Download the nervous system - Miss Gleason`s Science

THE NERVOUS SYSTEM
A. TWO PARTS
Central Nervous System(CNS)- brain/spinal
cord
 Peripheral Nervous System(PNS)-nerves
through the body

 31
pairs of spinal nerves
 12 pairs of cranial nerves
B. 3 BASIC FUNCTIONS
1.
Sensory- gathers info
- receptors of PNS send signals to CNS
2.
Integrative- info is brought together
- interpreted, create sensations, create thoughts, add
to memory, make decisions
3.
Motor – response to signals (impulses)
-
Signals sent from CNS to muscles/glands
Homeostasis- maintain stable conditions
MOTOR:
Somatic Nervous System- skeletal muscles
 Autonomic Nervous System- smooth muscles,
glands

C. NEURONS-NERVE CELLS
Body with many extensions(nerve fibers) that
conduct impulses
 2 types of processes

 Dendrites Receive
 Axons-
shorter more numerous
input
single long fiber
 Conducts
impulse away
D. NEUROGLIAL CELLS
Support tissue of the nervous system
 5 Types
1. Microglial : scattered throughout, digest debris
or bacteria

2. Oligodendrocytes: provide insulation around
the axons
Creates myelin sheath
that insulates axons
3. Astrocytes: connect blood vessels to neurons
4. Ependymal Cells: form a membrane that
covers brain-like parts
5. Schwann cells: form the insulating sheath
around the neurons within the PNS
 *Myelin Sheaths - necessary for insulation of
neurons

NEURON STRUCTURE
Cell body- contains cellular organelles
 Neurofibril - fibers- support organelles
 Chromatophilic substance (rough ER) transport system
 Myelin -insulation surrounding axons
 Nodes of Ranvier - gaps in the insulation
 Synaptic cleft- space between neurons

WHITE VS GREY MATTER
Myelinated (white matter) – myelinated axons
 Unmyelinated (grey matter) - unmyelinated

ALL NEURONS DO THREE THINGS:
1. Receive a signal.

Can be any type of stimulus (change in environment,
signal from another neuron, etc).
2. Transmit a signal to another location.

Ex: finger touching something • signal to spinal cord or
brain.
3. Stimulate another cell
Another neuron • transmit signal
 Muscle • contraction
 Gland • secretion

CLASSIFICATION OF NEURONS
Structural
-
Multipolar
Bipolar
unipolar
Functional
- sensory neurons
- motor neurons
- interneurons
Nerve- bundle of nerve fibers
Nerve Impulse- weak electric current
- series action potential along a nerve
SYNAPSE
Presynaptic neuron- brings impulse to synapse
 Postsynaptic neuron- neuron
stimulated/inhibited by impulse
 Synaptic Transmission- signal


Axon end- hold neurotransmitter
NEUROTRANSMITTERS
Excitatory - increase membrane permeability,
increases chance for threshold to be achieved
 Inhibitory - decrease membrane permeability,
decrease chance for threshold to be achieved


Synaptic Transmission
 Dendrite
cell body axon synapse
STEPS
1.
2.
3.
4.
5.
6.
7.
8.
Neuron membrane maintains resting potential
Threshold stimulus is received
Sodium channels open
Sodium ions diffuse inward, depolarizing the
membrane
Potassium channels open
Potassium ions diffuse outward, repolarizing
membrane
Resulting action potential causes a local bioelectric
current that stimulates adjacent portions of
membrane
Wave of action potentials travel the length of the
axon as a nerve impulse
http://highered.mcgrawhill.com/sites/0072495855/student_view0/ch
apter14/animation__the_nerve_impulse.html
 http://outreach.mcb.harvard.edu/animations/
actionpotential.swf

TYPES OF NEUROTRANSMITTERS
Acetylcholine - stimulates muscle contraction
 Monoamines - Norepinephrine & Dopamine
(sense of feeling good, low levels = depression)
 Serotonin (sleepiness)
 Endorphins (reduce pain, inhibit receptors)

DRUGS THAT AFFECT NEUROTRANSMITTERS
Curare
 Strychnine
 Cocaine,
 morphine, alcohol, ether and chloroform
 Mescaline and LSD
 Ecstasy

ANTIDEPRESSANTS

Zoloft is part of a class of drugs called selective
serotonin reuptake inhibitors, or SSRIs for short.
SSRIs act on a specific chemical within the brain
known as serotonin. This is one of several chemicals
used to send messages from one nerve cell to
another.
IMPULSE PROCESSING

Neuronal pool- Groups of neurons making
synaptic connections to perform a common
function
TYPES OF NERVES
Sensory Nerves - conduct impulses into the
brain or spinal cord
 Motor Nerves - carry impulses to muscles of
glands
 Mixed Nerves - contain both sensory and motor
nerves

NERVE PATHWAYS
ReceptorDetects stimulus
Sensory/Afferent Neuron
Central Nervous
System- processes
information
Muscle or Glandreacts
Motor/Efferent Neuron
NERVE PATHWAYS
Reflex Arc- simple pathway, includes few
neurons
 Reflex- simplest response
 Reflex Behavior- automatic, subconscious
response to stimuli

 Sneezing,
heart beat, vomiting, digestion
Knee-jerk reflex- stimulus knee- sensory nervespinal cord-motor nerve
 Withdrawal reflex- occurs when you touch
something painful
 http://www.intelligencetest.com/reflex/index.ht
m

CENTRAL NERVOUS SYSTEM
Brain = cranial cavity
 spinal cord= vertebral canal
 Protection=
Mengines- membranes located
between bone and soft tissue
of nervous system

MENINGES- 3 LAYERS
Dura mater- outermost layer, blood vessels,
nerves
 Arachnoid mater- no blood vessels, inbetween
layer
 Pia mater- inner layer, contains many nerves
and blood vessels to nourish cells

LAYER OF DURA
MATER

Cerebrospinal fluid= between arachnoid and
pia maters
SPINAL CORD
Nerve column, passes from brain down through
vertebral canal
 31 segments – each with a pair of spinal
nerves
 Spinal nerves- branch to various body parts

Cervical enlargement- supplies nerves to upper
limbs (neck)
 Lumbar enlargement- lower back, supplies
nerves to lower limbs

FUNCTION OF SPINAL CORD

Conduct impulses, serves as center for reflexes
Ascending tracts= carry sensory info to brain
 Descending tracts= carry motor impulses from
the brain to muscles/glands


Spinal reflexes- reflex arcs pass through the
spinal cord
BRAIN
Cerebrum – largest, sensory and motor
functions, higher mental function (memory,
reasoning)
 Cerebellum – coordinate voluntary muscles
 Brain stem – regulate visceral functions


Balance and Coordination
STRUCTURES OF THE CEREBRUM
1. Cerebral hemispheres- mirror images
2. Corpus callosum- nerve fibers that connect
hemispheres
3.CONVOLUTIONS OF THE BRAIN

Wrinkles and Grooves of the brain
gyri- ridges on brain
 Sulcus- deep grooves
 Fissure- very deep groove

4. FISSURES
Longitudinal fissure - separate right and left
sides
 Transverse fissure- Separates cerebrum from
cerebellum


Lateral fissure- separates the temporal lobe
from the Frontal and Parietal lobes
LOBES OF THE BRAIN
5. Frontal – reasoning, thinking, language
6. Parietal – touch, pain, relation of body parts
(somatosensory)
7. Temporal Lobe – hearing
8. Occipital – vision
9. Cerebral Cortex - thin layer of gray matter that
is the outermost portion of cerebrum (the part
with all the wrinkles)
FUNCTIONAL AREAS OF BRAIN
1. Motor- controls voluntary movements
- the right side of the brain generally controls
the left side of the body
-also has Broca's Area (speech)
2. Sensory Area-involved in feelings and
sensations
(visual, auditory, smell, touch, taste)
Sensory Homunculus
This model shows what a man's body
would look like if each part grew in
proportion to the area of the cortex of the
brain concerned with its sensory
perception.
3. Association Areas- higher levels of thinking,
interpreting and analyzing information
BRAIN STEM- 3 PARTS
Midbrain – visual reflexes, eye movements
 Pons - relay sensory information
 Medulla Oblongata– heart, respiration, blood
pressure

Diencephalon
1. Hypothalamus – regulates hormones, heart
rate, blood pressure, body temp, hunger, sleep
2. Thalamus - relay station

Optic Tract / Chiasma - optic nerves cross over
each other
MEMORY: HIPPOCAMPUS
Memory is controlled by the HIPPOCAMPUS
 The hippocampus plays a major role in forging
memories.

EMOTIONS: LIMBIC SYSTEM
The prefrontal lobe and the hippocampus are part
of a system of structures in the brain.
 The LIMBIC SYSTEM also includes olfactory lobes.
Therefore, memory, emotion, and smell are linked.
 Crayolas are created today with the same scent
because it reminds people of their happy times in
childhood.
 Why is the brain formed so that smell and
emotions are tied together? Because pheromones
are tied to emotions and behavior, so they need
the link.

MEMORY
We used to classify memory as being long-term
or short-term. The new classification is four
memory systems that process information for
storage and retrieval:
 Episodic, Semantic, Procedural, and Working.

EPISODIC

Involved in remembering personal experiences,
such as a phone conversation you had
yesterday or the movie you watched last week.
SEMANTIC
Manages the storage and retrieval of general
knowledge of facts, such as the number of days in
a year or the colors in a rainbow.
 People with problems in this system may have
difficulty in naming an object or describing a
named object.
 Semantic Memory Tasks

1. What month comes after October?
 2. Where do Kangaroos live?
 3. What actor played the Joker in the last Batman
movie?

PROCEDURAL

Allows us to learn activities and skills that will
then be performed automatically with little or
no conscious thought.
 Examples
are riding a bicycle or driving a car.
 Problems with this system leads to loss of skills or
significant difficulties in learning new skills.
WORKING
Governs attention, concentration, and short-term
retention.
 Problems here can impair her a person's ability to
pay attention or to accomplish multi-step tasks.
 Working Memory Tasks

1. Labeling a skeleton (remember that chapter?)
 2. Describing the parts of the brain.
 3. List all the things you ate yesterday.
 Test Working Memory

PHINEAS GAGE