Bio30_u30a_ch13_00_notes

Unit 30 A
Biology 30 Nervous and Endocrine Systems

Chapter 13
Nervous System

Unit 30 A

Ch. 13 - Lesson 1
13.1 The Importance of the
Nervous System
(pp.406–10)

3

Biology 30 Today’s Objectives

Today you must be able to:
1. describe the general structure and function of a
neuron and the myelin sheath.
2. identify the principal structures of the central and
peripheral nervous systems.
 Today we will also:
3. discuss the biological basis of the Parkinson’s
disease, a neurological disease, and how this
relates to treatment.

4

Biology 30 Parkinson’s Disease

 A good reason to study the nervous system:
 Do you recognize this face?
o This is Michael J. Fox
(A Canadian actor)
o Michael was born in Edmonton,
Alberta in 1961
o Michael is famous for many TV
shows and movies in his younger
days.
o Now, Michael is commonly seen
on TV promoting awareness for
Parkinson’s disease.
o He first started to show signs of the disease in 1990 5
while shooting the film “Doc Hollywood”.

 A good reason to study the nervous system: cont’d
 What is parkinson’s disease?
o Before we watch a video clip of Michael being
interviewed by Katie Couric, I want you to keep
these questions in mind.
– What are the visible symptoms of Parkinson’s
disease?
– What part of the nervous system do you think is
affected by this disease?

Link: “Michael J. Fox Talks with Katie Couric”

6

 A good reason to study the nervous system: cont’d
 What is Parkinson’s Disease?
o It is a progressive degenerative nerve disorder
that affects muscle activity.
– The cells that degenerate and die belong to two
areas of the brain:
» substantia nigra (basal ganglia)
– Normally, these cells secrete two chemicals
(neurotransmitters) called:
» dopamine
» norepinephrine

7

13.1 The Importance of
Biology 30 the Nervous System
What does the nervous system do for me?
 Your nervous system undertakes many tasks,
including, but not limited to, the following:
o Processing information:
– depth of breathing
– condition of breathing muscles
– amount of water in the respiratory tract
– sensory information
(temp., odour, light intensity, touch, etc.)
o Memory:
– happy times; sad times
– hopes for the future (ambitions)
8

13.1 The Importance of
Biology 30 the Nervous System
 What does the nervous system do for me? (cont’d)
o Emotions:
– The chemical composition of our brain strongly influences
how we feel.
– The way our brain responds to external events in our lives
will determine the chemical composition of our brain and
thus set our mood.
 In a nutshell, the nervous system allows us to
respond to our external environment.

9

Organization of the
Biology 30 Nervous System
There are 2 main divisions of the nervous
system:
 The Central Nervous System (CNS):
o Consists of the Brain and the Spinal Cord.
o Acts as a coordinating center for incoming and
outgoing information.

10

Organization of the
system: (cont’d)
 The Peripheral Nervous System (PNS):
o Consists of nerves carrying information between
body organs and the CNS.
o The PNS is further subdivided:
– Somatic nerves:
» Controls skeletal muscles, bones, and skin.
» Consists of motor and sensory neurons.
– Autonomic nerves:
» Contains special motor nerves that control the internal
organs of the body.
11

Organization of the
system: (cont’d)
 The Peripheral Nervous System (PNS): (cont’d)
– Autonomic nerves: (cont’d)
» There are 2 divisions of the ANS:

Sympathetic nervous system

Parasympathetic nervous system

12

Organization of the
Nervous System:
 This diagram
shows the:
o CNS
o ANS
– branch of the
PNS
 This diagram
doesn’t show the:
o Somatic nerves
– branch of the
PNS 13

Organization of the
Nervous System:
 This diagram
shows the:
o Somatic nerves
– branch of the
PNS

14

Organization of the
Figure 1, p.408 (Nelson)
 The main divisions of the nervous system

15

Anatomy of a
Biology 30 Nerve Cell
Cells of the Nervous System:
 The Neuron:
o The neuron is the functional unit of the nervous
system.
– Neurons are specialized cells that are able to conduct
electrochemical impulses over substantial distances very
quickly.
 Glial Cells:
o Non-conducting cells.
o Important for structural support and metabolism of
neurons.
16

Anatomy of a
Anatomy of a Nerve Cell:
 Cell body:
o contains the nucleus and is responsible for routine
maintenance of the neuron.
 Dendrite:
o carries impulses towards the cell body.
 Axon:
o conducts nerve impulses away from the cell body.

17

Anatomy of a
 Structure of a neuron. The arrow shows the
direction in which a nerve impulse travels.

dendrites

axon

18

Anatomy of a
Anatomy of a Nerve Cell: (cont’d)
 Myelin Sheath:
o glistening white coat of fatty protein.
o acts as insulation for the neurons.
– prevents the loss of charged ions from the neuron.
(More on this in a couple of classes)
o formed by special glial cells called Schwann cells.
 Neurilemma:
o found on all nerve fibres in the PNS.
o a thin outer membrane, formed by Schwann cells,
which surrounds the neuron.
19
o promotes regeneration of damaged axons.

Anatomy of a

dendrites

Schwann myelin
cell sheath

axon

20

Anatomy of a
 Node of Ranvier:
o the areas between sections of myelin sheaths.
o important for conduction of nerve impulses.
 Synaptic End:
o the end of the axon.
 Synaptic Vesicle:
o contain neurotransmitters, like dopamine.
– chemicals that can activate, or inhibit, the firing of a post-
synaptic neuron.
21

Anatomy of a

dendrites
node of
Schwann myelin Ranvier
sheath synaptic
cell
ends

axon

22

Anatomy of a
 Synapse:
o the gap between the synaptic end of one neuron
(presynaptic neuron) and a dendrite of another
neuron (postsynaptic neuron).

23

Anatomy of a
Types of Neurons:
 There are 3 distinct types of neurons:
o Sensory neurons: (afferent neurons)
– Detect stimuli via sensory receptors (like taste buds)
and transmit the stimulus to the CNS for processing.
– Cell bodies of sensory neurons are located in
clusters called ganglia located outside of the spinal
cord.
o Interneurons:
– Link neurons to other neurons.
– Located only within the CNS.

24

Anatomy of a
Types of Neurons: (cont’d)
o Motor Neurons: (efferent neurons)
– Transmit impulses from the CNS to muscles, organs,
or glands.
» Muscles, organs, and glands are classified as
effectors because they produce responses to the
stimuli.

25

Anatomy of a
 3 Types of neurons.

26

Biology 30 Activity

Building Neurons:
 During this activity you will accomplish two
tasks:
1. You will build, and label, a model of a neuron
using pipe cleaners.
2. You will build a model of a neuron using:
– 2 paper plates (cell body)
– twine (for the axon)
– yarn (for the dendrites)
– small beads (for neurotransmitters)
– large bead (representing an Action Potential)
» more detail on this in a couple of classes.
27
– 3–4 plastic cups (synaptic ends)

Biology 30 Microscope

Examining Neurons:
 If available, your teacher will make a
microscope and slides of neurons available
to you.
 If not available, your teacher will find
microscope images of neurons for you
online.

28

Biology 30 Closure

Can you:
1. describe the general structure and function of a
neuron and the myelin sheath.
2. identify the principal structures of the central and
peripheral nervous systems.

29

Biology 30 Assignment

Nelson (2007), p.410
 Practice Questions #1–4
Nelson (2007), p.414
 Section 13.1 Question #6

30

Unit 30 A

Ch. 13 - Lesson 2
13.1 The Importance of the
Nervous System
(pp.411–14)

31


1. describe, using an example, the
organization of neurons into nerves.
composition and function of reflex arcs;
e.g., the patellar reflex, the pupillary reflex
3. design and perform an experiment to
investigate the physiology of reflex arcs

32

Anatomy of a
Nerves:
 Recall from last class:
o There are 3 types of neurons:
– Sensory, Interneurons, and Motor.
 Within the CNS:
o The CNS consists of mainly interneurons that
highly interconnected.
– This permits the complex processing that goes on in
the brain.
o The CNS does send output and receive input
to and from the PNS.
– This is done by motor (output) and sensory (input) 33
neurons.

Anatomy of a
Nerves: (cont’d)
 Within the PNS:
o Neurons are typically organized into nerves, or
nerve bundles.
– Neurons that connect to similar parts of the body will
be bundled, or grouped, together.
– For example,
» Sensory neurons that terminate in the left index finger
will be bundled together.
» They will connect to the spinal cord as a unified group.

34

Anatomy of a
 A Nerve

35

Anatomy of a
The Nervous System:

36

Biology 30 The Reflex Arc

Ponder the following questions:
 Have you ever wondered why, or how, you
respond so quickly when you accidently
touch a hot surface?
 Have you noticed that everyone reacts
pretty much the same way?

37


Reflexes:
 Reflexes allow you to respond to the
environment without thinking.
o This is very important, as you are able to react
to a situation before your brain has time to
process the information.
 Reflexes are a survival mechanism.
o When working properly, they should allow you
to react to a situation in order to minimize
damage to your body.

38


The Physiology of a Reflex Arc:
 The Components:
1. A sensory receptor:
– pain, pressure, photo/light, sound, temperature, etc.
2. A sensory neuron.
3. An interneuron.
4. A motor neuron.
5. An effector:
– Usually a muscle of some type.

39


The Physiology of a Reflex Arc: (cont’d)
 The Sequence of Events:
1. Sensory receptor:
– A sensory receptor is stimulated by some external
factor. (i.e., your finger touches a tack)
2. Sensory neuron:
– The sensory receptor then sends an impulse down the
sensory neuron towards the CNS (usually the spinal
cord).

40


The Physiology of a Reflex Arc: (cont’d)
 The Sequence of Events: (cont’d)
3. Interneuron:
– In the CNS, the sensory neuron relays the impulse to
an interneuron.
– The interneuron will send the impulse:
» to other interneurons sending the impulse up the CNS
to the brain (for processing).
» to a motor neuron.
4. Motor neuron:
– An impulse travels down the motor neuron towards the
effector (usually a muscle).
5. Effector: 41

– The muscle contracts.

Biology 30 Reflex Arcs

Investigation 13.1, p.436 (Nelson)
 Your teacher will now pass out the worksheet,
“Investigation 13.1: Reflex Arcs”.
 You will be assigned into groups of 2–3.
 Procedure:
o Read through each step of the investigation
carefully. (Ask for clarification)
o Do Parts 1 – 4
– Record observations on your worksheet.

42

Biology 30 Reflex Arcs

Investigation 13.1, p.436 (Nelson)
 Procedure: (cont’d)
o Do Part 5:
– Develop a brief experimental design keeping
manipulated, responding, and controlled variables in
mind.
– Carry out your procedure.
o Answer all Analysis and Evaluation questions.

43

Chapter 13
Unit 30 A
Biology
Nervous System
13.1 Summary The Importance of the Nervous System

Biology 30 Closure

Can you:
organization of neurons into nerves.
composition and function of reflex arcs;
e.g., the patellar reflex, the pupillary reflex
3. design and perform an experiment to
investigate the physiology of reflex arcs

45


Nelson (2007), p.414
 Section 13.1 Questions #1–3

46

Unit 30 A

Ch. 13 - Lesson 3
13.2 Electrochemical Impulse
(pp.415–8)

47


1. explain the formation and transmission of
an action potential.

48

13.2 Electrochemical
Biology 30 Impulse
A little History:
 1900:
o A German physiologist (Julius Bernstein)
suggested that nerve impulses were an
electrochemical message created by the
movement of ions through the neuron
membrane.
 1939:
o Researchers at Columbia University (K.S. Cole
& H.J. Curtis) came up with an experiment to
prove this German physiologist correct.
49

Biology 30 Impulse
A little History: (cont’d)
 The Experiment:
o They conducted their experiment on a large
neuron of a squid.
o Researchers placed a tiny electrode inside the
axon and found the following:
– The resting membrane had a potential of –70 mV.
– When the neuron became excited, the potential on
the inside of the neuron became +40 mV.
» This reversal of potential is what we now call an
action potential (AP).
– A few milliseconds after an action potential occurred
the potential on the inside of the neuron went back to
50
–70 mV (the resting potential).

Biology 30 Impulse
 The Experiment:

51

Biology 30 The Resting Potential

What gives plasma membranes this
potential?
 This potential is setup by concentrating
potassium ions (K+) and sodium ions (Na+)
across the nerve cell’s membrane.
o K+ is concentrated on the inside of the cell.
o Na+ is concentrated on the outside of the cell.
 The potential changes from –70 mV to +40 mV
when:
o K+ moves out of the cell (facilitated diffusion).
o Na+ moves into the cell (facilitated diffusion). 52


 Ion distribution and movement.

53


Cell Membrane Properties:
 Recall:
o Cell membranes are selectively permeable.
– The neuron’s cell membrane is impermeable to both
potassium and sodium ions.
o Entities like potassium and sodium must, initially,
be moved across the cell membrane by active
transport.
– This is accomplished by the sodium-potassium pump.
» This is an active process requiring energy in the form of
ATP.
– The Na-K pump is responsible for setting up the resting
membrane potential of –70 mV. 54


 The Na-K pump

55


Cell Membrane Properties: (cont’d)
 Recall: (cont’d)
o Since the membrane is impermeable to both Na+
and K+ ions, these ions cannot move down their
concentration gradients without help.
– The movement of these ions is facilitated by the opening
of gated ion channels.
– When open the specific ion can move down it’s
concentration gradient (hence, facilitated diffusion).
– Each gated ion channel is matched to a specific type of
ion.
» For example, K+ channels only allow K+ ions to flow through
them.
56


 Gated Ion Channels

57


Cell Membrane Properties: (cont’d)
 What would happen if the membrane wasn’t
impermeable to Na+ and K+ ions?
o The K+ and Na+ ions being pumped across the
membrane by the Na-K pump would simply diffuse
back down their concentration gradients so that
their concentrations would be equal on both sides
of the membrane.
– Thus, there would be no membrane potential.

58

Biology 30 The Action Potential

The Phases:
 Polarized Membrane:
o The resting membrane is polarized to –70 mV.
o This is due to the unequal distribution of the
positively charged sodium and potassium ions
inside and outside of the neuron.
 Depolarization:
o The diffusion of Na+ into the nerve cell when
Na+ gates open.
o This results in a charge reversal (+40 mV).
59


The Phases: (cont’d)
 Repolarization:
o The process of restoring the membrane back to
the resting potential of –70 mV.
o How repolarization happens:
– When the membrane potential becomes positive,
the sodium channels close and the potassium
channels open.
» Na+ ions stop diffusing
» K+ ions begin to slowly diffuse out of the neuron.

60


 Hyperpolarization:
o When the inside of the neuron membrane has a
greater negative charge than the resting
membrane (< –70 mV).
o This occurs because the potassium channels
are slow to close.
– This allows for more K+ to diffuse out of the cell
creating a larger negative potential.

61


 Refractory Period:
o The recovery time required before a neuron can
produce another action potential (AP).
o During this time, the Na-K pump is working to
restore the membrane back to it’s resting
membrane potential (–70 mV) by:
– moving Na+ back outside of the neuron and
– moving K+ back inside the neuron.
o This can last between 1 to 10 ms (milliseconds).

62


 The phases of an
action potential.

63


Movement of the Action Potential:
 Now the question becomes, “How does the
action potential move along the neuron?”
o In fact, the AP does not move.
o Instead, AP’s occur in succession along the
neuron.
– This looks like a “wave” of depolarization.
– Like “domino’s” falling in succession.

64


Movement of the Action Potential: (cont’d)
 The sequence of events:
1. The first AP is generated as Na+ ions rush in
through the opened sodium channels.
– This creates a local increase in the Na+ concentration.
2. The Na+ ions inside the neuron now move down
their concentration gradient to adjacent areas of
lower Na+ concentration.
– This influx of Na+ ions to adjacent areas inside of the
neuron creates an electrical disturbance.
» This disturbance causes sodium channels in this
adjacent area to open.
65


 The sequence of events: (cont’d)
3. Now, a new AP is generated in this adjacent
area as Na+ ions rush into the neuron.
4. Steps 1 – 3 repeat over and over as new AP’s
are created ‘down-stream’.

66


 Successive APs along an
axon.

67


 Can an AP move backwards?
No!
o Recall:
– Shortly after the Na+ channels open, the following
phases occur:
» the K+ channels open (repolarization).
» then the Na-K pump needs to reset the concentration
gradients (the refractory period).
– While this is going on no new AP’s can be initiated.

68


Speeding up Impulse Transmission:
 Imagine the following:
o Two students are asked to race down the hallway
with the following task:
– Student 1:
» Open every locker door on your way down the hall.
– Student 2:
» Open every 10th locker door on your way down the hall.
o Who wins the race?
– Ans: Student 2

69


Speeding up Impulse Transmission: (cont’d)
 Saltatory Conduction:
o Definition:
– The generation of APs only at nodes of Ranvier in
myelinated axons, resulting in the rapid transmission of
nerve impulses.
o Recall:
– Specialized Schwann cells wrap around axons creating
‘bare’ areas on the axon called nodes of Ranvier.
» These ‘bare’ areas are full of sodium and potassium
channels.
» Since these areas are well spaced out, the Na+ ions flow
very quickly from node to node creating APs as they
open sodium channels. (Remember: Step 2) 70


 Saltatory conduction.

71

Biology 30 Closure

Can you:
1. explain the formation and transmission of
an action potential.

72


Nelson (2007), p.418
 Practice #1–4
Nelson (2007), p.425

73

Unit 30 A

Ch. 13 - Lesson 4
13.2 Electrochemical Impulse
Threshold Levels &
Synaptic Transmission
(pp.418–21)

74


1. explain the all-or-none response and
intensity of response.
2. describe the transmission of a signal
across a synapse.
3. describe the main chemicals and
transmitters involved, i.e., norepinephrine,
acetylcholine and cholinesterase.

75

Threshold Levels and the
Biology 30 All-or-None Response
Threshold Level:
 Definition:
o The minimum level of a stimulus to produce a
response.
 Let’s look at a classic experiment to
explore threshold levels.
o A single neuron leading to a muscle is isolated
and a mild electrical shock is applied to the
neuron.

76

 The setup of the classic experiment.

77

Threshold Level: (cont’d)
 The Observations:
1. A stimuli of less than 2 mV did not produce any muscle
contraction.
2. A stimuli of 2 mV, or more, caused the muscles to contract
with a force of 3 N.
 The Conclusions:
o A stimuli of less than 2 mV did not reach the threshold for
this particular neuron.
– Different neurons can have different threshold levels.
o All stimuli of 2 mV, or more, caused the same magnitude of
force in the muscle.
– This is why it is called the all-or-none response.
– An AP either occurs, or doesn’t occur, there is nothing in the 78
middle.

 The question now becomes, “How can we
differentiate between warm and hot objects?”
o Different intensities of stimuli can be detected in
two ways:
1. The nerves can send impulses at different frequencies.
» Warm objects placed on your hand cause neurons to
fire at a slow rate.
» When a hot object is placed on your hand, the neurons
fire at a faster rate.

79

o Different intensities of stimuli can be detected in
two ways: (cont’d)
2. Different neurons can have different threshold levels.
» A glass rod at 40 °C may cause a single neuron to reach
threshold level.
» However, a glass rod at 50 °C may cause two or more
neurons to reach threshold level. The second neuron
would have a higher threshold level than the first.
» The greater the number of impulses reaching the brain,
the greater the intensity of the response.

80

Biology 30 Synaptic Transmission

Synapse:
 Definition:
o A region between neurons, or between neurons
and effectors; also known as the synaptic cleft.
 The synapse is very small (20 nm).
 Nerve transmission is slow across the
synapse.
o This is due to the diffusion of neurotransmitters
across the synapse. (A relatively slow process)

81


Synapse: (cont’d)
 Synapses rarely involve just two neurons.

82


 Presynaptic neurons:
o Contain many synaptic vesicles.
– Synaptic vesicles contain neurotransmitters (chemical
messengers)
o Release the neurotransmitters when an AP
reaches the synaptic end.
– The neurotransmitters diffuse across the synapse to
trigger receptors on postsynaptic neurons (or effectors).

83


 Postsynaptic neurons:
o Contain many membrane receptors for
neurotransmitters.
– There are two types of membrane receptors:
» Excitatory – open up sodium channels to help initiate
an AP.
» Inhibitory – open up potassium channels to inhibit
an AP.

84


 A Synapse

85

Biology 30 Neurotransmitters

Common Neurotransmitters:
 Acetylcholine:
o Can act as an excitatory neurotransmitter.
– Opens up sodium gates and allows Na+ ions to rush
into the neuron.
– If enough Na+ ions rush in, the membrane will
depolarize and an AP will move down the neuron.
o After an AP has been generated, the
acetylcholine must be removed.
– If not, no further APs would be possible, as the
postsynaptic end would not be allowed to repolarize.
o Acetylcholine is destroyed by it’s enzyme
cholinesterase. 86


Common Neurotransmitters: (cont’d)
 Acetylcholine: (cont’d)
o Can act as an inhibitory neurotransmitter.
– Opens up potassium gates and allows K+ ions to
rush into the neuron.
– If enough K+ ions rush in, the membrane will become
hyperpolarized and it will become more difficult for an
AP to occur.
o Other details:
– Acetylcholine is commonly excitatory to skeletal
muscles causing muscular contractions.
– It functions both in the PNS and CNS.
87


 Norepinephrine:
o Can be both excitatory and inhibitory.
o Acts in both the PNS and CNS.
o Responsible mainly for wakefulness / alertness.
 Dopamine:
o Generally excitatory.
o Responsible for voluntary movement and
emotions.
– Recall: Parkinson’s disease (lack of dopamine) 88


 Serotonin:
o Generally inhibitory.
o Acts in the CNS only.
o Responsible mainly for sleep.
 GABA:
o Generally excitatory.
o Responsible for motor behavior.

89


Summation:
 Recall:
o There are many presynaptic neurons at most
synapses.
 How is the creation of an AP on a
postsynaptic neuron controlled?
o Let’s take a look a figure 11 on p.422 (Nelson)

90


 Summation

91


Summation: (cont’d)
 Excitatory Neurons:
o Looking at the diagram, both presynaptic
neurons A and B are excitatory.
o Independently neither neuron can trigger an AP
in the postsynaptic neuron (D).
– The amount of excitatory neurotransmitters released
by either A or B does not open enough sodium
channels in neuron D for neuron D to reach its
threshold.

92


 Excitatory Neurons: (cont’d)
o However, when both presynaptic neurons A
and B release their neurotransmitters at the
same time, they do cause an AP in neuron D.
– This is essentially summation.

93


 Inhibitory Neurons:
o Summation can include inhibitory neurons as well.
o These presynaptic neurons release
neurotransmitters than open potassium channels
instead.
– This causes the postsynaptic neuron (D) to
hyperpolarize instead.
– Hyperpolarization of a neurons membrane makes it
more difficult for an AP to occur.
» However, it is not impossible.

94

Chapter 13
Unit 30 A
Biology
Nervous System
13.2 Summary Electromagnetic Impulse
• Nerves conduct electrochemical impulses from the dendrites
along the axon to the end plates of the neuron.
• Active transport and diffusion of sodium and potassium ions
establish a polarized membrane.
• An action potential is caused by the inflow of sodium ions.
• Nerve cells exhibit an all-or-none response.
• Neurotransmitters allow the nerve message to move across
synapses.

Biology 30 Closure

Can you:
1. explain the all-or-none response and
intensity of response.
2. describe the transmission of a signal
across a synapse.
3. describe the main chemicals and
transmitters involved, i.e., norepinephrine,
acetylcholine and cholinesterase.

96


Nelson (2007), p.420
 Practice #5–7
Nelson (2007), p.425
 Section 13.2 Questions #6 & 7

97

Unit 30 A

Ch. 13 - Lesson 5
13.3 The Central Nervous System
The Brain
(pp.426–32)

98


1. identify the principal structures of the
central nervous system and explain their
functions in regulating the voluntary
(somatic) and involuntary (autonomic)
systems of the human organism; i.e.,
cerebral hemispheres and lobes,
cerebellum, pons, medulla oblongata,
hypothalamus, & spinal cord.

99

Brain Structure and
Biology 30 Function
Brain Protection:
The skull:
 Supports the structures of
the face.
 Protects the brain from
injury.

Unit A - Nervous and Endocrine 100
Systems

Brain Structure and
Biology 30 Function
Brain Protection: - cont’d
The Meninges:
 Made up of 3 membranes that wrap around the
brain.
odura matter
– outer membrane
oarachnoid
– contains blood vessels
– subarachnoid space contains cerebrospinal fluid
(CSF)
opia matter
– directly on top of the brain 101

Brain Structure and
Biology 30 Function
 The Meninges:
(Diagram)

Unit A - Nervous and Endocrine Systems 102

Brain Structure and
Biology 30 Function
Brain Protection: - cont’d
Cerebrospinal Fluid (CSF):
 The brain is also cushioned by CSF between the
arachnoid and pia matter layers.
 CSF also acts as a transport medium.
o It transports nutrients to the brain cells, and wastes
away from the brain cells to the blood.
 There are four chambers in brain (ventricles) also
filled with CSF.
Systems

Brain Structure and
Biology 30 Function


Brain Structure and
Biology 30 Function
Structures of the Brain:
2 Hemispheres:
 The right
hemisphere controls
left side of the body
 The left hemisphere
controls right side of
the body

Systems

Brain Structure and
Biology 30 Function

Systems

Brain Structure and
Biology 30 Function
Structures of the Brain: - cont’d
2 Hemispheres: - cont’d
 The left hemisphere is associated with the
following tasks:
o logical
o symbolic
o sequential

Systems

Brain Structure and
Biology 30 Function
2 Hemispheres: - cont’d
 A structure called the corpus callosum connects
the two hemispheres.
o It allows the two hemispheres to communicate with
each other.
o Thus, the two hemispheres are never really working in
isolation from each other.
o If damaged physically, or by disease, very interesting
observations can be made.
Systems

Brain Structure and
Biology 30 Function
Corpus callosum damaged: (Diagram)

Because the right hemi-
sphere is responsible for
facial recognition.
Who does she
see & why?

Systems

Brain Structure and
Biology 30 Function
There are 3 major divisions:
 Hindbrain (medulla oblongata, cerebellum, & pons)
 Midbrain (reticular formation)
 Forebrain (cerebrum, thalamus, hypothalamus,
pituitary gland, pineal gland, and
basal ganglia)
There are 12 cranial nerve pairs that extend
from the brain. (Bonus material)
 most are mixed nerves (motor and sensory)
 except olfactory and optic nerves (sensory only110
)

Brain Structure and
Biology 30 Function
Cranial
nerves:


Brain Structure and
Biology 30 Function
1. Hindbrain:
 Medulla oblongata:
o Control of body functions like heart rate and
breathing rate.
o Destruction = death
 Cerebellum:
o Co-ordinating body movements
o Balance

Systems

Brain Structure and
Biology 30 Function
1. Hindbrain: cont’d
 Pons:
o Relays nerve impulses between hindbrain and
forebrain.

Systems

Brain Structure and
Biology 30 Function
Structures of the Brain: -
cont’d
1. Hindbrain:
- cont’d

Pons
Medulla oblongata
Cerebellum

Brain Structure and
Biology 30 Function
2. Midbrain:
 Reticular formation:
o Activates forebrain to analyze sensory information.
o Selects which information is to be analyzed by
forebrain.
o Is not a single structure, but rather links various
structures together.

Systems

Brain Structure and
Biology 30 Function
cont’d
2. Midbrain:
- cont’d

Reticular formation

Brain Structure and
Biology 30 Function
3. Forebrain:
 Thalamus:
o “Gate-keeper” of the cerebral cortex
o All sensory information passes through thalamus
o Consciousness (awareness)
 Hypothalamus:
o Monitors and regulates temperature and water levels
in blood
o Co-ordinating center for internal organs (e.g., thirst,
hunger, rage, sex drive, and satiety) 117

Brain Structure and
Biology 30 Function
cont’d
3. Forebrain:
- cont’d

Thalamus

Hypothalamus


Brain Structure and
Biology 30 Function
3. Forebrain: - cont’d
 Pituitary gland:
o Master gland (controls all other glands)
o Link to the endocrine system

Systems

Brain Structure and
Biology 30 Function
cont’d
3. Forebrain:
- cont’d

Pituitary gland


Brain Structure and
Biology 30 Function
 Pineal gland:
o More important in lower animals
o Detects body temperature and exposure to sun
o It is a regressive structure
o Secretes melatonin
– Induces sleep in humans
– Stimulated by darkness
– Inhibited by daylight
o What impact does this have on Canadians?
(Especially those in the far north) 121

Brain Structure and
Biology 30 Function
cont’d
3. Forebrain:
- cont’d

Pineal gland


Brain Structure and
Biology 30 Function
 Basal ganglia:
o Located deep within the cerebrum
o Associated with the following functions:
– Motor control (posture & voluntary movement)
– Cognition (the process of thought)
– Emotions
– Learning

Systems

Brain Structure and
Biology 30 Function
cont’d
3. Forebrain:
 Basal
ganglia:


Brain Structure and
Biology 30 Function
 Cerebrum (Cerebral cortex):
o Most prominent part of the brain
o Occupies approx. 1.35 L of space
(largest of all animals)
o Has a mass of approx. 3 lbs.
o The cerebrum is separated into 4 lobes
– Each lobe is separated by a deep fissure called a ‘sulcus’
o The 4 lobes are:
1. Frontal 3. Occipital
2. Parietal 4. Temporal 125

Brain Structure and
Biology 30 Function
 Cerebrum (Cerebral cortex): cont’d
o Frontal lobe:
– Motor control (movement, speech, etc.)
» The basal ganglia are imbedded within the frontal lobe
– Intellectual activities
– Personality

Systems

Brain Structure and
Biology 30 Function
 Cerebrum (Cerebral cortex): - cont’d
o Occipital lobe:
– Sensory areas interpret visual information (optic nerve)
o Temporal lobe:
– Sensory areas interpret vision and hearing information
– Interpreting speech
– Association areas linked with memory

Systems

Brain Structure and
Biology 30 Function
 Cerebrum (Cerebral cortex): - cont’d
o Parietal lobe:
– Sensory areas for touch and temperature awareness
– Emotions

Systems

Brain Structure and
Biology 30 Function

129

Brain Structure and
Biology 30 Function
Structures of the Brain: - Parietal lobe
cont’d Occipital lobe
 Cerebrum

Frontal lobe

Temporal lobe



Michael J. Fox: - cont’d
Now we will view another video on
 Afterwards, we will discuss how this relates to
what we have learned today.
 Make sure you identify the brain structure that is
mostly responsible for the symptoms of

Link: “Understanding Parkinson’s Disease” 131


Follow up questions to the video,
“Understanding Parkinson’s Disease”.
 What was the brain structure responsible for the
symptoms of Parkinson’s disease?
o Basal ganglia
 What are the symptoms of Parkinson’s disease?
o Trembling hand, stiffness of limbs, depression, etc.

Systems

More follow up questions to the video,
 What is the physiological problem with the
neurons?
o The pre-synaptic axons are not producing or secreting
enough dopamine.
 Parkinson’s disease is treated by taking drugs
like Levodopa. What would be the physiological
effect of Levodopa on the body?
o It is converted into dopamine in the brain. 133

More follow up questions to the video,
 There are other types of drugs, like Mirapex ®,
that stimulate dopamine receptors to function with
lower levels of dopamine.

Systems

Biology 30 The Brain

13.3 The Central Nervous System:
 Review of the Brain:
o Watch Mr. Woods DEMO the making of your
‘thinking’ cap.
o Procedure:
– Make your ‘thinking’ cap.
– Outline the 4 lobes of the cerebrum on your cap.
– Label each lobe.
– Write down 1 function of each lobe within the outlined
area.
» For the temporal lobe, write down the function on both
sides of your cap.
135

Biology 30 The Brain

13.3 The Central Nervous System:
 Review of the Brain:
o As we watch the following video, I want you to
do the following:
– Point to the areas of your brain.
– This is a good time to wear your ‘thinking’ caps.

Link: “Pinky & the Brain”

136

Chapter 13
Unit 30 A
Biology
Nervous System
13.3 Summary The Central Nervous System

Biology 30 Closure

Can you:

138


Nelson (2007), p.430
 Case Study Questions #1–3
Nelson (2007), p.432

139

Unit 30 A

Ch. 13 - Lesson 6
13.3 The Central Nervous System
The Spine
13.4 The Peripheral Nervous System
(pp.433–5)

140



141

Biology 30 The Spinal Cord

Recall:
 The spinal cord is part of the Central
Nervous System (CNS).
 The spinal cord represents the connection
point where the Peripheral Nervous
System (PNS) connects to the CNS.

142


Anatomy:
 The spinal cord is surrounded by vertebrae.
o The vertebrae provide protection against physical
trauma.
 The vertebrae is separated by intervertebral
disks composed of cartilage.

143


Anatomy: (cont’d)
 The spinal cord is made up of two types of
nerve tissue:
o Grey matter:
– Non-myelinated nerve fibres.
– The grey matter is made up of interneurons only.
o White matter:
– Myelinated nerve fibres.
– Both motor and sensory nerves are present.
» Dorsal root: Nerve tract made up of sensory neurons.
» Ventral root: Nerve tract made up of motor neurons.

144


 Anatomy of the spinal cord:

145

13.4 The Peripheral
General Composition:
 Consists of:
o Sensory neurons:
– Relays information from stimulus receptors to the
CNS.
o Motor neurons:
– Runs from the CNS to effectors (muscles or organs).
 The PNS has two distinct divisions:
o The Sensory-Somatic System
o The Autonomic Nervous System

146

13.4 The Peripheral
 The PNS:

147

The Sensory-Somatic
Biology 30 System
In General:
 Relays sensory information about the
external environment to the CNS.
 A response from the CNS (the spine or the
brain) is relayed back to an effector muscle.
 The sensory-somatic system is considered
to be under voluntary (somatic) control.
o For the most part, you can control your muscles
in response to an external stimulus.
o The only exception is the reflex arc.
148

The Sensory-Somatic
Biology 30 System
 The Sensory-Somatic System:

149

The Autonomic
In General:
 Relays sensory information about the
internal environment to the CNS.
 A response from the CNS (the brain) is
relayed back to an effector (smooth muscle,
cardiac muscle, internal organs, or glands).
 The autonomic nervous system is
considered to be under involuntary control.
o For example,
– If your blood oxygen levels fall below normal, the
autonomic nerves acts to restore oxygen levels by 150
increasing breathing and heart rates.

The Autonomic
The ANS is made up of two distinct units:
 The Sympathetic Nervous System (SNS):
o Prepares the body for stress.
– Increases heart rate.
– Causes the release of epinephrine from the adrenal
glands.
– Increases release of glucose from the liver.
– Dilates the pupils.
– Decreases peristalsis in the digestive tract.
– Increases blood flow to the skin.
– Relaxes the bladder’s sphincter.
o Releases epinephrine (a neurotransmitter) onto
the effector. 151

The Autonomic
 The ANS is made up of two distinct units: ( cont’d)
 The Parasympathetic Nervous System (PSNS):
o Restores the body back to normal.
– Decreases heart rate.
– Glucose is stored in the liver.
– Constricts the pupils.
– Increases peristalsis in the digestive tract.
– Decreases blood flow to the skin.
– Constricts the bladder’s sphincter.
o Releases acetylcholine and nitric oxide
(neurotransmitters) onto the effector.
152

The Autonomic
Figure 2,
p.434 (Nelson)
 The ANS
of the PNS:

153

Chapter 13
Unit 30 A
Biology
Nervous System
13.4 Summary The Peripheral Nervous System
• The peripheral nervous system is made up of the sensory-somatic
and the autonomic nervous systems. Together they sense and
respond to external and internal stimuli.
• The autonomic nervous system consists of the sympathetic and
parasympathetic systems. The sympathetic system prepares the
body for stress; the parasympathetic system returns the body to
a resting state.

Chapter 13
Unit 30 A
Biology
Nervous System
Chapter 13 Summary: Outcomes
Knowledge
• describe a neuron and myelin sheath, explaining the formation
and transmission of an action potential and the transmission of
a signal across a synapse and the main chemicals and
transmitters involved (13.1, 13.2)
• identify structures of the central and peripheral nervous
systems and explain their functions in regulating the voluntary
(somatic) and involuntary (autonomic) systems, (13.1, 13.3,
13.4)
• describe the organization of neurons into nerves and simple
reflex arcs (13.1)

Chapter 13
Unit 30 A
Biology
Nervous System
STS
• explain that scientific knowledge and theories develop through
hypotheses, collection of experimental evidence and by
providing explanations (13.1)
• explain that scientific investigation includes analyzing evidence
and providing explanations based on scientific theories and
concepts (13.2)
• explain that the goal of technology is to provide solutions to
practical problems (13.3)

Chapter 13
Unit 30 A
Biology
Nervous System
Skills
• conduct investigations and record data by: investigating the
physiology of reflex arcs (13.1); observing neurons and
synapses (13.3); and observing a mammalian brain and
identifying structures (13.3)
• analyze data and apply concepts (13.1, 13.3)
• work as members of a team (all)

Unit 30 A
Biology

General Outcomes
In this unit, you will
• explain how the nervous system controls physiological
processes
• explain how the endocrine system contributes to homeostasis

Biology 30 Closure

Can you:

159


Nelson (2007), p.435
 Section 13.4 Questions #1,2,4,5
Nelson (2007), pp.441–3
 Chapter 13 REVIEW #1–11, 12–20

160

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