystem
(involuntary)
Sensory Pathways Motor Pathways
Sensory neuronsregistering external
stimuli
Nervous System Organization
Nervous System Organization
If you are surprised by a “predator”, what happens in your nervous system?
A. Sympathetic nervous system increases heart rate
B. Somatic nervous system increases heart rate
C. Autonomic nervous system increases saliva
D. Parasympathetic NS increases saliva secretion
How far can you safely drive behind the car in front if you are travelling at 60 mph?
Thought Question:
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:
Brains: What are the major differences?
Vertebrate Brains
cerebrum
EMBRYONIC VERTEBRATE BRAIN
SHARK BRAIN
GOOSE BRAIN
HUMAN BRAIN
(a)
(b)
(c)
(d)
cerebrumthalamus
optic lobe
cerebellum
medulla
forebrain midbrain hindbrain
cerebrum midbraincerebellum
cerebrum
midbrain
cerebellum
cerebellummidbrain(inside)
The Brain:
1) Hindbrain:
Automatic BehaviorsA) Medulla: Controls
breathing, heart rate,
blood pressure
B) Pons: Controls
wake/sleep transitions;
sleep stages
C) Cerebellum:
Coordinates movement
spinal cord
meningesskull
cerebellumponsmedulla
hindbrain
Human Brain
The Brain:
2) Midbrain: Relay /
“Screening” Center A) Reticular Formation:
Controls arousal of brain
• Filters sensory input from body
B) Visual / Auditory Reflex Centers
pituitarygland pineal
gland
midbrain- Reticular Formation
Human Brain
The Brain:
3) Forebrain (Cerebrum):
“Seat of Consciousness”
A) Cerebral Cortex
• Two hemispheres (Connection =
Corpus Callosum)
• Left hemisphere controls right side
of body (and vise versa)
cerebralcortex
corpuscallosum
Human Brain
The Brain:
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
OccipitalLobe
ParietalLobe
FrontalLobe
TemporalLobe
OccipitalLobe
primarysensory area
sensoryassociationarea
sensoryassociationarea
primaryvisualarea
primaryvisualarea
visualassociationarea
visualassociationarea
auditory associationarea: languagecomprehension
auditory associationarea: languagecomprehension
memorymemory
speechmotor areaspeechmotor area
higherintellectualfunctions
higherintellectualfunctions
primaryauditoryarea
primaryauditoryarea
premotorareapremotorarea
primarymotor areaprimarymotor area
legleg
trunktrunk
armarm
handhand
faceface
tonguetongue
ParietalLobe
FrontalLobe
TemporalLobe
Human Brain
Motor and Sensory
areas
Human Brain
Which is a correct match between brain region and function:
A. Parietal lobe : visual processing
B. Reticular formation : filters sensory input
C. Cerebellum : controls sleep stages
D. Cerebrum : dictates breathing rate
Cortical Regions Involved in Different Tasks:
Human Brain
Seeing Words
max0
Reading Words Generating Verbs
Hearing Words
The Brain:
hypothalamusthalamus
B) Limbic System
• Produce emotions; form memories
C) Thalamus
• Relays information from body to limbic system / cerebral cortex
3) Forebrain (Cerebrum)
Human Brain
The Brain:
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
Human Brain
hypothalamus
corpus callosum
limbic regionof cortex
cerebral cortex
amygdala
hippocampus
thalamus
Damage to the hippocampus could result in:
A. Failure to understand speech
B. Reduced fear response
C. Lack of homeostatic control
D. 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.