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Specialized Cells
I. Specialized Cells
-all multicellular
organisms have
specialized cells that
work together.
A. Tissue
-group of cells that
have a common
structure and
function.
*both animals and
plants have tissues
that perform specific
jobs.
ex. tissue that
covers plant’s leaves
protects the leaf.
1. Epithelial Tissue
-sheets of cells that
cover surfaces.
-they also line certain
body cavities and
blood vessels.
*usually smooth
2. Connective Tissue
-joins other tissue
together and also
stores fat and makes
blood cells.
- made of specialized
cells and fibers that
stick to living cells.
*exs. Bone,
cartilage, and blood.
3. Muscle Tissue
-animals use this
tissue to move.
-all muscle tissue
create movement in
one direction only,
either by getting
longer or shorter.
4. Nervous Tissue
-send electrical
impulses through your
body to help muscles
contract.
-some send signals,
while others protect
nerves and provides
them with nutrients.
B. Organs
-are made up of
several tissue types
that work together to
perform one or more
functions.
*exs.
-heart beating
-eating
-walking
-running
- a plant’s leaves,
roots, and flowers
are the organs.
C. Organ Systems
-group of organs that
work together to
perform complex
tasks.
*exs. All plant’s
leaves make up an
organ system that
provides energy for
the plant.
- the more complex
the organism, the
greater the number of
organ systems that
are needed to carry
out life processes.
-humans have 11
organ systems.
-some organs work
for more than one
organ system.
1. Circulatory System
a. carries oxygen
through the body and
removes carbon
dioxide and other
wastes.
b. also helps keep our
body temperature
constant.
c. this system
includes your:
*heart
* arteries
*and veins
- at the kidneys, it
connects to the
2. urinary system.
* this system
helps regulate the
amount of water and
salt in the blood, as
well as removing
liquid wastes.
3. Musculoskeletal System
a. supports all parts of
your body and allows
you to move.
b. bones anchor other
body parts and
provide the structure
needed for
movement.
c. muscles also
generate warmth for
your body.
4. Nervous System
a. the brain is an
indispensable organ, the
headquarters.
-all your senses feed
information into the brain.
-the brain processes
and responds to this
information often,
responding by sending
signals down the nerves
to the muscles.
* the brain also
controls the other
organ systems.
5. Skin
* the internal and
external layers of skin
cells protect you from
injury and retain
moisture.
6. Digestive System
- obtains nutrients
from food
7. Respiratory System
-the air you breath in
travels through evernarrower
passageways.
-the passageways
ends at alveoli-tiny
sacs where oxygen
diffuses into blood
and carbon dioxide
diffuses out.
8. Endocrine System
- works like chemical
messenger system.
-the glands of this system
act as the communication
centers.
*the glands are a
specialized group of cells
that make and send out
hormones.
*humans contain 50
different hormones.
* some glands help
regulate growth and energy
use. (thyroid)
* others control blood
sugar, minerals, and other
chemicals. (adrenal, pancreas)
*some cause specific
changes in the body. (thymus)
-ex. dramatic
changes in muscles and bones
as you grow up.
- Growth hormones also
influence when your
growth will stop.
-Many plants use
hormones too.
*the hormones in
plants may cause a stem
to bend towards the light.
*some could direct a
plant to grow taller
instead of wider.
II. Cells and Disease
A. Causes of Disease
1. invasions by alien
organisms or viruses
2. when body
systems do not
function properly.
a. infectious
disease-caused by
harmful organisms or
viruses
-examples: *bacteria
and some other types
of fungi are common
causes of infectious
disease.
*worms
can lodge in the
intestines or muscles,
causing several
serious diseases.
*protozoa carried
by mosquitoes cause
malaria.
3. Many organisms
enter the body
through the food
people eat.
-ex. Salmonella
bacteria
*live in chickens
and other animals.
*cooking destroys
the bacteria.
-cholera is
transmitted by water
that has been
contaminated by
humans or animal
waste products.
4. Contagious disease
can be spread easily from
one person to another.
5. Viruses are not
organisms because they
are not made of cells.
-common cause of
infectious disease
-contain genetic
instructions that take over
a cell’s normal
instructions.
6. Many viral
diseases are mild.
-exs. cold, flu, and
chicken pox
7. Other viral
diseases are more
dangerous, even
deadly.
-exs. hepatitis and
AIDS
b. non-infectious
diseases
1. occur when a body
system does not function
properly.
2. can not spread from
person to person.
3. sometimes the
diseases are caused by a
condition that is inherited.
-ex. sickle cell
anemia
4. other times a
disease appears as a
person’s body ages.
*healthy life style
and habits can help
prevent many of
these later in life
diseases.
5. Type II Diabetes
-can often be
prevented by diet and
exercise.
6. Poor nutrition causes
many non-infectious
diseases.
* orange juice
contains vitamin C, which
helps prevent scurvy.
*people who do not
receive the proper
vitamins in their food can
suffer a variety of
illnesses.
B. Fighting Disease
1. Your body has three
main lines of defense
against invasion by
disease agents.
a. First line of
defense is made up of
your body’s physical and
chemical barriers.
*these barriers
include skin, tears, saliva,
ear wax, and mucus.
b. second line of
defense consists of
processes that kick in,
should harmful agents
enter.
-ex. Should you
cut your skin and the
cut becomes infected,
defense mechanisms
in the blood are
activated.
* the second line of
defense can include
the production of
special cells called
phagocytes.
-they surround
and consume harmful
disease agents that
invade your body.
- Phagocytes are one
type of white blood
cells.
C. Immune System
1. a very powerful
weapon to fight
specific harmful
agents
2. third line of defense
3. uses special cells
that travel throughout
the body and
recognize invading
pathogens, the
agents of disease.
* they can recognize
harmful invaders because
they have different
surface structures of
normal body cells.
*many cells produced
by the immune system
are designed to attack the
invading disease agents
and destroy them.
*certain types of white
blood cells produce
special proteins called
antibodies that also
fight invaders.
4. After the immune
system destroys the
invaders, the body
begins to recover
from illness.
*if the same
pathogens invade the
body again, these
cells can immediately
produce the needed
antibodies.
-this means
that the body is now
immune to, or
protected from, that
particular illness.
D. Disease Prevention and
Treatment
1. Vaccine
-a way of stopping
a disease before it
enters the body.
-usually contains
an inactive version of
a pathogen.
-when the body is
exposed to the
vaccine, it slowly
makes antibodies
against it.
* later if should the
real pathogen enters
the body, the
antibodies are ready
right away to stop it.
-vaccines have
helped stop diseases
such as:
a. small pox
b. polio
c. measles
2. Today scientists
continue working on
new ways to prevent,
treat, and cure
diseases.