35 nervous system.ppt by ert554898

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									35–1 Human Body Systems
The levels of organization in a
multicellular organism include:
•organ systems
Every cell in the human body is both an
independent unit and an interdependent
part of a larger community—the entire

A cell is the basic unit of structure and
function in living things.
Individual cells in multicellular organisms
are specialized.
Specialized cells are suited to perform a
particular function.

A group of cells that perform a
single function is called a tissue.
There are four basic types of
tissue in the human body:
epithelial, connective, nervous,
and muscle.
                             Organization of the
Epithelial tissue includes glands and tissues that
cover interior and exterior body surfaces.
Connective tissue supports the body and
connects its parts.
Nervous tissue transmits nerve impulses through
the body.
Muscle tissue, along with bones, enables the
body to move.
Organs and Organ Systems
A group of different types of tissues that
work together to perform a single
function is called an organ.
A group of organs that perform closely
related functions is an organ system.
There are eleven organ systems in the
Nervous System
Structures: Brain,
spinal cord, peripheral
Function: Recognizes
and coordinates the
body’s response to
changes in its internal
and external
Integumentary System
Structures: Skin, hair,
nails, sweat and oil
Function: Serves as a
barrier against infection
and injury; helps to
regulate body
temperature; provides
protection against
ultraviolet radiation from
the sun
Skeletal System
Structures: Bones,
cartilage, ligaments,
Function: Supports the
body; protects internal
organs; allows
movement; stores
mineral reserves;
provides a site for
blood cell formation
Muscular System
Structures: Skeletal
muscle, smooth muscle,
cardiac muscle
Function: Works with
skeletal system to
produce voluntary
movement; helps to
circulate blood and move
food through the digestive
Circulatory System
Structures: Heart, blood
vessels, blood
Function: Brings
oxygen, nutrients, and
hormones to cells;
fights infection;
removes cell wastes;
helps to regulate body
Respiratory System
Structures: Nose,
pharynx, larynx,
trachea, bronchi,
bronchioles, lungs
Function: Provides
oxygen needed for
cellular respiration and
removes excess carbon
dioxide from the body
Digestive System
Structures: Mouth,
pharynx, esophagus,
stomach, small and
large intestines, rectum
Function: Converts
food into simpler
molecules that can be
used by the cells of the
body; absorbs food;
eliminates wastes
Excretory System
Structures: Skin, lungs,
kidneys, ureters,
urinary bladder, urethra
Function: Eliminates
waste products from
the body in ways that
maintain homeostasis
Endocrine System
Structures: Hypothalamus,
pituitary, thyroid, parathyroid,
adrenals, pancreas, ovaries (in
females), testes (in males)

Function: Controls
development and
metabolism; maintains
Reproductive System
Structures: Testes,
epididymis, vas
deferens, urethra, and
penis (in males),
ovaries, Fallopian tubes,
uterus, vagina (in
Function: Produces
reproductive cells; in
females, nurtures and
protects developing
Structures: White blood
cells, thymus, spleen,
lymph nodes, lymph
Function: Helps protect the
body from disease; collects
fluid lost from blood
vessels and returns the
fluid to the circulatory
Homeostasis is the process by
which organisms keep internal
conditions relatively constant
despite changes in external

Homeostasis in the body is
maintained by feedback inhibition.
Feedback inhibition, or negative feedback, is the
process in which a stimulus produces a response
that opposes the original stimulus.
Systems controlled by feedback inhibition are
fully automated and very stable.
An Example of Feedback Inhibition
                   Thermostat senses
                   temperature change
                   and switches off
                   heating system

Room temperature                        Room temperature
increases                               decreases

                   Thermostat senses
                   temperature change
                   and switches on
                   heating system
Homeostasis In the Body

Maintenance of homeostasis requires the
integration of all organ systems at all
One example is the maintenance of a
stable body temperature.
The hypothalamus monitors the temperature of
the skin and the temperature of organs.
If core body temperature drops, the

  • causes blood vessels in the skin to
    constrict reducing heat loss from skin.
  • causes the skeletal muscles to contract
    involuntarily—to “shiver.”
This causes the body temperature to
If the core body temperature increases, the

  • causes blood vessels in the skin to
    dilate so heat can escape from the skin.
  • the body produces sweat, which cools
    the body by evaporation.
This causes the body temperature to
35-2 The Nervous System
The nervous system controls and
coordinates functions throughout the body
and responds to internal and external

  • The messages carried by the nervous
   system are electrical signals called

  • The cells that transmit
   impulses (electrical signals) are
   called neurons.
Neurons are classified according to
the direction in which an impulse
 • Sensory neurons carry impulses from the
   sense organs to the spinal cord and brain.
 • Motor neurons carry impulses from the
   brain and spinal cord to muscles and
 • Interneurons connect sensory and motor
   neurons and carry impulses between
Structures of a Neuron
 terminals           Cell body

                 Myelin sheath


The largest part of a typical neuron is the cell
It contains the nucleus and much of the

                    Cell body

Dendrites extend from the cell body and carry
impulses from the environment toward the cell


The axon is the long fiber that carries impulses
away from the cell body.



The axon ends in axon terminals.


The axon is sometimes surrounded by an
insulating membrane called the myelin sheath.
There are gaps in the myelin sheath, called
nodes, where the membrane is exposed.
Impulses jump from one node to the next.

                 Myelin sheath

                        The Nerve Impulse
The Resting Neuron
 • When resting, the outside of the neuron
  has a net positive charge.
 • The inside of the neuron has a net
  negative charge.
 • The cell membrane is electrically
  charged because there is a difference
  in electrical charge between its outer
  and inner surfaces.
                             The Nerve Impulse

The sodium-potassium pump in the nerve cell
membrane pumps sodium (Na+) ions out of the
cell and potassium (K+) ions into the cell by
means of active transport.
As a result, the inside of the cell contains more
K+ ions and fewer Na+ ions than the outside.
             The Nerve Impulse
• Sodium-Potassium Pump
                             The Nerve Impulse

More K+ ions leak across the membrane than Na+
ions. This produces a negative charge on the
inside and a positive charge on the outside.
The electrical charge across the cell membrane of
a neuron at rest is known as the resting potential.
                     The Nerve Impulse

The Moving Impulse

An impulse begins when a neuron
is stimulated by another neuron
or by the environment.
                             The Nerve Impulse
At the leading edge of the impulse, gates in the
sodium channels open allowing positively
charged Na+ ions to flow inside the cell
                          The Nerve Impulse

The inside of the membrane temporarily becomes
more positive than the outside, reversing the
resting potential.
                             The Nerve Impulse

This reversal of charges is called a nerve
impulse, or an action potential.
                             The Nerve Impulse

As the action potential passes, gates in the
potassium channels open, allowing K+ ions to
flow out restoring the negative potential inside
the axon.
                           The Nerve Impulse
The impulse continues to move along the axon.
An impulse at any point of the membrane causes
an impulse at the next point along the membrane.
                       The Nerve Impulse

 • A stimulus must be of adequate
  strength to cause a neuron to transmit
  an impulse.
 • The minimum level of a stimulus that is
  required to activate a neuron is called
  the threshold.
                       The Nerve Impulse

• A stimulus that is stronger than the
 threshold produces an impulse.
• A stimulus that is weaker than the
 threshold produces no impulse.
                         The Synapse
The Synapse

  • At the end of the neuron, the impulse
   reaches an axon terminal. Usually the
   neuron makes contact with another cell
   at this site.
  • The neuron may pass the impulse
   along to the second cell.
  • The location at which a neuron can
   transfer an impulse to another cell is
   called a synapse.
              The Synapse

• A Synapse

                               The Synapse

The synaptic cleft
separates the axon
terminal from the
dendrites of the
adjacent cell.

                     Synaptic cleft
Terminals contain      The Synapse
vesicles filled with
are chemicals
used by a neuron
to transmit an
impulse across a
synapse to
another cell.                Neurotransmitter
• As an impulse       The Synapse
 reaches a
 terminal, vesicles
 send                               Receptor
 into the synaptic
• These diffuse
 across the cleft
 and attach to
 receptors on the
 next cell.
                             The Synapse

Sodium ions then rush across the membrane,
stimulating the next cell.

If the stimulation exceeds the cell’s threshold, a
new impulse begins.
                            The Synapse

Moments after binding to receptors,
neurotransmitters are released from the cell

The neurotransmitters may then be broken down
by enzymes, or taken up and recycled by the
axon terminal.
35-3 Divisions of the Nervous System
The human nervous system has
two major divisions:
  a. central nervous system
  b. peripheral nervous system
The central nervous system
relays messages, processes
information, and analyzes
a.The central nervous system
  consists of the brain and the
  spinal cord.
b. Both the brain and spinal cord are
   wrapped in three layers of
   connective tissue known as
Between the meninges and the central
nervous system tissue is a space filled
with cerebrospinal fluid.
Cerebrospinal fluid acts as a shock
absorber that protects the central nervous
Cerebrospinal fluid also permits exchange
of nutrients and waste products between
blood and nervous tissue.
The Brain
   a. The brain is the place to which
      impulses flow and from which
      impulses originate.
Parts of The Human Brain FIGURE 35-9
                                      Pineal gland

Pituitary gland
    Brain stem    Medulla
                  oblongata   Spinal cord
The Cerebrum
a. The largest and most prominent
   region of the human brain is the

           the voluntary, or
b. It controls
  conscious, activities of the
c. It is the site of intelligence, learning,
   and judgment.
A deep groove divides the cerebrum into
hemispheres, which are connected by a
band of tissue called the corpus callosum.
Each hemisphere is divided into regions
called lobes.
Lobes of the Cerebrum
Each half of the cerebrum deals with the
opposite side of the body:
   a. The left half of the cerebrum
      controls the right side of the body.
   b. The right half of the cerebrum
      controls the left side of the body.
The outer layer of the cerebrum is called
the cerebral cortex and consists of gray
The inner layer of the cerebrum consists of
white matter, which is made up of bundles
of axons with myelin sheaths.
The Cerebellum
a. The second largest region of the
   brain is the cerebellum.

b.It coordinates and balances
  the actions of the muscles so
  that the body can move gracefully
  and efficiently.
The Brain Stem
a. The brain stem connects the brain and
   spinal cord.

                      pons and the
b. It has two regions: the
  medulla oblongata regulate
  information flow between the
  brain and the rest of the body.
c.Blood pressure, heart rate,
  breathing, and swallowing are
  controlled in the brain stem.
Brain stem
             Medulla oblongata
The Thalamus and Hypothalamus
a. The thalamus receives messages
   from all sensory receptors
   throughout the body and relays the
   information to the proper region of
   the cerebrum for further processing.
a.The hypothalamus controls
  recognition and analysis of
  hunger, thirst, fatigue, anger,
  and body temperature.
b. It controls coordination of the
   nervous and endocrine systems.

The Spinal Cord
   a. The spinal cord is the main
      communications link between the
      brain and the rest of the body.
   b. Certain information, including
     some kinds of reflexes, are
     processed directly in the
     spinal cord.
   c. A reflex is a quick, automatic
      response to a stimulus.
The Peripheral Nervous System

 a.The peripheral nervous system is
   all of the nerves and associated
   cells that are not part of the brain
   and the spinal cord.
 b. The peripheral nervous system includes
    cranial nerves, spinal nerves, and ganglia.
 c. Ganglia are collections of nerve cell
The sensory division of the
peripheral nervous system
transmits impulses from sense
organs to the central nervous
The motor division transmits
impulses from the central
nervous system to the muscles
or glands.
The motor division is divided into the
somatic nervous system and the
autonomic nervous system.
The Somatic Nervous System

a.The somatic nervous system
  regulates activities that are
  under conscious control, such
  as the movement of skeletal
b.Some somatic nerves are
  involved with reflexes = react to
A reflex arc includes a sensory receptor,
sensory neuron, motor neuron, and
effector that are involved in a quick
response to a stimulus.
        Sensory neuron

a. Reflex Arc                        Interneuron   Spinal cord

                                          Effector (responding

The Autonomic Nervous System

a.The autonomic nervous
  system regulates involuntary
b. The autonomic nervous system is
   subdivided into two parts:
   sympathetic nervous system
   parasympathetic nervous system
The sympathetic and
parasympathetic nervous
systems have opposite effects on
the same organ system.
These opposing effects help maintain
35–4 The Senses
Neurons that react directly to stimuli from
the environment are called sensory

Sensory receptors react to stimuli
by sending impulses to other
neurons and to the central
nervous system.
Sensory receptors are located throughout
the body but are concentrated in the sense
Sense organs include the:
5 categories of sensory receptors:
a.pain receptors
b.Thermoreceptors- heat
c.Mechanoreceptors- pressure
d.Chemoreceptors- chemicals
e.Photoreceptors- light
Pain receptors are located throughout the
body except in the brain.
They respond to chemicals released by
damaged cells.
Pain usually indicates danger, injury, or
Thermoreceptors are located in the skin,
body core, and hypothalamus.
They detect variations in temperature.
Mechanoreceptors are found in the skin,
skeletal muscles, and inner ears.
They are sensitive to touch, pressure,
stretching of muscles, sound, and motion.
Chemoreceptors, located in the nose and
taste buds, are sensitive to chemicals in
the external environment.
Photoreceptors, found in the eyes, are
sensitive to light.
   a. The sense organ that animals use to
      sense light is the eye.
   b. The eye has three layers:
         the retina
         the choroid
         the sclera
The retina is the inner layer of
eye that contains

The choroid is the middle layer of eye that
is rich in blood vessels.

The sclera is the outer layer of eye that
maintains its shape.
The sclera serves as point of attachment
for muscles that move the eye.

Light enters the eye through the cornea,
a tough transparent layer of cells.

The cornea helps focus light, which
then passes through a chamber filled
with a fluid called aqueous humor.


At the back of the chamber is a disklike
structure called the iris, which is the
colored part of the eye.

In the middle of the iris is a small opening
called the pupil. Muscles in the iris adjust
pupil size to regulate the amount of light
that enters the eye.

In dim light, the pupil becomes larger.
In bright light, the pupil becomes
Just behind the iris is the lens.
Muscles attached to the lens change its
shape to adjust focus to see near or
distant objects.

Behind the lens is a large chamber filled
with a transparent, jellylike fluid called
vitreous humor.
                              Vitreous humor
The lens focuses light onto the
Photoreceptors are arranged in a layer in
the retina.

The photoreceptors convert light
energy into nerve impulses that
are carried to the central nervous
There are two types of photoreceptors:
rods and cones.
Rods are sensitive to light, but
not color.
Cones respond to light of
different colors, producing color
Cones are concentrated in the fovea,
which is the site of sharpest vision.

There are no photoreceptors where the
optic nerve passes through the back of the
eye, which is called the blind spot.
The impulses leave each eye by way of the
optic nerve. Optic nerves carry impulses
to the brain.
The brain interprets them as visual images
and provides information about the
external world.

  Optic nerve
The Ear

   a.The human ear has two
     sensory functions:
a. Ears can distinguish both the pitch
   and loudness of those vibrations.
The Human Ear Figure 35-14 pg908
Locate- Tympanum, hammer, anvil, stirrup,
& cochlea
Vibrations enter the ear through the
auditory canal.

            cause the
The vibrations
tympanum, or eardrum, to vibrate.

The vibrations are picked up by the
hammer, anvil, and stirrup.
                Hammer       Stirrup

The stirrup transmits the
vibrations to the oval window.


                           Oval window
Vibrations of the oval window
create pressure waves in the fluid-
filled cochlea of the inner ear.

The fluid-filled cochlea is lined
with tiny hair cells that are
pushed back and forth by these
pressure waves.

In response to the waves, the   hair cells
produce nerve impulses that are
sent to the brain through the cochlear
a. Your ears help you to maintain your
   balance, or equilibrium.
Within the inner ear, just above the
cochlea are three semicircular canals.
                      Semicircular canals
The canals are filled with fluid and lined
with hair cells.
As the head changes position, fluid in the
canals changes position, causing the hair
on the hair cells to bend.
This sends impulses to the brain that
enable it to determine body motion and
   a. The sense of smell is actually an
      ability to detect chemicals.
   b. Chemoreceptors in the nasal
      passageway respond to chemicals
      and send impulses to the brain
      through sensory nerves.
   a. The sense of taste is also a chemical
   b. The sense organs that detect taste
      are the taste buds. Most taste buds
      are on the tongue.
   c. Tastes detected by the taste buds
      are classified as salty, bitter, sweet,
      and sour.
   d. Sensitivity to these tastes varies on
      different parts of the tongue.
Touch and Related Senses
   a. The skin’s sensory receptors
      respond to temperature, touch, and
   b. Not all parts of the body are equally
      sensitive to touch, because not all
      parts have the same number of
   c. The greatest density of sensory
      receptors is found on your fingers,
      toes, and face.
35–5 Drugs and the Nervous
A drug is any substance, other than food,
that changes the structure or function of
the body.
Some drugs, such as cocaine and heroin
are illegal. Other drugs, such as penicillin
and codeine are prescribed by doctors.
Still other drugs, including cough
medicines can be purchased over the
All drugs can be harmful if used
improperly or abused.
Drugs differ in the ways in which they
affect the body.
   a. Some kill bacteria and are useful in
      treating disease.
   b. Others affect a particular system of
      the body.
   c. Others cause changes to the brain
      and synapses.

     Stimulants increase heart rate, blood
     pressure, and breathing rate. In addition,
     stimulants increase the release of
     neurotransmitters at some synapses in the
     Common stimulants include amphetamines,
     cocaine, nicotine, and caffeine.
a. Depressants slow down heart
   rate and breathing rate, lower
   blood pressure, relax muscles,
   and relieve tension.

b. Barbiturates, tranquilizers, and
   alcohol are some examples of
a. Cocaine causes the sudden release
   in the brain of a neurotransmitter
   called dopamine.

b. Cocaine also acts as a powerful
a. Opiates mimic endorphins which
   normally help to overcome
   sensations of pain.

b. Common opiates include
   morphine and codeine.
a. The most widely abused illegal drug
   is marijuana.
b. Marijuana comes from Cannabis
   sativa, a hemp plant.
c. Hashish, or hash, is a potent form of
d. The active ingredient in marijuana is
Long-term use of marijuana can result in:
   a. loss of memory
   b. inability to concentrate
   c. in males, reduced levels of the
      hormone testosterone in males
a. Alcohol is a depressant that slows
   down the rate at which the central
   nervous system functions.

b. Alcohol slows down reflexes,
   disrupts coordination, and impairs
Heavy drinking fills the blood with so
much alcohol that the central nervous
system cannot function properly.
People who drink a lot of alcohol usually
cannot walk or talk properly, and they are
not able to safely control an automobile.
Pregnant women who drink alcohol risk
having a child with FAS.
Fetal alcohol syndrome (FAS) is a group of
birth defects caused by the effects of
alcohol on the fetus.
FAS can cause minor to serious brain
damage, heart defects, malformed faces,
delayed growth, and poor motor
Alcohol and Disease
a. People who have become addicted
   to alcohol suffer from a disease
   called alcoholism.
b. If a person cannot function properly
   without satisfying the craving for
   alcohol, that person has an alcohol-
   abuse problem.
c. Long-term alcohol use destroys liver
Drug Abuse
   a. Drug abuse is the intentional misuse
      of any drug for nonmedical
   b. Drug abuse can cause psychological
      dependence or serious physical
      damage to the body.
Uncontrollable dependence on a drug is
called an addiction.
Some drugs cause a strong psychological
dependence, or mental craving.

  The type of tissue that holds organs in
  place and binds different parts of the
  body together is called
   a. muscle tissue.
   b. epithelial tissue.
   c. connective tissue.
   d. skeletal tissue.
  One major function of the
  integumentary system is to
      a. help regulate body temperature.
      b. cause the body to move.
      c. provide a surface for gas exchange.
      d. control growth, development, and
  Which of the following is NOT an
  example of feedback inhibition?
      a. shivering to warm the body
      b. sweating to cool the body
      c. nervous tissue receiving messages
      d. turning on the heating system of a
  The process by which an organism
  keeps internal conditions relatively
  constant is called
      a. a feedback loop.
      b. negative feedback.
      c. homeostasis.
      d. normal temperature.
Which of the following organ systems
transports oxygen, nutrients, and
hormones to cells?
a. circulatory system
b. muscular system
c. excretory system
d. nervous system

   Neurons that carry impulses from the
   brain and spinal cord to the muscles
       a. interneurons.
       b. sensory neurons.
       c. resting neurons.
       d. motor neurons.

   The part of the neuron that carries
   impulses toward the cell body is the
       a. axon.
       b. myelin sheath.
       c. dendrite.
       d. nodes.

   The minimum level of a stimulus that is
   required to activate a neuron is called
       a. action potential.
       b. resting potential.
       c. threshold.
       d. synapse.

   Chemicals that are used by a neuron to
   transmit impulses are called
       a. neurotransmitters.
       b. synapses.
       c. axons.
       d. inhibitors.

   An action potential begins when
       a. sodium ions flow into the neuron.
       b. potassium ions flow into the neuron.

       c. sodium and potassium ions flow
          into the neuron.
       d. sodium and potassium ions flow out
          of the neuron.

   The brain stem functions as
       a. a location for memory and learning.
       b. the control site responsible for heart rate,
          blood pressure, and breathing.
       c. the location where all sensory information is
          processed and delivered to the cerebrum.
       d. an area that recognizes hunger, thirst, and
          body temperature.

   The left half of the cerebrum largely controls
       a. the left side of the body.
       b. both the right and left sides of the body.
       c. the right side of the body.
       d. the right half of the brain.

   The part of the brain that is responsible for
   coordination and balance is the
       a. cerebellum.
       b. cerebrum.
       c. brain stem.
       d. thalamus.

   Reflex arcs are actions that are a part of the
   peripheral nervous system's
       a. sensory division.
       b. somatic system.
       c. autonomic system.
       d. motor division.

   Which of the following is NOT under the control
   of the autonomic nervous system?
       a. heartbeat
       b. digestion
       c. walking
       d. sweating

   The sensory receptor that detects variations in
   body temperature is a
       a. chemoreceptor.
       b. mechanoreceptor.
       c. thermoreceptor.
       d. photoreceptor.

   The part of the eye containing tiny muscles that
   adjust the size of the pupil is the
       a. cornea.
       b. iris.
       c. lens.
       d. retina.

   The part of the ear that produces the nerve
   impulses sent to the brain is the
       a. tympanum.
       b. Eustachian tube.
       c. cochlea.
       d. oval window.

   The structures in your ears that help maintain
   your sense of balance
       a. is the auditory canal.
       b. is the hammer.
       c. is the tympanum.
       d. are the semicircular canals.

   Photoreceptors in the eye that are sensitive to
   color are
       a. rods.
       b. cones.
       c. rods and cones.
       d. the optic nerve.

   A drug that increases the heart rate and
   breathing rate is a
       a. depressant.
       b. opiate.
       c. stimulant.
       d. barbiturate.

   A powerful stimulant that increases blood
   pressure and heart rate that can lead to a heart
   attack is
       a. cocaine.
       b. opium.
       c. marijuana.
       d. caffeine.

   Many drugs that affect the brain and behavior do
   so because they
       a. affect organ systems and those changes are
          detected by the brain.
       b. interfere with the normal functioning of
       c. cause the brain to release endorphins.
       d. enter the cell bodies of brain neurons
          causing them to behave differently.

   True or False? Medically prescribed drugs
   cannot cause addiction.
       a. True
       b. False

   Alcohol acts on the brain as a
       a. general stimulant of the nervous system.
       b. general depressant of the nervous system.
       c. pain reliever acting in the cerebrum.
       d. stimulant of the brain stem and cerebellum.

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