Download The Central Nervous System

The brain and spinal cord
Psychology Unit 3
Keywords
 Central nervous system
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(CNS)
Cerebrospinal fluid (CSF)
Meninges
Neurons
 Cell body
 Dentrites
 Axon
Myelin sheath
Sensory neurons
Motor neurons
Interneurons
Cerebrum
 Cortex
 Convolusions
 Sulci
 Fissures - Longitudinal
fissure
 Lobes
 Frontal
 Parietal
 Temporal
 Occipital
 Cerebellum
 Spinal cord
 Ascending tracts
 Descending tracts
The Nervous System
 The nervous system is the control centre and
communication network of the body
The Nervous System
 The nervous system can
be divided into 2 parts:
1. The central nervous
system (CNS)
2. The peripheral
nervous system
(PNS)
• The CNS includes the
brain and the spinal
cord
 The PNS is divided into the:
Autonomic nervous system
 Sympathetic nervous
system
 Parasympathetic
nervous system
Somatic nervous system
 Skeletal muscle
Structure of nerve cells
 Nerve cells are called
neurons. They are the
functional unit of the
nervous system.
Neurons have:
 A cell body that contains
the nucleus
 Dendrites, short
extensions on one side of
the cell body
 An axon, a long extension
on the other side of the cell
body
Structure of nerve cells
 Most axons are covered
in a white, fatty
material called the
myelin sheath
 An axon with its
covering is called a
nerve fibre
 There are myelinated
fibres and
unmyelinated fibres
Types of neurons: function
Neurons are classified
according to their function
 Sensory neurons carry
messages from the
receptors to the CNS
 Motor neurons carry
messages from the CNS to
muscles and glands
 Interneurons are located
in the CNS and are the link
between sensory and
motor neurons
The Central Nervous System (CNS)
 Most of the neurons in the
 The brain is the control
centre of the body
 The spinal cord goes out
from the brain and sends a
network of nerve fibres to
the rest of the body
CNS are interneurons
 They have many branches
that are able to send or
receive messages
 The CNS consists of:
 grey matter, made up of
neurons with
unmyelinated fibres
(axons)
 white matter, composed
of neurons with
myelinated fibres (axons)
The brain
 The brain is divided into 3
main sections
 Cerebrum
 Cerebellum
 Brain stem
The cerebrum carries out the
higher order functions
 Example: language
The cerebellum is concerned
with fine motor co-ordination
 Example: balance
The brain stem carries out the
lower order functions
 Example: breathing & heart
rate
The cerebrum
Grey matter
White matter
 The cerebrum is the largest
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section of the brain
It consists of two layers of grey
matter sandwiching a layer of
white matter
The outer layer is called the
cerebral cortex
The cerebral cortex is greatly
folded to increase surface area
Folding produces convolutions
which are separated by shallow
downfolds called sulci and deep
folds called fissures
Sulci
Fissures
The cerebrum
Cerebrum
Longitudinal
fissure
Cerebellum
Spinal cord
 The deepest fissure is the
longitudinal fissure
which separates the
cerebrum into 2 halves;
the left and right
hemispheres
 Each cerebral
hemisphere is divided
into 4 lobes: the frontal,
temporal, occipital and
parietal lobes.
The functional areas
3 functional areas in the cortex:
 Sensory area interprets impulses from receptors
 Motor area controls muscular movements
 Association areas are concerned with emotional
and intellectual processes – deciding how to
respond
The lobes
Frontal lobe
 Reasoning, planning,
moral compass
 Broca’s area
 Involved with speech
production
 Primary motor cortex
 Motor association area
Occipital lobe
 Primary visual cortex
 Visual association area
Parietal lobe
 Sensory information – dealing
with & reacting to the
environment
 Primary somatosensory cortex
 Somatosensory association
area
Temporal lobe
 Language and hearing
 Wernicke’s area
 concerned with the
comprehension of language
Wernicke’s
area
Broca’s
area
Frontal lobe
 Responsible for our most
complex mental behaviours,
such as planning, problem-
solving, thinking, memory,
learning and analysing.
 Responsible for the control
of voluntary movement.
Contains the primary motor
cortex, which directs the
body’s skeletal muscles.
Frontal lobe: Broca’s Area
 Named after Paul Broca who identified it
 Found in the left frontal lobe and is an important language
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centre.
Broca’s area directs the part of the primary motor cortex
that controls muscles of the throat, mouth, jaw, tongue
and face.
By controlling the movement of these muscles, Broca’s
area is primarily responsible for the production of
articulate (clear and fluent) speech.
It is also involved in the structuring sentences and
analysing grammar.
If Broca’s area is damaged, a person may be unable to
produce clear and articulate speech.
Frontal lobe –
motor cortex
Parietal lobe
 Responsible for processing
bodily (somatic) sensations.
 Touch, temperature,
pressure and other somatic
sensations are registered in
the parietal lobe’s primary
somatosensory cortex.
Temporal lobe –
somatosensory cortex
Occipital lobe
 Registering and processing visual information
transmitted from the retinas of both eyes through the
optic nerve
 The primary visual cortex contains a variety of neurons
specialised to respond to specific features of visual
information – colour, shape, motion
 Damage to the occipital lobe may result in visual
impairment even if the eyes and the optic nerve are
uninjured.
Example: individuals who experience a tumour in one of
their occipital lobes may experience blind spots in
their vision.
Temporal lobe
 Responsible for processing auditory
(sound) information received by
both ears
Right temporal lobe
 is specialised to process non-verbal
sounds (for example, the sound of a
siren or a door slamming).
Left temporal lobe
 processes verbal sounds that are
associated with language.
Temporal lobe - Wernicke’s Area
 Identified by Carl Wernicke
 Generally found in the left temporal lobe
 It is connected to Broca’s area by nerve fibres (arcuate
fasciculus).
 Responsible for accessing words stored in memory and
the comprehension of speech and formulation of
meaningful sentences.
 People with damage to Wernicke’s area can hear words
or see them when written, but they do not understand
their meaning. They can pronounce strings of words
but their grammatical errors make their speech
meaningless
Association areas
 Association areas integrate information. They combine
and process sensory information and link it with preexisting ideas, concepts and memories. This role is
crucial to our ability to recognise familiar objects, people
and experiences.
Example
 if you see a rose, the primary visual cortex would register
the shape, colour, size and texture of the rose; and the
association cortex near the visual cortex would link that
information with past knowledge of a rose (its name, the
fact it has thorns, a mental comparison with other
flowers)
Corpus callosum
 A thick band of nerve fibres in the middle of the brain
that connects the left and right hemispheres and
transfers information registered in one hemisphere to
the other.
 Although each hemisphere can perform specialised
functions, most of our thoughts, feelings and
behaviours involve both hemispheres working
together.
Roger Sperry & split brain studies
 Sperry received the Nobel prize in physiology of
medicine for his discoveries concerning the functional
specialization of the cerebral hemispheres.
 With the help of so called "split brain" patients, he
carried out experiments, increasing our knowledge
about the left and right hemispheres was revealed.
 The studies demonstrated that the left and right
hemispheres are specialized in different tasks.
Left and right hemispheres
Left side
 Responsible for analytical and verbal tasks.
 The left side speaks much better than the right side
Right side
 Responsible for space perception tasks and music, the
creative part.
 Example: making a map or giving directions on how to get to
your home from the bus station.
 It can only produce rudimentary words and phrases, but
contributes emotional context to language.
 Without the help from the right hemisphere, you would be
able to read the word "pig" for instance, but you wouldn't be
able to imagine what it is.
The cerebellum
 The cerebellum lies
under the rear of the
cerebrum
 It controls:
 Posture
 Balance
 Fine motor
coordination (muscle
movement)
The hypothalamus
 The hypothalamus lies
in the middle of the
brain between the two
hemispheres
 It is mostly concerned
with homeostasis
The medulla oblongata
 The medulla oblongata
lies within the brain
stem and contains the:
 Cardiac centre -
regulates the rate and
force of the heart beat
 Respiratory centre –
controls the depth and
rate of breathing
 Vasomotor centre controls the diameter of
blood vessels
The brain
Bozeman Science
https://www.youtube.com/wa
tch?v=kMKc8nfPATI
The brain 13 mins
The spinal cord
 The spinal cord is a continuation of the brain stem
 It consists of gray matter in the shape of an H called the
central canal which runs the length of the spinal cord
and contains CSF
The spinal cord
3 functions of the spinal
cord:
 It carries sensory
impulses towards the
brain
 It carries motor
impulses away from
the brain
 Reflexes – impulses
that bypass the brain
The spinal cord
 Myelinated nerve fibres of white matter are
arranged in bundles called ascending and
descending tracts
 Ascending tracts are sensory axons that carry
impulses upwards towards the brain
 Descending tracts contain motor axons that
conduct nerve impulses downwards away from the
brain