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Ch. 1
Sec. 1 Body Organization
& Homeostasis
Levels of organization in
the body
•
•
The smallest unit of
organization is the cell
The largest unit of organization
is the organ system
cells
tissues
organs
organ systems
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Cell
The basic unit of
structure and
function in a living
thing
6 basic types in an
animal cell
Cell Types
Bone
Cell
Cartilage
Cell
Muscle
Cell
Blood
Cell
Nerve
Cell
Small
Intestine
Cell
Cell Membrane
forms
outside boundary of cell
2
Nucleus
control center- directs cell’s
activities
The nuclei can be seen in the
photograph of human cheek cells below.
Cytoplasm
clear,
jellylike substance
contains organelles
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Mental Break
Tissue
A group of similar cells that perform the same
function
Four basic types: muscle, nervous,
connective, and epithelial
4 basic types of
tissues
Muscle tissue
Nerve tissue
Connective
tissue
Epithelial tissue
Makes parts of
body move
Contracts and
shortens
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What it looks like…
4 basic types of tissues
Muscle tissue
Nerve tissue
Connective tissue
Makes parts of body
move
Directs and controls the
movement
Contracts and shortens
Carries electrical
messages between
brain and parts of body
Epithelial tissue
What it looks like…
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4 basic types of tissues
Muscle tissue
Nerve tissue
Connective tissue
Epithelial tissue
Makes parts of body
move
Directs and controls the
movement
Provides support for the
body
Contracts and shortens
Carries electrical
messages between
brain and parts of body
Connects all the parts
What it looks like…
4 basic types of tissues
Muscle tissue
Nerve tissue
Connective tissue
Epithelial tissue
Makes parts of body
move
Directs and controls the
movement
Provides support for the
body
Covers inside and
outside body surfaces
Contracts and shortens
Carries electrical
messages between
brain and parts of body
Connects all the parts
Releases and absorbs
chemicals
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What it looks like…
Mental Break
An organ is a structure that is made
of different kinds of tissue.
Your stomach, heart, brain, and lungs
are all organs.
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Organs continued…
An organ performs a specific job
The job is more complex than that of a tissue
Example – the heart
Pumps blood throughout your body, over and over
again
It contains all four kinds of tissue
Organ System
A group of organs that work together to
perform a major function
Each organ in the body is part of a system
Example
Your heart is part of your
circulatory system, which
carries oxygen and other
materials throughout the
body.
Besides the heart, blood
vessels are organs in the
circulatory system.
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organ
systems
We will
review 10
organ
systems in
the body
Mental Break
Homeostasis
process by which an organism’s
internal environment is kept stable in
spite of changes in external
environment
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Example of homeostasis
Internal body temperature is always around
98° no matter what the temperature outside
Maintaining Homeostasis
Regardless of the
surrounding
temperature, your
body temperature
remains fairly
constant at about
98°. Sweating and
shivering help
regulate your body
temperature.
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stress
reaction of your body and mind to
potentially threatening, challenging or
disturbing events
disrupts homeostasis
Mental Break
11
List the 4 levels of organization in the
human body. Give an example of each
level.
cell-
bone cell
tissue- muscle tissue
organ- heart
organ system- circulatory system
What are the 4 types of tissue found in the
human body? What is the general
function of each type?
muscle tissue= movement
nerve tissue= carries messages between the
brain and other parts of the body
connective tissue= provides support and
connects all parts of the body
epithelial tissue= covers surfaces of body;
absorbs & releases substances
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What is homeostasis ?
process by which an organism’s
internal environment is kept
stable in spite of changes in
external environment
What is stress? How does it
affect homeostasis?
reaction
of your body and mind
to threatening, challenging or
disturbing events
upsets homeostasis
Homework
Write a paragraph that explains what body
systems are involved when you sit down to
do your homework. Be sure to begin your
paragraph with a topic sentence and include
supporting details.
Use the graphic organizer to complete this
assignment.
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