Transcript The Brain and The Nervous System

Brain and Nervous System
(NS)
Nervous System
Made up of neurons
- 2 main types
• 1) Central NS
• 2) Peripheral NS
Central Nervous System
• Role: coordinates incoming info and initiates
outgoing messages/behaviours.
• Consists of brain and spinal cord.
• Brain = controls the decisions
• Spinal cord = communication between the
brain and PNS.
(sensory info inwards and
motor info outwards)
- coordinates reflexes.
• Note –
• Spinal cord does not carry signals
between the CNS and PNS – this is wrong
as the spinal cord is part of the CNS.
• Must be Brain to PNS
Neurons
• Building blocks of the nervous system that carry
messages as an electrical impulse.
• E.g. = what you touch must travel from your
hand to your brain to be understood and then
from your brain to your hand for a response to
occur
Watch
• http://www.youtube.com/watch?v=CMnDie
pv5Os
• http://www.youtube.com/watch?v=vyNkAu
X29OU
3 kinds of neurons
• 1) Sensory Neurons “AFFERENT”: respond to
sensory receptors then send signals to the CNS.
Transmit info inwards.
• 2) Motor Neurons “EFFERENT” : Transmit
signals from the CNS to specific muscles.
Transfer info outwards (Efferent = EXIT)
• work together to allow the body to identify a
stimuli and then respond to it
• 3) Interneuron: connects afferent and
efferent neurons in the CNS(mostly at the
spinal cord)
• Most common!!
• Found only in CNS
• Responsible for the reflex arc
The Reflex Arc
• An automatic response in which sensory
neurons (inwards) do not pass to the brain
• Communicate in the spinal cord = reflex
action
• Acts as a survival mechanism
Parts of a neuron
Parts of a Neuron
http://www.youtube.com/watch?v=cUGuWh2UeMk
• Dendrites: thin extensions of a neuron that
receive information from other neurons
• Cell Body/soma: contains the nucleus and
decides what it will do with the information
• Nucleus: contains genetic material (brains
of the neuron)
• Axon: carries the signals and covered by
myelin sheath
• Axon Terminals buttons: end of the axon that
and release neurotransmitters
• Synapse: the junction that permits the transfer of
electrochemical messages form cell to cell.
Connection point which has the synaptic cleft,
neurotransmitters and receptor sites
• Synaptic Cleft: small gap between 2 neurons
which neurotransmitters cross
• Neurotransmitters: chemicals that are
released into the synaptic cleft, where they
bind to receptor sites on the other neuron
receiving the signal.
• Receptor Sites: sensitive to neuron
transmitters which change the charge of
the post neuron
Communication between
neurons = Action Potential
• http://www.youtube.com/watch?v=XGINQ
7xhPkM
Communication between
neurons = Action Potential
• Action Potential = happens during the firing of
a neuron. Pre neuron is + and Post neuron is - .
Neurotransmitters cross and turn the post
neuron +.
• Information is transmitted from one neuron to the
next via NEUROTRANSMITTERS
• Happens at the synapse. Terminal buttons 
neurotransmitters  cross synaptic gap 
receptor sites  next neuron  continue the
process
1) Pre neuron – signal travels down axon
2) Axon Terminals (at the end of the axon) hold
neurotransmitters
3) Neurotransmitters are released into the
synaptic gap
4) They bind with
receptor sites of the
post
neuron
5) All this happens
at the synapse
The Peripheral Nervous System
• All nerves outside the brain and spinal
cord.
• Links the CNS to all other parts of the
body
• - divided into
• A) somatic
• B) autonomic
Somatic Nervous System
• Controls voluntary skeletal muscle movements.
• Has a sensory (sends signal via sensory neurons )
and motor function (movement via motor
neurons).
• EYES
• Cutting your
finger
• Bee sting
Anything on the outside of the
body
• Gathers information from the sensory
receptors in the body and transmits
this information to the CNS.
• Effect movements by carrying motor
messages from the CNS to the
muscles and glands. The somatic
nervous system is responsible for
voluntary skeletal muscle movement.
• Carries sensory information to the
brain and movement information to
the body
Autonomic Nervous System (PNS)
• Modifies automatic (visceral / involuntary)
muscles.
• Digestion, heart rate, respiration, kidneys
• Walking down a dark ally
• Divided into 2 which control opposite reactions
• 1) Sympathetic NS
• 2) Parasympathetic NS
Divided into the
Parasympathetic
NS
Calms body down
after threat has
passed –
Returns to
‘homeostasis’
equilibrium
Sympathetic NS
Readies the body
to confront a
threat – activates
the organism for
“Flight or Fight”
• Parasympathetic dominates in day to day
functioning.
• Sympathetic dominates when under
threat.
• They work in cooperation,
• One always dominates depending on the situation
Flight or Fight Response
• Adaptive purpose with the aim of survival
• A state of high arousal that prepares the
body to confront a situation or fight it, or,
flee from the situation or flight it.
• Arousal = general
level of alertness.
• Confront NOT deal
All Physiological
Arousals
Sympathetic
Parasympathetic
Eyes
Dilate
Constrict
Heart
Increase rate/pumps
blood faster
Decreases to normal
Lungs/Bronchi
Expands/relaxes airways
Constricts/decreases O2
consumption
Salivary Glands Decreases
Normal
Bladder
Relaxes
Normal
Adrenal Glands
Increase
Decrease
Sex
Organs
Sweat
Glands
Increases
Inhibits
Stomach
Slows digestion
Normal
Physical Responses by the
Sympathetic NS - 168
• Pupils dilate – allows to gather info immediately
• Tears – inhibited
• Heart Rate increases – increase blood flow to
working/essential muscles
• Bronchi relax/expand – increase O2 consumption
• Digestion – inhibited
• Salivary glands – decreases/dries up
• Adrenaline increase – released to speed up HR
• Sugar – increased to provide extra energy
• Bladder – relaxes (temporary loss)
• Not more blood – we do not get more
blood in the body.
•
•
•
•
Role of the hormones
Adrenal glands release adrenaline
Allows for burst of energy
Takes some time for hormones to leave the
blood stream due to increased arousal.
• Enter fast and remove slow
• http://www.youtube.com/watch?v=tmYGOFhhHE
• ____________ neurons carry information
from organs and muscles to the central
nervous system while ____________
neurons carry information to organs,
muscles and glands from the central
nervous system.
• A. Sensory, motor
• B. Motor, sensory
• C. Peripheral, autonomic
• D. Autonomic, peripheral
• The motor function of the somatic nervous
system can be demonstrated by
• A. experiencing the cold sensation of
ice on your skin.
• B. reflexively moving your hand away
from a hot stove.
• C. feeling muscle soreness after
playing sport.
• D. scratching your head.
• The sympathetic and parasympathetic
nervous systems
• A. are part of the reflex arc.
• B. cannot both be active at the same
time.
• C. have opposite effects although they
work together.
• D. are inactive unless the fight/flight
response is activated.
• Which of the following is true of the
autonomic nervous system (ANS)?
• A. The ANS is a vital part of the central
nervous system (CNS).
• B. It is impossible to consciously
influence the functioning of the ANS.
• C. The ANS ensures that the constantly
changing energy requirements of the
body are met.
• D. The ANS relays messages between
the CNS and the voluntary muscles that
control our internal organs and glands.
Questions
• Attempting to become part of the
Australian Olympic team, Renee is waiting
to compete in her 400m trial. In reference
to this scenario, explain how Renee’s
somatic NS and Autonomic NS
(sympathetic and parasympathetic) would
work together to help her compete in this
race?
• 4 marks
• Her somatic NS controls voluntary actions via its
connections with the skeletal muscles. Renee’s
ears would relay the information about the starting
gun, and her CNS would send instructions for
Renee’s muscle groups in her arms and legs to
move.
• Her autonomic NS controls involuntary actions of
internal organs. At the start of the race her
sympathetic NS would be activated, resulting in an
increase in Renees’ adrenaline, heart rate,
respiration and sweating. After the race her
parasympathetic NS would slow her heart rate and
respiration rates to restore her body to a balanced
state.
• http://www.biologymad.com/nervoussyste
m/nervoussystemintro.htm - website
Brain / Cerebrum
- ‘master organ’ – makes the decisions
Facts
• Weighs 1.4 kg
• 100 billion neurons
• Structure = what it looks like
• Function = what it does
Cerebral Cortex
Location
• Folded outer covering the cerebrum
Structure
• 2 – 4 mm thick
• Largest area of the brain = 2/3 of all
neurons
• Wrinkled/ folded /convoluted – Increase
surface area
Function
Covers all of the brain therefore, is
responsible for all major cognitive functions
-
Motor coordination
Processing of sensory info
Higher mental processes – language, thinking, problem solving
Personality
Comparison of human cerebral cortex to
animals
Our cortex is more proportionally significant to other areas
of the brain (contains 75% of all neurons).
• The human brain structure which contains
almost three quarters of the brain’s
neurons and which is responsible for
processing information as well as
reasoning, planning and imagining is the
• A. frontal lobe.
• B. temporal lobe.
• C. cerebral cortex.
• D. cerebral hemisphere.
• The cerebral cortex
• A. is wrinkled and this increases the
surface area.
• B. connects the two hemispheres of the
brain.
• C. is approximately 3.5 cm thick.
• D. controls sleep functions
• Which one of the following statements
about the human adult brain is correct?
• A. The adult brain weighs around 500 g.
• B. The brain is divided into sections,
each of which has one specifi c
function.
• C. The brain’s cerebral cortex is folded
to increase cortical surface area.
• D. The brain is responsible for many
bodily functions but not body
temperature.
• Cerebral Hemispheres
• Corpus Callosum
- Cerebral Hemispheres
• Left and Right
• Connected by
corpus callosum
• Separated by the longitudinal fissure
- Corpus Callosum
• Is a structure of nerve fibres that allows
communication/transfers between the left
and right hemispheres
• The main function of the corpus callosum
is to
• A. exchange neurons between
hemispheres.
• B. process information from both
hemispheres.
• C. protect the brain from injury.
• D. transfer information from one
hemisphere to the other.
• The two hemispheres of the brain are
connected by
• A. the cerebral cortex.
• B. the corpus callosum.
• C. a deep fi ssure that separates all the
nerve fi bres.
• D. a small strip of tissue with no
neurons.
• Which of the following statements best describes
the corpus callosum?
• A. The corpus callosum transfers information
between the cerebral hemispheres of the brain.
• B. Patients with brain damage are unable to send
neural information through the corpus callosum.
• C. The corpus callosum ensures that each
hemisphere of the brain is able to function
independently.
• D. The corpus callosum is found in the cerebral
cortex, and connects the two hemispheres of the
brain.
4 lobes of the Brain
(F.TOP)
• http://www.youtube.com/watch?v=Vy8Evy
QoQIE
• Each lobe is divided into 2 basic zones
1) Primary/cortex areas = process some type of
sensory information
2) Association area = Integrate information from
different parts of the brain (all the other areas other
than the primary cortex areas). Makes up 95% of
human cortex
• Which of the following is the most accurate
description of the association areas of the
cortex?
• A. They are located in the left
hemisphere and associate input from
the right hemisphere.
• B. They integrate information from
different parts of the brain.
• C. They include the motor and sensory
areas in each lobe.
• D. They are crucial for providing basic
survival needs.
Frontal Lobe
Cortex area
Primary Motor Cortex = controls
voluntary skeletal muscle
movement on
a) The opposite side of the body
(left PMC controls right side)
b) Amount of cortex is related to
precision/dexterity of movement
e.g.) fingers and mouth = more area
c) Our body is represented upside
down on the motor cortex
Other Function: Association area
Higher order functioning
Planning, emotions,
personality, reasoning,
deciding appropriate social
behaviours
Dexterity= Fine motor skill is
the coordination of small muscle
movements which occur in body
parts such as the fingers.
Homunculus: human figure represents body
parts in terms of their space
Contralaterally =
taking place or
originating in a
corresponding part on
an opposite side.
More Area =
Fine muscle
movements
When a basketballer shoots
for a goal, which part of the
brain sends the message
instructing her to raise her
shooting arm?
A. the somatosensory
cortex
B. the prefrontal lobe
C. the occipital lobe
D. the motor cortex
Parietal Lobe
Cortex
Primary Somatosensory = receives
touch, pressure, pain and temp
sensory message from the body.
a) Crossover = receives
information from the opposite
side of the body
b) More space devoted to body
parts with most sensors eg)
fingers, lips
c) Upside down = information
from the lower parts of the
body is processed at the top
Other Functions: Association
Area
SPATIAL AWARNESS and
BODY AWARNESS = where
things are in space e.g.) sense of
direction
Does not receive all sensory
information
- sounds = PAC
- sight = PVC
Motor Cortex = precision
Sensory Cortex = more sensory
receptors
Occipital Lobe
Cortex
Primary Visual Cortex =
receives visual
information.
Step 1
Other Function:
Association Area
Enables
perception/interpretation.
Step 2
The Visual Pathway
2 eyes open =
opposite
hemisphere.
1 eye open =
both
hemispheres.
types of questions on an exam
Left visual field = right hemisphere
Right visual field = left hemisphere
(visual field = the environment on the outside)
1 eye open = both hemispheres as it becomes a
central visual field.
Visual information received by the right eye =
both hemispheres
Visual information received by the left eye =
both hemispheres
Questions about the Visual Field = opposite
Hemisphere
• Visual images received in the left visual
field are processed in the = Right
Hemisphere
Questions about the eyes = both
Hemispheres
• the visual information from your left eye
would be processed in the = right and left
hemispheres
Info from the Visual Field = Goes to both
eyes (right visual field = left side of the
eyes)
Visual images received in the left visual
field are processed in the
A. occipital lobe of the left and right
hemispheres.
B. temporal lobe of the right
hemisphere only.
C. occipital lobe of the right
hemisphere only.
D. occipital lobe of the left hemisphere
only.
If you put your hand over your right eye,
and use your left eye to tell the time on
the clock on the wall in the
examination room, the visual information
from your left eye would be processed in
the
A. left occipital lobe.
B. right occipital lobe.
C. somatosensory cortex.
D. left and right occipital lobes.
Temporal Lobe
Cortex
Primary Auditory Cortex
registering auditory
information
Step 1
Association
Sounds are turned into
recognisable info
involved in memory, and the
ability to recognise faces
Step 2
Akmal bumped his head in a heavy
fall at a skate park. When he was
still recovering in hospital, he could
describe a man who came to visit
him each day but he could not
recognise this man as his father.
Akmal has most likely sustained
damage to the association area in
the cortex of the ______________
lobe.
A. occipital
B. parietal
C. frontal
D. temporal
Which of the four lobes is typically
responsible for receiving and
processing auditory information?
A. frontal
B. parietal
C. occipital
D. temporal
http://www.youtube.com/watch?v=luXDQrmMoUU
Language Centres
Both verbal and written
Area
Broca’s Area
Wernicke’s Area
Hemisphere
Left
Left
Lobe
Frontal Lobe
Temporal Lobe
Function
•Controls the muscles
associated with language
•Producing clear speech using
the rules of grammar
•Involved in understanding
complex grammatical
structures
•Enables us to understand
spoken and written language
• Creates meaningful,
coherent and
grammatically correct
speech and writing by
locating words.
•PRODUCTION
•COMPREHENSION
Damage
Aphasia: language disorder apparent in speech produced by injury to the
brain
Broca’s Aphasia
- You make sense but
produce limited speech
- Difficulty in small
connecting words
- Poor use of grammar
- Slow and uses verbs and
nouns
E.G went beach made castle
Wernicke’s Aphasia
- Difficulty understanding
written or spoken language
- Can make fluent speech
but it is meaningless
- Not aware of defect
E.G beach made went castle
‘word salad’
Note: Still read and understand the
speech of others is not a symptom
of Broca’s Aphasia.
= The role of Broca’s area.
Summary of Aphasia
Broca’s Aphasia: When people have damage to
Broca’s area their speech becomes slow, laboured
and lacks grammatical accuracy, although what they
say makes sense.
Wernicke’s Aphasia: When people have damage to
Wernicke’s area their speech remains fluid (correct
pace and intonation), although they use the incorrect
words and appear unaware of their deficit. Their
speech is often referred to as ‘word salad’ because it
is jumbled.
Mandy fell off her bike and suffered some mild
brain damage. Doctors tested her and found
that Mandy could pronounce the word ‘accident’
but she was unable to give a meaningful verbal
description of her accident.
The doctors were most likely to conclude that
the part of Mandy’s brain affected was
A. Broca’s area.
B. the frontal lobe.
C. the parietal lobe.
D. Wernicke’s area
http://www.youtube.com/watch?
v=fFGmCRc0njk – Language
Hemispheric Specialisation
• Refers to the specialisation/dominance of certain
functions by each of hemispheres of the brain.
Left Hemisphere (verbal and
analytical functions)
Right Hemisphere (non
verbal functions)
Behavioural
Functioning
Motor control of voluntary muscles
on right side of the body
Also muscles involved with
speaking
Motor control on left
side
Cognitive
Functioning
Verbal understanding, production of
reading & writing, spelling
Analytical Tasks:
Logical, Sequential Thinking,
Problem Solving
Tasks that involve breaking things
into steps
Maths (+, -, x, /) and science
Non-verbal thinking
Understanding music and
pictures. Reading a map.
Creativity, Colour
Using imagination, fantasy
Identifying faces
Detection/expression of
emotions
Spatial activities – jigsaw
puzzles
Recognises melodies
Holistic approach – all at
once
Hemispheric Specialisation
• Research has found that damage to the
right hemisphere often resulted in
difficulties with visual and spatial tasks
such as reading maps.
• Damage to left hemisphere often resulted
in difficulties with language related tasks
such as understanding speech, talking
fluently reading and writing.
• Damage to the right hemisphere often
result in slower recognition of pictures.
Can we be labelled a left or right
brained person?
• NO
= Although each hemisphere can be
dominant or specialise in a distinguishable
function, both hemispheres are involved in
nearly all functions working together in an
interactive way.
Left = understanding and producing speech
Right = identify sarcasm, understanding
jokes, irony ect…
http://www.youtube.com/watch?v=t2pEGEdLBVg – summary
Recent research has shown that abilities in
subjects such as math are actually
strongest when both halves of the brain
work together. Today, neuroscientists
know that the two sides of the brain work
together to perform a wide variety of tasks
and that the two hemispheres
communicate through the corpus
collosum.
•
Evidence for hemispheric specialisation
comes from two sources of investigation
1. People with damaged brains (including
split brain surgery). – Roger Sperry
or spatial neglect.
2. People with intact brains
Damaged brains
• Sperry & Gazzaniga
• Split Brain Surgery: corpus callosum
connecting the 2 hemispheres is cut
Known as - Commissurotomy
• individuals were said to have a ‘split-brain’
b’c hemispheres could not communicate.
Aimed to stop seizures.
• Clip on split brain
Experiment
Step 1) seated in front of a screen.
Participants fixed their sight on a point
(black dot) in the centre of the screen.
- Visual stimuli are projected onto the left or
the right side of a black dot.
• Step 2) the person needs to demonstrate
what they have seen. They can do this in
one of three ways:
• A) they can say out loud what they have
seen (only of it is flashed to the right side)
• B) they can reach for and touch the
accompanying object that is placed on the
other side of the screen (can do it with
opposite hand),
• C) they can draw the image (if flashed to
the left visual field and will use left hand).
Results from split brain patients
• Damage to the right hemisphere usually leaves
language unaffected
• When words/pictures were presented quickly in
the right visual field (processed in left
hemisphere) patients could describe what they
had seen (because the left hemisphere
specialises in language)
• When words/pictures presented in the left visual
field (processed in right hemisphere) patient
could not describe what they had seen.
However they could use their left hand which is
controlled by the right hemisphere to pick out
the item that corresponded with the word they
had seen
Hemisphere
Can Say
Can
touch/point/
pick up
Flashed to
right visual
field
Left
Yes
Right hand
Flashed to
left visual
field
Right
No
Left Hand
(left) Spatial Neglect
• What it is:
- Attention disorder (neglect syndrome)
- Fail to notice anything either on their left or
right side (body/visual space)
- Commonly observed in stroke or
accident victims who have extensive
damage to parietal lobe of right
hemisphere.
• Most common: neglect to the left side of
the world (damage to right hemisphere).
• E.g ‘ball’ instead of ‘football’
What happens to the
lobes if damage occurs
Lobe
Frontal
Damage
- Impair body movement
- Alterations to personality
Diminishing executive functioning/higher order functioning
- Broca’s Aphasia: Speech is slow but makes sense
-
Parietal
Occipital
-
- Diminished sensitivity to touch – pain
Left Spatial Neglect – damage to right parietal lobe
Visual Agnosia – cannot organise visual images into
meaningful whole.
-
Temporal
-
Difficult with facial recognition
Difficult with object recognition
- Memory problems
- Understanding emotions
Wenicke’s Aphasia: Cannot make meaningful speech
Key Researches
• Broaca - Broca’s Aphasia
• Wernicke’s – Wernicke’s Aphasia
• Roger Sperry and Michael Gazzaniga –
Split Brain Studies