1. Describe the division of the Nervous system?
2. Differentiate
between
the
functions
of
the
sympathetic
parasympathetic divisions of the autonomic nervous system
3. Identify the source gland for adrenalin and explain its role in the “fight or
flight” response.
4. Differentiate between sympathetic and parasympathetic neurons?
5. List the important function of sympathetic and parasympathetic
nervous system?
6. Identify and give the functions for each of the following
Medulla oblongata
Cerebrum
Thalamus
Cerebellum
Hypothalamus
Corpus callosum
7. Explain how the hypothalamus and pituitary gland interact as the
neuroendocrine control centre (p. 371-373).
and
1. Your brain uses 20% of your body's energy, but it makes up
only 2% of your body's weight.
2. Your cerebral cortex is about as thick as a tongue
depressor. It grows thicker as you learn and use it.
3. Your brain is about the size of a cantaloupe and wrinkled
like a walnut.
4. Your brain generates 25 watts of power while you're awake--enough to illuminate a light bulb.
5. A newborn baby’s brain grows almost 3 times in course of
first year .
6. Toxins in commonplace items such as carpeting and shower
curtains may be contributing to memory loss over time? And
overexposure to aluminum compounds—in foil, cookware,
deodorants, antacids, and toothpaste—can affect brain function
7. Lavender can help you sleep. A cooked potato can jump-start
your brain when you're feeling foggy. The essential oil of
jasmine can restore mental alertness
8. Eating foods rich in vitamins E and C, & beta-carotene may help
lower your risk of Alzheimer’s disease.
9. The human brain is ~75% water.
10. Neurons multiply at a rate 250,000 neurons per minute during
early pregnancy.
The nervous system is not
a ‘normal’ system.
It is made up of neurons
(3 types) not organs.
It controls almost every
organ system through
negative and positive
feedback loops.
involuntary
voluntary
The Central Nervous System (CNS) integrates
the information it receives from all over the
body in order to make decisions.
CNS composed of the brain and spinal cord.
The CNS is entirely enclosed 3 layers of
membranes (meninges) and in bone: the
skull and vertebrae.
Cerebral Spinal Fluid and tissue also insulate
the brain and spinal cord.
After puberty, we lose ~10,000 neurons in the
CNS every day, and no new neurons are
made.
During embryonic development, the
brain forms as a tube (neural cord).
1. Anterior becomes the brain.
2. Posterior becomes the spinal cord.
The brain has 3 main parts:
1. The Cerebrum
2. The Cerebellum
3. The Medulla oblongata
The cerebrum is the largest
portion of the brain. It is divided
into a right and left cerebral
hemispheres, which are separated
by the corpus callosum.
The hemispheres are covered by a
thin layer known as the cerebral
cortex, which is the most recently
evolved part of the brain. It is
responsible for intelligence
The cerebrum coordinates sensory
data and motor functions.
It is where memory is kept; where
conscious thought processes are
made; where a lot of interneural
connections are made.
When impulses require some
processing before responses are
made, this is where they go (ie:
responding to a verbal question).
Overall, the cerebrum governs
intelligence and reasoning,
planning, learning, memory, and
personality.
The cerebrum is divided into 4 lobes.
1. Frontal Lobe
2. Parietal Lobe
3. Occipital Lobe
4. Temporal Lobe
No region of the brain functions alone, although the major
functions of the lobes are:
1. The occipital lobe (back of the head) receives and
processes visual information.
2. The temporal lobe receives auditory signals, olfactory
signals, processing language and the meaning of words.
3. The parietal lobe is
associated with the sensory
cortex and processes
information about touch,
taste, pressure, pain, and
heat/cold.
4. The frontal lobe conducts 3
functions:
a) Motor activity &
integration of muscle
activity
b) Speech
c) Thought processes
The corpus callosum is the
dense tissue that holds the
two hemispheres of the
cerebrum together.
It also conducts impulses
from one side of the brain
to the other.
It is through this part of the
brain that coordinates the
activities of the two sides of
the brain.
The cerebellum is the 2nd
largest part of the brain.
This is the place where the
impulses that give rise to
movements are coordinated.
The cerebellum coordinates
small, smooth movements (as
in fine motor control).
The cerebellum also maintains normal muscle tone &
posture, and coordinates balance (proprioception).
The brain stem is the smallest
and the oldest and most
primitive part of the brain.
The brain stem is continuous with
the spinal cord, and is composed
of:
1. Medulla oblongata
2. Pons
The medulla oblongata is closest
to the spinal cord, and is
involved with the regulation of
heartbeat, breathing,
vasoconstriction (blood
pressure).
It also has reflex centers for
vomiting, coughing, sneezing,
swallowing, and hiccuping.
The medulla oblongata contains receptors that are receptive to the
conditions of the blood (such as too much CO2 which causes
inhalation).
Has control over the internal organs; it is the ‘unconscious’ part of
the brain.
The midbrain connects
the hindbrain and
forebrain.
It controls our eye
reflexes.
The Thalamus directs the
impulses that travel up the
spinal cord to the correct
region of the cerebrum.
It is often referred to as the
‘sorting centre’ or ‘gatekeeper
of the cerebrum’.
It filters out extraneous and
unimportant sensory stimuli to
the higher brain.
The Hypothalamus regulates
homeostasis.
It has regulatory areas for thirst,
hunger, body temperature, water
balance, and blood pressure.
It also links the Nervous System to
the Endocrine System.
This part of the brain also has control over the internal organs.
The hypothalamus samples the blood that travels through it and responds,
either through the initiation of nerve impulses or by causing the pituitary
gland to release hormones.
The Pituitary Gland is also
known as the ‘Master Gland’.
This is a small gland with two
parts: the anterior and
posterior lobes.
It produces a large number of
hormones, many of which
control the release of hormones
from other glands in the body.
Posterior Pituitary:
This part of the gland releases
the hormones that are made
in the Hypothalamus, but are
stored in the Posterior Pituitary.
The hormones are transferred
and stored in special hollow
nerve fibres that run from the
hypothalamus to the posterior
pituitary.
Examples of hormones: (eg. ADH and Oxytocin)
Anterior Pituitary:
This part of the gland makes and
releases its own hormones.
It is stimulated to release its
hormones by the hypothalamus.
There is a blood connection
between the hypothalamus and
the anterior pituitary.
Examples of hormones: Growth hormone, Prolactin, FSH & LH,
Thyroid Stimulating Hormone (TSH), Adrenal Cortex Stimulating
Hormone (ACTH), Melatonin
The spinal cord (dorsal nerve cord) runs along the
dorsal side of the body and links the brain to the
rest of the body.
Vertebrates have their spinal cords encased in a
series of (usually) bony vertebrae.
Some tracts nerves are ascending (carrying
messages to the brain), others are descending
(carrying messages from the brain).
The spinal cord is also involved in reflexes that do
not immediately involve the brain.
The spinal cord has 4 parts:
Cervical: the neck region.
*No peripheral nerves originate
from this region.
Thoracic: the thoracic cavity
(lungs etc…)
Lumbar: the abdominal cavity
(guts, kidneys, liver…)
Saccral: the tail bone area
The Peripheral Nervous System
(PNS) contains only nerves.
It connects the brain and spinal
cord (central nervous system) to
the rest of the body.
There are 12 pairs of Cranial
nerves in the PNS that take
impulses to and from the
brain (CNS).
These Cranial nerves can be
either sensory
(optic/olfactory) or motor
(facial nerves) or a mixture of
the two (tongue, facial skin).
There are also 31 pairs of Spinal
nerves which take impulses to and
away from the spinal cord.
There are 2 main components of the Peripheral Nervous System:
1. Somatic Nervous System
2. Autonomic Nervous System
This system includes all of the nerves controlling:
a) Voluntary musculo-skeletal region
b) Exterior sense organs (with cranial nerves)
c) Reflex arcs
These are primarily under VOLUNTARY control.
Most sensory input carried in the PNS remains
below the level of conscious awareness.
Input that does reach the conscious level
contributes to perception of our external
environment.
Senses:
Input to the nervous system is in the form of
our five special senses: touch, vision, taste,
smell, and hearing.
There are also the somatic senses:
Pain, temperature, and pressure.
Sensory input begins with sensors that react
to stimuli in the form of energy that is
transmitted into an action potential and sent
to the CNS.
This system is made up of
smooth muscle, cardiac
muscle, and glands.
The autonomic nervous
system is that part of PNS
consisting of motor neurons
that control internal organs
(ie: heart, intestine, bladder,
uterus…)
These are all under
involuntary control; they
happen automatically and
without awareness.
The autonomic nervous
system is divided into 2 parts:
1. Sympathetic Nervous
System
2. Parasympathetic Nervous
System
Sympathetic
involves expenditure of
energy (“fight or flight”)
Parasympathetic
restores or conserves energy
(“return to normal”)
Involved in the ‘fight or flight’
response.
This system is stimulatory and
prepares the body for action.
These nerves come off the ganglia
from the mid-region of the spinal
cord.
Sudden, simultaneous release of noradrenalin from all the
sympathetic neurons (as in times of fright) has a critical effect.
It causes the release of the hormone adrenalin from the medulla of
the adrenal glands (located on top of the kidneys).
The noradrenalin and adrenalin prepare the body for fight
or flight in the following ways:
1. Increases heart rate & BP; more blood supplied to the body quickly
2. Widens air passageways so more air can be exchanged each breath
3. Sudden contraction of muscles to tense the body up for action.
Included in this is the contraction of the diaphragm causing a ‘gasp’.
4. Iris of the eye contracts & widens pupil = maximum visual alertness.
5. Increased blood flow to skeletal muscles so they are more able to act.
6. Decreased digestive activity, circulation and control.
The parasympathetic nervous system is involved
in relaxation. The nerves come off the ganglia in
the upper & lower parts of the spinal cord.
It releases acetylcholine to return the body to its
normal state after stress. It maintains a relaxed
state.
It has the exact opposite effect than the
sympathetic NS.
1.
2.
3.
4.
5.
6.
Decreases heart rate & BP to normal (120/80).
Constricts air passageways back to normal.
Relaxation of muscles.
Iris of the eye relaxes and pupil returns to its normal size.
Decreased blood flow to skeletal muscles.
Increased digestive activity, circulation and control.
Basis of Comparison
Sympathetic
Neurons
Parasympathetic
Neurons
Effect
Active body function
Spinal origin
Thoracic and lumbar
Vegetative body
function
Cranial and sacral
Neurotransmitter
Noradrenalin
Acetylcholine
Restoring enzyme
Monoamine oxidase
Acetylcholinesterase
Location of motor
ganglion
Closer to the CNS
Farther from the CNS