Transcript Structural Levels of Organization

Levels of Organization and
Homeostasis
Structural Levels of Organization
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I. Chemical level (Atoms):
All matter, living and nonliving is composed of the
smallest particles called
atoms.
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There are 98 naturally
occurring atoms in the
universe.
96% of the human body is
made of only four:
 Carbon, Hydorgen,
Oxygen and Nitrogen
 65-75% of body mass is
water!
Structural Levels of Organization
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Atoms may react together to form ions and
molecules
– Ions such as H+, Na+, Ca+, K+, Fe++, Mg++, Cl– Molecules such as H2CO3, H2O, O2
– Large molecules or Macromolecules, provide
structural foundation for the body include
 Carbohydrates
 Fats (lipids)
 Proteins
 And Nucleic acids (DNA and RNA)
Levels of Organization In
Multicellular Organisms:
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I. Individual cells: Like the bricks that a
building is constructed, cells are the building
blocks of all living things.
Function of cells
related to structure
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Muscle cells are long
Bone cells are hard
Nerve cells are branched
Covering cells are flat
Structure and function change with age
(Thymus disappears, bones become
brittle…)
Sizes and Shapes
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Size and shape depends on function
Nerve cells: are long and may have the
length of several feet (from muscles of the
foot to the brain)
Levels of Organization
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II. Tissue Level: Tissues are a
group of cells similar in structure
and function containing similar
intercellular fluid and organelles
There are Four Primary types
of tissues and each has several
subtypes.
– Connective: Tissue that
connects one tissue to
another
– Epithelial: Tissue that
covers and protects.
– Muscle: Specialized for
movement
– Nervous: Tissue that
receives, sends,
processes and stores
information.
Levels of Organization
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III: Organ Level: Organs are two or more
tissues put together in a specific pattern to
carry out a particular job.
Levels of Organization
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IV. System Level: Several organs working together
to carry out larger body process.
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There are 11 systems in the human body:
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Integumentary
Skeletal
Muscular
Nervous
Endocrine
Cardiovascular
Lymphatic
Respiratory
Digestive
Urinary
Reproductive
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Sizes and Shapes
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Blood cells – are flat for gas exchange
Levels of Organization
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V. Organism Level: The entire body’s
collection of all systems
Criteria for Life
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Responds to stimuli- Excitable
Ingest food- eats
Digest food- metabolize food to get energy
Excrete- get rid of wastes and unused food
Secretion- makes and uses them (saliva, digestive
enzymes…)
Reproduce- repair, grow, continue the species
Movement- of materials within cells, through the
environment
Homeostasis: The Balance Of Life
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Nearly constant internal state
The body normally maintains in function such
as composition of body fluids, temperature,
and levels of acid and bases (like the
thermostat in a house)
Homeostasis and
Negative feedback
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Refers to a mechanism that reverses a
response back to a normal state.
Example: When salt concentration rises
above normal after a meal, Kidneys increase
the rate of removing salt by excreting it in the
urine.
Homeostasis and
Positive feedback
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Refers to a change from the normal state to promote the
change even further.
Unlike negative feedback, positive feedback does not restore
the body functions back to normal.
In some cases, can lead to a “vicious circle” of continuing
deterioration.
Some positive feedbacks that operate under normal
conditions.
Example: Uterine contraction during child birth- progressive
stronger contractions until child is passed completely through
the birth canal.
Health and Disease
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Disruption of homeostasis
Can vary from minor to grave and even fatal.
Task of the physician is to identify these
imbalances (diseases) at an early stage so
that effective actions may be taken.
Health is restored when homeostasis is
brought back to balance.
Classification of Disease
Diseases may be classified into groups that
share similar development
Infectious –
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Viral: diseases caused by viruses such as
Measles, Mumps, Rubella, Influenza
Bacterial: diseases caused by single celled
organisms.
Classification of Disease
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Congenital: arise sometime before birth.
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Can be inherited (Down’s Syndrome) or
caused by disease causing agent that crosses the placental barrier
(German measles).
Immunological: Body’s defense system (initiated by other
infections) respond by causing destruction of the body’s own
tissues,
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strep throat - may cause heart defects,
measles - may cause deafness and or blindess.
Classification of Disease
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Metabolic Diseases: Disease that affect the body’s
use of energy. Diabetes is an example. The body
cannot use glucose sugar properly.
Neoplastic Diseases: Loss of control of normal cell
growth and reproduction. Cells become abnormal
and develop into tumors that threaten normal
activity of tissues and organs. cancer arises in this
manner.