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NS Review
Nervous system
• Coordinates and regulates the function of all
other body systems
• 2 major division
– Central Nervous System (CNS)
• Brain
• Spinal Cord
– Peripheral Nervous System (PNS)
• Nerves
– carry sensory info to the CNS
– Motor commands from CNS to muscles
Neurons
3 types of neurons
 Sensory neurons
Take messages to the CNS
Sensory receptors detect changes in the environment
 Interneuron
Receive input from the sensory neurons before communicate to
motor neuron
 Motor neuron
Takes message away from CNS to rest of body (organ, muscle or
gland)
Neurons
• Anatomy of a neuron
– Cell body
– Dendrites
• Receive signals from other neurons and send them to
cell body
– Axon
• Conducts nerve impulses away from the cell body and
send them toward other neurons
Neurons
• Myelin Sheath
– Formed by Schwann Cells around the axon
– Gaps between Schwan Cells are called nodes of
Ranvier
– Myelin Sheath gives nerves white colour
– Helps protect and insulate the nerve
– Helps conduct nerve impulse
Neurons DIAGRAM
Nerve impulse
• Nervous system uses a nerve impulse to send
information
• When an axon is not conducting a nerve
impulse we call it at resting potential
– More negative inside the axon
– Positive outside the axon
Nerve impulse
Difference in polarity is due to ion
concentration
 More Na+ ions outside the axon
 More K+ ions inside the axon
 Sodium-potassium pumps
Actively transport Na+ out of axon and K+ into axon
3 Na+ for every 2 K+
Nerve Impulse
Action potential
 Rapid change in polarity across the axon
 Nerve impulse
During an action potential
 DEPOLARIZATION
Sodium channels open up
Sodium enters the axon
Axon becomes more positive
 REPOLARIZATION
Potassium gates open
K+ moves outside of axon
Axon returns to original negative charge
Synapse
• During an action potential the impulse travel
along the axon until it reaches the axon
terminal
• Here gated Ca+ channels open up and Ca+
enters the axon terminal
• Synaptic vesicles merge with presynaptic
membrane and bind with a specific protein
receptors
Synapse
• Depending on the type of neurotransmitter
and receptor the response of the postsynaptic
neuron
– Excitation
• Action potential occurs
– Inhibition
• Action potential does not occur
Types of neurotransmitters
• Acetylcholine
– triggers muscle contraction
– In the central nervous system, it is involved in
wakefulness, attentiveness, anger, aggression,
sexuality, and thirst
• Dopamine
– involved in controlling movement and posture
– It also modulates mood
Types of neurotransmitters
• GABA (gamma-aminobutyric acid)
– GABA contributes to motor control, vision, and
many other cortical function
• Norepinephrine
– is important for attentiveness, emotions, sleeping,
dreaming, and learning
– Norepinephrine is also released as a hormone into
the blood, where it causes blood vessels to
contract and heart rate to increase.
Types of neurotransmitters
• Serotonin
– contributes to various functions, such as
regulating body temperature, sleep, mood,
appetite, and pain
The Central Nervous System
• Brain and Spinal Cord make up the CNS
• CNS controls many bodily functions
– Breathing
– Heart rate
– Body temperature
– Blood pressure
– Emotions
– Memory
– Creativity
Functions of Spinal cord
• Provides communication between the brain
and the peripheral nerves
– Sends sensory information to brain
– Realays motor impulses from brain to muscles
• Center for thousands of arc reflexes
– Allow nerves and muscles to respond quickly to
dangerous stimuli
The Brain
• The four major parts of the brain (in order of
highest to lowest functioning)
– the cerebrum
– the diencephalon
– the cerebellum
– the brain stem
The Brain: Major Parts DIAGRAM
The Cerebrum
The cerebrum is the largest portion of the
brain.
The cerebrum carries out the higher thought
processes required for learning and memory
and for language and speech.
The Cerebrum
• Cerebral Cortex
– Think layer of gray matter
• Sulci – grooves
• Gyrus – folds
The Cerebrum
• Primary Motor Area
– Controls skeletal muscles
– Each body part is controlled by a certain section
• Primary Somatosensory area
– Sensory information from skin and muscles arrives
• Processing Centers
Wernicke’s Area: understand written and spoken
language
Broca’s Area: speech muscle control
The Diencephalon
 The hypothalamus is the integrating center that
helps maintain homeostasis by regulating hunger,
sleep, thirst, body temperature, and water balance.
 The thalamus integrates sensory input from the
visual, auditory, taste, and somatosensory systems.
The Cerebellum
The cerebellum receives sensory input from
the joints, muscles, and other sensory
pathways about the present position of body
parts.
It also receives motor output from the
cerebral cortex about where these parts
should be located.
The cerebellum maintains balance and
posture.
The Brainstem
The brain stem contains:
 Midbrain: relay station
 Pons: bundles of axons traveling b/t cerebellum and rest
of brain
 medulla oblongata: contains a number of reflex centers
for regulating heartbeat, breathing, and blood pressure.
The Brain DIAGRAM
The Brain
• The brain is divided into 2 cerebral
hemispheres
– Left hemisphere
– Right hemisphere
• Hemispheres communicate with each other
though a bridge of white matter called corpus
callosum
The Brain
• Brain divided into 4 lobes
– Frontal Lobe
• reasoning, motor skills, higher level cognition, and
expressive language.
– Parietal Lobe
• Sensory information
– Temporal Lobe
• Hearing, formation of memories
– Occipital lobe
• Vision, interpreting vision
Lobes of the brain DIAGRAM
The Limbic System
Limbic System
 Emotions & higher mental functions
 Blends primitive emotions (rage, fear, joy, sadness)
with high mental functions (reason, memory)
The Limbic system
• Anatomy
– Hippocampus
• Involved in storage of long-term memory
– Injured cannot form new memories
– Amygdala
• Allows us to feel certain emotions and to perceive them
in other people
– This includes fear and the many changes that it causes in the
body
Memory
• Types of memory
– Short-term memory
• This ability to hold on to a piece of information
temporarily in order to complete a task
• It holds a small amount of information (typically around
7 items or even less)
• readily-available state for a short period of time
(typically from 10 to 15 seconds, or sometimes up to a
minute).
Memory
• Long-term memory
– anything you remember that happened more than
a few minutes ago
– Long-term memories can last for just a few days,
or for many years
Memory
– Semantic memory
• General knowledge about the world
– Names of colours, capital of Canada
– Basic facts that have been collected over lifetimes
– Episodic memory
• recollection of specific events, situations and experiences
– Skill memory
• Involved in performing skills
– Riding bike, playing hockey, using a keyboard
• Skills that become automatic or learned
RETREIVING MEMORY

Retrieval cues are stimuli that help the process of retrieval
 Associations
 Priming - recalling a particular word becomes easier if another, related
word is recalled first
 Context
 People can often remember an event by placing
themselves in the same context they were in when the
event happened.
 Mood
 If people are in the same mood they were in during an event, they may
have an easier time recalling the event
Cranial Nerves
Somatic Nervous System
• responsible for carrying motor and sensory
information both to and from the CNS
• Responsible for all voluntary muscle
movements and processing sensory
information (hearing, touch, sight)
• Made up of nerves that connect to skin,
sensory organs and skeletal muscles
Autonomic Nervous System
• regulates the functions of our internal organs
like the heart, stomach and intestines.
• We are often unaware of the ANS because it
functions involuntary and reflexively
• 2 divisions
– Sympathetic
– Parasympathetic
ANS
• The ANS is most important in two situations:
– In emergencies that cause stress and require us to
"fight" or take "flight" (run away)
– In non-emergencies that allow us to "rest" and
"digest."