Download Chapters 45, 48, 49 PPT

Body Systems – Part II
Chemical Signals – CH 45
Nervous Signals– CH 48
Nervous System – CH 49
1
Chapter 45
Hormones and the Endocrine
System
2
Hormone  chemical excreted into body fluids
- used for communication within an organism
- helps maintain homeostasis
- modified amino acids and steroids
- carried by the circulatory system to target cells
Target Cells  equipped to respond to particular hormone;
typically have membrane proteins that allow SPECIFIC
hormones to bind
**So this means that hormones in the blood can cause changes
in SOME cells, and other cells will ignore them**
3
Nervous vs. Endocrine System
Nervous System 
high speed signals;
Ex. Jerking your hand
away from a flame
Endocrine System 
slower
communication; Ex.
Maturation of a
butterfly; two parts:
4
Local Regulators
Affects activity between neighbor cells; only uses
LOCAL targets; there are 3 types:
Growth Factors  peptides/proteins stimulate cell growth and
development in target cells; includes nerve growth factors
Nitric Oxide (NO)  a gas that has multiple functions including acting as a
neurotransmitter (when secreted by neurons) and relaxing smooth muscle
(when secreted by endothelial cells); it triggers a change in a target cell
then breaks down quickly; it is also highly reactive and can be toxic
Prostaglandins  modified fatty acids first isolated in semen produced by
prostrate; effect the female reproductive system (can cause smooth
muscle contractions to help sperm reach egg; also induces uterine
contraction in childbirth); aspirin and ibuprofen can inhibit the effects of
PGs
5
Local Regulators  divided
into 2 groups:


Paracrine 
act on cells
NEAR the
secreting cell
Autocrine 
secreted
regulators
that act on
the secreting
cell itself!
6
Synaptic
Signaling vs.
Neuroendocrine
Signaling
Signaling 
neurons form specialized
junctions called synapses
with target cells, such as
other neurons and
muscle cells; at
synapses, neurons
secrete molecules called
neurotransmitters,
which diffuse a very short
distance to bind to
receptors on the target
cell
 Synaptic
Neuroendocrine Signaling  specialized
neurons called neurosecretory cells secrete
chemical signals that diffuse from nerve cell
endings into the bloodstream;
these signals are a class of hormones called
neurohormones (ex. ADH)
- Endocrine – Ductless (secretes hormones into body
fluids)
- Exocrine – Uses ducts to send to specific locations
(ex. sweat glands)
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Signal Transduction Pathway
3 main Processes:
- Reception signal binds to a receptor
protein
- Signal Transduction  causes a change in
the target cell
- Response  causes a change in the
receptor cell’s behavior
Different types of
cells respond
differently, so the
SAME SIGNAL can
bring about a
DIFFERENT
RESPONSE in
various target cells.
Only small amounts
of regulators (ex.
Hormones) are
necessary because
the pathway
triggers enzyme
cascades that can
greatly amplify the
signal.
8
The endocrine system and the nervous system
are very closely related


Several chemicals serve as both hormones of
the endocrine system and signals in the nervous
systems
 Ex. Epinephrine (This shows how the two
systems are CHEMICALLY related)
○ Nervous system = neurotransmitter
○ Endocrine system = “fight or flight” hormone
Each system affects the output of the other
 Ex. Breast feeding – uses interdependent
nervous and hormonal signals:
○ Suckling = simulates sensory cells and
nervous signals in the hypothalamus then
trigger the release of oxytocin from the
pituitary gland; this oxytocin cause the
mammary cells to secrete milk
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Tropic
Hormones

Tropic Hormone:
have other
endocrine
glands as their
targets
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Feedback
Feedback is COMMON TO BOTH THE ENDOCRINE AND
THE NERVOUS SYSTEM!!
Positive Feedback: causes a change in the same direction; ex.
increasing milk release, labor during childbirth (oxytocin!)
Negative Feedback: causes a change in the opposite
direction; is responsible for the endocrine system’s ability to
regulate homeostasis mechanisms; ex. sweating = cools the
body
11
Pancreas



Secretes bicarbonate ions to balance the pH from the acid
chyme in the stomach
Alpha cells secrete glucagon  signals the liver to release
glucose back into blood stream (increases blood sugar
levels); used when someone has not eaten in a while and
blood sugar levels are low
Beta cells secrete insulin  signals body cells to take up
glucose from the blood (decreases blood sugar levels); used
when someone just ate and blood sugar levels are high
Exocrine  (secrete
into ducts)
bicarbonate ions and
digestive enzymes
Endocrine 
(ductless)
insulin/glucagon
antagonists
12


**Insulin and Glucagon are not steroids…they are
PROTEIN hormones made of AA’s**
Glucagon and Insulin are antagonistic hormones and work
together to regulate the blood sugar levels in the body (recall
our other antagonistic hormones are calcitonin and PTH for
calcium)
13
Diabetes

Most common endocrine disorder = Diabetes  caused by
a deficiency in insulin or loss of response to insulin in target
cells
 Type I diabetes  autoimmune disorder; immune system
attacks pancreas; occurs in childhood and causes kid to
not be able to make insulin; treated with insulin injections
or a pump
Type II diabetes 
characterized by deficiency of
insulin or reduced
responsiveness in target cells;
90% of diabetics are type II;
can usually be managed by
diet and exercise; caused by
genetics and obesity
14
Hypothalamus


Integrates the endocrine and nervous systems
 A good example of how they are structurally related is the
NEUROSECRETORY CELLS located in the hypothalamus
It is part of the lower brain
** It is important in
homeostatic regulation (ex.
body’s thermostat, regulates
hunger/thirst, role in
sexual/mating behaviors)
** It regulates the Pituitary
Gland
** The neurosecretory cells
of the hypothalamus
secrete two hormones:
oxytocin and ADH
15
Pituitary

Located at base of the brain
 Referred
to as “Master Gland” because it
regulates so many other endocrine functions
It obeys orders from the hypothalamus
 Has 2 discrete parts:

○ Anterior Pituitary (front)
○ Posterior Pituitary (back)
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Posterior Pituitary


Posterior Pituitary Hormones  made by hypothalamus but
secreted by posterior pituitary; these hormones act on
specific structures rather than affecting other endocrine
glands
Stores and secretes two hormones:
1. Oxytocin  acts on muscles of
uterus; induces contractions during
childbirth and controls milk secretion
during nursing
2. Antidiuretic Hormone (ADH) 
acts on the kidneys; causes kidneys
to increase water retention thus
decreasing urine volume; helps
regulate the osmolarity of the blood
17
Anterior Pituitary
Secretes hormones directly into blood
 Hypothalamus secretes two kinds of hormones:

 Releasing hormones  makes anterior pituitary
secrete its hormones
 Inhibiting hormones  makes anterior pituitary STOP
secreting hormones

The anterior pituitary secretes many
hormones…
18
Anterior Pituitary Hormones



Growth Hormone (GH)  promotes growth
directly and also stimulates growth factors
 Human Growth disorders are related to GH
production:
 Too much GH (hypersecretion) =
gigantism
 Too little GH (hyposecretion) = pituitary
dwarfism; this can be treated using
growth hormones from cadavers
Insulinlike Growth Factors (IGF)  stimulate
bone and cartilage growth
Prolactin (PRL)  similar to GH; produces a
variety of effects in different vertebrates (so
scientists think this is an ANCIENT
HORMONE); mammals = stimulates
mammary gland growth and milk synthesis;
freshwater fish = salt and water balance
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Anterior Pituitary Hormones


Follicle-stimulating
Hormone (FSH) 
stimulates production of
ova and sperm
Luteinizing Hormone
(LH)  stimulates
ovaries and testes
** Gonadotropins =
stimulate the activity of
male and female gonads;
FSH and LH are examples
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Anterior Pituitary Hormones




Thyroid Stimulating Hormone (TSH)  stimulates the
thyroid gland (releases thyroid hormone which increases
metabolic rate, raising body temp)
Adrenocorticotropic Hormone (ACTH)  stimulates the
production and secretion of steroid hormones by the adrenal
cortex (part of the adrenal gland)
Melanocyte-stimulating Hormone (MSH)  regulates the
activity of pigment-containing cells in the skin; has a role in
fat metabolism
Endorphins  body’s natural opiates; inhibit the perception
of pain
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




Consists of 2 lobes on the trachea
Thyroid hormone increases the metabolic rate,
increasing the body temperature
Thyroid has a critical role in vertebrate
development
& maturation (ex. Human development),
homeostasis (blood pressure, heart rate, muscle
tone, digestion)
The term “thyroid hormone” refers to two closely
related hormones:
 Triiodothyronine (T3)  causes changes
to target cells
 Thyroxine (T4)  thyroid secretes mainly
T4, but the target cells convert it to T3; this
hormone stimulates and maintains
metabolic processes
 BOTH T3 and T4 affect metabolic
processes; important in bioenergetics
Calcitonin  LOWERS calcium levels in blood
(works antagonistically with PTH)
Thyroid
Gland
22
23
Thyroid Imbalances Include…
Cretinism  deficiency in development, retarded
skeletal/mental growth, develops in infants from hypothyroidism
Goiter  deficiency of iodine in diet
Hyperthyroidism  Too much thyroid hormones; symptoms =
weight loss, profuse sweating, high blood pressure
Hypothyroidism  Too little thyroid hormones; symptoms =
weight gain, lethargy
Cretinism
Goiter
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Parathyroid




Found on the surface of the thyroid; function in homeostasis of calcium
ions (very important to the normal functioning of all cells)
Parathyroid Hormone (PTH)  raises calcium levels in blood; VERY
important!
Calcitonin  decreases calcium levels in the blood
PTH and Calcitonin are antagonistic hormones and work together to
regulate the calcium levels in the blood (example of homeostasis)
25
Adrenal Gland
Adjacent to kidneys
 Two parts:

 Adrenal cortex (outside)
 Adrenal medulla (inside)
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Close ties to the nervous system – FIGHT
OR FLIGHT
 Catecholamines – secreted in response to
positive or negative stress
Norepinephrine  sustaining blood
pressure
Epinephrine  heart and metabolic
rates (Epi pen for anaphylactic shock);
also acts as a neurotransmitter;
GOOD EXAMPLE of how the
endocrine and nervous systems are
chemically related
 Mechanism:
*Adrenal medulla under control of nerve cells
from sympathetic division
*Nerve cells excited by stressful stimulus
*Acetylcholine released in adrenal medulla,
and combines with receptors to release
epinephrine

Adrenal
Medulla
(inside)
27


In contrast to the adrenal medulla,
which reacts to nervous input, the
adrenal cortex responds to
endocrine signals.
Corticosteroids include:
 Glucocorticoids  glucose
metabolism; increases glucose
in blood; secreted in response to
stress and promotes the
synthesis of glucose from noncarbohydrate substrates (ex. fats
and/or proteins)  helps with
long-term environmental issues
 Mineralocorticoids  helps
inflammatory conditions; effects
salt and water balance in
kidneys
 BOTH help the body deal with
LONG TERM stress (whereas
epinephrine and norepinephrine
deal with SHORT TERM stress)
Adrenal
Cortex
(outside)
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Adrenal Medulla vs. Adrenal Cortex
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Controlled by
gonadotropins from
the anterior pituitary
gland
 Produced in both
males and females (in
different proportions);
produced in testes in
males and ovaries in
females; general
function = affect
growth and
development and also
regulate reproductive
cycles and sexual
behavior
 3 major types

Gonadal Steroids
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Types of Gonadal Steroids



Androgens  ex. testosterone; development and
maintenance of male reproductive system; produced in
an embryo to turn the fetus into a male instead of a
female; produced during puberty to stimulate secondary
sex characteristics (hair growth, low voice)
Estrogens  ex. estradiol; effects the female
reproductive system and secondary sex characteristics in
females
Progestins  ex. progesterone; prepares and maintains
the uterus which supports the growth and development of
an embryo
31
Pineal Gland
Small mass of tissue near the center of the
brain
 Secretes the hormone melatonin, which
regulates functions related to light/dark and
seasons marked by changes in day length;
related to biological clock rhythms

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Vertebrate Endocrine System
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34
Chapter 48
Neurons, Synapses, and
Signaling
35
Nervous System



Neurons (functional unit of
the nervous system) are
nerve cells that transfer
information within the body.
Communication by neurons
is based on two distinct
types of signals:
 long-distance electrical
signals
 short-distance chemical
signals
If an organism does NOT
have an integration center, it
would not be able to
interpret stimuli.
36
-Axons 
Neurons (nerve cells)
-Structural and functional unit of the nervous
system
-Has a cell body (contains the nucleus) and
fiber-like extensions (dendrites and axons)
-Dendrites
-Short branched; many per cell body;
receive INCOMING information and
pass it to the cell body
-Long; one per cell body;
convey OUTGOING
messages from the
neuron to other cells
-Axon hillock – part where
the axon joins the cell
body
-Covered by myelin
sheaths (insulated layer)
-Synaptic terminals –
specialized endings; relay
signals from neuron to
other cells by releasing
chemical messengers
called neurotransmitters
-Site of contact between a
synaptic terminal and a
target cell is called a
synapse
-Presynaptic cell =
transmitting cell
-Postsynaptic cell = target
cell
37
38
-Supporting Cells (called Glia)
-Help support the nervous system and help it function properly
-Originally thought to only have a structural role, but some synaptic interactions do
occur between glia and neurons
-In mature CNS, the glia are called astrocytes – they provide metabolic and
structural support for neurons
-Help form the blood-brain barrier  restricts passage of most substances
into the brain which controls the extracellular chemical environment of the
CNS (FORMED BY TIGHT JUNCTIONS)
-Oligodendrocytes (in CNS) and Schwann cells (in PNS) are glia that form
myelin sheaths around the axons of neurons
-Necessary b/c can’t use regular cell membranes b/c they are made of
lipids which are poor conductors of electrical currents; the myelin works
better
39
Overview
-Nervous system is made up of living neurons
-Neurons are specialized for the fast transmission of impulses
-Three major overlapping functions:
-Sensory Input  sensory receptors take info from inside body and
outside world and convey it to integrations centers
-Integration  carried out in the CNS (central nervous system; brain and
spinal cord); input is interpreted and body responds appropriately; if there
was no integration center, organisms wouldn’t be able to interpret stimuli
-Motor Output  conduction of signal from integration center to the
effector cells (muscles or glands that carry out the signal)
-Signals are conducted by
nerves
-PNS (peripheral nervous
system) = nerves that
communicate motor and
sensory signals between
the CNS and the rest of the
body
-Information is communicated
by both electrical and chemical
signals
40
Cerebrospinal Fluid

Made in the brain by filtering the blood; fills the space in the brain and
spinal cord
41
The Nature of Nerve Signals
-Nerve
signals are changes in voltage across the membrane due to
movement of ions
-Membrane Potential  the potential charge difference between the
cytoplasm and the extracellular fluid of a cell
-Resting Potential  membrane potential of an unstimulated neuron
-Can measure membrane potential as a voltage; typical animal cell is –
50 to –100 mV (the negative means the inside of the cell is negative in
charge w.r.t the outside)…in resting neurons, the membrane potential
is more negative than the threshold potential
The inside of
the cell is
NEGATIVELY
charged in
comparison to
the outside of
the cell
42
-Differences in membrane
potential are sustained by the
actions of the sodiumpotassium pump
-Na+ pumped OUT (3 at a
time)
-K+ pumped IN (2 at a
time)
-THEREFORE…outside
= positive; inside =
negative
-Goes against the
gradient, so needs to use
energy (ATP)  active
transport
-Ion channels are selective for
specific ions; so a membrane
can have different
permeability's to different ions
-They determine WHAT
can pass through, but not
the RATE
Sodium
Potassium
Pump
43
Gated Ion
Channels
Gated ion channels are specialized
proteins that span the membrane, and
allow ions to diffuse back and forth across
the membrane according to their
respective gradients.
Chemically-gated ion channels 
respond to a chemical stimulus (ex.
neurotransmitter)
Voltage-gated ion channels 
respond to a change in membrane
potential
Allows only ONE kind of ion to pass
through
44
-Graded Potentials  magnitude of change depends on the strength of the stimulus (larger
stimulus will open more channels)
-Hyperpolarization – increase in voltage across the membrane
-Open K+ channel; K+ flows out and causes the inside of the cell to become more
negative
-Depolarization – reduction in the voltage across the membrane
-Open a Na+ channel; Na+ flows in and causes the inside of the cell to become more
positive
45
-Action Potentials  ALL OR NOTHING depolarization
-DEPOLARIZATION causes an action potential
-Triggered by graded potentials
-When it reaches a certain point, the threshold potential (usually 15-20 mV
more positive than the resting potential) it causes an action potential
(NERVE IMPULSE!); all or none event
SEE Fig. 48.11
-Occurs in the axons (not dendrites)
pg. 1068
-HYPERPOLARIZATION does NOT cause action potentials
explains
everything
-Action Potential Mechanism:
perfectly…
-Resting State – Na+ and K+ channels closed
-Threshold – some stimulus opens Na+ channels; it reaches threshold
potential, and therefore more Na+ channels open triggering an action
potential
-Depolarization - because Na+ channels are open and K+ channels are
closed, the inside of the cell becomes more positive
-Repolarization – Inactivation gates close the Na+ channels and the K+
channels open; K+ leaves the cell and the inside becomes more negative
than the outside
-Undershoot – K+ gates remain open because they are slow, but the Na+ gates
are closed; resting state is restored very quickly (hyperpolarization happens
for a millisecond)
Action potentials arise because some ion channels in neurons are voltage-gated ion
channels, opening or closing when the membrane potential passes a particular level
46
47
-Because both gates of the Na+
channel are closed, if another
stimulus arrives during this period, it is
unable to trigger a change
(inactivation gates had not had time to
open back up yet)  called
refractory period (neuron is
insensitive to depolarization)
-It is the number of action potentials
per second, not their amplitude, that
codes for a stimulus intensity in the
nervous system
-Action potentials propagate
themselves along an axon (like tipping
over the first of a long line of
dominoes)
-Factors that affect the speed of
the action potentials (how fast
they go along the axon):
-Diameter of axon (larger diameter
 faster transmission)
-Saltatory conduction  action
potentials that jump from node to
node
48
Synapses
-Communication between cells occurs at synapses
-Synapses – unique cell junctions that control communication between a neuron
and another cell; two types: electrical or chemical
-Electrical Synapses
-Allows action potentials to spread from presynaptic cell to postsynaptic cell
via gap junctions
-Not as common as chemical synapses
-Chemical Synapses
-Very common
-Chemical synapses are called synaptic clefts; they separate presynaptic
cell from postsynaptic cell
-The cleft prevents an action potential from going directly from the pre
to the postsynaptic cell
-A series of events converts the electrical signal of the action
potential arriving at the synaptic terminal into a chemical signal
that travels across the synapse, where it is converted back into an
electrical signal in the postsynaptic cell. (electrical signal 
chemical signal  electrical signal)
Fig. 48.16 pg. 1072…
49
***A series of events
converts the electrical
signal of the action
potential arriving at the
synaptic terminal into a
chemical signal that
travels across the
synapse, where it is
converted back into an
electrical signal in the
postsynaptic cell.
(electrical signal 
chemical signal 
electrical signal)
1. An action potential DEPOLARIZES the PRESYNAPTIC membrane
2. The depolarization opens voltage gated channels, allowing Ca 2+ to enter the cell
(neuron).
3. Calcium causes synaptic vesicles to fuse with the pre-synaptic membrane
4. Neurotransmitters are released into the synaptic cleft
5. Neurotransmitters bind to the POSTSYNAPTIC membrane
6. Ion channels open, allowing Na+ and K+ ions to enter the postsynaptic cell
50
-Neurotransmitters (intracellular
messengers) are held in the tip of
the pre-synaptic axon
-Action potential releases these
neurotransmitter molecules into the
synapse (the action potential
depolarizes the membrane)
-The postsynaptic membrane has
special receptors for
neurotransmitters
-Neurotransmitter binds  opens
ion channels (chemically gated!)
– postsynaptic membrane is
either hyperpolarized or
depolarized (depending on
receptor)
-Neurotransmitter is removed
quickly (enzyme degradation)
 therefore the effect is brief
and precise
-NOTE: nerve impulses can only
transmit ONE way
Structure of a
Chemical
Synapse
51
-BOTH 
-Graded potentials
-The electrical impact on the postsynaptic cell
decreases with the distance away from the
synapse
-Excitatory  EPSP
-Allows Na+ in and K+ out (more
permeable to Na+, so more of that is
allowed in)
-Inside of cell becomes positive =
DEPOLARIZES the plasma membrane
(gets it closer to the action potential)
-Excitatory Postsynaptic Potential (EPSP)
 the name for the whole process that
uses an excitatory synapse
-Inhibitory  NO ACTION POTENTIAL!
IPSP
-K+ out and Cl- in (higher permeability to
K+)
-Inside of cell becomes negative =
HYPERPOLARIZE the plasma membrane
-Inhibitory Postsynaptic Potential (IPSP) 
the name for the process that uses an
inhibitory synapse
Excitatory
Synapse vs.
Inhibitory
Synapse
52
53
Summation
-Several synaptic terminals working simultaneously on the same postsynaptic cell
can have an additive effect  summation!
-Temporal Summation  one or more synaptic terminals rapid fire with signals
(voltage has no time to return to resting)
-Spatial Summation  several synaptic terminals (on DIFFERENT cells) all send
signals to the same postsynaptic cell (additive effect)
54
Neurotransmitters
-Same neurotransmitter can produce different effects on different types of cells (depends on the
receptors)
-Major neurotransmitters 
-Acetylocholine – most common; vital for nervous system functions that include muscle
stimulation, memory formation, and learning; can be either inhibitory or excitatory
-Biogenic Amines – derived from amino acids
-Epinephrine & Norepinephrine (excite and inhibit)  MORE ON THESE NEXT
CHAPTER
-Dopamine (generally excite)  affect sleep, mood, attention, and learning
-Serotonin (generally inhibit)  affect sleep, mood, attention, and learning
-Amino Acids –
-GABA (gamma aminobutyric
acid) – found at most inhibitory
synapses; creates IPSP
(increases Cl- permeability) 
no action potential
-Neuropeptides – short chains of
AA’s
-Substance P – excite
Signal; mediates
perception of pain
-Endorphins – decreases
perception of pain;
emotional effects
55
Gas signals of Nervous System
-Nitric Oxide (NO)  NO diffuses into
neighboring target cells, produces a
change, and is broken down within a few
seconds; in its target cells, NO works
like many hormones, stimulating an
enzyme to synthesize a second
messenger that directly affects cellular
metabolism
- Carbon Monoxide (CO)  In the
brain, CO regulates the release of
hypothalamic hormones; in the PNS, it
acts as an inhibitory neurotransmitter
that hyperpolarizes intestinal smooth
muscle cells
-Gasses not stored; cells make them on
demand
- They are used as LOCAL regulators
56
Chapter 49
Nervous Systems
57
Evolution and Diversity of Nervous
Systems
-Great Diversity in organization
of new systems
-Lack nerve systems
(sponges)
-Nerve nets (cnidarians)
-Cephalization (neurons
clustered in head)
-Nerve cords
(planarians)
-Clearly defined
CNS….etc.
58
Glia and Blood Brain Barrier
-The major types of glia (connective tissue of nervous system) nourish, support
and regulate neurons.
-Oligodendrocytes and Schwann cells function in axon myelination, a
critical activity in the vertebrate nervous system.
-Astrocytes induce cells that line the capillaries in the CNS to form tight
junctions.
The result is the blood-brain barrier, which controls the
extracellular environment of the CNS by restricting the entry of
substances from the blood.
59
The brain integrates the complex
behavior of vertebrates.
 The spinal cord conveys information
to and from the brain and generates
basic patterns of locomotion.
 The spinal cord acts independently
as part of the simple nerve circuits
that produce reflexes, the body’s
automatic responses to stimuli (ex.
pulling hand away from hot stove.)
 Cerebrospinal fluid is formed in the
brain by filtering blood.
 In mammals, it fills the spaces in
the brain and the spinal cord. The
function is to act as a shock
absorber.
 The brain and the spinal cord contain
gray and white matter.
 Gray matter consists of cell bodies,
dendrites, and unmyelinated axons.
 White matter contains axons with
myelin sheaths.

Central Nervous
System
60
Vertebrate Nervous System
CNS  brain and spinal cord
PNS  everything else!
Parts of the peripheral nervous system:
- Sensory (AFFERENT) division  incoming neurons
- Motor (EFFERENT) division  outgoing neurons
motor subdivides:
- Somatic  carries signals to SKELETAL muscles
- Autonomic  regulates internal environment
autonomic subdivides:
- Sympathetic  ACTIVE (fight/flight)
- Heart beats faster, arousal/energy
Cerebrospinal Fluid =
- Parasympathetic  INACTIVE (rest/digest)
made in the brain by
filtering blood; fills the
- Calming/conserving energy/ selfspaces in the brain
maintenance
and spinal cord
- Enteric  control the organs of the digestive,
cardiovascular, excretory, and endocrine
systems
61
Actions of two divisions of autonomic system
62
The Brain
- The vertebrate brain has three major
regions: the forebrain, midbrain,
and hindbrain.
- The FOREBRAIN activities include
processing olfactory input (smell),
regulation of sleep, learning, and any
complex processing.
Cerebrum, Diencephalons,
Thalmus, Hypothalamus,
Epithalmus
- The MIDBRAIN coordinates routing of
sensory input
- The HINDBRAIN controls involuntary
activities, such as blood circulation,
and coordinates motor activities, such
as locomotion.
Pons, Medulla oblongata,
Cerebellum
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Brainstem (lower brain)
- Major Functions: homeostasis,
coordination of movement;
conduction of information to higher
brain centers
- Consists of 3 parts
- Medulla oblongata  controls
homeostatic functions (including
breathing, swallowing, digestion,
heart and circulation)
- Pons  also helps control
automatic functions (“assists”
medulla)
- Midbrain  acts as a projection
center; sends coded sensory
information to forebrain
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Cerebellum
Develops from the
metencephalon (hindbrain)
 Functions in coordination;
muscle actions; involved in
learning and remembering
motor responses
 Balance, hand-eye
coordination

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Thalamus/ Hypothalamus




Develops from diencephalon (forebrain)
Epithalamus – produces cerebrospinal fluid
Thalamus – main input center for sensory
information going to cerebrum and main output
center for motor information leaving the cerebrum
Hypothalamus – important in homeostatic regulation
- Source of hormones
- Regulates the pituitary gland
- Body’s thermostat
- Regulates hunger/thirst
- Role in sexual/mating behaviors; fight or
flight; pleasure/rage
 Circadian Rhythms 
- Regular, repeated rhythmic behaviors
(sleep/ wake)
- Hormone release and sex drive
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



Most HIGHLY DEVELOPED STRUCTURE of the
mammalian brain
Divided into left and right hemispheres; each
hemisphere consists of:
 Gray matter (cerebral cortex) – covering
 White matter – internal part
 Basal nuclei – found deep within the white matter;
important in planning and learning movement
sequences
Cerebral Cortex (“gray matter”)
 LARGEST and MOST COMPLEX part of the
mammalian brain
 Evolved a lot through evolution
 Neocortex – 6 layers of tissue outside of the
cortex; unique to mammals
○ Right half of brain controls the functions of the
left side of the body; left half controls the right
side
Corpus callosum – part of the brain that
communicates between the left and right hemispheres
Cerebrum
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Lobes of Cerebrum






Frontal, Parietal, Temporal, Occipital
Primary motor cortex and primary somatosensory cortex form the
boundary between the frontal lobe and parietal lobe
 Motor Cortex  sends commands to skeletal muscles
 Somatosensory Cortex  gets and integrates signals from touch,
pain, pressure and temp receptors throughout the body
Frontal Lobe  speech, motor cortex, emotions
Parietal Lobe  somatosensory cortex, taste, speech, reading,
touch, pain, pressure, temp
SIDES OF THE
Temporal Lobe  smell, hearing
CEREBRUM
Occipital Lobe  vision
Left Side  adept at language, math,
logic, serial sequences of information
Right Side  pattern recognition, space
recognition, spatial relations, nonverbal,
emotions
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Reticular Formation

Arousal and sleep are
controlled in part by the
reticular formation, a
system of neurons that
passes through the
brainstem
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Emotions


Due to frontal lobe and
limbic system
Limbic System  forms a
ring around the brainstem;
composed of hippocampus
and the olfactory cortex
 Responsible for
emotions (laughing,
crying, feeding,
aggression, sexuality)
 Amygdala  nucleus in
the temporal lobe;
recognizes emotional
content of facial
expressions and
emotional memories
Interesting note: frontal
lobotomies, which disrupt the
frontal lobes and limbic system,
used to be performed to treat
severe emotional disorders
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Language and Speech

Processed by multiple areas of the cortex
 Broca’s area – frontal lobe  controls the muscles in the face
 Wernicke’s area – temporal lobe  controls the ability to
comprehend speech but not the ability to speak
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Memory and Learning



Short term memory (frontal lobe)  released if memory is
irrelevant
Long term memory (limbic system, hippocampus)  if info
is pertinent; goes from short term to long term with
repetition (“practice makes permanent”…not always
perfect!)
Skill memory  ex. walking, riding a bike, etc; once
learned, it is hard to unlearn; learned by repetition (bad
habits are hard to break!)  practice makes permanent
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Research for CNS Injuries
CNS can’t repair itself
 Nerve Cell Development
 Neurons develop by cell to cell communication, control of gene
expression, and genetic basis HARD TO REPLICATE!!
 Axons grow to target cells and use molecular signals to direct
them (don’t grow in a straight line)
 Sequence and time of development are important – therefore,
again, it is HARD TO REPLICATE
 Scientists are trying to get axons to regrow using different
combinations of proteins
 Neural Stem Cells
 In adults, new cells are found in the hippocampus (memory/
learning)
 Function of the new stem cells = unclear!
 Issues with stem cell research  what can we use as a
source?!?! LOTS OF DEBATES OVER THIS!!
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
Relationship and similarities between nervous
and endocrine systems
* use chemical signals
* response depends on action of receptor
* chemical messengers produced by
axons in parts of both
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