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CHAPTER 3
8TH GRADE
I Human Body
A. The perfect machine—all parts work together for
the whole- life.
B. Atoms—basic particles of all matter—smallest
part of matter.
C. Body needs
a. Elements—made of only one kind of atom
i. Ex: periodic table
b. Compounds—made up of more than one
element—chemically combined
i. Ex: CO
c. Inorganic substances—come from non-living
sources air, soil, water
i. Minerals—inorganic and help with many
body chemical reactions—need only small
amounts (pg 65 Table 1)
ii. Needed by body—water
1. 70% of all body tissues
2. Helps with body functions
3. Not enough water—headache,
fatigue, dry skin.
d. Organic substances—compounds containing
carbon. Except- carbon dioxide and carbon
monoxide
i. 4 groups
1. Carbohydrates-provide energy,
made of carbon, hydrogen, and
oxygen
2. Lipids-fats and oils stored for
energy
3. nucleic acids-large complex organic
compounds. They store information
in codes---DNA.
4. Proteins-forms structures for body
carry out important processes.
II Cell
A. Basic unit of life.
B. Microscopic
C. All shapes and sizes—pg 69
D. Take in food, O, HO, and minerals make proteins
and release energy.
E. All cells or groups of cells have specific functions.
III Levels of Organization
A. Cells- basic unit of life.
B. Tissues-groups of similar cells that do same sort
of work—nerve tissue
C. Organ-structure made up of different types of
tissues –heart, lungs
D. Organ system-group of organs that work together
to do a job
SECTION 2
I Body systems
A. Feeding cells
a. Chemicals are in blood to feed cells.
b. Blood carries chemicals from respitory
system (O) and digestive system (minerals).
B. Digestive system
a. Like an assembly line-disassembly line
b. Breaks down food so body can use them.
c. Basically a tube runs through the body.
d. Food is made smaller and simple as it passes
through.
e. Other body parts help too.
i. Brain-saliva released to soften food.
Enzymes are released to help with
chemical reactions.
ii. Stomach-has bile, HCL, and enzymes
C. Digestive and Circulatory System
a. Small intestine contains villi.
b. Villi-fingerlike projections that have
capillaries in them.
c. Absorption occurs in villi-nutrients move into
blood.
d. Cells in blood carry nutrients to body cells.
e. Wastes are not absorbed and expelled from
the body.
II Body energy
A. Mitochondria- cellular respiration occurs.
B. Cellular respiration- series of chemical processes
in which O combines with foodenergy is
released.
C. Carbon dioxide (CO) and water are given off as
waste by cells.
D. Food and O must be constant supply.
E. Low O lactic acid produced and causes muscles
to fatigue and rapid breathing.
III Respitory system
A. Brings in O and releases CO.
B. Capillaries surround alveoli in lungs.
C. Alveoli-thin lined sacs at end of bronchial tubes.
D. O comes in and goes into capillaries CO is
released back into lungs exhaled.
E. Diaphragm causes the lungs to expand.
IV Excretory system
A. Removal of waste from body-toxic levels if not
removed.
B. Respitory—CO
C. Urinary—urine
D. Kidneys remove cell wastes and excess water
a. Nephrons-filter the blood
b. Water, sugar, and salt
V Homeostasis
A. Process by which body maintains a stable internal
environment.
B. Body temperature regulation
a. Breathing heavy- lets heat out
b. Flushing-brings blood to skin surface cooling
c. Sweating-water on skin cools body
C. Achieved 2 ways
a. Negative feedback-changes internal condition
to go back to normal
i. Ex: pancreas-insulin to reduce glucose—
glucogen released when sugar is lowdone by the liver.
b. Positive feedback-changes normal state to
abnormal state-body does not try to be in a
normal state---rare
i. Ex: contraction of uterus more intense
as head goes into birth canal.
ii. Ex: blood clotting-platelets and
fibrinogen make clots-White blood cells
eat any bacteria around the wound.